将H.264使用RTMP打包后发送给RED5/FMS进行实时发布

╰半夏微凉° 2022-05-15 03:40 135阅读 0赞

需要从硬压卡上获取的NALU封装成RTMP协议格式发送给RED5/FMS进行实时发布.

RTMP中传送 H.264使用的视频封装格式既是 FLV规范 中的 VideoTag

**Frame Type** UB \[4\]

Type of video frame. The following values are defined:  
1 = key frame (for AVC, a seekable frame)  
2 = inter frame (for AVC, a non-seekable frame)  
3 = disposable inter frame (H.263 only)  
4 = generated key frame (reserved for server use only)  
5 = video info/command frame

**CodecID** UB \[4\]

Codec Identifier. The following values are defined:  
2 = Sorenson H.263  
3 = Screen video  
4 = On2 VP6  
5 = On2 VP6 with alpha channel  
6 = Screen video version 2  
7 = AVC

**AVCPacketType** F UI8

The following values are defined:  
0 = AVC sequence header  
1 = AVC NALU  
2 = AVC end of sequence (lower level NALU sequence ender is  
not required or supported)

**CompositionTime**  SI24  
IF AVCPacketType == 1  
Composition time offset  
ELSE  
0  
See ISO 14496-12, 8.15.3 for an explanation of composition  
times. The offset in an FLV file is always in milliseconds.

在第一个RTMP Message的数据包中,需要发送 **AVC sequence header** , 也就是AVCDecoderConfigurationRecord

其中就包含有Profile / Level / SPS / PPS 等解码需要的信息

然后就开始发送NALU了。

NALU在一个RTMP Message可以发送1个或者多个。

根据 NALU的 reference idc 可以得出 帧类型

typedef enum \{ NALU\_PRIORITY\_HIGHEST = 3, NALU\_PRIORITY\_HIGH = 2, NALU\_PRIORITY\_LOW = 1, NALU\_PRIORITY\_DISPOSABLE = 0 \} NaluRefIdc;

如果这个 VideoTag中含有 **NALU\_PRIORITY\_HIGHEST** 的NALU, 那么它的VideoTag的 Frame Type 应该是 **FrameType\_KeyFrame**

enum FrameType \{ FrameType\_KeyFrame = 1, FrameType\_InterFrame = 2, FrameType\_DisposableInterFrame = 3, FrameType\_GeneratedKeyFrame = 4, FrameType\_VideoInfo = 5, \};