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如上文所说，建立了NetConnection，就可以建立NetStream了。在ngx_rtmp是如何实现的呢？
CMD模块回调注册
nginx在初始化启动的时候调用ngx_rtmp_cmd_module模块ngx_rtmp_cmd_postconfiguration()中进行回调注册，具体回调如下：
static ngx_rtmp_amf_handler_t ngx_rtmp_cmd_map[] = {
{ ngx_string("connect"), ngx_rtmp_cmd_connect_init },
{ ngx_string("createStream"), ngx_rtmp_cmd_create_stream_init },
{ ngx_string("closeStream"), ngx_rtmp_cmd_close_stream_init },
{ ngx_string("deleteStream"), ngx_rtmp_cmd_delete_stream_init },
{ ngx_string("publish"), ngx_rtmp_cmd_publish_init },
{ ngx_string("play"), ngx_rtmp_cmd_play_init },
{ ngx_string("play2"), ngx_rtmp_cmd_play2_init },
{ ngx_string("seek"), ngx_rtmp_cmd_seek_init },
{ ngx_string("pause"), ngx_rtmp_cmd_pause_init },
{ ngx_string("pauseraw"), ngx_rtmp_cmd_pause_init },
};
create stream流程
createStream大体流程如下：
- 如本人的前文《RTMP的connection协议》中所讲，客户端收到客户端回复的"connect"回应消息后，给服务器发送createstream消息
- 服务端通过ngx_rtmp_recv收到消息后进行组包、头解析后调用ngx_rtmp_receive_message
- ngx_rtmp_receive_message根据上一步解析出来的消息头带的type定位到回调函数ngx_rtmp_cmd_create_stream_init
而ngx_rtmp_cmd_create_stream_init主要做的工作如下： - 具体回调是就是从缓冲区中读取数据ngx_rtmp_receive_amf()
-调用ngx_rtmp_cmd_create_stream() - ngx_rtmp_cmd_create_stream()功能相对简单，就是回复消息给客户端，amf消息如下：
static ngx_rtmp_amf_elt_t out_elts[] = {
{ NGX_RTMP_AMF_STRING,
ngx_null_string,
"_result", 0 },
{ NGX_RTMP_AMF_NUMBER,
ngx_null_string,
&trans, 0 },
{ NGX_RTMP_AMF_NULL,
ngx_null_string,
NULL, 0 },
{ NGX_RTMP_AMF_NUMBER,
ngx_null_string,
&stream, sizeof(stream) },
};
Stream状态
对于创建的stream,存在各个状态，用于服务端和客户端进行应对，具体如下，如何应对后文在详讲。
- "NetStream.Play.Reset" --- 播放列表重置
- "NetStream.Play.Start" --- 播放开始
- "NetStream.Buffer.Empty" --- 视频正在缓冲
- "NetStream.Buffer.Full" --- 缓冲区已填满
- "NetStream.Play.StreamNotFound" --- 找不到此视频
- "NetStream.Play.Stop" --- 视频播放完成
- "NetStream.Pause.Notify" --- 流已暂停
- "NetStream.Unpause.Notify" --- 流已恢复
- "NetStream.Seek.Failed" --- 搜寻失败
- "NetStream.SeekStart.Notify" --- 搜寻开始
- "NetStream.Seek.Notify" --- 正在搜寻
- "NetStream.Seek.Complete" --- 搜寻完毕
- "NetStream.Publish.Start" --- 发布开始
- "NetStream.Unpublish.Success" --- 停止发布
- "NetStream.Record.Start" --- 开始录制
- "NetStream.Record.Stop" --- 停止录制
- "NetStream.Publish.BadName" --- 警告！试图发布已经被他人发布的流
- "NetStream.Play.PublishNotify" --- 发布开始，信息已经发送到所有订阅者
- "NetStream.Play.UnpublishNotify" --- 发布停止，信息已经发送到所有订阅者
- "NetStream.Play.InsufficientBW" --- 警告！客户端没有足够的带宽，无法以正常速度播放数据"
