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.2633 = Screen video4 = On2 VP65 = On2 VP6 with alpha channel6 = Screen video version 27 = AVC
AVCPacketType F UI8
The following values are defined:0 = AVC sequence header1 = AVC NALU2 = AVC end of sequence (lower level NALU sequence ender isnot required or supported)
CompositionTime SI24IF AVCPacketType == 1Composition time offsetELSE0See ISO 14496-12, 8.15.3 for an explanation of compositiontimes. 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, };
