將最近學(xué)習(xí)的直播推流技術(shù)做個(gè)筆記宦赠。
iOS推流的主要流程如下：
這篇是直播推流的最后一篇
推流
上一篇介紹了音視頻編解碼暇矫，完成編解碼后我們把數(shù)據(jù)分別封裝到LFAudioFrame（音頻數(shù)據(jù)）和LFVideoFrame（視頻數(shù)據(jù)）中，接下來(lái)需要對(duì)這兩數(shù)據(jù)進(jìn)行推流。
我們的推流工具使用的是librtmp，用來(lái)推rtmp協(xié)議流。
- 先跟流服務(wù)器建立連接，連接成功后拓轻，這個(gè)過(guò)程需要在初始化整個(gè)推流器時(shí)完成。
- 建立連接后需要把視頻和音頻元數(shù)據(jù)即音頻和視頻的相關(guān)參數(shù)推送過(guò)去经伙，方便服務(wù)端解析扶叉。
- (void)sendMetaData {
PILI_RTMPPacket packet;
char pbuf[2048], *pend = pbuf + sizeof(pbuf);
packet.m_nChannel = 0x03; // control channel (invoke)
packet.m_headerType = RTMP_PACKET_SIZE_LARGE;
packet.m_packetType = RTMP_PACKET_TYPE_INFO;
packet.m_nTimeStamp = 0;
packet.m_nInfoField2 = _rtmp->m_stream_id;
packet.m_hasAbsTimestamp = TRUE;
packet.m_body = pbuf + RTMP_MAX_HEADER_SIZE;
char *enc = packet.m_body;
enc = AMF_EncodeString(enc, pend, &av_setDataFrame);
enc = AMF_EncodeString(enc, pend, &av_onMetaData);
*enc++ = AMF_OBJECT;
enc = AMF_EncodeNamedNumber(enc, pend, &av_duration, 0.0);
enc = AMF_EncodeNamedNumber(enc, pend, &av_fileSize, 0.0);
// videosize
enc = AMF_EncodeNamedNumber(enc, pend, &av_width, _stream.videoConfiguration.videoSize.width);
enc = AMF_EncodeNamedNumber(enc, pend, &av_height, _stream.videoConfiguration.videoSize.height);
// video
enc = AMF_EncodeNamedString(enc, pend, &av_videocodecid, &av_avc1);
enc = AMF_EncodeNamedNumber(enc, pend, &av_videodatarate, _stream.videoConfiguration.videoBitRate / 1000.f);
enc = AMF_EncodeNamedNumber(enc, pend, &av_framerate, _stream.videoConfiguration.videoFrameRate);
// audio
enc = AMF_EncodeNamedString(enc, pend, &av_audiocodecid, &av_mp4a);
enc = AMF_EncodeNamedNumber(enc, pend, &av_audiodatarate, _stream.audioConfiguration.audioBitrate);
enc = AMF_EncodeNamedNumber(enc, pend, &av_audiosamplerate, _stream.audioConfiguration.audioSampleRate);
enc = AMF_EncodeNamedNumber(enc, pend, &av_audiosamplesize, 16.0);
enc = AMF_EncodeNamedBoolean(enc, pend, &av_stereo, _stream.audioConfiguration.numberOfChannels == 2);
// sdk version
enc = AMF_EncodeNamedString(enc, pend, &av_encoder, &av_SDKVersion);
*enc++ = 0;
*enc++ = 0;
*enc++ = AMF_OBJECT_END;
packet.m_nBodySize = (uint32_t)(enc - packet.m_body);
if (!PILI_RTMP_SendPacket(_rtmp, &packet, FALSE, &_error)) {
return;
}
}
- 接下來(lái)把Frame放到一個(gè)數(shù)組中，對(duì)數(shù)組根據(jù)時(shí)間排序帕膜，保證推流順序
- 把數(shù)組第一條數(shù)據(jù)加入推流緩沖區(qū)枣氧。
- 從緩沖區(qū)取出第一條數(shù)據(jù)
- 如果是視頻幀（LFVideoFrame），判斷是否發(fā)送頭信息垮刹，頭信息即pps和sps达吞，意思是推送幀數(shù)據(jù)時(shí)要先推pps和sps 否則后端無(wú)法正常解析數(shù)據(jù)，這個(gè)頭信息只需要在一次連接會(huì)話中發(fā)送一次荒典，如果中間出現(xiàn)斷開(kāi)重連需要重新推送pps和sps數(shù)據(jù)酪劫。
推送pps和sps有格式要求的，代碼如下：
- (void)sendVideoHeader:(LFVideoFrame *)videoFrame {
unsigned char *body = NULL;
NSInteger iIndex = 0;
NSInteger rtmpLength = 1024;
const char *sps = videoFrame.sps.bytes;
const char *pps = videoFrame.pps.bytes;
NSInteger sps_len = videoFrame.sps.length;
NSInteger pps_len = videoFrame.pps.length;
body = (unsigned char *)malloc(rtmpLength);
memset(body, 0, rtmpLength);
body[iIndex++] = 0x17;
body[iIndex++] = 0x00;
body[iIndex++] = 0x00;
body[iIndex++] = 0x00;
body[iIndex++] = 0x00;
body[iIndex++] = 0x01;
body[iIndex++] = sps[1];
body[iIndex++] = sps[2];
body[iIndex++] = sps[3];
body[iIndex++] = 0xff;
/*sps*/
body[iIndex++] = 0xe1;
body[iIndex++] = (sps_len >> 8) & 0xff;
body[iIndex++] = sps_len & 0xff;
memcpy(&body[iIndex], sps, sps_len);
iIndex += sps_len;
/*pps*/
body[iIndex++] = 0x01;
body[iIndex++] = (pps_len >> 8) & 0xff;
body[iIndex++] = (pps_len) & 0xff;
memcpy(&body[iIndex], pps, pps_len);
iIndex += pps_len;
[self sendPacket:RTMP_PACKET_TYPE_VIDEO data:body size:iIndex nTimestamp:0];
free(body);
}
然后再發(fā)送幀數(shù)據(jù)：
- (void)sendVideo:(LFVideoFrame *)frame {
NSInteger i = 0;
NSInteger rtmpLength = frame.data.length + 9;
unsigned char *body = (unsigned char *)malloc(rtmpLength);
memset(body, 0, rtmpLength);
if (frame.isKeyFrame) {
body[i++] = 0x17; // 1:Iframe 7:AVC
} else {
body[i++] = 0x27; // 2:Pframe 7:AVC
}
body[i++] = 0x01; // AVC NALU
body[i++] = 0x00;
body[i++] = 0x00;
body[i++] = 0x00;
body[i++] = (frame.data.length >> 24) & 0xff;
body[i++] = (frame.data.length >> 16) & 0xff;
body[i++] = (frame.data.length >> 8) & 0xff;
body[i++] = (frame.data.length) & 0xff;
memcpy(&body[i], frame.data.bytes, frame.data.length);
[self sendPacket:RTMP_PACKET_TYPE_VIDEO data:body size:(rtmpLength) nTimestamp:frame.timestamp];
free(body);
}
- (NSInteger)sendPacket:(unsigned int)nPacketType data:(unsigned char *)data size:(NSInteger)size nTimestamp:(uint64_t)nTimestamp {
NSInteger rtmpLength = size;
PILI_RTMPPacket rtmp_pack;
PILI_RTMPPacket_Reset(&rtmp_pack);
PILI_RTMPPacket_Alloc(&rtmp_pack, (uint32_t)rtmpLength);
rtmp_pack.m_nBodySize = (uint32_t)size;
memcpy(rtmp_pack.m_body, data, size);
rtmp_pack.m_hasAbsTimestamp = 0;
rtmp_pack.m_packetType = nPacketType;
if (_rtmp) rtmp_pack.m_nInfoField2 = _rtmp->m_stream_id;
rtmp_pack.m_nChannel = 0x04;
rtmp_pack.m_headerType = RTMP_PACKET_SIZE_LARGE;
if (RTMP_PACKET_TYPE_AUDIO == nPacketType && size != 4) {
rtmp_pack.m_headerType = RTMP_PACKET_SIZE_MEDIUM;
}
rtmp_pack.m_nTimeStamp = (uint32_t)nTimestamp;
NSInteger nRet = [self RtmpPacketSend:&rtmp_pack];
PILI_RTMPPacket_Free(&rtmp_pack);
return nRet;
}
推送時(shí)需要注意要把時(shí)間戳帶上
[self sendPacket:RTMP_PACKET_TYPE_VIDEO data:body size:(rtmpLength) nTimestamp:frame.timestamp];
rtmp是以包為單位進(jìn)行發(fā)送數(shù)據(jù)寺董。
7.如果是音頻幀, 同樣的邏輯覆糟，需要先推送頭信息，才能推幀數(shù)據(jù)螃征，代碼如下
- (void)sendAudioHeader:(LFAudioFrame *)audioFrame {
NSInteger rtmpLength = audioFrame.audioInfo.length + 2; /*spec data長(zhǎng)度,一般是2*/
unsigned char *body = (unsigned char *)malloc(rtmpLength);
memset(body, 0, rtmpLength);
/*AF 00 + AAC RAW data*/
body[0] = 0xAF;
body[1] = 0x00;
memcpy(&body[2], audioFrame.audioInfo.bytes, audioFrame.audioInfo.length); /*spec_buf是AAC sequence header數(shù)據(jù)*/
[self sendPacket:RTMP_PACKET_TYPE_AUDIO data:body size:rtmpLength nTimestamp:0];
free(body);
}
- (void)sendAudio:(LFFrame *)frame {
NSInteger rtmpLength = frame.data.length + 2; /*spec data長(zhǎng)度,一般是2*/
unsigned char *body = (unsigned char *)malloc(rtmpLength);
memset(body, 0, rtmpLength);
/*AF 01 + AAC RAW data*/
body[0] = 0xAF;
body[1] = 0x01;
memcpy(&body[2], frame.data.bytes, frame.data.length);
[self sendPacket:RTMP_PACKET_TYPE_AUDIO data:body size:rtmpLength nTimestamp:frame.timestamp];
free(body);
}
不耍流氓搪桂，附上代碼：
Demo傳送門(mén)
