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• Covert opengl framebuffer into ffmpeg encoded mp4 c++ [closed]

  14 mai 2022, par user19068953

  I want to make a program that takes an mp4 file as an input and draws something on top of it then gives the new video as an output. So far I have a program that takes a file name, have ffmpeg decode it and draw whatever i want with opengl (I have followed this tutorial that draws on top of the video separately : https://gist.github.com/hradec/a8b8ae0bf82891a5d853b06619839d9d) and have an opengl framebuffer. My question is how do put opengl's framebuffer on top of ffmpeg frames and generate a new video with it then give a new file as an output ? The framebuffer is allocated in fbo, so i want to encode it to ffmpeg, something like

  


   av_write_frame(state->fmt_ctx, &fbo) 


  


  is there a function like this that allows me to write frame data into a newly created video ?

  


  Here is my encoder :

  


      int VideoDecoder::write_frame()
{
    // Find a way to write OpenGL Frames here.
    av_packet_rescale_ts(&state->packet, VideoSt.Ctx->time_base, VideoSt.Stream->time_base);
    state->packet.stream_index = VideoSt.Stream->index;
    return av_interleaved_write_frame(state->fmt_ctx, &state->packet);
}


bool VideoDecoder::encode_video()
{

    // TODO: This is horrible fix this function.

    state->packet = { nullptr };
    av_init_packet(&state->packet);

    fflush(stdout);

    IMG_Buffer.SetNum(ColorBuffer.Num() * 4);
    uint8* DestPtr = nullptr;
    for (auto i = 0; i < ColorBuffer.Num(); i++)
    {
        DestPtr = &IMG_Buffer[i * 4];
        auto SrcPtr = ColorBuffer[i];
        *DestPtr++ = SrcPtr.R;
        *DestPtr++ = SrcPtr.G;
        *DestPtr++ = SrcPtr.B;
        *DestPtr++ = SrcPtr.A;
    }

    uint8* inData[1] = { IMG_Buffer.GetData() };


    sws_scale(SwsCtx, inData, InLineSize, 0, VideoSt.Ctx->height, VideoSt.Frame->data, VideoSt.Frame->linesize);

    VideoSt.Frame->pts = VideoSt.NextPts++;
    if (FFmpegEncode(VideoSt.Frame) < 0)
        return false;

    auto ret = WriteFrame();

    if (ret < 0)
    {
        auto errstr = FString(av_err2str(ret));
    }
    av_packet_unref(&state->packet);


    GotOutput = 0;
    auto ret = avcodec_send_frame(VideoSt.Ctx, frame);
    if (ret < 0 && ret != AVERROR_EOF) {
        auto errstr = FString(av_err2str(ret));
        return -1;
    }

    ret = avcodec_receive_packet(VideoSt.Ctx, &Pkt);
    if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
        return 0;

    if (ret < 0)
    {
        auto errstr = FString(av_make_error_string(ret).c_str());
        av_packet_unref(&Pkt);
        return -1;
    }

    GotOutput = 1;
    return 0;


    for (GotOutput = 1; GotOutput; count++)
    {
        fflush(stdout);

        FFmpegEncode(nullptr);

        if (GotOutput)
        {
            auto ret = WriteFrame(false);
            if (ret < 0)
            {
                auto errstr = FString(av_err2str(ret));
            }
            av_packet_unref(&Pkt);
        }
    }

    auto ret = av_write_trailer(FmtCtx);
    if (ret < 0)
    {
        auto errstr = FString(av_err2str(ret));
    }
}


  


  and here is my simple frame buffer :

  


  bool OpenGLRenderer::alloc_frame_buffer()
{
    unsigned int fbo;
    glGenFramebuffers(1, &fbo);

    if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE) return false;

    glBindFramebuffer(GL_FRAMEBUFFER, fbo);

    unsigned int texture;
    glGenTextures(1, &texture);
    glBindTexture(GL_TEXTURE_2D, texture);

    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, 800, 600, 0, GL_RGB, GL_UNSIGNED_BYTE, NULL);

    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, texture, 0);
}


  


• avcodec/mpegvideo_enc : Reduce stack usage

  18 mai, par Andreas Rheinhardt

  avcodec/mpegvideo_enc : Reduce stack usage
  Multiple PutBitContexts are used when encoding partitioned
  
  frames. When there are multiple candidates for macroblock types,
  
  multiple states (namely the state before encoding the current MB,
  
  the best state among the ones already tried and the current one)
  
  need to be kept ; duplicates of the PutBitContexts are among this
  
  state. The temporary buffers for them are kept on the stack
  
  in encode_thread() and their size is quite generous (MAX_MB_SIZE
  
   3000 bytes). This commit uses tighter bounds, bringing the
  
  size of the pb2 buffer down to 15 bytes.
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
  

  • [DH] libavcodec/mpeg4videoenc.h
  • [DH] libavcodec/mpegvideo_enc.c

• fftools/ffmpeg_filter : do not assume av_buffersrc_get_nb_failed_requests()>0

  7 mars 2024, par Anton Khirnov

  fftools/ffmpeg_filter : do not assume av_buffersrc_get_nb_failed_requests()>0
  Apparently it can happen that avfilter_graph_request_oldest() returns
  
  EAGAIN, yet av_buffersrc_get_nb_failed_requests() returns 0 for every
  
  input.
  Works around #10795, though the root issue is most likely in the
  
  scale2ref filter.
  

  • [DH] fftools/ffmpeg_filter.c