音视频流媒体开发视频解析：

FFmpeg之音视频同步原理分析

音视频推流直播技术要点分析

这一节主要讲述srs推拉流转发原理以及和配置文件的关系，重点内容：

• RTMP端口监听逻辑
• RTMP推流怎么创建连接
• RTMP拉流怎么创建连接
• 服务器怎么读取RTMP推流数据
• 服务器怎么给RTMP拉流端转发数据
• 哪些配置文件会影响RTMP的延迟

本文不纠结细节，只是理清整个RTMP推拉流脉络以及延迟的问题，并且不能单靠本文理解，还要结合对应的视频去理解。

我们主要通过gdb调试的方式分析RTMP推拉流逻辑，为了方便debug，需要修改配置srs.conf配置文件

PS：不只是SRS使用gdb调试分析源码有效，在分析nginx、redis源码时该方法同样有效。

阅读前须知：

本文撰写和视频录制时是采用SRS v4.0.98，和目最新版本（v4.0.115）有几个类在命名上有一定的区别，但作用是不变的：

1 RTMP端口监听逻辑

RTMP基于TCP连接，必然存在：

• listen监听端口
• accept接收一个套接字中已建立的连接
• 然后new一个RTMP连接对象关联accept得到的fd。

我们可以从该逻辑出发探索SRS 是如何监听和创建RTMP连接。

1.1 listen监听逻辑

通过在配置文件对应的接口打断点分析SRS代码逻辑屡试不爽，比如我们知道RTMP监听端口对应配置文件的配置项为：

，我们可以在srs_app_config.cpp(所有的配置文件读取解析都在该文件)文件的vector<string> SrsConfig::get_listens()接口打断点。

最终发现RTMP监听是通过SrsTcpListener::listen()调用srs_tcp_listen，SrsTcpListener类并创建Coroutine处理accept。

可以根据该调用栈去分析源码：

#0 SrsConfig::get_listens[abi:cxx11]() (this=0xf5d3a0) at src/app/srs_app_config.cpp:4124#1 0x00000000004f78de in SrsServer::listen_rtmp (this=0xf5daa0) at src/app/srs_app_server.cpp:1326

#2 0x00000000004f4681 in SrsServer::listen (this=0xf5daa0) at src/app/srs_app_server.cpp:906

#3 0x000000000061008e in SrsServerAdapter::run (this=0xf5de30) at src/app/srs_app_hybrid.cpp:177

#4 0x0000000000610828 in SrsHybridServer::run (this=0xf592e0) at src/app/srs_app_hybrid.cpp:279

#5 0x00000000006c246b in run_hybrid_server () at src/main/srs_main_server.cpp:483

#6 0x00000000006c1ff0 in run_directly_or_daemon () at src/main/srs_main_server.cpp:418

#7 0x00000000006c096c in do_main (argc=3, argv=0x7fffffffe4e8) at src/main/srs_main_server.cpp:210

#8 0x00000000006c0b4e in main (argc=3, argv=0x7fffffffe4e8) at src/main/srs_main_server.cpp:221

进一步阅读SrsServer::listen_rtmp()函数。

1.2 accept有新socket到来

每个监听都会绑定一个Coroutine处理accept，当有新socket连接到来，则触发accept，通过一层层回调调用到SrsServer::accept_client。

::accept 断点

#0 accept () at ../sysdeps/unix/syscall-template.S:84#1 0x00000000006c5068 in st_accept (fd=0xf881e0, addr=0x0, addrlen=0x0, timeout=18446744073709551615) at io.c:282

#2 0x00000000004da66c in srs_accept (stfd=0xf881e0, addr=0x0, addrlen=0x0, timeout=-1) at src/protocol/srs_service_st.cpp:436

#3 0x00000000005eeacf in SrsTcpListener::cycle (this=0xf8c6b0) at src/app/srs_app_listener.cpp:278

#4 0x0000000000542ab6 in SrsFastCoroutine::cycle (this=0xf8c790) at src/app/srs_app_st.cpp:270

#5 0x0000000000542b4c in SrsFastCoroutine::pfn (arg=0xf8c790) at src/app/srs_app_st.cpp:285

#6 0x00000000006c311d in _st_thread_main () at sched.c:363

#7 0x00000000006c399a in st_thread_create (start=0x7ffff6f07b78 <main_arena+88>, arg=0x7ffff6f07b78 <main_arena+88>,

joinable=0, stk_size=9998) at sched.c:694

可以分析到是在 SrsTcpListener::cycle进行accept。

我们可以在srs_app_listener.cpp:287行打上断点，当有RTMP客户端请求连接时触发该断点，然后进入handler->on_tcp_client。

最终RTMP业务回调到SrsServer::accept_client函数，这里我就不绕弯子，直接在SrsServer::accept_client也断点。

SrsServer::accept_client断点

可以从以下堆栈显然得出对于RTMP业务，最终是：

SrsTcpListener::cycle -> SrsBufferListener::on_tcp_client ->SrsServer::accept_client

#0 SrsServer::accept_client (this=0xf5daa0, type=SrsListenerRtmpStream, stfd=0x1043540) at src/app/srs_app_server.cpp:1574

#1 0x00000000004ee490 in SrsBufferListener::on_tcp_client (this=0xf8bc90, stfd=0x1043540)

at src/app/srs_app_server.cpp:134

#2 0x00000000005eeb87 in SrsTcpListener::cycle (this=0xf8bec0) at src/app/srs_app_listener.cpp:287

#3 0x0000000000542ab6 in SrsFastCoroutine::cycle (this=0xf8bfa0) at src/app/srs_app_st.cpp:270

#4 0x0000000000542b4c in SrsFastCoroutine::pfn (arg=0xf8bfa0) at src/app/srs_app_st.cpp:285

#5 0x00000000006c311d in _st_thread_main () at sched.c:363

#6 0x00000000006c399a in st_thread_create (start=0x7ffff6f07b78 <main_arena+88>,

arg=0x7ffff6f07b78 <main_arena+88>, joinable=0, stk_size=9998) at sched.c:694

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1.3 new SrsRtmpConn新建一个连接对象

不管RTMP是推流还是拉流，每个连接在服务器都对应一个SrsRtmpConn对象。SrsRtmpConn持有连接对应的fd。在SrsRtmpConn::SrsRtmpConn(SrsServer* svr, srs_netfd_t c, string cip, int cport)构造函数断点。

堆栈如下所示：

#0 SrsRtmpConn::SrsRtmpConn (this=0x1043570, svr=0xf5daa0, c=0x1043540, cip="\340\313\371\000\000\000\000\000\016\000\000\000\000\000\000\000\062\062\060.202.216.45\000\000\220+\004\001\000\000\000\000\060+\004\001\000\000\000\000\220+\004\001\000\000\000\000\000\257\337Xu\347\377A\001", '\000' <repeats 15 times>, "\200\314\371\000\000\000\000\000\206\206M\000\000\000\000\000\260\314\371\000\000\000\000\000\200\315\371\000\000\000\000\000p\323\365\000\000\000\000\000h\323\365", '\000' <repeats 13 times>, "(", '\000' <repeats 15 times>, "\060+\004\001\000\000\000\000\030\214\234\000\000\000\000\000\210\314\371\000\000\000\000\000\b\000\000\000\000\000\000\000b6b8j39u\000\000\000\000\000\000\000\000"..., cport=17852, __in_chrg=<optimized out>,

__vtt_parm=<optimized out>) at src/app/srs_app_rtmp_conn.cpp:108

#1 0x00000000004f9972 in SrsServer::fd_to_resource (this=0xf5daa0,type=SrsListenerRtmpStream, stfd=0x1043540,

pr=0xf9cd58) at src/app/srs_app_server.cpp:1646

#2 0x00000000004f937f in SrsServer::accept_client (this=0xf5daa0, type=SrsListenerRtmpStream, stfd=0x1043540)

at src/app/srs_app_server.cpp:1579

#3 0x00000000004ee490 in SrsBufferListener::on_tcp_client (this=0xf8bc90, stfd=0x1043540)

at src/app/srs_app_server.cpp:134

#4 0x00000000005eeb87 in SrsTcpListener::cycle (this=0xf8bec0) at src/app/srs_app_listener.cpp:287

#5 0x0000000000542ab6 in SrsFastCoroutine::cycle (this=0xf8bfa0) at src/app/srs_app_st.cpp:270

#6 0x0000000000542b4c in SrsFastCoroutine::pfn (arg=0xf8bfa0) at src/app/srs_app_st.cpp:285

#7 0x00000000006c311d in _st_thread_main () at sched.c:363

#8 0x00000000006c399a in st_thread_create (start=0x7ffff6f07b78 <main_arena+88>,

arg=0x7ffff6f07b78 <main_arena+88>, joinable=0, stk_size=9998) at sched.c:694

2 RTMP推流、拉流怎么创建连接

RTMP推流和拉流创建连接对象的方式是一致的，都是创建了SrsRtmpConn。

每个SrsRtmpConn都绑定一个SrsCoroutine，具体的业务处理在SrsCoroutine的循环进行，对于RTMP而言最终的循环为SrsRtmpConn::cycle。

对于推流和拉流都是在SrsRtmpConn::cycle，只是最终：

• 推流SrsRtmpConn::do_publishing
• 拉流SrsRtmpConn::do_playing

具体是在SrsRtmpConn::stream_service_cycle根据RTMP交换协议决定的流程走向。

要启动协程，需要调用：SrsRtmpConn::start()

PS：熟悉协程的原理，对于理解SRS源码非常有帮助。

2.1 推流

2.1.1 判断是不是推流SrsRtmpServer::identify_client

在SrsRtmpConn::stream_service_cycle调用SrsRtmpServer::identify_client判断是不是推流。从这里也可以看出来SrsRtmpConn不会直接和socket数据打交道。

Breakpoint 8, SrsRtmpServer::identify_fmle_publish_client (this=0x104d3c0, req=0x10efbc0, type=@0x11059c8: SrsRtmpConnUnknown, stream_name="") at src/protocol/srs_rtmp_stack.cpp:3009

3009 srs_error_t err = srs_success;

(gdb) bt

#0 SrsRtmpServer::identify_fmle_publish_client (this=0x104d3c0, req=0x10efbc0,

type=@0x11059c8: SrsRtmpConnUnknown, stream_name="") at src/protocol/srs_rtmp_stack.cpp:3009

#1 0x0000000000493078 in SrsRtmpServer::identify_client (this=0x104d3c0, stream_id=1,

type=@0x11059c8: SrsRtmpConnUnknown, stream_name="", duration=@0x10efba8: -1)

at src/protocol/srs_rtmp_stack.cpp:2579

#2 0x000000000050c6f5 in SrsRtmpConn::stream_service_cycle (this=0x104ccc0) at src/app/srs_app_rtmp_conn.cpp:472

#3 0x000000000050c304 in SrsRtmpConn::service_cycle (this=0x104ccc0) at src/app/srs_app_rtmp_conn.cpp:420

#4 0x000000000050adc5 in SrsRtmpConn::do_cycle (this=0x104ccc0) at src/app/srs_app_rtmp_conn.cpp:233

#5 0x0000000000513af5 in SrsRtmpConn::cycle (this=0x104ccc0) at src/app/srs_app_rtmp_conn.cpp:1474

#6 0x0000000000542ab6 in SrsFastCoroutine::cycle (this=0x10cbb30) at src/app/srs_app_st.cpp:270

#7 0x0000000000542b4c in SrsFastCoroutine::pfn (arg=0x10cbb30) at src/app/srs_app_st.cpp:285

#8 0x00000000006c311d in _st_thread_main () at sched.c:363

#9 0x00000000006c399a in st_thread_create (start=0x542b2c <SrsFastCoroutine::pfn(void*)>, arg=0x10cbb30,

joinable=1, stk_size=65536) at sched.c:694

调用SrsProtocol::decode_message(SrsCommonMessage* msg, SrsPacket** ppacket) 去判断对应数据是属于哪一种类型消息。这里具体的细节需要去阅读RTMP手册。

2.1.2 进入推流循环SrsRtmpConn::do_publishing

SrsRtmpConn::do_publishing 不实际读取推流过来的数据，具体读取推流数据是通过SrsPublishRecvThread类。

Breakpoint 5, SrsRtmpConn::do_publishing (this=0x105f740, source=0x104bdc0, rtrd=0x1072480) at src/app/srs_app_rtmp_conn.cpp:879

879 {

(gdb) bt

#0 SrsRtmpConn::do_publishing (this=0x105f740, source=0x104bdc0, rtrd=0x1072480)

at src/app/srs_app_rtmp_conn.cpp:879

#1 0x00000000005100d8 in SrsRtmpConn::publishing (this=0x105f740, source=0x104bdc0)

at src/app/srs_app_rtmp_conn.cpp:860

#2 0x000000000050d5ac in SrsRtmpConn::stream_service_cycle (this=0x105f740) at src/app/srs_app_rtmp_conn.cpp:566

#3 0x000000000050c304 in SrsRtmpConn::service_cycle (this=0x105f740) at src/app/srs_app_rtmp_conn.cpp:420

#4 0x000000000050adc5 in SrsRtmpConn::do_cycle (this=0x105f740) at src/app/srs_app_rtmp_conn.cpp:233

#5 0x0000000000513af5 in SrsRtmpConn::cycle (this=0x105f740) at src/app/srs_app_rtmp_conn.cpp:1474

#6 0x0000000000542ab6 in SrsFastCoroutine::cycle (this=0x1060020) at src/app/srs_app_st.cpp:270

#7 0x0000000000542b4c in SrsFastCoroutine::pfn (arg=0x1060020) at src/app/srs_app_st.cpp:285

#8 0x00000000006c311d in _st_thread_main () at sched.c:363

#9 0x00000000006c399a in st_thread_create (start=0x542b2c <SrsFastCoroutine::pfn(void*)>, arg=0x1060020,

joinable=1, stk_size=65536) at sched.c:694

2.2 拉流

2.2.1 判断是不是推流SrsRtmpServer::identify_client

和RTMP推流判断同理

2.2.2 进入拉流循环SrsRtmpConn::do_playing

Breakpoint 16, SrsRtmpConn::do_playing (this=0x11011c0, source=0x1044580, consumer=0x1045de0, rtrd=0x113f0f0) at src/app/srs_app_rtmp_conn.cpp:713

713 {

(gdb) bt

#0 SrsRtmpConn::do_playing (this=0x11011c0, source=0x1044580, consumer=0x1045de0, rtrd=0x113f0f0)

at src/app/srs_app_rtmp_conn.cpp:713

#1 0x000000000050ebc2 in SrsRtmpConn::playing (this=0x11011c0, source=0x1044580)

at src/app/srs_app_rtmp_conn.cpp:699

#2 0x000000000050d4d2 in SrsRtmpConn::stream_service_cycle (this=0x11011c0)

at src/app/srs_app_rtmp_conn.cpp:556

#3 0x000000000050c304 in SrsRtmpConn::service_cycle (this=0x11011c0) at src/app/srs_app_rtmp_conn.cpp:420

#4 0x000000000050adc5 in SrsRtmpConn::do_cycle (this=0x11011c0) at src/app/srs_app_rtmp_conn.cpp:233

#5 0x0000000000513af5 in SrsRtmpConn::cycle (this=0x11011c0) at src/app/srs_app_rtmp_conn.cpp:1474

#6 0x0000000000542ab6 in SrsFastCoroutine::cycle (this=0x1102780) at src/app/srs_app_st.cpp:270

#7 0x0000000000542b4c in SrsFastCoroutine::pfn (arg=0x1102780) at src/app/srs_app_st.cpp:285

#8 0x00000000006c311d in _st_thread_main () at sched.c:363

#9 0x00000000006c399a in st_thread_create (start=0x542b2c <SrsFastCoroutine::pfn(void*)>, arg=0x1102780,

joinable=1, stk_size=65536) at sched.c:694

服务器怎么把推流的音视频消息转发给拉流端，后续讲解。

3 服务器怎么读取RTMP推流数据

通过SrsPublishRecvThread读取推流数据。通过SrsSource和SrsConsumer的关系转发RTMP音视频数据。

推流数据转发给拉流

• SrsSource::on_video_imp(SrsSharedPtrMessage* msg)
• SrsSource::on_audio_imp(SrsSharedPtrMessage* msg)

拉流通过SrsConsumer::enqueue缓存音视频数据

3.1 SrsSource::on_video_imp调用栈

#0 SrsSource::on_video_imp (this=0x105fb30, msg=0x7ffff7fc5a70) at src/app/srs_app_source.cpp:2333#1 0x000000000051fb11 in SrsSource::on_video (this=0x105fb30, shared_video=0x10aac50)

at src/app/srs_app_source.cpp:2309

#2 0x0000000000511798 in SrsRtmpConn::process_publish_message (this=0x1043570, source=0x105fb30,

msg=0x10aac50) at src/app/srs_app_rtmp_conn.cpp:1079

#3 0x0000000000511598 in SrsRtmpConn::handle_publish_message (this=0x1043570, source=0x105fb30,

msg=0x10aac50) at src/app/srs_app_rtmp_conn.cpp:1051

#4 0x00000000005d364c in SrsPublishRecvThread::consume (this=0x105dbc0, msg=0x10aac50)

at src/app/srs_app_recv_thread.cpp:396

#5 0x00000000005d1e35 in SrsRecvThread::do_cycle (this=0x105dbd0) at src/app/srs_app_recv_thread.cpp:150

#6 0x00000000005d1c92 in SrsRecvThread::cycle (this=0x105dbd0) at src/app/srs_app_recv_thread.cpp:119

#7 0x0000000000542ab6 in SrsFastCoroutine::cycle (this=0x10aa9b0) at src/app/srs_app_st.cpp:270

#8 0x0000000000542b4c in SrsFastCoroutine::pfn (arg=0x10aa9b0) at src/app/srs_app_st.cpp:285

#9 0x00000000006c311d in _st_thread_main () at sched.c:363

#10 0x00000000006c399a in st_thread_create (start=0x10aa990, arg=0x10aa990, joinable=0, stk_size=5849344)

at sched.c:694

3.2 分发数据SrsConsumer::enqueue

通过调用SrsConsumer::enqueue，给每个拉流端对应的SrsConsumer queue发送音视频消息。比如这里拉流客户端刚连接时，先把SrsSource对应的metadata以及Gop cache发送给该客户端对应的SrsConsumer queue。

Breakpoint 4, SrsConsumer::enqueue (this=0x10bda70, shared_msg=0x10aaf40, atc=false, ag=SrsRtmpJitterAlgorithmFULL) at src/app/srs_app_source.cpp:465

465 srs_error_t err = srs_success;

(gdb) bt

#0 SrsConsumer::enqueue (this=0x10bda70, shared_msg=0x10aaf40, atc=false, ag=SrsRtmpJitterAlgorithmFULL)

at src/app/srs_app_source.cpp:465

#1 0x000000000051b77a in SrsMetaCache::dumps (this=0x1060590, consumer=0x10bda70, atc=false,

ag=SrsRtmpJitterAlgorithmFULL, dm=true, ds=true) at src/app/srs_app_source.cpp:1569

#2 0x0000000000521465 in SrsSource::consumer_dumps (this=0x105fb30, consumer=0x10bda70, ds=true, dm=true,

dg=true) at src/app/srs_app_source.cpp:2620

#3 0x000000000050ea4c in SrsRtmpConn::playing (this=0x10db880, source=0x105fb30)

at src/app/srs_app_rtmp_conn.cpp:685

#4 0x000000000050d4d2 in SrsRtmpConn::stream_service_cycle (this=0x10db880)

at src/app/srs_app_rtmp_conn.cpp:556

#5 0x000000000050c304 in SrsRtmpConn::service_cycle (this=0x10db880) at src/app/srs_app_rtmp_conn.cpp:420

#6 0x000000000050adc5 in SrsRtmpConn::do_cycle (this=0x10db880) at src/app/srs_app_rtmp_conn.cpp:233

#7 0x0000000000513af5 in SrsRtmpConn::cycle (this=0x10db880) at src/app/srs_app_rtmp_conn.cpp:1474

#8 0x0000000000542ab6 in SrsFastCoroutine::cycle (this=0x10c0160) at src/app/srs_app_st.cpp:270

#9 0x0000000000542b4c in SrsFastCoroutine::pfn (arg=0x10c0160) at src/app/srs_app_st.cpp:285

#10 0x00000000006c311d in _st_thread_main () at sched.c:363

#11 0x00000000006c399a in st_thread_create (start=0x542b2c <SrsFastCoroutine::pfn(void*)>, arg=0x10c0160,

joinable=1, stk_size=65536) at sched.c:694

我们可以多触发几次 SrsConsumer::enqueue，就可以知道后续转发音视频消息的调用栈如《3.1 SrsSource::on_video_imp调用栈》小节所示。

比如转发视频消息：

转发音频同理见：srs_error_t SrsSource::on_audio_imp(SrsSharedPtrMessage* msg) 函数。

4 服务器怎么给RTMP拉流端转发数据

要回到SrsRtmpConn::do_playing函数

1. consumer->dump_packets(&msgs, count) 从SrsConsumer queue读取音视频消息
2. rtmp->send_and_free_messages(msgs.msgs, count, info->res->stream_id) 把音视频消息发给拉流客户端

5 哪些配置文件会影响RTMP的延迟

主要是merge read、merge write以及gop cache影响延迟。

• merge read默认是关闭的
• merge write默认开启
• gop cache默认开启

低延迟配置可以参考：realtime.conf配置文件

listen 1935;

max_connections 1000;

daemon off;

srs_log_tank console;

vhost __defaultVhost__ {

tcp_nodelay on // 开启tcp nodelay

min_latency on; // 开启最小延迟，默认关闭

play {

gop_cache off; // 关闭gop cache，默认开启

queue_length 10; // consumer queue的时长 单位是秒

mw_latency 100; // 合并写入的延迟ms

}

publish {

mr off; // 关闭合并读取，默认关闭

}

}

注：更多的配置参数详解请参考full.conf，该配置文件是对配置项最权威的解释。

5.1 推流相关的延迟

可以在以下函数打上断点分析：

• bool SrsConfig::get_mr_enabled(string vhost)
• srs_utime_t SrsConfig::get_mr_sleep(string vhost)
• SrsPublishRecvThread::on_start

SrsConfig::get_mr_enabled和get_mr_sleep

#0 SrsConfig::get_mr_enabled (this=0xf5d3a0, vhost="__defaultVhost__") at src/app/srs_app_config.cpp:5690#1 0x00000000005d2c14 inSrsPublishRecvThread::SrsPublishRecvThread (this=0x7ffff7f82700,

rtmp_sdk=0x1060560, _req=0x10bca20, mr_sock_fd=9, tm=0, conn=0x10c4690, source=0x1060390,

parent_cid=..., __in_chrg=<optimized out>, __vtt_parm=<optimized out>)

at src/app/srs_app_recv_thread.cpp:303

#2 0x0000000000510098 in SrsRtmpConn::publishing (this=0x10c4690, source=0x1060390)

at src/app/srs_app_rtmp_conn.cpp:859

#3 0x000000000050d5ac in SrsRtmpConn::stream_service_cycle (this=0x10c4690)

at src/app/srs_app_rtmp_conn.cpp:566

#4 0x000000000050c304 in SrsRtmpConn::service_cycle (this=0x10c4690) at src/app/srs_app_rtmp_conn.cpp:420

#5 0x000000000050adc5 in SrsRtmpConn::do_cycle (this=0x10c4690) at src/app/srs_app_rtmp_conn.cpp:233

#6 0x0000000000513af5 in SrsRtmpConn::cycle (this=0x10c4690) at src/app/srs_app_rtmp_conn.cpp:1474

#7 0x0000000000542ab6 in SrsFastCoroutine::cycle (this=0x10ab1c0) at src/app/srs_app_st.cpp:270

#8 0x0000000000542b4c in SrsFastCoroutine::pfn (arg=0x10ab1c0) at src/app/srs_app_st.cpp:285

#9 0x00000000006c311d in _st_thread_main () at sched.c:363

SrsConfig::get_mr_sleep也是同一个位置读取。

SrsConfig::get_realtime_enabled也是同一个位置读取。

SrsPublishRecvThread::on_start

#0 SrsPublishRecvThread::on_start (this=0x1072600) at src/app/srs_app_recv_thread.cpp:438#1 0x00000000005d1c7b in SrsRecvThread::cycle (this=0x1072610) at src/app/srs_app_recv_thread.cpp:117

#2 0x0000000000542ab6 in SrsFastCoroutine::cycle (this=0x10c1890) at src/app/srs_app_st.cpp:270

#3 0x0000000000542b4c in SrsFastCoroutine::pfn (arg=0x10c1890) at src/app/srs_app_st.cpp:285

#4 0x00000000006c311d in _st_thread_main () at sched.c:363

SrsPublishRecvThread::on_stop

Breakpoint 5, SrsPublishRecvThread::on_stop (this=0x1072600) at src/app/srs_app_recv_thread.cpp:456456 srs_cond_signal(error);

(gdb) bt

#0 SrsPublishRecvThread::on_stop (this=0x1072600) at src/app/srs_app_recv_thread.cpp:456

#1 0x00000000005d1d15 in SrsRecvThread::cycle (this=0x1072610) at src/app/srs_app_recv_thread.cpp:126

#2 0x0000000000542ab6 in SrsFastCoroutine::cycle (this=0x10c1890) at src/app/srs_app_st.cpp:270

#3 0x0000000000542b4c in SrsFastCoroutine::pfn (arg=0x10c1890) at src/app/srs_app_st.cpp:285

#4 0x00000000006c311d in _st_thread_main () at sched.c:363

#5 0x00000000006c399a in st_thread_create (start=0x1072240, arg=0x1072300, joinable=0, stk_size=6151579)

at sched.c:694

SrsPublishRecvThread::on_read

#0 SrsPublishRecvThread::on_read (this=0x105e3c0, nread=218373) at src/app/srs_app_recv_thread.cpp:470#1 0x00000000004af887 in SrsFastStream::grow (this=0x10442c0, reader=0x1043e90, required_size=1)

at src/protocol/srs_protocol_stream.cpp:190

#2 0x000000000048a0cc in SrsProtocol::read_basic_header (this=0x10441b0, fmt=@0x7ffff7fc5b8b: 0 '\000',

cid=@0x7ffff7fc5b8c: 0) at src/protocol/srs_rtmp_stack.cpp:1007

#3 0x0000000000489e0c in SrsProtocol::recv_interlaced_message (this=0x10441b0, pmsg=0x7ffff7fc5bf0)

at src/protocol/srs_rtmp_stack.cpp:912

#4 0x0000000000487891 in SrsProtocol::recv_message (this=0x10441b0, pmsg=0x7ffff7fc5ca8)

at src/protocol/srs_rtmp_stack.cpp:401

#5 0x0000000000490708 in SrsRtmpServer::recv_message (this=0x1044180, pmsg=0x7ffff7fc5ca8)

at src/protocol/srs_rtmp_stack.cpp:2303

#6 0x00000000005d1dff in SrsRecvThread::do_cycle (this=0x105e3d0) at src/app/srs_app_recv_thread.cpp:149

#7 0x00000000005d1c92 in SrsRecvThread::cycle (this=0x105e3d0) at src/app/srs_app_recv_thread.cpp:119

#8 0x0000000000542ab6 in SrsFastCoroutine::cycle (this=0x10ab1c0) at src/app/srs_app_st.cpp:270

#9 0x0000000000542b4c in SrsFastCoroutine::pfn (arg=0x10ab1c0) at src/app/srs_app_st.cpp:285

#10 0x00000000006c311d in _st_thread_main () at sched.c:363

5.2 拉流相关的延迟

SrsConfig::get_mw_sleep 默认350ms

SrsConfig::get_mw_msgs 默认是8帧消息

mw_msgs和mw_sleep是与的关系，即是要两个条件同时成立。

SrsConfig::get_mw_sleep

#0 SrsConfig::get_mw_sleep (this=0xf5d3a0, vhost="__defaultVhost__", is_rtc=false) at src/app/srs_app_config.cpp:5732

#1 0x000000000050f38c in SrsRtmpConn::do_playing (this=0x10d1da0, source=0x1060390, consumer=0x10cdb20,

rtrd=0x105e430) at src/app/srs_app_rtmp_conn.cpp:733

#2 0x000000000050ebc2 in SrsRtmpConn::playing (this=0x10d1da0, source=0x1060390)

at src/app/srs_app_rtmp_conn.cpp:699

#3 0x000000000050d4d2 in SrsRtmpConn::stream_service_cycle (this=0x10d1da0)

at src/app/srs_app_rtmp_conn.cpp:556

#4 0x000000000050c304 in SrsRtmpConn::service_cycle (this=0x10d1da0) at src/app/srs_app_rtmp_conn.cpp:420

#5 0x000000000050adc5 in SrsRtmpConn::do_cycle (this=0x10d1da0) at src/app/srs_app_rtmp_conn.cpp:233

#6 0x0000000000513af5 in SrsRtmpConn::cycle (this=0x10d1da0) at src/app/srs_app_rtmp_conn.cpp:1474

#7 0x0000000000542ab6 in SrsFastCoroutine::cycle (this=0x10d1530) at src/app/srs_app_st.cpp:270

#8 0x0000000000542b4c in SrsFastCoroutine::pfn (arg=0x10d1530) at src/app/srs_app_st.cpp:285

#9 0x00000000006c311d in _st_thread_main () at sched.c:363

SrsConfig::get_mw_msgs

#0 SrsConfig::get_mw_msgs (this=0xf5d3a0, vhost="__defaultVhost__", is_rtc=false) at src/app/srs_app_config.cpp:5762

#1 0x000000000050f38c in SrsRtmpConn::do_playing (this=0x10d1da0, source=0x1060390, consumer=0x10cdb20,

rtrd=0x105e430) at src/app/srs_app_rtmp_conn.cpp:732

#2 0x000000000050ebc2 in SrsRtmpConn::playing (this=0x10d1da0, source=0x1060390)

at src/app/srs_app_rtmp_conn.cpp:699

#3 0x000000000050d4d2 in SrsRtmpConn::stream_service_cycle (this=0x10d1da0)

at src/app/srs_app_rtmp_conn.cpp:556

#4 0x000000000050c304 in SrsRtmpConn::service_cycle (this=0x10d1da0) at src/app/srs_app_rtmp_conn.cpp:420

#5 0x000000000050adc5 in SrsRtmpConn::do_cycle (this=0x10d1da0) at src/app/srs_app_rtmp_conn.cpp:233

#6 0x0000000000513af5 in SrsRtmpConn::cycle (this=0x10d1da0) at src/app/srs_app_rtmp_conn.cpp:1474

#7 0x0000000000542ab6 in SrsFastCoroutine::cycle (this=0x10d1530) at src/app/srs_app_st.cpp:270

#8 0x0000000000542b4c in SrsFastCoroutine::pfn (arg=0x10d1530) at src/app/srs_app_st.cpp:285

#9 0x00000000006c311d in _st_thread_main () at sched.c:363

SrsConfig::get_queue_length

#0 SrsConfig::get_queue_length (this=0xf5d3a0, vhost="__defaultVhost__") at src/app/srs_app_config.cpp:5515

#1 0x0000000000521188 in SrsSource::consumer_dumps (this=0x1060390, consumer=0x10cdb20, ds=true, dm=true,

dg=true) at src/app/srs_app_source.cpp:2601

#2 0x000000000050ea4c in SrsRtmpConn::playing (this=0x10d1da0, source=0x1060390)

at src/app/srs_app_rtmp_conn.cpp:685

#3 0x000000000050d4d2 in SrsRtmpConn::stream_service_cycle (this=0x10d1da0)

at src/app/srs_app_rtmp_conn.cpp:556

#4 0x000000000050c304 in SrsRtmpConn::service_cycle (this=0x10d1da0) at src/app/srs_app_rtmp_conn.cpp:420

#5 0x000000000050adc5 in SrsRtmpConn::do_cycle (this=0x10d1da0) at src/app/srs_app_rtmp_conn.cpp:233

#6 0x0000000000513af5 in SrsRtmpConn::cycle (this=0x10d1da0) at src/app/srs_app_rtmp_conn.cpp:1474

#7 0x0000000000542ab6 in SrsFastCoroutine::cycle (this=0x10d1530) at src/app/srs_app_st.cpp:270

#8 0x0000000000542b4c in SrsFastCoroutine::pfn (arg=0x10d1530) at src/app/srs_app_st.cpp:285

#9 0x00000000006c311d in _st_thread_main () at sched.c:363

go cacache延迟

SrsConfig::get_gop_cache

#0 SrsConfig::get_gop_cache (this=0xf5d3a0, vhost="__defaultVhost__") at src/app/srs_app_config.cpp:5385#1 0x000000000050d1b6 in SrsRtmpConn::stream_service_cycle (this=0x10d1da0)

at src/app/srs_app_rtmp_conn.cpp:541

#2 0x000000000050c304 in SrsRtmpConn::service_cycle (this=0x10d1da0) at src/app/srs_app_rtmp_conn.cpp:420

#3 0x000000000050adc5 in SrsRtmpConn::do_cycle (this=0x10d1da0) at src/app/srs_app_rtmp_conn.cpp:233

#4 0x0000000000513af5 in SrsRtmpConn::cycle (this=0x10d1da0) at src/app/srs_app_rtmp_conn.cpp:1474

#5 0x0000000000542ab6 in SrsFastCoroutine::cycle (this=0x10d1530) at src/app/srs_app_st.cpp:270

#6 0x0000000000542b4c in SrsFastCoroutine::pfn (arg=0x10d1530) at src/app/srs_app_st.cpp:285

#7 0x00000000006c311d in _st_thread_main () at sched.c:363

SrsGopCache::cache保存Gop

缓存最新的Gop，这里实际上包括音频。

#0 SrsGopCache::cache (this=0x1060760, shared_msg=0x7ffff7f3fa70) at src/app/srs_app_source.cpp:619#1 0x00000000005201a1 in SrsSource::on_video_imp (this=0x1060390, msg=0x7ffff7f3fa70)

at src/app/srs_app_source.cpp:2379

#2 0x000000000051fb11 in SrsSource::on_video (this=0x1060390, shared_video=0x10df640)

at src/app/srs_app_source.cpp:2309

#3 0x0000000000511798 in SrsRtmpConn::process_publish_message (this=0x10c4690, source=0x1060390,

msg=0x10df640) at src/app/srs_app_rtmp_conn.cpp:1079

#4 0x0000000000511598 in SrsRtmpConn::handle_publish_message (this=0x10c4690, source=0x1060390,

msg=0x10df640) at src/app/srs_app_rtmp_conn.cpp:1051

#5 0x00000000005d364c in SrsPublishRecvThread::consume (this=0x7ffff7f82700, msg=0x10df640)

at src/app/srs_app_recv_thread.cpp:396

#6 0x00000000005d1e35 in SrsRecvThread::do_cycle (this=0x7ffff7f82710)

at src/app/srs_app_recv_thread.cpp:150

#7 0x00000000005d1c92 in SrsRecvThread::cycle (this=0x7ffff7f82710) at src/app/srs_app_recv_thread.cpp:119

#8 0x0000000000542ab6 in SrsFastCoroutine::cycle (this=0x10abff0) at src/app/srs_app_st.cpp:270

#9 0x0000000000542b4c in SrsFastCoroutine::pfn (arg=0x10abff0) at src/app/srs_app_st.cpp:285

#10 0x00000000006c311d in _st_thread_main () at sched.c:363

SrsGopCache::dump 拷贝Gop

拷贝gop

Breakpoint 11, SrsGopCache::dump (this=0x1060760, consumer=0x10cdb20, atc=false, jitter_algorithm=SrsRtmpJitterAlgorithmFULL) at src/app/srs_app_source.cpp:685

685 {

(gdb) bt

#0 SrsGopCache::dump (this=0x1060760, consumer=0x10cdb20, atc=false,

jitter_algorithm=SrsRtmpJitterAlgorithmFULL) at src/app/srs_app_source.cpp:685

#1 0x00000000005214e1 in SrsSource::consumer_dumps (this=0x1060390, consumer=0x10cdb20, ds=true, dm=true,

dg=true) at src/app/srs_app_source.cpp:2625

#2 0x000000000050ea4c in SrsRtmpConn::playing (this=0x10d1da0, source=0x1060390)

at src/app/srs_app_rtmp_conn.cpp:685

#3 0x000000000050d4d2 in SrsRtmpConn::stream_service_cycle (this=0x10d1da0)

at src/app/srs_app_rtmp_conn.cpp:556

#4 0x000000000050c304 in SrsRtmpConn::service_cycle (this=0x10d1da0) at src/app/srs_app_rtmp_conn.cpp:420

#5 0x000000000050adc5 in SrsRtmpConn::do_cycle (this=0x10d1da0) at src/app/srs_app_rtmp_conn.cpp:233

#6 0x0000000000513af5 in SrsRtmpConn::cycle (this=0x10d1da0) at src/app/srs_app_rtmp_conn.cpp:1474

#7 0x0000000000542ab6 in SrsFastCoroutine::cycle (this=0x10d1530) at src/app/srs_app_st.cpp:270

#8 0x0000000000542b4c in SrsFastCoroutine::pfn (arg=0x10d1530) at src/app/srs_app_st.cpp:285

#9 0x00000000006c311d in _st_thread_main () at sched.c:363

6 总结

• rtmp监听
• 推流对应连接
• 推拉流怎么去读取和发送数据
• 延迟的问题