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• OUTDATED - FFMPEG decoding artifacts between keyframes

  24 février 2023, par user2369412

  Marked question as outdated as using the deprecated avcodec_decode_video2

  


  ---

  
I'm currently experiencing artifacts when decoding video using ffmpegs api. On what I would assume to be intermediate frames, artifacts build slowly only from active movement in the frame. These artifacts build for 50-100 frames until I assume a keyframe resets them. Frames are then decoded correctly and the artifacts proceed to build again.


  One thing that is bothering me is I have a few video samples that are 30fps(h264) that work correctly, but all of my 60fps videos(h264) experience the problem.

  


  I don't currently have enough reputation to post an image, so hopefully this link will work.
http://i.imgur.com/PPXXkJc.jpg

  


  int numBytes;
int frameFinished;
AVFrame* decodedRawFrame;
AVFrame* rgbFrame;

    //Enum class for decoding results, used to break decode loop when a frame is gathered
DecodeResult retResult = DecodeResult::Fail;

decodedRawFrame = av_frame_alloc();
rgbFrame = av_frame_alloc();
if (!decodedRawFrame) {
    fprintf(stderr, "Could not allocate video frame\n");
    return DecodeResult::Fail;
}

numBytes = avpicture_get_size(PIX_FMT_RGBA, mCodecCtx->width,mCodecCtx->height);
uint8_t* buffer = (uint8_t *)av_malloc(numBytes*sizeof(uint8_t));

avpicture_fill((AVPicture *) rgbFrame, buffer, PIX_FMT_RGBA, mCodecCtx->width, mCodecCtx->height);

AVPacket packet;

while(av_read_frame(mFormatCtx, &packet) >= 0 && retResult != DecodeResult::Success)
{
    // Is this a packet from the video stream?
    if (packet.stream_index == mVideoStreamIndex)
    {
        // Decode video frame
        int decodeValue = avcodec_decode_video2(mCodecCtx, decodedRawFrame, &frameFinished, &packet);

        // Did we get a video frame?
        if (frameFinished)// && rgbFrame->pict_type != AV_PICTURE_TYPE_NONE )
        {
            // Convert the image from its native format to RGB
            int SwsFlags = SWS_BILINEAR;
            // Accurate round clears up a problem where the start
                            // of videos have green bars on them
            SwsFlags |= SWS_ACCURATE_RND;
            struct SwsContext *ctx = sws_getCachedContext(NULL, mCodecCtx->width, mCodecCtx->height, mCodecCtx->pix_fmt, mCodecCtx->width, mCodecCtx->height, 
                PIX_FMT_RGBA, SwsFlags, NULL, NULL, NULL);
            sws_scale(ctx, decodedRawFrame->data, decodedRawFrame->linesize, 0, mCodecCtx->height, rgbFrame->data, rgbFrame->linesize);
            
            //if(count%5 == 0 && count < 105)
            //  DebugSavePPMImage(rgbFrame, mCodecCtx->width, mCodecCtx->height, count);
            
            ++count;
            // Viewable frame is a struct to hold buffer and frame together in a queue
            ViewableFrame frame;
            frame.buffer = buffer;
            frame.frame = rgbFrame;
            mFrameQueue.push(frame);
            
            
            retResult = DecodeResult::Success;
                        
            sws_freeContext(ctx);
        }
    }
    
    // Free the packet that was allocated by av_read_frame
    av_free_packet(&packet);
}

// Check for end of file leftover frames
if(retResult != DecodeResult::Success)
{
    int result = av_read_frame(mFormatCtx, &packet);
    if(result < 0)
        isEoF = true;
    av_free_packet(&packet); 
}   

// Free the YUV frame
av_frame_free(&decodedRawFrame);


  


  I'm attempting to build a queue of the decoded frames that I then use and free as needed. Is my seperation of the frames causing the intermediate frames to be decoded incorrectly ? I also break the decoding loop once I've successfully gathered a frame(Decode::Success, most examples I've seen tend to loop through the whole video.

  


  All codec contect, video stream information, and format contexts are setup up exactly as shown in the main function of https://github.com/chelyaev/ffmpeg-tutorial/blob/master/tutorial01.c

  


  Any suggestions would be greatly appreciated.

  


• Anomalie #3539 : 2 fois prévisualiser pour voir le bloc de prévisualisation

  30 octobre 2015, par chan kalan

  De mon côté je reproduis le problème.
  plugin Forum 1.9.29
  Un bug au chargement ajax ?

• Anomalie #3816 (Nouveau) : Compatiblité avec PHP 7.0.9 et 5.6.24 et les fonctions "expected to be ...

  10 août 2016

  Suite à http://forum.spip.net/fr_264848.html#forum264908

  Apparemment SPIP et PHP 7.0.9 génère une page blanche.

  D’après Tatu, il faudrait modifier le paramètre de la fonction f_queue() à la ligne 246 du fichier "spip/ecrire/inc/pipelines.php"

  Ainsi la fonction :
  function f_queue(&$texte)
  Devient :
  function f_queue($texte)

  D’après Luc, cela pourrait venir de https://bugs.php.net/bug.php?id=72698

  Si c’est le cas, il faudrait faire une revue du code et chercher les appels de type &$