使用 libavformat 不播放的 H.264 混合到 MP4

This is more or less a prototype and is not clean in any respects. It probably leaks bad. I do however, hope this helps anyone else out trying to achieve something similar to what I am.

全局变量:

AVFormatContext* oc = NULL;
AVCodecContext* videoContext = NULL;
AVStream* videoStream = NULL;
AVCodecContext* audioContext = NULL;
AVStream* audioStream = NULL;
AVCodec* videoCodec = NULL;
AVCodec* audioCodec = NULL;
int vi = 0;  // Video stream
int ai = 1;  // Audio stream

uint64_t firstVideoTimeStamp = 0;
uint64_t firstAudioTimeStamp = 0;
int audioStartOffset = 0;

char* filename = NULL;

Boolean first = TRUE;

int videoFrameNumber = 0;
int audioFrameNumber = 0;

主要内容:

int main(int argc, char* argv[])
{
    if (argc != 3)
    {   
        cout << argv[0] << " <stream playback file> <output mp4 file>" << endl;
        return 0;
    }
    char* input_stream_file = argv[1];
    filename = argv[2];

    av_register_all();    

    fstream inFile;
    inFile.open(input_stream_file, ios::in);

    // Used to store the latest pps & sps frames
    unsigned char* ppsFrame = NULL;
    int ppsFrameLength = 0;
    unsigned char* spsFrame = NULL;
    int spsFrameLength = 0;

    // Setup MP4 output file
    AVOutputFormat* fmt = av_guess_format( 0, filename, 0 );
    oc = avformat_alloc_context();
    oc->oformat = fmt;
    strcpy(oc->filename, filename);

    // Setup the bitstream filter for AAC in adts format.  Could probably also achieve
    // this by stripping the first 7 bytes!
    AVBitStreamFilterContext* bsfc = av_bitstream_filter_init("aac_adtstoasc");
    if (!bsfc)
    {       
        cout << "Error creating adtstoasc filter" << endl;
        return -1;
    }

    while (inFile.good())
    {
        TcpAVDataBlock* block = new TcpAVDataBlock();
        block->readStruct(inFile);
        DateTime dt = block->getTimestampAsDateTime();
        switch (block->getPacketType())
        {
            case TCP_PACKET_H264:
            {       
                if (firstVideoTimeStamp == 0)
                    firstVideoTimeStamp = block->getTimeStamp();
                unsigned char* data = block->getData();
                unsigned char videoFrameType = data[4];
                int dataLen = block->getDataLen();

                // pps
                if (videoFrameType == 0x68)
                {
                    if (ppsFrame != NULL)
                    {
                        delete ppsFrame; ppsFrameLength = 0;
                        ppsFrame = NULL;
                    }
                    ppsFrameLength = block->getDataLen();
                    ppsFrame = new unsigned char[ppsFrameLength];
                    memcpy(ppsFrame, block->getData(), ppsFrameLength);
                }
                else if (videoFrameType == 0x67)
                {
                    // sps
                    if (spsFrame != NULL)
                    {
                        delete spsFrame; spsFrameLength = 0;
                        spsFrame = NULL;
                    }
                    spsFrameLength = block->getDataLen();
                    spsFrame = new unsigned char[spsFrameLength];
                    memcpy(spsFrame, block->getData(), spsFrameLength);                   
                }                                           

                if (videoFrameType == 0x65 || videoFrameType == 0x41)
                {
                    videoFrameNumber++;
                }
                // Extract a thumbnail for each I-Frame
                if (videoFrameType == 0x65)
                {
                    decodeIFrame(h264, spsFrame, spsFrameLength, ppsFrame, ppsFrameLength, data, dataLen);
                }
                if (videoStream != NULL)
                {
                    AVPacket pkt = { 0 };
                    av_init_packet(&pkt);
                    pkt.stream_index = vi;
                    pkt.flags = 0;           
                    pkt.pts = videoFrameNumber;
                    pkt.dts = videoFrameNumber;           
                    if (videoFrameType == 0x65)
                    {
                        pkt.flags = 1;                           

                        unsigned char* videoFrame = new unsigned char[spsFrameLength+ppsFrameLength+dataLen];
                        memcpy(videoFrame, spsFrame, spsFrameLength);
                        memcpy(&videoFrame[spsFrameLength], ppsFrame, ppsFrameLength);

                        memcpy(&videoFrame[spsFrameLength+ppsFrameLength], data, dataLen);
                        pkt.data = videoFrame;
                        av_interleaved_write_frame(oc, &pkt);
                        delete videoFrame; videoFrame = NULL;
                    }
                    else if (videoFrameType != 0x67 && videoFrameType != 0x68)
                    {                       
                        pkt.size = dataLen;
                        pkt.data = data;
                        av_interleaved_write_frame(oc, &pkt);
                    }                       
                }
                break;
            }

        case TCP_PACKET_AAC:

            if (firstAudioTimeStamp == 0)
            {
                firstAudioTimeStamp = block->getTimeStamp();
                uint64_t millseconds_difference = firstAudioTimeStamp - firstVideoTimeStamp;
                audioStartOffset = millseconds_difference * 16000 / 1000;
                cout << "audio offset: " << audioStartOffset << endl;
            }

            if (audioStream != NULL)
            {
                AVPacket pkt = { 0 };
                av_init_packet(&pkt);
                pkt.stream_index = ai;
                pkt.flags = 1;           
                pkt.pts = audioFrameNumber*1024;
                pkt.dts = audioFrameNumber*1024;
                pkt.data = block->getData();
                pkt.size = block->getDataLen();
                pkt.duration = 1024;

                AVPacket newpacket = pkt;                       
                int rc = av_bitstream_filter_filter(bsfc, audioContext,
                    NULL,
                    &newpacket.data, &newpacket.size,
                    pkt.data, pkt.size,
                    pkt.flags & AV_PKT_FLAG_KEY);

                if (rc >= 0)
                {
                    //cout << "Write audio frame" << endl;
                    newpacket.pts = audioFrameNumber*1024;
                    newpacket.dts = audioFrameNumber*1024;
                    audioFrameNumber++;
                    newpacket.duration = 1024;                   

                    av_interleaved_write_frame(oc, &newpacket);
                    av_free_packet(&newpacket);
                }   
                else
                {
                    cout << "Error filtering aac packet" << endl;

                }
            }
            break;

        case TCP_PACKET_START:
            break;

        case TCP_PACKET_END:
            break;
        }
        delete block;
    }
    inFile.close();

    av_write_trailer(oc);
    int i = 0;
    for (i = 0; i < oc->nb_streams; i++)
    {
        av_freep(&oc->streams[i]->codec);
        av_freep(&oc->streams[i]);       
    }

    if (!(oc->oformat->flags & AVFMT_NOFILE))
    {
        avio_close(oc->pb);
    }

    av_free(oc);

    delete spsFrame; spsFrame = NULL;
    delete ppsFrame; ppsFrame = NULL;

    cout << "Wrote " << videoFrameNumber << " video frames." << endl;

    return 0;
}

在名为 addVideoAndAudioStream() 的函数中添加流流/编解码器并创建标头.这个函数是从 decodeIFrame() 调用的，所以有一些假设(不一定很好)1.先有视频包2. AAC 存在

void addVideoAndAudioStream(AVCodecContext* decoder = NULL)
{
    videoStream = av_new_stream(oc, 0);
    if (!videoStream)
    {
        cout << "ERROR creating video stream" << endl;
        return;       
    }
    vi = videoStream->index;   
    videoContext = videoStream->codec;       
    videoContext->codec_type = AVMEDIA_TYPE_VIDEO;
    videoContext->codec_id = decoder->codec_id;
    videoContext->bit_rate = 512000;
    videoContext->width = decoder->width;
    videoContext->height = decoder->height;
    videoContext->time_base.den = 25;
    videoContext->time_base.num = 1;
    videoContext->gop_size = decoder->gop_size;
    videoContext->pix_fmt = decoder->pix_fmt;       

    audioStream = av_new_stream(oc, 1);
    if (!audioStream)
    {
        cout << "ERROR creating audio stream" << endl;
        return;
    }
    ai = audioStream->index;
    audioContext = audioStream->codec;
    audioContext->codec_type = AVMEDIA_TYPE_AUDIO;
    audioContext->codec_id = CODEC_ID_AAC;
    audioContext->bit_rate = 64000;
    audioContext->sample_rate = 16000;
    audioContext->channels = 1;

    if (oc->oformat->flags & AVFMT_GLOBALHEADER)
    {
        videoContext->flags |= CODEC_FLAG_GLOBAL_HEADER;
        audioContext->flags |= CODEC_FLAG_GLOBAL_HEADER;
    }

    av_dump_format(oc, 0, filename, 1);

    if (!(oc->oformat->flags & AVFMT_NOFILE))
    {
        if (avio_open(&oc->pb, filename, AVIO_FLAG_WRITE) < 0) {
            cout << "Error opening file" << endl;
        }
    }

    avformat_write_header(oc, NULL);
}

// Extradata contains PPS & SPS for AVCC format
int extradata_len = 8 + spsFrameLen-4 + 1 + 2 + ppsFrameLen-4;
videoContext->extradata = (uint8_t*)av_mallocz(extradata_len);
videoContext->extradata_size = extradata_len;
videoContext->extradata[0] = 0x01;
videoContext->extradata[1] = spsFrame[4+1];
videoContext->extradata[2] = spsFrame[4+2];
videoContext->extradata[3] = spsFrame[4+3];
videoContext->extradata[4] = 0xFC | 3;
videoContext->extradata[5] = 0xE0 | 1;
int tmp = spsFrameLen - 4;
videoContext->extradata[6] = (tmp >> 8) & 0x00ff;
videoContext->extradata[7] = tmp & 0x00ff;
int i = 0;
for (i=0;i<tmp;i++)
    videoContext->extradata[8+i] = spsFrame[4+i];
videoContext->extradata[8+tmp] = 0x01;
int tmp2 = ppsFrameLen-4;   
videoContext->extradata[8+tmp+1] = (tmp2 >> 8) & 0x00ff;
videoContext->extradata[8+tmp+2] = tmp2 & 0x00ff;
for (i=0;i<tmp2;i++)
    videoContext->extradata[8+tmp+3+i] = ppsFrame[4+i];