将H.264使用RTMP打包后发送给RED5/FMS进行实时发布

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,
};