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• FFmpeg : Decoding AVPackets received from UDP socket

  8 août 2022, par strong_kobayashi

  I am trying to stream video frames encoded with FFmpeg from an Unity game to a client UI via UDP. To be specific, I am sending AVPackets (which contain the compressed frames, as far as I understand) from the server, which are then, on the client side, extracted as follows :

  



  inline UDPpacket* SDLGameClient::receiveData()
{
    if(SDLNet_UDP_Recv(socket, packet))
        return packet;
    else
        return NULL;
}

int main()
{
    ...
    // Initialize UDP
    ...
    UDPpacket *udpPacket;

    int i = 0;

    for(;;)
    {
        udpPacket = client->receiveData();

        if(udpPacket != nullptr)
        {
            i++;
            std::cout << "Packet " << i << " received!" << std::endl;

            AVPacket packet;
            av_init_packet(&packet);

            packet.data = new uint8_t[udpPacket->len];
            memcpy(packet.data, udpPacket->data, udpPacket->len);
            packet.size = udpPacket->len;

            ...


  



  To realize networking, I use the SDL_net library. Fragmenting, sending and receiving the packets seem to work without any problem. My question is, how do I decode the incoming AVPackets and stream the frames recorded in Unity to the client ?
I am aware that I need to use avcodec_send_packet and avcodec_receive_frame for decoding (since avcodec_decode_video2, that is used in many example decoding code, is deprecated), but when I do something like this :

  



  int ret = avcodec_send_packet(codecContext, &packet);
if(ret < 0 || ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
    std::cout << "avcodec_send_packet: " << ret << std::endl;
else
{
    while(ret >= 0)
    {
        ret = avcodec_receive_frame(codecContext, frame);
        if(ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
            std::cout << "avcodec_receive_frame: " << ret << std::endl;

        std::cout << "Frame: " << codecContext->frame_number << std::endl;
    }
}

av_packet_unref(packet);


  



  ret always returns a negative value (-22), so perhaps something is wrong with the AVPackets, or I'm sending the frames way too fast, I really have no clue :/

  



  Thanks in advance for any help !

  


• Unity : Converting Texture2D to YUV420P using FFmpeg

  23 juillet 2021, par strong_kobayashi

  I'm trying to create a game in Unity where each frame is rendered into a texture and then put together into a video using FFmpeg. The output created by FFmpeg should eventually be sent over the network to a client UI. However, I'm struggling mainly with the part where a frame is caught, and passed to an unsafe method as a byte array where it should be processed further by FFmpeg. The wrapper I'm using is FFmpeg.AutoGen.

  



  The render to texture method :

  



  private IEnumerator CaptureFrame()
{
    yield return new WaitForEndOfFrame();

    RenderTexture.active = rt;
    frame.ReadPixels(rect, 0, 0);
    frame.Apply();

    bytes = frame.GetRawTextureData();

    EncodeAndWrite(bytes, bytes.Length);
}


  



  The unsafe encoding method so far :

  



  private unsafe void EncodeAndWrite(byte[] bytes, int size)
{
    GCHandle pinned = GCHandle.Alloc(bytes, GCHandleType.Pinned);
    IntPtr address = pinned.AddrOfPinnedObject();

    sbyte** inData = (sbyte**)address;
    fixed(int* lineSize = new int[1])
    {
        lineSize[0] = 4 * textureWidth;
        // Convert RGBA to YUV420P
        ffmpeg.sws_scale(sws, inData, lineSize, 0, codecContext->width, inputFrame->extended_data, inputFrame->linesize);
    }

    inputFrame->pts = frameCounter++;

    if(ffmpeg.avcodec_send_frame(codecContext, inputFrame) < 0)
        throw new ApplicationException("Error sending a frame for encoding!");

    pkt = new AVPacket();
    fixed(AVPacket* packet = &pkt)
        ffmpeg.av_init_packet(packet);
    pkt.data = null;
    pkt.size = 0;

    pinned.Free();
    ...
}


  



  sws_scale takes a sbyte** as the second parameter, therefore I'm trying to convert the input byte array to sbyte** by first pinning it with GCHandle and doing an explicit type conversion afterwards. I don't know if that's the correct way, though.

  



  Moreover, the condition if(ffmpeg.avcodec_send_frame(codecContext, inputFrame) < 0) alwasy throws an ApplicationException, where I also really don't know why this happens. codecContext and inputFrame are my AVCodecContext and AVFrame objects, respectively, and the fields are defined as the following :

  



  codecContext

  



  codecContext = ffmpeg.avcodec_alloc_context3(codec);
codecContext->bit_rate = 400000;
codecContext->width = textureWidth;
codecContext->height = textureHeight;

AVRational timeBase = new AVRational();
timeBase.num = 1;
timeBase.den = (int)fps;
codecContext->time_base = timeBase;
videoAVStream->time_base = timeBase;

AVRational frameRate = new AVRational();
frameRate.num = (int)fps;
frameRate.den = 1;
codecContext->framerate = frameRate;

codecContext->gop_size = 10;
codecContext->max_b_frames = 1;
codecContext->pix_fmt = AVPixelFormat.AV_PIX_FMT_YUV420P;


  



  inputFrame

  



  inputFrame = ffmpeg.av_frame_alloc();
inputFrame->format = (int)codecContext->pix_fmt;
inputFrame->width = textureWidth;
inputFrame->height = textureHeight;
inputFrame->linesize[0] = inputFrame->width;


  



  Any help in fixing the issue would be greatly appreciated :)

  


• Evolution #3964 : mise en forme minimum des formulaires

  6 juin 2018, par nico d_

  C’est l’avis de tetue mais pas le mien :)

  Dans cette logique, pour être cohérent jusqu’au bout il faudrait aussi déplacer les h3.legend, .editer, .choix .saisie_* etc, qui sont explicitement liés à spip, dans spip.css
  Et déplacer ce qui reste de margin, font-weight et tous les Elements de notifications des boites succes, info, notice, alerte dans theme.css

  Bref, vider forms.css quoi :)

  Tel que je le conçois, form.css devrait contenir tout le style de base des formulaires spip ainsi que boutons réponses et erreurs.
  Tout dans ce fichier, pour pouvoir facilement le surcharger intégralement.

  Et dans theme.css, les ajustements de marges, couleurs, pour la dist, comme actuellement.