SRS之接收推流线程：recv
SrsPublishRecvThread、SrsRecvThread、SrsReusableThread2、SrsThread 之间的关系图
1. recv 线程函数：SrsThread::thread_fun
void *SrsThread::thread_fun(void *arg)
{
SrsThread* obj = (SrsThread*)arg;
srs_assert(obj);
/* 进入线程循环 */
obj->thread_cycle();
// for valgrind to detect.
SrsThreadContext* ctx = dynamic_cast<SrsThreadContext*>(_srs_context);
if (ctx) {
ctx->clear_cid();
}
st_thread_exit(NULL);
return NULL;
}
void SrsThread::thread_cycle()
{
int ret = ERROR_SUCCESS;
/* 生成 recv 线程的一个上下文 id */
_srs_context->generate_id();
srs_info("thread %s cycle start", _name);
/* 将生成的 recv 上下文 id 赋给 _cid，以便 recv 的父线程醒来后
* 可以继续往下执行，此时父线程会设置 can_run 为 true */
_cid = _srs_context->get_id();
srs_assert(handler);
/* 调用 SrsReusableThread2 实现的 on_thread_start 函数 */
handler->on_thread_start();
// thread is running now.
really_terminated = false;
/* 上面生成好 recv 线程的上下文 id 后，这里会陷入休眠，接着会
* 调度到 recv 的父线程执行，父线程检测到 _cid 准备好后，
* 即会设置 can_run 为 true，表示 recv 线程可以继续往下执行了 */
// wait for cid to ready, for parent thread to get the cid.
while (!can_run && loop) {
st_usleep(10 * 1000);
}
while (loop) {
/* 该函数没有具体做任何事，忽略 */
if ((ret = handler->on_before_cycle()) != ERROR_SUCCESS) {
srs_warn("thread %s on before cycle failed, ignored and retry, ret=%d",
_name, ret);
goto failed;
}
srs_info("thread %s on before cycle success", _name);
/* 调用 SrsReusableThread2 实现的 cycle 函数 */
if ((ret = handler->cycle()) != ERROR_SUCCESS) {
if (!srs_is_client_gracefully_close(ret) && !srs_is_system_control_error(ret))
{
srs_warn("thread %s cycle failed, ignored and retry, ret=%d", _name, ret);
}
goto failed;
}
srs_info("thread %s cycle success", _name);
if ((ret = handler->on_end_cycle()) != ERROR_SUCCESS) {
srs_warn("thread %s on end cycle failed, ignored and retry, ret=%d",
_name, ret);
goto failed;
}
srs_info("thread %s on end cycle success", _name);
failed:
if (!loop) {
break;
}
// to improve performance, donot sleep when interval is zero.
// @see: https://github.com/ossrs/srs/issues/237
if (cycle_interval_us != 0) {
st_usleep(cycle_interval_us);
}
}
// readly terminated now.
really_terminated = true;
handler->on_thread_stop();
srs_info("thread %s cycle finished", _name);
}
void SrsReusableThread2::on_thread_start()
{
handler->on_thread_start();
}该函数中接着调用 SrsRecvThread 实现的 on_thread_start 函数。
1.2.1 SrsRecvThread::on_thread_start
void SrsRecvThread::on_thread_start()
{
// the multiple messages writev improve performance large,
// but the timeout recv will cause 33% sys call performance,
// to use isolate thread to recv, can improve about 33% performance.
// @see https://github.com/ossrs/srs/issues/194
// @see: https://github.com/ossrs/srs/issues/217
rtmp->set_recv_timeout(ST_UTIME_NO_TIMEOUT);
handler->on_thread_start();
}函数先设置 recv 的超时时间为 -1，然后接着调用 SrsPublishRecvThread 实现的 on_thread_start 函数。
1.2.2 SrsPublishRecvThread::on_thread_start
void SrsPublishRecvThread::on_thread_start()
{
// we donot set the auto response to false,
// for the main thread never send message.
/* 若配置文件中没有设置 mr 配置项，则默认没有启用该功能，可忽略 */
#ifdef SRS_PERF_MERGED_READ
if (mr) {
// set underlayer buffer size
set_socket_buffer(mr_sleep);
// disable the merge read
// @see https://github.com/ossrs/srs/issues/241
rtmp->set_merge_read(true, this);
}
#endif
}
int SrsReusableThread2::cycle()
{
return handler->cycle();
}接着调用 SrsRecvThread 实现的 cycle 函数，该函数才开始真正接收客户端推流的数据。
2. 接收推流数据：SrsRecvThread::cycle
int SrsRecvThread::cycle()
{
int ret = ERROR_SUCCESS;
/* 若当前没有被中断的情况下，进入循环开始接收客户端的消息 */
while (!trd->interrupted()) {
/* 调用 SrsPublishRecvThread 实现的 can_handle 函数，该函数
* 默认返回 true，即默认推流线程总是可以处理消息 */
if (!handler->can_handler()) {
st_usleep(timeout * 1000);
continue;
}
SrsCommonMessage* msg = NULL;
// recv and handle message
ret = rtmp->recv_message(&msg);
if (ret == ERROR_SUCCESS) {
/* 调用 SrsPublishRecvThread 实现的 handle 函数处理接收到的消息 */
ret = handler->handle(msg);
}
/* 若发生错误，则中断当前 recv 线程 */
if (ret != ERROR_SUCCESS) {
if (!srs_is_client_gracefully_close(ret) && !srs_is_system_control_error(ret))
{
srs_error("thread process message failed. ret=%d", ret);
}
// we use no timeout to recv, should never got any error.
trd->interrupt();
// notice the handler got a recv error
handler->on_recv_error(ret);
return ret;
}
srs_verbose("thread loop recv message. ret=%d", ret);
}
return ret;
}3. 接收推流数据：SrsRtmpServer::recv_message
int SrsRtmpServer::recv_message(SrsCommonMessage** pmsg)
{
return protocol->recv_message(pmsg);
}该函数接着调用 SrsProtocol 实现的 recv_message 函数。
int SrsProtocol::recv_message(SrsCommonMessage** pmsg)
{
*pmsg = NULL;
int ret = ERROR_SUCCESS;
while (true) {
SrsCommonMessage* msg = NULL;
if ((ret = recv_interlaced_message(&msg)) != ERROR_SUCCESS) {
if (ret != ERROR_SOCKET_TIMEOUT && !srs_is_client_gracefully_close(ret)) {
srs_error("recv interlaced message failed. ret=%d", ret);
}
srs_freep(msg);
return ret;
}
srs_verbose("entire msg received");
/* 若获取到一个空消息，则继续获取下一个消息 */
if (!msg) {
srs_info("got empty message without error.");
continue;
}
if (msg->size <= 0 || msg->header.payload_length <= 0) {
srs_trace("ignore empty message(type=%d, size=%d, time=%"PRId64", sid=%d).",
msg->header.message_type, msg->header.payload_length,
msg->header.timestamp, msg->header.stream_id);
srs_freep(msg);
continue;
}
/* 该函数首先检测当前接收到的字节数是否已经达到当前窗口大小，若是，则回应客户端窗口消息
* 然后接着对接收到的若为 应答窗口大小(5)、设置块大小(1)、用户控制消息(4) 则会进行解码，
* 并根据解析后的内容更新当前 rtmp 服务器的上下文信息 */
if ((ret = on_recv_message(msg)) != ERROR_SUCCESS) {
srs_error("hook the received msg failed. ret=%d", ret);
srs_freep(msg);
return ret;
}
srs_verbose("got a msg, cid=%d, type=%d, size=%d, time=%"PRId64,
msg->header.perfer_cid, msg->header.message_type, msg->header.payload_length,
msg->header.timestamp);
*pmsg = msg;
break;
}
}
int SrsProtocol::recv_interlaced_message(SrsCommonMessage** pmsg)
{
int ret = ERROR_SUCCESS;
// chunk stream basic header.
char fmt = 0;
int cid = 0;
/* 读取 chunk 的基本头 */
if ((ret = read_basic_header(fmt, cid)) != ERROR_SUCCESS) {
if (ret != ERROR_SOCKET_TIMEOUT && !srs_is_client_gracefully_close(ret)) {
srs_error("read basic header failed. ret=%d", ret);
}
return ret;
}
srs_verbose("read basic header success. fmt=%d, cid=%d", fmt, cid);
// the cid must not negative.
srs_assert(cid >= 0);
// get the cached chunk stream.
SrsChunkStream* chunk = NULL;
/* 一个消息客户端可能会分成几个 chunk 发送，因此需要把每次读取
* 的 chunk 的信息和负载缓存起来 */
// use chunk stream cache to get the chunk info.
// @see https://github.com/ossrs/srs/issues/249
if (cid < SRS_PERF_CHUNK_STREAM_CACHE) {
// chunk stream cache hit.
srs_verbose("cs-cache hit, cid=%d", cid);
// already init, use it direclty
chunk = cs_cache[cid];
srs_verbose("cached chunk stream: fmt=%d, cid=%d, size=%d, "
"message(type=%d, size=%d, time=%"PRId64", sid=%d)",
chunk->fmt, chunk->cid, (chunk->msg? chunk->msg->size : 0),
chunk->header.message_type, chunk->header.payload_length,
chunk->header.timestamp, chunk->header.stream_id);
} else {
// chunk stream cache miss, use map.
if (chunk_streams.find(cid) == chunk_streams.end()) {
chunk = chunk_streams[cid] = new SrsChunkStream(cid);
// set the perfer cid of chunk,
// which will copy to the message received.
chunk->header.perfer_cid = cid;
srs_verbose("cache new chunk stream: fmt=%d, cid=%d", fmt, cid);
} else {
chunk = chunk_streams[cid];
srs_verbose("cached chunk stream: fmt=%d, cid=%d, size=%d, "
"message(type=%d, size=%d, time=%"PRId64", sid=%d)",
chunk->fmt, chunk->cid, (chunk->msg? chunk->msg->size : 0),
chunk->header.message_type, chunk->header.payload_length,
chunk->header.timestamp, chunk->header.stream_id);
}
}
// chunk stream message header
if ((ret = read_message_header(chunk, fmt)) != ERROR_SUCCESS) {
if (ret != ERROR_SOCKET_TIMEOUT && !srs_is_client_gracefully_close(ret)) {
srs_error("read message header failed. ret=%d", ret);
}
return ret;
}
srs_verbose("read message header success. fmt=%d, ext_time=%d, size=%d, "
"message(type=%d, size=%d, time=%"PRId64", sid=%d)",
fmt, chunk->extended_timestamp, (chunk->msg? chunk->msg->size : 0),
chunk->header.message_type, chunk->header.payload_length,
chunk->header.timestamp, chunk->header.stream_id);
// read msg payload from chunk stream.
SrsCommonMessage* msg = NULL;
if ((ret = read_message_payload(chunk, &msg)) != ERROR_SUCCESS) {
if (ret != ERROR_SOCKET_TIMEOUT && !srs_is_client_gracefully_close(ret)) {
srs_error("read message payload failed. ret=%d", ret);
}
return ret;
}
// not got an entire RTMP message, try next chunk.
if (!msg) {
srs_verbose("get partial message success. size=%d, "
"message(type=%d, size=%d, time=%"PRId64", sid=%d)",
(msg? msg->size : (chunk->msg? chunk->msg->size : 0)),
chunk->header.message_type, chunk->header.payload_length,
chunk->header.timestamp, chunk->header.stream_id);
return ret;
}
/* 获取到完整的消息 */
*pmsg = msg;
srs_info("get entire message success. size=%d, "
"message(type=%d, size=%d, time=%"PRId64", sid=%d)",
(msg? msg->size : (chunk->msg? chunk->msg->size : 0)),
chunk->header.message_type, chunk->header.payload_length,
chunk->header.timestamp, chunk->header.stream_id);
return ret;
}4. 处理推流消息：SrsPublishRecvThread::handle
int SrsPublishRecvThread::handle(SrsCommonMessage* msg)
{
int ret = ERROR_SUCCESS;
// when cid changed, change it.
if (ncid != cid) {
_srs_context->set_id(ncid);
cid = ncid;
}
/* 每接收到一个消息，该将该消息计数值加 1 */
_nb_msgs++;
/* 若当前消息为视频，则视频帧数加 1 */
if (msg->header.is_video()) {
video_frames++;
}
/* log to show the time of recv thread. */
srs_verbose("recv thread now=%"PRId64"us, got msg time=%"PRId64"ms, size=%d",
srs_update_system_time_ms(), msg->header.timestamp, msg->size);
/* the rtmp connection will handle this message. */
ret = _conn->handle_publish_message(_source, msg, _is_fmle, _is_edge);
/* must always free it,
* the source will copy it if need to use. */
srs_freep(msg);
return ret;
}该函数接着主要调用 SrsRtmpConn 实现的 handle_publish_message 函数。
int SrsRtmpConn::handle_publish_message(SrsSource* source, SrsCommonMessage* msg,
bool is_fmle, bool vhost_is_edge)
{
int ret = ERROR_SUCCESS;
/* process publish event. */
if (msg->header.is_amf0_command() || msg->header.is_amf3_command()) {
SrsPacket* pkt = NULL;
if ((ret = rtmp->decode_message(msg, &pkt)) != ERROR_SUCCESS) {
srs_error("fmle decode unpublish message failed. ret=%d", ret);
return ret;
}
SrsAutoFree(SrsPacket, pkt);
/* for flash, any packet is republish. */
if (!is_fmle) {
/* flash unpublish.
* TODO: maybe need to support republish. */
srs_trace("flash flash publish finished.");
return ERROR_CONTROL_REPUBLISH;
}
/* for fmle, drop others except the fmle start packet. */
if (dynamic_cast<SrsFMLEStartPacket*>(pkt)) {
SrsFMLEStartPacket* unpublish = dynamic_cast<SrsFMLEStartPacket*>(pkt);
if ((ret = rtmp->fmle_unpublish(res->stream_id, unpublish->transaction_id))
!= ERROR_SUCCESS) {
return ret;
}
return ERROR_CONTROL_REPUBLISH;
}
srs_trace("fmle ignore AMF0/AMF3 command message.");
return ret;
}
/* video, audio, data message */
if ((ret = process_publish_message(source, msg, vhost_is_edge)) != ERROR_SUCCESS) {
srs_error("fmle process publish message failed. ret=%d", ret);
return ret;
}
return ret;
}这里暂先不分析接收到 unpublish 的情况，而对于接收到 video、audio 和 data message 等消息情况下，直接调用 SrsRtmpConn 实现的 process_publish_message 进行处理。
5. 媒体数据的处理：SrsRtmpConn::process_publish_message
int SrsRtmpConn::process_publish_message(SrsSource* source, SrsCommonMessage* msg,
bool vhost_is_edge)
{
int ret = ERROR_SUCCESS;
// for edge, directly proxy message to origin.
if (vhost_is_edge) {
if ((ret = source->on_edge_proxy_publish(msg)) != ERROR_SUCCESS) {
srs_error("edge publish proxy msg failed. ret=%d", ret);
return ret;
}
return ret;
}
// process audio packet
if (msg->header.is_audio()) {
if ((ret = source->on_audio(msg)) != ERROR_SUCCESS) {
srs_error("source process audio message failed. ret=%d", ret);
return ret;
}
return ret;
}
// process video packet
if (msg->header.is_video()) {
if ((ret = source->on_video(msg)) != ERROR_SUCCESS) {
srs_error("source process video message failed. ret=%d", ret);
return ret;
}
return ret;
}
// process aggregate packet
if (msg->header.is_aggregate()) {
if ((ret = source->on_aggregate(msg)) != ERROR_SUCCESS) {
srs_error("source process aggregate message failed. ret=%d", ret);
return ret;
}
return ret;
}
// process onMetadata
if (msg->header.is_amf0_data() || msg->header.is_amf3_data()) {
SrsPacket* pkt = NULL;
/* 解析元数据 */
if ((ret = rtmp->decode_message(msg, &pkt)) != ERROR_SUCCESS) {
srs_error("decode onMetaData message failed. ret=%d", ret);
return ret;
}
SrsAutoFree(SrsPacket, pkt);
if (dynamic_cast<SrsOnMetaDataPacket*>(pkt)) {
SrsOnMetaDataPacket* metadata = dynamic_cast<SrsOnMetaDataPacket*>(pkt);
if ((ret = source->on_meta_data(msg, metadata)) != ERROR_SUCCESS) {
srs_error("source process onMetaData message failed. ret=%d", ret);
return ret;
}
srs_info("process onMetaData message success.");
return ret;
}
srs_info("ignore AMF0/AMF3 data message.");
return ret;
}
return ret;
}通常接收到的第一个媒体数据包一般为 onMetaData，抓包图如下图所示。
接收到 onMetaData 数据包后，需要调用 SrsRtmpServer 实现的 decode_message 函数对该包进行解码。
5.1.1 SrsRtmpServer::decode_message
int SrsRtmpServer::decode_message(SrsCommonMessage* msg, SrsPacket** ppacket)
{
return protocol->decode_message(msg, ppacket);
}该函数接着调用 SrsProtocol 实现的 decode_message 函数。
5.1.2 SrsProtocol::decode_message
int SrsProtocol::decode_message(SrsCommonMessage* msg, SrsPacket** packet)
{
*ppacket = NULL;
int ret = ERROR_SUCCESS;
srs_assert(msg != NULL);
srs_assert(msg->payload != NULL);
srs_assert(msg->size > 0);
SrsStream stream;
// initialize the decode stream for all message,
// it's ok for the initialize if fast and without memory copy.
if ((ret = stream.initialize(msg->payload, msg->size)) != ERROR_SUCCESS) {
srs_error("initialize stream failed. ret=%d", ret);
return ret;
}
srs_verbose("decode stream initialized success");
// decode the packet.
SrsPacket* packet = NULL;
if ((ret = do_decode_message(msg->header, &stream, &packet)) != ERROR_SUCCESS) {
srs_freep(packet);
return ret;
}
// set to output ppacket only when success.
*ppacket = packet;
return ret;
}该函数将消息的负载转化为一个字节流，便于调用 SrsProtocol 实现的 do_decode_message 函数对负载数据进行解码。
5.1.3 SrsProtocol::do_decode_message
int SrsProtocol::do_decode_message(SrsMessageHeader& header,
SrsStream* stream, SrsPacket* ppacket)
{
int ret = ERROR_SUCCESS;
SrsPacket* packet = NULL;
// decode specified packet type
if (header.is_amf0_command() || header.is_amf3_command() ||
header.is_amf0_data() || header.is_amf3_data(0)
{
srs_verbose("start to decode AMF0/AMF3 command message.");
// skip 1bytes to decode the amf3 command.
if (header.is_amf3_command() && stream->require(1)) {
srs_verbose("skip 1bytes to decode AMF3 command");
stream->skip(1);
}
// amf0 command message.
// need to read the command name.
std::string command;
if ((ret = srs_amf0_read_string(stream, command)) != ERROR_SUCCESS) {
srs_error("decode AMF0/AMF3 command name failed. ret=%d", ret);
return ret;
}
srs_verbose("AMF0/AMF3 command message, command_name=%s", command.c_str());
// result/error packet
if (command == RTMP_AMF0_COMMAND_RESULT || command == RTMP_AMF0_COMMAND_ERROR) {
/* 这里先忽略，仅考虑对 amf0_data 类型的解码 */
...
}
// reset to zero(amf3 to 1) to restart decode.
stream->skip(-1 * stream->pos());
if (header.is_amf3_command()) {
stream->skip(1);
}
// decode command object.
if (command == RTMP_AMF0_COMMAND_CONNECT)
{
...
}
...
/* "@setDataFrame" or "onMetaData" */
else if (command == SRS_CONSTS_RTMP_SET_DATAFRAME ||
command == SRS_CONSTS_RTMP_ON_METADATA) {
srs_info("decode the AMF0/AMF3 data(onMetaData message).");
*ppacket = packet = new SrsOnMetaDataPacket();
/* 调用 SrsOnMetaDataPacket 类实现的 decode 函数 */
return packet->decode(stream);
}
...
// default packet to drop message.
srs_info("drop the AMF0/AMF3 command message, command_name=%s", command.c_str());
*ppacket = packet = new SrsPacket();
return ret;
} else if (header.is_user_control_message()) {
...
} else if
...
return ret;
}对于接收到的 amf_data 类型的数据，统一构造一个 SrsOnMetaDataPacket 类，然后调用该类实现的 decode 函数进行解码。
5.1.4 SrsOnMetaDataPacket 构造函数
/**
* the stream metadata.
* FMLE: @setDataFrame
* others: onMetaData
*/
SrsOnMetaDataPacket::SrsOnMetaDataPacket()
{
name = SRS_CONSTS_RTMP_ON_METADATA;
/**
* Metadata of stream.
* @remark, never be NULL, an AMF0 object instance.
*/
metadata = SrsAmf0Any::object();
}若为 FMLE（Flash Media Live Encoder） 软件，则发送的 amf0_data 消息名为 "@setDataFrame"，其他的则为 "onMetaData"。
5.1.5 SrsOnMetaDataPacket::decode
int SrsOnMetaDataPacket::decode(SrsStream* stream)
{
int ret = ERROR_SUCCESS;
if ((ret = srs_amf0_read_string(stream, name)) != ERROR_SUCCESS) {
srs_error("decode metadata name failed. ret=%d", ret);
return ret;
}
// ignore the @setDataFrame
if (name == SRS_CONSTS_RTMP_SET_DATAFRAME) {
/* 名称以 "onMetaData" 为准 */
if ((ret = srs_amf0_read_string(stream, name)) != ERROR_SUCCESS) {
srs_error("decode metadata name failed. ret=%d", ret);
return ret;
}
}
srs_verbose("decode metadata name success. name=%s", name.c_str());
// the metadata mayby object or ecma array
SrsAmf0Any* any = NULL;
/* 由上图知，该 metadata 的数据类型是 ecma array */
if ((ret = srs_amf0_read_any(stream, &any)) != ERROR_SUCCESS) {
srs_error("decode metadata metadata failed. ret=%d", ret);
return ret;
}
srs_assert(any);
if (any_is_object()) {
srs_freep(metadata);
metadata = any->to_object();
srs_info("decode metadata object success");
return ret;
}
SrsAutoFree(SrsAmf0Any, any);
if (any->is_ecma_array()) {
SrsAmf0EcmaArray* arr = any->to_ecma_array();
// if ecma array, copy to object.
for (int i = 0; i < arr->count(); i++) {
/* 将解析出来的数据拷贝到 metadata 的 properties 中，
* metadata 是指向 SrsAmf0Object 对象的指针 */
metadata->set(arr->key_at(i), arr->value_at(i)->copy());
}
srs_info("decode metadata array success");
}
return ret;
}该函数主要是解析 metadata 数据，然后将其保存在 SrsOnMetaDataPacket 类的成员 metadata 中。
5.1.6 srs_amf0_read_any
int srs_amf0_read_any(SrsStream* stream, SrsAmf0Any** ppvalue)
{
int ret = ERROR_SUCCESS;
/* 读取 marker，发现是 ecma array 类型，则会构造一个 SrsAmf0EcmaArray 对象，
* 通过 ppvalue 返回该对象 */
if ((ret = SrsAmf0Any::discovery(stream, ppvalue)) != ERROR_SUCCESS) {
srs_error("amf0 discovery any elem failed. ret=%d", ret);
return ret;
}
srs_assert(*ppvalue);
/* 调用 SrsAmf0EcmaArray 类实现的 read 函数读取metadata携带的各项property */
if ((ret = (*ppvalue)->read(stream)) != ERROR_SUCCESS) {
srs_error("amf0 parse elem failed. ret=%d", ret);
srs_freep(*ppvalue);
return ret;
}
return ret;
}5.1.7 SrsAmf0EcmaArray::read
int SrsAmf0EcmaArray::read(SrsStream* stream)
{
int ret = ERROR_SUCCESS;
// marker
if (!stream->require(1)) {
ret = ERROR_RTMP_AMF0_DECODE;
srs_error("amf0 read ecma_array marker failed. ret=%d", ret);
return ret;
}
/* 读取 AMF0 type：ECMA array 为 0x08 */
char marker = stream->read_1bytes();
if (marker != RTMP_AMF0_EcmaArray) {
ret = ERROR_RTMP_AMF0_DECODE;
srs_error("amf0 check ecma_array marker failed. "
"marker=%#x, required=%#x, ret=%d", marker, RTMP_AMF0_EcmaArray, ret);
return ret;
}
srs_verbose("amf0 read ecma_array marker success");
// count
if (!stream->require(4)) {
ret = ERROR_RTMP_AMF0_DECODE;
srs_error("amf0 read ecma_array count failed. ret=%d", ret);
return ret;
}
/* 读取该 ECMA array 中有多少个 property */
int32_t count = stream->read_4bytes();
srs_verbose("amf0 read ecma_array count success. count=%d", count);
// value
this->_count = count;
while (!stream->empty()) {
// detect whether is eof.
if (srs_amf0_is_object_eof(stream)) {
SrsAmf0ObjectEOF pbj_eof;
/* ECMA array 类型同样以 0x00 0x00 0x09 结尾，与 object 一样 */
if ((ret = pbj_eof.read(stream)) != ERROR_SUCCESS) {
srs_error("amf0 ecma_array read eof failed. ret=%d", ret);
return ret;
}
srs_info("amf0 read ecma_array EOF.");
break;
}
// property-name: utf8 string
std::string property_name;
/* 读取 property 的名称 */
if ((ret =srs_amf0_read_utf8(stream, property_name)) != ERROR_SUCCESS) {
srs_error("amf0 ecma_array read property name failed. ret=%d", ret);
return ret;
}
/* 读取 property 的值：number or string or boolean */
// property-value: any
SrsAmf0Any* property_value = NULL;
if ((ret = srs_amf0_read_any(stream, &property_value)) != ERROR_SUCCESS) {
srs_error("amf0 ecma_array read property_value failed. "
"name=%s, ret=%d", property_name.c_str(), ret);
return ret;
}
/* 将获取到的每一个 property 以该 property 的名称为 key，保存到 SrsAmf0EcmaArray 类的
* 成员 properties 中，该 properties 是一个指向 SrsUnSortedHashtable 类的指针，该类的
* 成员 properties 维护了一个 std::vector<SrsAmf0ObjectPropertyType> 容器，该容器用于
* 存放所有获取到的 property 项 */
// add property
this->set(property_name, property_value);
}
return ret;
}解析 metadata 数据成功后，接下来是调用 SrsSource 实现的 on_meta_data 函数对解析后的 metadata 做进一步的处理。
5.1.8 SrsSource::on_meta_data
int SrsSource::on_meta_data(SrsCommonMessage* msg, SrsOnMetaDataPacket* metadata)
{
int ret = ERROR_SUCCESS;
/* hls 和 dvr 的暂时忽略 */
#ifdef SRS_AUTO_HLS
if (metadata && (ret = hls->on_meta_data(metadata->metadata)) != ERROR_SUCCESS) {
srs_error("hls process onMetaData message failed. ret=%d", ret);
return ret;
}
#endif
#ifdef SRS_AUTO_DVR
if (metadata && (ret = dvr->on_meta_data(metadata)) != ERROR_SUCCESS) {
srs_error("dvr process onMetaData message failed. ret=%d", ret);
return ret;
}
#endif
SrsAmf0Any* prop = NULL;
// when exists the duration, remove it to make ExoPlayer happy.
if (metadata->metadata->get_property("duration") != NULL) {
metadata->metadata->remove("duration");
}
// generate metadata info to print
std::stringstream ss;
if ((prop = metadata->metadata->ensure_property_number("width")) != NULL) {
ss << ", width=" << (int)prop->to_number();
}
if ((prop = metadata->metadata->ensure_property_number("height")) != NULL) {
ss << ", height=" << (int)prop->to_number();
}
if ((prop = metadata->metadata->ensure_property_number("videocodecid")) != NULL) {
ss << ", vcodec=" << (int)prop->to_number();
}
if ((prop = metadata->metadata->ensure_property_number("audiocodecid")) != NULL) {
ss << ", acodec=" << (int)prop->to_number();
}
srs_trace("got metadata%s", ss.str().c_str());
// add server info to metadata.
metadata->metadata->set("server", SrsAmf0Any::str(RTMP_SIG_SRS_SERVER));
metadata->metadata->set("srs_primary", SrsAmf0Any::str(RTMP_SIG_SRS_PRIMARY));
metadata->metadata->set("srs_authors", SrsAmf0Any::str(RTMP_SIG_SRS_AUTHROS));
// version, for example, 1.0.0
// add version to metadata, please donot remove it, for debug.
metadata->metadata->set("server_version", SrsAmf0Any::str(RTMP_SIG_SRS_VERSION));
// if allow atc_auto and bravo-atc detected, open atc for vhost.
atc = _srs_config->get_atc(_req->vhost);
if (_srs_config->get_atc_auto(_req->vhost)) {
if ((prop = metadata->metadata->get_property("bravo_atc")) != NULL) {
if (prop->is_string() && prop->to_str() == "true") {
atc = true;
}
}
}
// encode the metadata to payload
int size = 0;
char* payload = NULL;
/* 调用继承自父类 SrsPacket 的函数 encode 将 metadata 中的元数据信息编码成
* payload */
if ((ret = metadata->encode(size, payload)) != ERROR_SUCCESS) {
srs_error("encode metadata error. ret=%d", ret);
srs_freep(payload);
return ret;
}
srs_verbose("encode metadata success.");
if (size <= 0) {
srs_warn("ignore the invalid metadata. size=%d", size);
return ret;
}
// when already got metadata, drop when reduce sequence header.
bool drop_for_reduce = false;
if (cache_metadata && _srs_config->get_reduce_sequence_header(_req->vhost)) {
drop_for_reduce = true;
srs_warn("drop for reduce sh metadata, size=%d", msg->size);
}
// create a shared ptr message.
srs_freep(cache_metadata);
cache_metadata = new SrsSharedPtrMessage();
// dump message to shared ptr message.
// the payload/size managed by cache_metadata, user should not free it.
if ((ret = cache_metadata->create(&msg->header, payload, size)) != ERROR_SUCCESS) {
srs_error("initialize the cache metadata failed. ret=%d", ret);
return ret;
}
srs_verbose("initialize shared ptr metadata success.");
// copy to all consumer
if (!drop_for_reduce) {
/* 若有其他客户端订阅了该直播流，则通知这些客户端 */
std::vector<SrsConsumer*>::iterator it;
for (it = consumer.begin(); it != consumers.end(); ++it) {
SrsConsumer* consumer = *it;
if ((ret = consumer->enqueue(cache_metadata, atc, jitter_algorithm))
!= ERROR_SUCCESS) {
srs_error("dispatch the metadata failed. ret=%d", ret);
return ret;
}
}
}
// copy to all forwarders
if (true) {
std::vector<SrsForwarder*>::iterator it;
for (it = forwarders.begin(); it != forwarders.end(); ++it) {
SrsForwarder* forwarder = *it;
if ((ret = forwarder->on_meta_data(cache_metadata)) != ERROR_SUCCESS) {
srs_error("forwarder process onMetaData message failed. ret=%d", ret);
return ret;
}
}
}
return ret;
}5.1.9 SrsPacket::encode
/*
* the subpacket can override this encode,
* for example, video and audio will directly set the payload without memory copy,
* other packet which need to serialize/encode to bytes by override the
* get_size and encode_packet.
*/
int SrsPacket::encode(int& psize, char*& ppayload)
{
int ret = ERROR_SUCCESS;
int size = get_size();
char* payload = NULL;
SrsStream stream;
if (size > 0) {
payload = new char[size];
if ((ret = stream.initialize(payload, sizse)) != ERROR_SUCCESS) {
srs_error("initialize the stream failed. ret=%d", ret);
srs_freepa(payload);
return ret;
}
}
/* 调用 SrsOnMetaDataPacket 类实现的 encode_packet 函数 */
if ((ret = encode_packet(&stream)) != ERROR_SUCCESS) {
srs_error("encode the packet failed. ret=%d", ret);
srs_freepa(payload);
return ret;
}
psize = size;
ppayload = payload;
srs_verbose("encode the packet success. size=%d", size);
return ret;
}5.1.10 SrsOnMetaDataPacket::encode_packet
int SrsOnMetaDataPacket::encode_packet(SrsStream* stream)
{
int ret = ERROR_SUCCESS;
if ((ret = srs_amf0_write_string(stream, name)) != ERROR_SUCCESS) {
srs_error("encode name failed. ret=%d", ret);
return ret;
}
srs_verbose("encode name success.");
/* 调用 SrsAmf0Object 类实现的 write 函数 */
if ((ret = metadata->write(stream)) != ERROR_SUCCESS) {
srs_error("encode metadata failed. ret=%d", ret);
return ret;
}
srs_verbose("encode metadata success.");
srs_info("encode onMetaData packet success.");
return ret;
}5.1.11 SrsAmf0Object::write
int SrsAmf0Object::write(SrsStream* stream)
{
int ret = ERROR_SUCCESS;
// marker
if (!stream->require(1)) {
ret = ERROR_RTMP_AMF0_ENCODE;
srs_error("amf0 write object marker failed. ret=%d", ret);
return ret;
}
/* 写入 1 字节的 amf 类型 */
stream->write_1bytes(RTMP_AMF0_Object);
srs_verbose("amf0 write object marker success");
// value
for (int i = 0; i < properties->count(); i++) {
std::string name = this->key_at(i);
SrsAmf0Any* any = this->value_at(i);
if ((ret = srs_amf0_write_utf8(stream, name)) != ERROR_SUCCESS) {
srs_error("write object property name failed. ret=%d", ret);
return ret;
}
if ((ret = srs_amf0_write_any(stream, any)) != ERROR_SUCCESS) {
srs_error("write object property value failed. ret=%d", ret);
return ret;
}
srs_verbose("write amf0 property success. name=%s", name.c_str());
}
/* 写入结束标志 0x00 0x00 0x09 */
if ((ret = eof->write(stream)) != ERROR_SUCCESS) {
srs_error("write object eof failed. ret=%d", ret);
return ret;
}
srs_verbose("write amf0 object success.");
return ret;
}5.1.12 SrsSharedPtrMessage 构造函数
/*
* shared ptr message.
* for audio/video/data message that need less memory copy.
* and only for output.
*
* create first object by constructor and create(),
* use copy if need reference count message.
*/
SrsSharedPtrMessage::SrsSharedPtrMessage()
{
ptr = NULL;
}5.1.13 SrsSharedPtrMessage::create
/*
* create shared ptr message,
* from the header and payload.
* @remark user should never free the payload.
* @param pheader, the header to copy to the message. NULL to ignore.
*/
int SrsSharedPtrMessage::create(SrsMessageHeader* pheader, char* payload, int size)
{
int ret = ERROR_SUCCESS;
if (ptr) {
ret = ERROR_SYSTEM_ASSERT_FAILED;
srs_error("should not set the payload twice. ret=%d", ret);
srs_assert(false);
return ret;
}
/* 构造 SrsSharedPtrPayload */
ptr = new SrsSharedPtrPayload();
/* 将解析自 metadata 消息的消息头内容赋给 ptr->header 的相应成员 */
// direct attach the data.
if (pheader) {
/* amf0_data: 0x12 */
ptr->header.message_type = pheader->message_type;
/* 负载的大小 */
ptr->header.payload_length = size;
ptr->header.perfer_cid = pheader->perfer_cid;
this->timestamp = pheader->timestamp;
this->stream_id = pheader->stream_id;
}
ptr->payload = payload;
ptr->size = size;
// message can access it.
/*
* payload:
* the payload of message, the SrsCommonMessage never know about the detail of payload,
* user must use SrsProtocol.decode_message to get concrete packet.
* @remark, not all message payload can be decoded to packet. for example,
* video/audio packet use raw bytes, no video/audio packet.
*/
this->payload = ptr->payload;
/*
* current message parsed size,
* size <= header.payload_length
* for the payload maybe sent in multiple chunks.
*/
this->size = ptr->size;
return ret;
}5.1.14 SrsSharedPtrPayload 构造函数
SrsSharedPtrMessage::SrsSharedPtrPayload::SrsSharedPtrPayload()
{
/* actual shared payload. */
payload = NULL;
/* size of payload. */
size = 0;
/* the reference count */
shared_count = 0;
}5.1.15 通知消费者：SrsConsumer::enqueue
/**
* enqueue an shared ptr message.
* @param shared_msg, directly ptr, copy it if need to save it.
* @param whether atc, donot use jitter correct if true.
* @param ag the algorithm of time jitter.
*/
int SrsConsumer::enqueue(SrsSharedPtrMessage* shared_msg, bool atc,
SrsRtmpJitterAlgorithm ag)
{
int ret = ERROR_SUCCESS;
/* 拷贝一个副本返回给 msg */
SrsSharedPtrMessage* msg = shared_msg->copy();
/* 若 atc 为 false，则使用 jitter 进行校正 */
if (!atc) {
if ((ret = jitter->correct(msg, ag)) != ERROR_SUCCESS) {
srs_freep(msg);
return ret;
}
}
if ((ret = queue->enqueue(msg, NULL)) != ERROR_SUCCESS) {
return ret;
}
#ifdef SRS_PERF_QUEUE_COND_WAIT
srs_verbose("enqueue msg, time=%"PRId64", size=%d, "
"duration=%d, waiting=%d, min_msg=%d",
msg->timestamp, msg->size, queue->duration(), mw_waiting, mw_min_msgs);
// fire the mw when msgs is enough.
/* 若有消费者，即播放客户端正在等待 msg 准备好，即上面的 queue->enqueue 成功返回 */
if (mw_waiting) {
int duration_ms = queue->duration();
bool match_min_msgs = queue->size() > mw_min_msgs;
// For ATC, maybe the SH timestamp bigger than A/V packet,
// when encoder republish or overflow.
// @see https://github.com/ossrs/srs/pull/749
if (atc && duration_ms < 0) {
st_cond_signal(mw_wait);
mw_waiting = false;
return ret;
}
// when duration ok, signal to flush.
if (match_min_msgs && duration_ms > mw_duration) {
st_cond_signal(mw_wait);
mw_waitting = false;
return ret;
}
}
#endif
return ret;
}5.1.16 SrsRtmpJitter::correct
int SrsRtmpJitter::correct(SrsSharedPtrMessage* msg, SrsRtmpJitterAlgorithm ag)
{
int ret = ERROR_SUCCESS;
// for performance issue
if (ag != SrsRtmpJitterAlgorithmFULL) {
// all jitter correct features is disabled, ignore.
if (ag == SrsRtmpJitterAlgorithmOFF) {
return ret;
}
// start at zero, but donot ensure monotonically increasing.
if (ag == SrsRtmpJitterAlgothmZERO) {
// for the first time, last_pkt_corrent_time is -1.
if (last_pkt_correct_time == -1) {
last_pkt_correct_time = msg->timestamp;
}
msg->timestamp -= last_pkt_correct_time;
return ret;
}
// other algorithm, ignore.
return ret;
}
// full jitter algorithm, do jitter correct.
// set to 0 for metadata.
if (!msg->is_av()) {
msg->timestamp = 0;
return ret;
}
/**
* we use a very simple time jitter detect/correct algorithm:
* 1. delta: ensure the delta is positive and valid,
* we set the delta to DEFAULT_FRAME_TIME_MS,
* if the delta of time is nagative or greater than CONST_MAX_JITTER_MS.
* 2. last_pkt_time: specifies the original packet time,
* is used to detect next jitter.
* 3. last_pkt_correct_time: simply add the positive delta,
* and enforce the time monotonically.
*/
int64_t time = msg->timestamp;
int64_t delta = time - last_pkt_time;
// if jitter detected, reset the delta.
if (delta < CONST_MAX_JITTER_MS_NED || delta > CONST_MAX_JITTER_MS) {
// use default 10ms to notice the problem of stream.
// @see https://github.com/ossrs/srs/issues/425
delta = DEFAULT_FRAME_TIME_MS;
srs_info("jitter detected, last_pts=%"PRId64", pts=%"PRId64", "
"diff=%"PRId64", last_time=%"PRId64", time=%"PRId64", diff=%"PRId64"",
last_pkt_time, time, time - last_pkt_time, last_pkt_correct_time,
last_pkt_correct_time + delta, delta);
} else {
srs_verbose("timestamp no jitter. time=%"PRId64", "
"last_pkt=%"PRId64", correct_to=%"PRId64"",
time, last_pkt_time, last_pkt_correct_time + delta);
}
last_pkt_correct_time = srs_max(0, last_pkt_correct_time + delta);
msg->timestamp = last_pkt_correct_time;
last_pkt_time = time;
return ret;
}若传入的第二个参数为 SrsRtmpJitterAlgorithmOFF，则禁止所有的 jitter 校正，构造 SrsSource 的时候默认初始化为 SrsRtmpJitterAlgorithmOFF。
5.1.17 SrsMessageQueue::enqueue
/*
* enqueue the message, the timestamp always monotonically.
* @param msg, the msg to enqueue, user never free it whatever the return code.
* @param is_overflow, whether overflow and shrinked. NULL to ignore.
*/
int SrsMessageQueue::enqueue(SrsSharedPtrMessage* msg, bool* is_overflow)
{
int ret = ERROR_SUCCESS;
if (msg->is_av()) {
if (av_start_time == -1) {
av_start_time = msg->timestamp;
}
av_end_time = msg->timestamp;
}
/* 若声明了 SRS_PERF_QUEUE_FAST_VECTOR 宏，则调用 SrsFastVector 类
* 实现的 push_back 函数 */
msgs.push_back(msg);
/* 检测 msgs 队列是否溢出 */
while (av_end_time - av_start_time > queue_size_ms) {
// notice the caller queue already overflow and sharinked.
if (is_overflow) {
*is_overflow = true;
}
/* 满溢的情况下，移除一个 gop */
sharink();
}
return ret;
}5.1.18 SrsFastVector::push_back
void SrsFastVector::push_back(SrsSharedPtrMessage* msg)
{
// increase vector.
if (count >= nb_msgs) {
int size = nb_msgs * 2;
SrsSharedPtrMessage** buf = new SrsSharedPtrMessage*[size];
for (int i = 0; i < nb_msgs; i++) {
buf[i] = msgs[i];
}
srs_warn("fast vector incrase %d=>%d", nb_msgs, size);
// use new array.
srs_freep(msgs);
msgs = buf;
nb_msgs = size;
}
/* msgs 指向一个 SrsSharedPtrMessage 类型的二级数组，该数组的成员是
* SrsSharedPtrMessage* */
msgs[count++] = msg;
}该函数是直接将 msg 放入到 SrsFastVector 类的成员 msgs 数组中（若该数组大小足够的话）。
5.1.19 SrsMessageQueue::shrink
/*
* remove a gop from the front.
* if no iframe found, clear it.
*/
void SrsMessageQueue::shrink()
{
SrsSharedPtrMessage* video_sh = NULL;
SrsSharedPtrMessage* audio_sh = NULL;
int msgs_size = (int)msgs.size();
// remove all msg
// ignore the sequence header
for (int i = 0; i < (int)msgs.size(); i++) {
SrsSharedPtrMessage* msg = msgs.at(i);
if (msg->is_video() &&
SrsFlvCodec::video_is_sequence_header(msg->payload, msg->size))
{
srs_freep(video_sh);
video_sh = msg;
continue;
}
else if (msg->is_audio() &&
SrsFlvCodec::audio_is_sequence_header(msg->payload, msg->size))
{
srs_freep(audio_sh);
audio_sh = msg;
continue;
}
srs_freep(msg);
}
msgs.clear();
// update av_start_time
av_start_time = av_end_time;
// push_back sequence header and update timestamp
if (video_sh) {
video_sh->timestamp = av_end_time;
msgs.push_back(video_sh);
}
if (audio_sh) {
audio_sh->timestamp = av_end_time;
msgs.push_back(audio_sh);
}
if (_ignore_shrink) {
srs_info("shrink the cache queue, size=%d, removed=%d, max=%.2f",
(int)msgs.size(), msgs_size - (int)msgs.size(), queue_size_ms / 1000.0);
} else {
srs_trace("shrink the cache queue, size=%d, removed=%d, max=%.2f",
(int)msgs.size(), msgs_size - (int)msgs.size(), queue_size_ms / 1000.0);
}
}5.1.20 SrsMessageQueue::duration
/* get the duration of queue. */
int SrsMessageQueue::duration()
{
return (int)(av_end_time - av_start_time);
}计算当前消息队列中所有消息的总 duration。
5.1.21 st_cond_signal
int st_cond_signal(_st_cond_t *cvar)
{
return _st_cond_signal(cvar, 0);
}5.1.22 _st_cond_signal
static int _st_cond_signal(_st_cond_t *cvar, int broadcast)
{
_st_thread_t *thread;
_st_clist_t *q;
for (q = cvar->wait_q.next; q != &cvar->wait_q; q = q->next) {
thread = _ST_THREAD_WAITQ_PTR(q);
if (thread->state == _ST_ST_COND_WAIT) {
if (thread->flags & _ST_ST_ON_SLEEPQ)
_ST_DEL_SLEEPQ(thread);
/* Make thread runnable */
thread->state = _ST_ST_RUNNABLE;
_ST_ADD_RUNQ(thread);
if (!broadcast)
break;s
}
}
return 0;
}假设接收到的第一个音频包如下图。
对于接收到的音频包，在 SrsRtmpConn::process_publish_message 函数中直接调用 SrsSource 类实现的 on_audio 函数进行处理。
5.2.1 SrsSource::on_audio
int SrsSource::on_audio(SrsCommonMessage* shared_audio)
{
int ret = ERROR_SUCCESS;
// monotically increate detect.
if (!mix_correct && is_monotonically_increase) {
if (last_packet_time > 0 && shared_audio->header.timestamp < last_packet_time) {
is_monotonically_increate = false;
srs_warn("AUDIO: stream not monotonically increase, please open mix_correct.");
}
}
/* 记录接收到的 audio 帧的时间戳 */
last_packet_time = shared_audio->header.timestamp;
// convert shared_audio to msg, user should not use shared_audio again.
// the payload is transfer to msg, and set to NULL in shared_audio.
SrsSharedPtrMessage msg;
/* 构造一个 SrsSharedPtrMessage 类，并将接收到的音频消息的消息头还有负载
* 拷贝到该新构建的 SrsSharedPtrMessage 类中 */
if ((ret = msg.create(shared_audio)) != ERROR_SUCCESS) {
srs_error("initialize the audio failed. ret=%d", ret);
return ret;
}
srs_info("Audio dts=%"PRId64", size=%d", msg.timestamp, msg.size);
/* 若没有开启 mix_correct 校正，则直接处理音频数据 */
// directly process the audio message.
if (!mix_correct) {
return on_audio_imp(&msg);
}
// insert msg to the queue.
mix_queue->push(msg.copy());
// fetch someone from mix_queue.
SrsSharedPtrMessage* m = mix_queue->pop();
if (!m) {
return ret;
}
// comsumer the monotonically increase message.
if (m->is_audio()) {
ret = on_audio_imp(m);
} else {
ret = on_video_imp(m);
}
srs_freep(m);
return ret;
}5.2.2 SrsSource::on_audio_imp
int SrsSource::on_audio_imp(SrsSharedPtrMessage* msg)
{
int ret = ERROR_SUCCESS;
srs_info("Audio dts=%"PRId64", size=%d", msg->timestamp, msg->size);
bool is_aac_sequence_header =
SrsFlvCodec::audio_is_sequence_header(msg->payload, msg->size);
bool is_sequence_header = is_aac_sequence_header;
// whether consumer should drop for the duplicated sequnece header.
bool drop_for_reduce = false;
if (is_sequence_header && cache_sh_audio &&
_srs_config->get_reduce_sequence_header(_req->vhost)) {
if (cache_sh_audio->size == msg->size) {
drop_for_reduce = srs_bytes_equals(cache_sh_audio->payload,
msg->payload, msg->size);
srs_warn("drop for reduce sh audio, size=%d", msg->size);
}
}
/* 若是 AAC sequence header，则将该音频包的数据保存到 aac_extra_data 中 */
// cache the sequence header if aac
// donot cache the sequence header to gop_cache, return here.
if (is_aac_sequence_header) {
// parse detail audio codec
SrsAvcAacCodec codec;
SrsCodecSample sample;
/* 对接收到的音频数据进行解析 */
if ((ret = codec.audio_aac_demux(msg->payload, msg->size, &sample))
!= ERROR_SUCCESS) {
srs_error("source codec demux audio failed. ret=%d", ret);
return ret;
}
static int flv_sample_sizes[] = {8, 16, 0};
static int flv_shound_types[] = {1, 2, 0};
// when got audio stream info.
SrsStatistic* stat = SrsStatistic::instance();
if ((ret = stat->on_audio_info(_req, SrsCodecAudioAAC, sample.sound_rate,
sample.sound_type, codec.aac_object)) != ERROR_SUCCESS) {
return ret;
}
srs_trace("%dB audio sh, codec(%d, profile=%s, %dchannels, %dkbps, %dHZ), "
"flv(%dbits, %dchannels, %dHZ)",
msg->size, codec.audio_codec_id,
srs_codec_aac_object2str(codec.aac_object).c_str(), codec.aac_channels,
codec.audio_data_rate / 1000, aac_sample_rates[codec.aac_sample_rate],
flv_sample_sizes[sample.sound_size], flv_sound_types[sample.sound_type],
flv_sample_rates[sample.sound_rate]);
}
#ifdef SRS_AUTO_HLS
if ((ret = hls->on_audio(msg)) != ERROR_SUCCESS) {
// apply the error strategy for hls.
// @see https://github.com/ossrs/srs/issues/264
std::string hls_error_strategy = _srs_config->get_hls_on_error(_req->vhost);
if (srs_config_hls_is_on_error_ignore(hls_error_strategy)) {
srs_warn("hls process audio message failed, ignore and disable hls. ret=%d",
ret);
// unpublish, ignore ret.
hls->on_unpublish();
// ignore.
ret = ERROR_SUCCESS;
} else if (srs_config_hls_is_on_error_continue(hls_error_strategy)) {
if (srs_hls_can_continue(ret, cache_sh_audio, msg)) {
ret = ERROR_SUCCESS;
} else {
srs_warn("hls continue audio failed. ret=%d", ret);
return ret;
}
} else {
srs_warn("hls disconnect publisher for audio error. ret=%d", ret);
return ret;
}
}
#endif
#ifdef SRS_AUTO_DVR
if ((ret = dvr->on_audio(msg)) != ERROR_SUCCESS) {
srs_warn("dvr process audio message failed, ignore and disable dvr. ret=%d", ret);
// unpublish, ignore ret.
dvr->on_unpublish();
// ignore.
ret = ERROR_SUCCESS;
}
#endif
#ifdef SRS_AUTO_HDS
if ((ret = hds->on_audio(msg)) != ERROR_SUCCESS) {
srs_warn("hds process audio message failed, ignore and disable dvr. ret=%d", ret);
// unpublish, ignore ret.
hds->on_unpublish();
// ignore.
ret = ERROR_SUCCESS;
}
#endif
/* 将接收到的 audio message 放入到 consumer 所持有的 queue 队列中 */
// copy to all consumer
if (!drop_for_reduce) {
for (int i = 0; i < (int)consumers.size(); i++) {
SrsConsumer* consumer = consumers.at(i);
if ((ret = consumer->enqueue(msg, atc, jitter_algorithm)) != ERROR_SUCCESS) {
srs_error("dispatch the audio failed. ret=%d", ret);
return ret;
}
}
srs_info("dispatch audio success.");
}
// copy to all forwarders.
if (true) {
std::vector<SrsForwarder*>::iterator it;
for (it = forwarders.begin(); it != forwarders.end(); ++it) {
SrsForwarder* forwarder = *it;
if ((ret = forwarder->on_audio(msg)) != ERROR_SUCCESS) {
srs_error("forwarder process audio message failed. ret=%d", ret);
return ret;
}
}
}
// cache the sequence header of aac, or first packet of mp3.
// for example, the mp3 is used for hls to write the "right" audio codec.
// TODO: FIXME: to refine the stream info system.
if (is_aac_sequence_header || !cache_sh_audio) {
srs_freep(cache_sh_audio);
cache_sh_audio = msg->copy();
}
// when sequence header, donot push to gop cache and adjust the timestamp.
if (is_sequence_header) {
return ret;
}
// cache the last gop packets
if ((ret = gop_cache->cache(msg)) != ERROR_SUCCESS) {
srs_error("shrink gop cache failed. ret=%d", ret);
return ret;
}
srs_verbose("cache gop success.");
// if aac, update the sequence header to abs time.
if (atc) {
if (cache_sh_audio) {
cache_sh_audio->timestamp = msg->timestamp;
}
if (cache_metadata) {
cache_metadata->timestamp = msg->timestamp;
}
}
return ret;
}调用 SrsAvcAacCodec 类实现的 audio_aac_demux 对接收到的 aac 数据进行解析之前，需要构造两个类对象：SrsAvcAacCodec 和 SrsCodecSample。
5.2.3 SrsAvcAacCodec 构造函数
/*
* the h264/avc and aac codec, for media stream.
*
* to demux the FLV/RTMP video/audio packet to sample,
* add each NALUs of h.264 as a sample unit to sample,
* while the entire aac raw data as a sample unit.
*
* for sequence header,
* demux it and save it in the avc_extra_data and aac_extra_data。
*
* for the codec info, such as audio sample rate,
* decode from FLV/RTMP header, then use codec info in sequence
* header to override it.
*/
SrsAvcAacCodec::SrsAvcAacCodec()
{
/* for sequence header, whether parse the h.264 sps. */
avc_parse_sps = true;
width = 0;
height = 0;
duration = 0;
/* lengthSizeMinusOne, H.264-AVC-ISO_IEC_14496-15.pdf, page 16 */
NAL_unit_length = 0;
frame_rate = 0;
video_data_rate = 0;
video_codec_id = 0;
audio_data_rate = 0;
audio_codec_id = 0;
/* profile_idc, H.264-AVC-ISO_IEC_14496-10.pdf, page 45. */
avc_profile = SrsAvcProfileReserved;
/* level_idc, H.264-AVC-ISO_IEC_14496-10.pdf, page 45. */
avc_level = SrsAvcLevelReserved;
/**
* audio specified
* audioObjectType, in 1.6.2.1 AudioSpecificConfig, page 33,
* 1.5.1.1 Audio object type definition, page 23,
* in aac-mp4a-format-ISO_IEC_14496-3+2001.pdf.
*/
aac_object = SrsAacObjectTypeReserved;
/* samplingFrequencyIndex */
aac_sample_rate = SRS_AAC_SAMPLE_RATE_UNSET; // sample rate ignored
/* channelConfiguration */
aac_channels = 0;
/**
* the avc extra data, the AVC sequence header,
* without the flv codec header,
* @see: ffmpeg, AVCodecContext::extradata
*/
avc_extra_size = 0;
avc_extra_data = NULL;
/**
* the aac extra data, the AAC sequence header,
* without the flv codec header,
* @see: ffmpeg, AVCodecContext::extradata
*/
aac_extra_size = 0;
aac_extra_data = NULL;
sequenceParameterSetLength = 0;
sequenceParameterSetNALUnit = NULL;
pictureParameterSetLength = 0;
pictureParameterSetNALUnit = NULL;
/* the avc payload format. */
payload_format = SrsAvcPayloadFormatGuess;
stream = new SrsStream();
}5.2.4 SrsCodecSample 构造函数
/*
* the samples in the flv audio/video packet.
* the sample used to analysis a video/audio packet,
* split the h.264 NALUs to buffers, or aac raw data to a buffer,
* and decode the video/audio specified infos.
*
* the sample unit:
* a video packet codec in h.264 contains many NALUs, each is a sample unit.
* a audio packet codec in aac is a sample unit.
* @remark, the video/audio sequence header is not sample unit,
* all sequence header stores as extra data,
* @see SrsAvcAacCodec.avc_extra_data and SrsAvcAacCodec.aac_extra_data
* @remark, user must clear all samples before decode a new video/audio packet.
*/
SrsCodecSample::SrsCodecSample()
{
/* 复位所有保存的数据 */
clear();
}
/*
* clear all samples.
* the sample units never copy the bytes, it directly use the ptr,
* so when video/audio packet is destroyed, the sample must be clear.
* in a word, user must clear sample before demux it.
* @remark demux sample use SrsAvcAacCodec.audio_aac_demux or video_avc_demux.
*/
void SrsCodecSample::clear()
{
is_video = false;
nb_sample_units = 0;
cts = 0;
frame_type = SrsCodecVideoAVCFrameReserved;
avc_packet_type = SrsCodecVideoAVCTypeReserved;
has_sps_pps = has_aud = has_idr = false;
first_nalu_type = SrsAvcNaluTypeReserved;
acodec = SrsCodecAudioReserved1;
sound_rate = SrsCodecAudioSampleRateReserved;
sound_size = SrsCodecAudioSampleSizeReserved;
sound_type = SrsCodecAudioSoundTypeReserved;
aac_packet_type = SrsCodecAudioTypeReserved;
}5.2.5 SrsAvcAacCodec::audio_aac_demux
/*
* demux the audio packet in aac codec.
* the packet mux in FLV/RTMP format defined in flv specification.
* demux the audio specified data(sound format, sound_size, ...) to sample.
* demux the aac specified data(aac_profile, ...) to codec from sequence header.
* demux the aac raw sample units.
*/
int SrsAvcAacCodec::audio_aac_demux(char* data, int size, SrsCodecSample* sample)
{
int ret = ERROR_SUCCESS;
sample->is_video = false;
if (!data || size <= 0) {
srs_trace("no audio present, ignore it.");
return ret;
}
if ((ret = stream->initialize(data, size)) != ERROR_SUCCESS) {
return ret;
}
// audio decode
if (!stream->require(1)) {
ret = ERROR_HLS_DECODE_ERROR;
srs_error("aac decode sound_format failed. ret=%d", ret);
return ret;
}
// @see: E.4.2 Audio Tags, video_file_format_spec_v10_1.pdf, page 76
int8_t sound_format = stream->read_1bytes();
/* 音频类型，即声道 */
int8_t sound_type = sound_format & 0x01;
/* 音频采样精度 */
int8_t sound_size = (sound_format >> 1) & 0x01;
/* 音频采样率 */
int8_t sound_rate = (sound_format >> 2) & 0x03;
/* 音频格式，对于 AAC，为 10 */
sound_format = (sound_format >> 4) & 0x0f;
audio_codec_id = sound_format;
sample->acodec = (SrsCodecAudio)audio_codec_id;
sample->sound_type = (SrsCodecAudioSoundType)sound_type;
sample->sound_rate = (SrsCodecAudioSampleRate)sound_rate;
sample->sound_size = (SrsCodecAudioSampleSize)sound_size;
// supoort h.264+mp3 for hls.
if (audio_codec_id == SrsCodecAudioMP3) {
return ERROR_HLS_TRY_MP3;
}
// only support aac
if (audio_codec_id != SrsCodecAudioAAC) {
ret = ERROR_HLS_DECODE_ERROR;
srs_error("aac only support mp3/aac codec. actual=%d, ret=%d",
audio_codec_id, ret);
return ret;
}
if (!stream->require(1)) {
ret = ERROR_HLS_DECODE_ERROR;
srs_error("aac decode aac_packet_type failed. ret=%d", ret);
return ret;
}
/* 读取 1 字节的 AAC Packet Type，检测该 Audio data 为 AAC Sequence Header，还是 AAC Raw */
int8_t aac_packet_type = stream->read_1bytes();
sample->aac_packet_type = (SrsCodecAudioType)aac_packet_type;
/* 若为 AAC Sequence Header */
if (aac_packet_type == SrsCodecAudioTypeSequenceHeader) {
// AudioSpecificConfig
// 1.6.2.1 AudioSpecificConfig,
// in aac-mp4a-format-ISO_IEC_14496-3+2001.pdf, page 33.
aac_extra_size = stream->size() - stream->pos();
if (aac_extra_size > 0) {
srs_freepa(aac_extra_data);
aac_extra_data = new char[aac_extra_size];
memcpy(aac_extra_data, stream->data() + stream->pos(), aac_extra_size);
// demux the sequence header.
if ((ret = audio_aac_sequence_header_demux(aac_extra_data, aac_extra_size))
!= ERROR_SUCCESS) {
return ret;
}
}
/* 否则为 AAC Raw */
} else if (aac_packet_type == SrsCodecAudioTypeRawData) {
// ensure the sequence header demuxed
if (!is_aac_codec_ok()) {
srs_warn("aac ignore type=%d for no sequence header. ret=%d",
aac_packet_type, ret);
return ret;
}
// Raw AAC frame data in UI8 []
// 6.3 Raw Data, aac-iso-13818-7.pdf, page 28
if ((ret = sample->add_sample_unit(stream->data() + stream->pos(),
stream->size() - stream->pos())) != ERROR_SUCCESS) {
srs_error("aac add sample failed. ret=%d", ret);
return ret;
}
} else {
// ignored
}
// reset the sample rate by sequence header
if (aac_sample_rate != SRS_AAC_SAMPLE_RATE_UNSET) {
static int aac_sample_rates[] = {
96000, 88200, 64000, 48000,
44100, 32000, 24000, 22050,
16000, 12000, 11025, 8000,
7350, 0, 0, 0
};
switch (aac_sample_rates[aac_sample_rate]) {
case 11025:
sample->sound_rate = SrsCodecAudioSampleRate11025;
break;
case 22050:
sample->sound_rate = SrsCodecAudioSampleRate22050;
break;
case 44100:
sample->sound_rate = SrsCodecAudioSampleRate44100;
break;
default:
break;
}
}
srs_info("aac decoded, type=%d, codec=%d, asize=%d, rate=%d, format=%d, size=%d",
sound_type, audio_codec_id, sound_size, sound_rate, sound_format, size);
return ret;
}5.2.6 SrsAvcAacCodec::audio_aac_sequence_header_demux
/* directly demux the sequence header, without RTMP packet header. */
int SrsAvcAacCodec::audio_aac_sequence_header_demux(char* data, int size)
{
int ret = ERROR_SUCCESS;
if ((ret = stream->initialize(data, size)) != ERROR_SUCCESS) {
return ret;
}
/* only need to decode the first 2bytes:
* audioObjectType, aac_profile, 5bits.
* samplingFrequencyIndex, aac_sample_rate, 4bites.
* channelConfiguration, aac_channels, 4bits */
if (!stream->require(2)) {
ret = ERROR_HLS_DECODE_ERROR;
srs_error("audio codec decode aac sequence header failed. ret=%d", ret);
return ret;
}
u_int8_t profile_ObjectType = stream->read_1bytes();
u_int8_t samplingFrequencyIndex = stream->read_1bytes();
aac_channels = (samplingFrequencyIndex >> 3) & 0x0f;
samplingFrequencyIndex = ((profile_ObjectType << 1) & 0x0e) |
((samplingFrequencyIndex >> 7) & 0x01);
profile_ObjectType = (profile_ObjectType >> 3) & 0x1f;
// set the aac sample rate.
aac_sampel_rate = samplingFrequencyIndex;
// convert the object tyep in sequence header to aac profile of ADTS.
aac_object = (SrsAacObjectType)profile_ObjectType;
if (aac_object == SrsAacObjectTypeReserved) {
ret = ERROR_HLS_DECODE_ERROR;
srs_error("audio codec decode aac sequence header failed, "
"adts object=%d invalid. ret=%d", profile_ObjectType, ret);
return ret;
}
// TODO: FIXME: to support aac he/he-v2, see: ngx_rtmp_codec_parse_aac_header
//
// donot force to LC, @see: https://github.com/ossrs/srs/issues/81
// the source will print the sequence header info.
//if (aac_profile > 3) {
// Mark all extended profiles as LC
// to make Android as happy as possible.
// @see: ngx_rtmp_hls_parse_aac_header
//aac_profile = 1;
//}
return ret;
}该函数主要是解析 AAC Sequence header。
5.2.7 SrsCodecSample::add_sample_unit
/*
* add the a sample unit, it's a h.264 NALU or aac raw data.
* the sample unit directly use the ptr of packet bytes,
* so user must never use sample unit when packet is destroyed.
* in a word, user must clear sample before demux it.
*/
int SrsCodecSample::add_sample_unit(char* bytes, int size)
{
int ret = ERROR_SUCCESS;
if (nb_sample_units >= SRS_SRS_MAX_CODEC_SAMPLE) {
ret = ERROR_HLS_DECODE_ERROR;
srs_error("hls decode samples error, "
"exceed the max count: %d, ret=%d", SRS_SRS_MAX_CODEC_SAMPLE, ret);
return ret;
}
SrsCodecSampleUnit* sample_uint = &sample_units[nb_sample_units++];
sample_uint->bytes = bytes;
sample_uint->size = size;
// for video, parse the nalu type, set the IDR flag.
if (is_video) {
SrsAvcNaluType nal_uint_type = (SrsAvcNaluType)(bytes[0] & 0x1f);
if (nal_unit_type == SrsAvcNaluTypeIDR) {
has_idr = true;
} else if (nal_unit_type == SrsAvcNaluTypeSPS ||
nal_unit_type == SrsAvcNaluTypePPS) {
has_sps_pps = true;
} else if (nal_unit_type == SrsAvcNaluTypeAccessUnitDelimiter) {
has_aud = true;
}
if (first_nalu_type == SrsAvcNaluTypeReserved) {
first_nalu_type = nal_unit_type;
}
}
return ret;
}5.2.8 SrsGopCache::cache
/* only for h264 codec
* 1. cache the gop when got h264 video packet.
* 2. clear gop when got keyframe.
* @param shared_msg, directly ptr, copy it if need to save it. */
int SrsGopCache::cache(SrsSharedPtrMessage* shared_msg)
{
int ret = ERROR_SUCCESS;
if (!enable_gop_cache) {
srs_verbose("gop cache is disabled.");
return ret;
}
// the gop cache know when to gop it.
SrsSharedPtrMessage* msg = shared_msg;
// got video, update the video count if acceptable
if (msg->is_video()) {
// drop video when not h.264
if (!SrsFlvCodec::video_is_h264(msg->payload, msg->size)) {
srs_info("gop cache drop video for none h.264");
return ret;
}
/* the video frame count, avoid cache for pure audio stream. */
cached_video_count++;
/*
* when user disabled video when publishing, and gop cache enabled,
* we will cache the audio/video for we already got video, but we never
* know when to clear the gop cache, for there is no video in future,
* so we must guess whether user disabled the video.
* when we got some audios after laster video, for instance, 600 audio packets,
* about 3s(26ms per packet) 115 audio packets, clear gop cache.
*
* @remark, it is ok for performance, for when we clear the gop cache,
* gop cache is disabled for pure audio stream.
* @see: https://github.com/ossrs/srs/issues/124
*/
audio_after_last_video_count = 0;
}
// no acceptable video or pure audio, disable the cache.
if (pure_audio()) {
srs_verbose("ignore any frame util got a h264 video frame.");
return ret;
}
// ok, gop cache enabled, and got an audio.
if (msg->is_audio()) {
audio_after_last_video_count++;
}
// clear gop cache when pure audio count overflow
if (audio_after_last_video_count > SRS_PURE_AUDIO_GUESS_COUNT) {
srs_warn("clear gop cache for guess pure audio overflow");
clear();
return ret;
}
// clear gop cache when got key frame
if (msg->is_video() && SrsFlvCodec::video_is_keyframe(msg->payload, msg->size)) {
srs_info("clear gop cache when got keyframe. vcount=%d, count=%d",
cached_video_count, (int)gop_cache.size());
clear();
// current msg is video frame, so we set to 1.
cached_video_count = 1;
}
// cache the frame.
gop_cache.push_back(msg->copy());
return ret;
}该函数是将接收到的音频/视频包保存到 gop_cache 中，但是有两点需要注意：
- 当接收到一个 video packet，且为 keyframe 时，需要将 gop_cache 清空，从新开始缓存，并设当前缓存的 video 计数值 cached_video_count 为 1；
- 用 audio_after_last_video_count 记录自上一次获得 video 后，到下一次再次接收到 video 时，当前已经接收到的 audio 个数，若该值超过 115（26ms per packet， 大概 3s），则假设客户端已经禁止发送 video 了，此时需要清空 gop_cache，不再缓存 audio。
假设接收到的第一个 video 如下图：
参考 多媒体文件格式之FLV 中关于 Video Tag 的分析，可知上图为 AVC Sequence Header，即 sps，pps 数据。
在 SrsRtmpConn::process_publish_message 函数中，若接收到 video，则调用 SrsSource::on_video 函数进行处理。
5.3.1 SrsSource::on_video
int SrsSource::on_video(SrsCommonMessage* shared_video)
{
int ret = ERROR_SUCCESS;
// monotically increate detect.
if (!mix_correct && is_monotically_increate) {
if (last_packet_time > 0 && shared_video->header.timestamp < last_packet_time) {
is_monotonically_increase = false;
srs_warn("VIDEO: stream not monotonically increase, please open mix_correct.");
}
}
last_packet_time = shared_video->header.timestamp;
// drop any unknown header video.
// @see https://github.com/ossrs/srs/issues/421
if (!SrsFlvCodec::video_is_acceptable(shared_video->payload, shared_video->size)) {
char b0 = 0x00;
if (shared_video->size > 0) {
b0 = shared_video->payload[0];
}
srs_warn("drop unknown header video, size=%d, bytes[0]=%#x",
shared_video->size, b0);
return ret;
}
// convert shared_video to msg, user should not use shared_video again.
// the payload is transfer to msg, and set to NULL in shared_video.
SrsSharedPtrMessage msg;
/* 将 shared_video 中的数据拷贝到 msg 中 */
if ((ret = msg.create(shared_video)) != ERROR_SUCCESS) {
srs_error("initialize the video failed. ret=%d", ret);
return ret;
}
srs_info("Video dts=%"PRId64", size=%d", msg.timestamp, msg.size);
// directly process the audio message.
if (!mix_correct) {
return on_video_imp(&msg);
}
// insert msg to the queue.
mix_queue->push(msg.copy());
// fetch someone from mix queue.
SrsSharedPtrMessage* m = mix_queue->pop();
if (!m) {
return ret;
}
// consume the monotonically increase message.
if (m->is_audio()) {
ret = on_audio_imp(m);
} else {
ret = on_video_imp(m);
}
srs_freep(m);
return m;
}该函数中先是检测接收到 video 是正确的消息后，然后构造一个 SrsSharedPtrMessage 类的对象，并将接收到的 video 数据拷贝到该对象中，然后调用 SrsSource::on_video_imp 进行处理.
5.3.2 SrsSource::on_video_imp
int SrsSource::on_video_imp(SrsSharedPtrMessage* msg)
{
int ret = ERROR_SUCCESS;
srs_info("Video dts=%"PRId64", size=%d", msg->timestamp, msg->size);
/* 检测是否是关键帧，并且 videodatatype 为 sequence header，即 sps，pps 数据 */
bool is_sequence_header =
SrsFlvCodec::video_is_sequence_header(msg->payload, msg->size);
// whether consumer should drop for the duplicated sequence header.
bool drop_for_reduce = false;
/* 若配置文件中使能了 reduce_sequence_header 配置项 */
if (is_sequence_header && cache_sh_video &&
_srs_config->get_reduce_sequence_header(_req->vhost)) {
if (cache_sh_video->size == msg->size) {
drop_for_reduce = srs_bytes_equals(cache_sh_video->payload,
msg->payload, msg->size);
srs_warn("drop for reduce sh video, size=%d", msg->size);
}
}
// cache the sequence header if h264
// donot cache the sequence header to gop_cache, return here.
if (is_sequence_header) {
srs_freep(cache_sh_video);
/* the cached video sequence header. */
cache_sh_video = msg->copy();
// parse detail audio codec
SrsAvcAacCodec codec;
/* 默认使能解析 sps */
// user can disable the sps parse to workaround when parse sps failed.
// @see https://github.com/ossrs/srs/issues/474
codec.avc_parse_sps = _srs_config->get_parse_sps(_req->vhost);
SrsCodecSample sample;
if ((ret = codec.video_avc_demux(msg->payload, msg->size, &sample))
!= ERROR_SUCCESS) {
srs_error("source codec demux video failed. ret=%d", ret);
return ret;
}
// when got video stream info.
SrsStatistic* stat = SrsStatistic::instance();
if ((ret = stat->on_video_info(_req, SrsCodecVideoAVC,
codec.avc_profile, codec.avc_level))
!= ERROR_SUCCESS) {
return ret;
}
srs_trace("%dB video sh, "
"codec(%d, profile=%s, level=%s, %dx%d, %dkbps, %dfps, %ds)",
msg->size, codec.video_codec_id,
srs_codec_avc_profile2str(codec.avc_profile).c_str(),
srs_codec_avc_level2str(codec.avc_level).c_str(), codec.width, codec.height,
codec.video_data_rate / 1000, codec.frame_rate, codec.duration);
}
#ifdef SRS_AUTO_HLS
...
#endif
#ifdef SRS_AUTO_DVR
...
#endif
#ifdef SRS_AUTO_HDS
...
#endif
// copy to all consumer
if (!drop_for_reduce) {
for (int i = 0; i < (int)consumers.size(); i++) {
SrsConsumer* consumer = consumers.at(i);
if ((ret = consumer->enqueue(msg, atc, jitter_algorithm)) != ERROR_SUCCESS) {
srs_error("dispatch the video failed. ret=%d", ret);
return ret;
}
}
srs_info("dispatch video success.");
}
// copy to all forwarders.
if (!forwarders.empty()) {
std::vector<SrsForwarder*>::iterator it;
for (it = forwarders.begin(); it != forwarders.end(); ++it) {
SrsForwarder* forwarder = *it;
if ((ret = forwarder->on_video(msg)) != ERROR_SUCCESS) {
srs_error("forwarder process video message failed. ret=%d", ret);
return ret;
}
}
}
// when sequence heeader, donot push to gop cache and adjust the timestamp.
if (is_sequence_header) {
return ret;
}
// cache the last gop packets
if ((ret = gop_cache->cache(msg)) != ERROR_SUCCESS) {
srs_error("gop cache msg failed. ret=%d", ret);
return ret;
}
srs_verbose("cache gop success.");
// if atc, update the sequence header to abs time.
if (atc) {
if (cache_sh_video) {
cache_sh_video->timestamp = msg->timestamp;
}
if (cache_metadata) {
cache_metadata->timestamp = msg->timestamp;
}
}
return ret;
}5.3.3 SrsAvcAacCodec::video_avc_demux
/* demux the video packet in h.264 codec.
* the packet mux in FLV/RTMP format defined in flv specification.
* demux the video specified data(frame_type, codec_id, ...) to sample.
* demux the h.264 specified data(avc_profile, ...) to codec from sequence header.
* demux the h.264 MALUs to sample units. */
int SrsAvcAacCodec::video_avc_demux(char* data, int size, SrsCodecSample* sample)
{
int ret = ERROR_SUCCESS;
sample->is_video = true;
if (!data || size <= 0) {
srs_trace("no video present, ignore it.");
return ret;
}
if ((ret = stream->initialize(data, size)) != ERROR_SUCCESS) {
return ret;
}
// video decode
if (!stream->require(1)) {
ret = ERROR_HLS_DECODE_ERROR;
srs_error("avc decode frame_type failed. ret=%d", ret);
return ret;
}
// @see: E.4.3 Video Tags, video_file_format_spec_v10_1.pdf, page 78
int8_t frame_type = stream->read_1bytes();
/* 获取编码 id，一般为 7，即 AVC 编码，SRS 仅支持 AVC 编码 */
int8_t codec_id = frame_type & 0x0f;
/* 获取帧类型，为 1 则为 keyframe */
frame_type = (frame_type >> 4) & 0x0f;
sample->frame_type = (SrsCodecVideoAVCFrame)frame_type;
// ignore info frame without error,
// @see https://github.com/ossrs/srs/issues/288#issuecomment-69863909
if (sample->frame_type == SrsCodecVideoAVCFrameVideoInfoFrame) {
srs_warn("avc igone the info frame, ret=%d", ret);
return ret;
}
// only support h.264/avc
if (codec_id != SrsCodecVideoAVC) {
ret = ERROR_HLS_DECODE_ERROR;
srs_error("avc only support video h.264/avc codec. actual=%d, ret=%d",
codec_id, ret);
return ret;
}
video_codec_id = codec_id;
if (!stream->require(4)) {
ret = ERROR_HLS_DECODE_ERROR;
srs_error("avc decode avc_packet_type failed. ret=%d", ret);
return ret;
}
/* 获取 AVC packet 类型，0：AVC Sequence Header，1: AVC NALU Units */
int8_t avc_packet_type = stream->read_1bytes();
/* 获取 cts，如果 avc_packet_type 为 1，则为 cts 偏移，否则为 0 则为 0 */
int32_t composition_time = stream->read_3bytes();
// pts = dts + ctx.
sample->ctx = composition_time;
sample->avc_packet_type = (SrsCodecVideoAVCType)avc_packet_type;
/* 若为 AVC Sequence Header，则解码 sps，pps */
if (avc_packet_type == SrsCodecVideoAVCTypeSequenceHeader) {
if ((ret = avc_demux_sps_pps(stream)) != ERROR_SUCCESS) {
return ret;
}
/* 若为 AVC NALU Unit，则解码 H.264 NALU */
} else if (avc_packet_type == SrsCodecVideoAVCTypeNALU) {
if ((ret = video_nalu_demux(stream, sample)) != ERROR_SUCCESS) {
return ret;
}
} else {
/ ignored.
}
srs_info("avc decoded, type=%d, codec=%d, avc=%d, cts=%d, size=%d",
frame_type, video_codec_id, avc_packet_type, composition_time, size);
return ret;
}5.3.4 SrsAvcAacCodec::avc_demux_sps_pps
int SrsAvcAacCodec::avc_demux_sps_pps(SrsStream* stream)
{
int ret = ERROR_SUCCESS;
// AVCDecoderConfigurationRecord
// 5.2.4.1.1 Syntax, H.264-AVC-ISO_IEC_14496-15.pdf, page 16
avc_extra_size = stream->size() - stream->pos();
if (avc_extra_size > 0) {
srs_freepa(avc_extra_data);
avc_extra_data = new char[avc_extra_size];
memcpy(avc_extra_data, stream->data() + stream->pos(), avc_extra_size);
}
if (!stream->require(6)) {
ret = ERROR_HLS_DECODE_ERROR;
srs_error("avc decode sequenc header failed. ret=%d", ret);
return ret;
}
// int8_t configurationVersion = stream->read_1bytes();
stream->read_1bytes(); // configurationVersion
// int8_t AVCProfileIndication = stream->read_1bytes();
/*
* the profile for avc/h.264.
* @see Annex A Profiles and levels, H.264-AVC-ISO_IEC_14496-10.pdf, page 205.
*/
avc_profile = (SrsAvcProfile)stream->read_1bytes(); // AVCProfileIndication
// int8_t profile_compatibility = stream->read_1bytes();
stream->read_1bytes(); // profile_compatibility
// int8_t AVCLevelIndication = stream->read_1bytes();
avc_level = (SrsAvcLevel)stream->read_1bytes(); // AVCLevelIndication
// parse the NALU size.
int8_t lengthSizeMinusOne = stream->read_1bytes();
lengthSizeMinusOne &= 0x03;
/* lengthSizeMinusOne，一般为 3, H.264-AVC-ISO_IEC_14496-15.pdf, page 16 */
NAL_unit_length = lengthSizeMinusOne;
// 5.3.4.2.1 Syntax, H.264-AVC-ISO_IEC_14496-15.pdf, page 16
// 5.2.4.1 AVC decoder configuration record
// 5.2.4.1.2 Semantics
// The value of this field shall be one of 0, 1, or 3 corresponding to a
// length encoded with 1, 2, or 4 bytes, respectively.
if (NAL_unit_length == 2) {
ret = ERROR_HLS_DECODE_ERROR;
srs_error("sps lengthSizeMinusOne should never be 2. ret=%d", ret);
return ret;
}
// 1 sps, 7.3.2.1 Sequence parameter set RBSP syntax
// H.264-AVC-ISO_IEC_14496-10.pdf, page 45.
if (!stream->require(1)) {
ret = ERROR_HLS_DECODE_ERROR;
srs_error("avc decode sequenc header sps failed. ret=%d", ret);
return ret;
}
int8_t numOfSequenceParameterSets = stream->read_1bytes();
/* 获取 SPS NALU 的个数，一般为 1 */
numOfSequenceParameterSets &= 0x1f;
if (numOfSequenceParameterSets != 1) {
ret = ERROR_HLS_DECODE_ERROR;
srs_error("avc decode sequenc header sps failed. ret=%d", ret);
return ret;
}
if (!stream->require(2)) {
ret = ERROR_HLS_DECODE_ERROR;
srs_error("avc decode sequenc header sps size failed. ret=%d", ret);
return ret;
}
/* 获取该 SPS NALU 的大小 */
sequenceParameterSetLength = stream->read_2bytes();
if (!stream->require(sequenceParameterSetLength)) {
ret = ERROR_HLS_DECODE_ERROR;
srs_error("avc decode sequenc header sps data failed. ret=%d", ret);
return ret;
}
if (sequenceParameterSetLength > 0) {
srs_freepa(sequenceParameterSetNALUnit);
sequenceParameterSetNALUnit = new char[sequenceParameterSetLength];
/* 将 SPS NALU 的数据拷贝到 sequenceParameterSetNALUnit 中 */
stream->read_bytes(sequenceParameterSetNALUnit, sequenceParameterSetLength);
}
// 1 pps
if (!stream->require(1)) {
ret = ERROR_HLS_DECODE_ERROR;
srs_error("avc decode sequenc header pps failed. ret=%d", ret);
return ret;
}
int8_t numOfPictureParameterSets = stream->read_1bytes();
/* 获取 PPS NALU 的个数，一般为 1 */
numOfPictureParameterSets &= 0x1f;
if (numOfPictureParameterSets != 1) {
ret = ERROR_HLS_DECODE_ERROR;
srs_error("avc decode sequenc header pps failed. ret=%d", ret);
return ret;
}
if (!stream->require(2)) {
ret = ERROR_HLS_DECODE_ERROR;
srs_error("avc decode sequenc header pps size failed. ret=%d", ret);
return ret;
}
pictureParameterSetLength = stream->read_2bytes();
if (!stream->require(pictureParameterSetLength)) {
ret = ERROR_HLS_DECODE_ERROR;
srs_error("avc decode sequenc header pps data failed. ret=%d", ret);
return ret;
}
if (pictureParameterSetLength > 0) {
srs_freepa(pictureParameterSetNALUnit);
pictureParameterSetNALUnit = new char[pictureParameterSetLength];
/* 将 PPS NALU 的数据拷贝到 pictureParameterSetNALUnit 中 */
stream->read_bytes(pictureParameterSetNALUnit, pictureParameterSetLength);
}
/* 解析 SPS NALU */
return avc_demux_sps();
}该函数分别将 SPS 和 PPS 提取保存到 sequenceParameterSetNALUnit 和 pictureParameterSetNALUnit，最后调用 avc_demux_sps 函数解析 SPS。
5.3.5 SrsAvcAacCodec::avc_demux_sps
/* decode the sps rbsp stream. */
int SrsAvcAacCodec::avc_demux_sps()
{
int ret = ERROR_SUCCESS;
if (!sequenceParameterSetLength) {
return ret;
}
SrsStream stream;
if ((ret = stream.initialize(sequenceParameterSetNALUnit, sequenceParameterSetLength))
!= ERROR_SUCCESS) {
return ret;
}
// for NALU, 7.3.1 NAL unit syntax
// H.264-AVC-ISO_IEC_14496-10-2012.pdf, page 61.
if (!stream.require(1)) {
ret = ERROR_HLS_DECODE_ERROR;
srs_error("avc decode sps failed. ret=%d", ret);
return ret;
}
int8_t nutv = stream.read_1bytes();
/* 禁止位 */
// forbidden_zero_bit shall be equal to 0.
int8_t forbidden_zero_bit = (nutv >> 7) & 0x01;
if (forbidden_zero_bit) {
ret = ERROR_HLS_DECODE_ERROR;
srs_error("forbidden_zero_bit shall be equal to 0. ret=%d", ret);
return ret;
}
/* 重要性指示位 */
// nal_ref_idc not equal to 0 specifies that the content
// of the NAL nuit contains a sequence parameter set or a picture
// parameter set or a slice of reference picture
// or a slice data partition of a reference picture.
int8_t nal_ref_idc = (nutv >> 5) & 0x03;
if (!nal_ref_idc) {
ret = ERROR_HLS_DECODE_ERROR;
srs_error("for sps, nal_ref_idc shall be not be equal to 0. ret=%d", ret);
return ret;
}
/* NAL 单元类型，这里必须为 7，即 SPS */
// 7.4.1 NAL unit semantics
// H.264-AVC-ISO_IEC_14496-10-2012.pdf, page 61.
// nal_unit_type specifies the type of RBSP data structure contained
// in the NAL unit as specified in Table 7-1.
SrsAvcNaluType nal_unit_type = (SrsAvcNaluType)(nutv & 0x1f);
if (nal_unit_type != 7) {
ret = ERROR_HLS_DECODE_ERROR;
srs_error("for sps, nal_unit_type shall be equal to 7. ret=%d", ret);
return ret;
}
// decode the rbsp from sps.
// rbsp[ i ] a raw byte sequence payload is specified as an ordered sequence of bytes.
int8_t* rbsp = new int8_t[sequenceParameterSetLength];
SrsAutoFreeA(int8_t, rbsp);
/* 遍历 EBSP 数据，找到并丢弃 0x03 字节，也即将 EBSP 转为 RBSP */
int nb_rbsp = 0;
while (!stream.empty()) {
rbsp[nb_rbsp] = stream.read_1bytes();
// XX 00 00 03 XX, the 03 byte should be drop.
if (nb_rbsp > 2 && rbsp[nb_rbsp - 2] == 0 && rbsp[nb_rbsp - 1] == 0 &&
rbsp[nb_rbsp] == 3) {
// read 1byte more.
if (stream.empty()) {
break;
}
rbsp[nb_rbsp] = stream.read_1bytes();
nb_rbsp++;
continue;
}
nb_rbsp++;
}
/* 对提取到的 RBSP 数据进行解析 */
return avc_demux_sps_rbsp((char*)rbsp, nb_rbsp);
}5.3.6 SrsAvcAacCodec::avc_demux_sps_rbsp
int SrsAvcAacCodec::avc_demux_sps_rbsp(char* rbsp, int nb_rbsp)
{
int ret = ERROR_SUCCESS;
/* 若配置文件中配置禁止解析 sps，则直接返回 */
// we donot parse the detail of sps.
// @see https://github.com/ossrs/srs/issues/474
if (!avc_parse_sps) {
return ret;
}
// reparse the rbsp.
SrsStream stream;
if ((ret = stream.initialize(rbsp, nb_rbsp)) != ERROR_SUCCESS) {
return ret;
}
// for SPS, 7.3.2.1.1 Sequence parameter set data syntax
// H.264-AVC-ISO_IEC_14496-10-2012.pdf, page 62.
if (!stream.require(3)) {
ret = ERROR_HLS_DECODE_ERROR;
srs_error("sps shall atleast 3bytes. ret=%d", ret);
return ret;
}
/* 本视频编码时遵循的 profile，profile 分为 Baseline，Main，Extended 等，
* 主要用来规定编码时是否采用某些特性，比如说 Baseline Profile 就规定了
* 只能使用 I、P slice 进行编码，关于 profile 的说明可以去查看标准的
* Annex A
*/
u_int8_t profile_idc = stream.read_1bytes();
if (!profile_idc) {
ret = ERROR_HLS_DECODE_ERROR;
srs_error("sps the profile_idc invalid. ret=%d", ret);
return ret;
}
int8_t flags = stream.read_1bytes();
if (flags & 0x03) {
ret = ERROR_HLS_DECODE_ERROR;
srs_error("sps the flags invalid. ret=%d", ret);
return ret;
}
/* 本视频遵循的 level，level 主要规定了每秒最多能处理多少个宏块，
* 最大的帧大小，最大的解码缓存，最大的比特率等这些性能相关的东西，
* 如果是硬解码，则比较容易出现由于视频 level 太高而不能解码的
* 情况。
*/
u_int8_t level_idc = stream.read_1bytes();
if (!level_idc) {
ret = ERROR_HLS_DECODE_ERROR;
srs_error("sps the level_idc invalid. ret=%d", ret);
return ret;
}
SrsBitStream bs;
if ((ret = bs.initialize(&stream)) != ERROR_SUCCESS) {
return ret;
}
/* 本 SPS 的 ID，这个 ID 主要是给 PPS 用的 */
int32_t seq_parameter_set_id = -1;
if ((ret = srs_avc_nalu_read_uev(&bs, seq_parameter_set_id)) != ERROR_SUCCESS) {
return ret;
}
if (seq_parameter_set_id < 0) {
ret = ERROR_HLS_DECODE_ERROR;
srs_error("sps the seq_parameter_set_id invalid. ret=%d", ret);
return ret;
}
srs_info("sps parse profile=%d, level=%d, sps_id=%d", profile_idc,
level_idc, seq_parameter_set_id);
int32_t chroma_format_idc = -1;
if (profile_idc == 100 || profile_idc == 110 || profile_idc == 122
|| profile_idc == 244 || profile_idc == 44 || profile_idc == 83
|| profile_idc == 86 || profile_idc == 118 || profile_idc == 128
) {
if ((ret = srs_avc_nalu_read_uev(&bs, chroma_format_idc)) != ERROR_SUCCESS) {
return ret;
}
if (chroma_format_idc == 3) {
int8_t separate_colour_plane_flag = -1;
if ((ret = srs_avc_nalu_read_bit(&bs, separate_colour_plane_flag))
!= ERROR_SUCCESS) {
return ret;
}
}
int32_t bit_depth_luma_minus8 = -1;
if ((ret = srs_avc_nalu_read_uev(&bs, bit_depth_luma_minus8)) != ERROR_SUCCESS) {
return ret;
}
int32_t bit_depth_chroma_minus8 = -1;
if ((ret = srs_avc_nalu_read_uev(&bs, bit_depth_chroma_minus8)) != ERROR_SUCCESS)
{
return ret;
}
int8_t qpprime_y_zero_transform_bypass_flag = -1;
if ((ret = srs_avc_nalu_read_bit(&bs, qpprime_y_zero_transform_bypass_flag))
!= ERROR_SUCCESS) {
return ret;
}
int8_t seq_scaling_matrix_present_flag = -1;
if ((ret = srs_avc_nalu_read_bit(&bs, seq_scaling_matrix_present_flag))
!= ERROR_SUCCESS) {
return ret;
}
if (seq_scaling_matrix_present_flag) {
int nb_scmpfs = ((chroma_format_idc != 3)? 8:12);
for (int i = 0; i < nb_scmpfs; i++) {
int8_t seq_scaling_matrix_present_flag_i = -1;
if ((ret = srs_avc_nalu_read_bit(&bs, seq_scaling_matrix_present_flag_i))
!= ERROR_SUCCESS) {
return ret;
}
}
}
}
int32_t log2_max_frame_num_minus4 = -1;
if ((ret = srs_avc_nalu_read_uev(&bs, log2_max_frame_num_minus4)) != ERROR_SUCCESS) {
return ret;
}
int32_t pic_order_cnt_type = -1;
if ((ret = srs_avc_nalu_read_uev(&bs, pic_order_cnt_type)) != ERROR_SUCCESS) {
return ret;
}
if (pic_order_cnt_type == 0) {
int32_t log2_max_pic_order_cnt_lsb_minus4 = -1;
if ((ret = srs_avc_nalu_read_uev(&bs, log2_max_pic_order_cnt_lsb_minus4))
!= ERROR_SUCCESS) {
return ret;
}
} else if (pic_order_cnt_type == 1) {
int8_t delta_pic_order_always_zero_flag = -1;
if ((ret = srs_avc_nalu_read_bit(&bs, delta_pic_order_always_zero_flag))
!= ERROR_SUCCESS) {
return ret;
}
int32_t offset_for_non_ref_pic = -1;
if ((ret = srs_avc_nalu_read_uev(&bs, offset_for_non_ref_pic))
!= ERROR_SUCCESS) {
return ret;
}
int32_t offset_for_top_to_bottom_field = -1;
if ((ret = srs_avc_nalu_read_uev(&bs, offset_for_top_to_bottom_field))
!= ERROR_SUCCESS) {
return ret;
}
int32_t num_ref_frames_in_pic_order_cnt_cycle = -1;
if ((ret = srs_avc_nalu_read_uev(&bs, num_ref_frames_in_pic_order_cnt_cycle))
!= ERROR_SUCCESS) {
return ret;
}
if (num_ref_frames_in_pic_order_cnt_cycle < 0) {
ret = ERROR_HLS_DECODE_ERROR;
srs_error("sps the num_ref_frames_in_pic_order_cnt_cycle invalid. ret=%d",
ret);
return ret;
}
for (int i = 0; i < num_ref_frames_in_pic_order_cnt_cycle; i++) {
int32_t offset_for_ref_frame_i = -1;
if ((ret = srs_avc_nalu_read_uev(&bs, offset_for_ref_frame_i))
!= ERROR_SUCCESS) {
return ret;
}
}
}
/* 参考帧最多能有多少个 */
int32_t max_num_ref_frames = -1;
if ((ret = srs_avc_nalu_read_uev(&bs, max_num_ref_frames)) != ERROR_SUCCESS) {
return ret;
}
/* 由于码流在传输过程中可能出现丢包的情况，从而导致中间有帧缺失，
* 如果制定了这个标记，则会在解码时对帧丢失的情况进行调整，否则
* 就当做意外丢失处理 */
int8_t gaps_in_frame_num_value_allowed_flag = -1;
if ((ret = srs_avc_nalu_read_bit(&bs, gaps_in_frame_num_value_allowed_flag))
!= ERROR_SUCCESS) {
return ret;
}
/* 图片宽度（宏块为单位）- 1 */
int32_t pic_width_in_mbs_minus1 = -1;
if ((ret = srs_avc_nalu_read_uev(&bs, pic_width_in_mbs_minus1))
!= ERROR_SUCCESS) {
return ret;
}
/* 图片高度（宏块为单位）- 1 */
int32_t pic_height_in_map_units_minus1 = -1;
if ((ret = srs_avc_nalu_read_uev(&bs, pic_height_in_map_units_minus1))
!= ERROR_SUCCESS) {
return ret;
}
width = (int)(pic_width_in_mbs_minus1 + 1) * 16;
height = (int)(pic_height_in_map_units_minus1 + 1) * 16;
return ret;
}手机扫一扫
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