ZLMediaKit/src/RtmpMuxer/AACRtmpCodec.cpp

//
// Created by xzl on 2018/10/24.
//

#include <Player/Player.h>
#include "AACRtmpCodec.h"

namespace mediakit{

AACRtmpDecoder::AACRtmpDecoder() {
    _adts = obtainFrame();
}

AACFrame::Ptr AACRtmpDecoder::obtainFrame() {
    //从缓存池重新申请对象，防止覆盖已经写入环形缓存的对象
    auto frame = ResourcePoolHelper<AACFrame>::obtainObj();
    frame->aac_frame_length = 7;
    frame->iPrefixSize = 7;
    return frame;
}

bool AACRtmpDecoder::inputRtmp(const RtmpPacket::Ptr &pkt, bool key_pos) {
    RtmpCodec::inputRtmp(pkt, false);

    if (pkt->isCfgFrame()) {
        _aac_cfg = pkt->getAacCfg();
        return false;
    }
    if (!_aac_cfg.empty()) {
        onGetAAC(pkt->strBuf.data() + 2, pkt->strBuf.size() - 2, pkt->timeStamp);
    }
    return false;
}

void AACRtmpDecoder::onGetAAC(const char* pcData, int iLen, uint32_t ui32TimeStamp) {
    if(iLen + 7 > sizeof(_adts->buffer)){
        WarnL << "Illegal adts data, exceeding the length limit.";
        return;
    }
    //写adts结构头
    makeAdtsHeader(_aac_cfg,*_adts);

    //拷贝aac负载
    memcpy(_adts->buffer + 7, pcData, iLen);
    _adts->aac_frame_length = 7 + iLen;
    _adts->timeStamp = ui32TimeStamp;

    //adts结构头转成头7个字节
    writeAdtsHeader(*_adts, _adts->buffer);

    //写入环形缓存
    RtmpCodec::inputFrame(_adts);
    _adts = obtainFrame();
}
/////////////////////////////////////////////////////////////////////////////////////

void AACRtmpEncoder::inputFrame(const Frame::Ptr &frame) {
    RtmpCodec::inputFrame(frame);
    if(frame->prefixSize() == 7 && _aac_cfg.empty()){
        //包含adts头
        _aac_cfg = makeAdtsConfig(reinterpret_cast<const uint8_t *>(frame->data()));
        makeAudioConfigPkt();
    }

    if(!_aac_cfg.empty()){
        RtmpPacket::Ptr rtmpPkt = ResourcePoolHelper<RtmpPacket>::obtainObj();
        rtmpPkt->strBuf.clear();

        //////////header
        uint8_t is_config = false;
        rtmpPkt->strBuf.push_back(_ui8AudioFlags);
        rtmpPkt->strBuf.push_back(!is_config);
        rtmpPkt->strBuf.append(frame->data() + frame->prefixSize(), frame->size() - frame->prefixSize());

        rtmpPkt->bodySize = rtmpPkt->strBuf.size();
        rtmpPkt->chunkId = CHUNK_AUDIO;
        rtmpPkt->streamId = STREAM_MEDIA;
        rtmpPkt->timeStamp = frame->stamp();
        rtmpPkt->typeId = MSG_AUDIO;
        inputRtmp(rtmpPkt, false);
    }

}

void AACRtmpEncoder::makeAudioConfigPkt() {
    makeAdtsHeader(_aac_cfg,*_adts);
    int iSampleRate , iChannel , iSampleBit = 16;
    getAACInfo(*_adts,iSampleRate,iChannel);

    uint8_t flvStereoOrMono = (iChannel > 1);
    uint8_t flvSampleRate;
    switch (iSampleRate) {
        case 48000:
        case 44100:
            flvSampleRate = 3;
            break;
        case 24000:
        case 22050:
            flvSampleRate = 2;
            break;
        case 12000:
        case 11025:
            flvSampleRate = 1;
            break;
        default:
            flvSampleRate = 0;
            break;
    }
    uint8_t flvSampleBit = iSampleBit == 16;
    uint8_t flvAudioType = 10; //aac

    _ui8AudioFlags = (flvAudioType << 4) | (flvSampleRate << 2) | (flvSampleBit << 1) | flvStereoOrMono;

    RtmpPacket::Ptr rtmpPkt = ResourcePoolHelper<RtmpPacket>::obtainObj();
    rtmpPkt->strBuf.clear();

    //////////header
    uint8_t is_config = true;
    rtmpPkt->strBuf.push_back(_ui8AudioFlags);
    rtmpPkt->strBuf.push_back(!is_config);
    rtmpPkt->strBuf.append(_aac_cfg);

    rtmpPkt->bodySize = rtmpPkt->strBuf.size();
    rtmpPkt->chunkId = CHUNK_AUDIO;
    rtmpPkt->streamId = STREAM_MEDIA;
    rtmpPkt->timeStamp = 0;
    rtmpPkt->typeId = MSG_AUDIO;
    inputRtmp(rtmpPkt, false);
}



}//namespace mediakit