metartc5_jz源码阅读-yang_push_h264_package_stap_a

//通过stap_a模式发送sps和pps包给对端。
int32_t yang_push_h264_package_stap_a(void *psession,
		YangPushH264Rtp *rtp, YangFrame *videoFrame) {
	int err = Yang_Ok;
	YangRtcSession *session=(YangRtcSession*)psession;
	//重置rtpPacket的字段
	yang_reset_rtpPacket(&rtp->videoStapPacket);

	//设置payloadType为h264
	rtp->videoStapPacket.header.payload_type = YangH264PayloadType;
	//设置ssrc为videoSsrc
	rtp->videoStapPacket.header.ssrc = rtp->videoSsrc;

	//设置帧类型为Video
	rtp->videoStapPacket.frame_type = YangFrameTypeVideo;

	//设置naluType为StapA，此模式下一个nalu包可以通过多个rtp包发送，此时多个rtp包的时间戳相同。
	rtp->videoStapPacket.nalu_type = (YangAvcNaluType) kStapA;

	//设置marker为false
	rtp->videoStapPacket.header.marker = false;

	//设置sequence为videoSeq
	rtp->videoStapPacket.header.sequence = rtp->videoSeq++;

	//设置timestamp为视频帧的显示时间戳
	rtp->videoStapPacket.header.timestamp = videoFrame->pts;

	//设置视频的payload_type为StapA的模式
	rtp->videoStapPacket.payload_type = YangRtspPacketPayloadTypeSTAP;

	//重置stapA的data
	yang_reset_h2645_stap(&rtp->stapData);

	//创建sps和pps的结构体变量
	YangSample sps_sample;
	YangSample pps_sample;

	//从视频帧的payload中取出sps和pps
	yang_decodeMetaH264(videoFrame->payload, videoFrame->nb, &sps_sample,&pps_sample);

	//从sps中取出NaluType赋值给stapData的nri
	uint8_t header = (uint8_t) sps_sample.bytes[0];
	rtp->stapData.nri = (YangAvcNaluType) header;

	//将sps和pps分别插入stapData.nalus中。
	yang_insert_YangSampleVector(&rtp->stapData.nalus, &sps_sample);
	yang_insert_YangSampleVector(&rtp->stapData.nalus, &pps_sample);

	//调用yang_push_h264_encodeVideo方法编码rtp的视频buffer，发送给p2p对端。
	if ((err = yang_push_h264_encodeVideo(session, rtp, &rtp->videoStapPacket))
			!= Yang_Ok) {
		return yang_error_wrap(err, "encode packet");
	}
	return err;
}