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• Right way to use vmaf with ffmpeg

  20 mai 2021, par dravit

  I am trying to calculate the VMAF score of a processed video wrt the original file.

  


  Command I have used :

  


  ffmpeg -y -loglevel info -stats -i original.mp4 -i processed.mp4 -lavfi "[0]null[refdeint];[refdeint]scale=1920:1080:flags=neighbor[ref];[1]setpts=PTS+0.0/TB[b];[b]scale=1920:1080:flags=neighbor[c];[c][ref]libvmaf=log_fmt=json:phone_model=1:model_path={model_path_here}/vmaf_v0.6.1.json:n_subsample=1:log_path=log.json" -f null -


  


  Now as per the official documentation of vmaf with ffmpeg found here, it says source/reference file followed by the encoded/distorted/processed file.

  


  But almost all of the blogs I came across, they are using the other way round order of the args, i.e. processed file followed by the original file.

  


  Few examples :

  


  


  1. https://medium.com/@eyevinntechnology/keep-an-eye-on-the-video-quality-b9bcb58dd5a1 : search for "Using VMAF within FFMPEG" in it.

     


  


  2. https://websites.fraunhofer.de/video-dev/calculating-vmaf-and-psnr-with-ffmpeg/ : search for "Metric Calculation with FFmpeg" in it.

     


  


  


  EDIT

  


  NOTE : Changing the order does change the VMAF score.

  


• FFmpeg decode OGG Vorbis audio as float, how to get float data from decoder

  19 novembre 2020, par cs guy

  I am trying to decode a OGG Vorbis audio file with the following :

  


  // if opening input failed
    if (avformat_open_input(&pFormatContext, filePath.c_str(), av_find_input_format("ogg"),
                            nullptr) != 0) {
        
        LOGE("FFmpegExtractor can not open the file! %s", filePath.c_str());
        return FAILED_TO_LOAD;
    }

    durationInMillis = pFormatContext->duration / AV_TIME_BASE * secondsToMilli;
    LOGD("FFmpegExtractor opened the file, Duration: %llu", durationInMillis);

    avformat_find_stream_info(pFormatContext, nullptr);

    LOGD("pFormatContext streams num: %ui", pFormatContext->nb_streams);

    int sendPacketResult = 0;
    int receiveFrameResult = 0;

    for (int i = 0; i < pFormatContext->nb_streams; i++) {
        AVCodecParameters *pLocalCodecParameters = pFormatContext->streams[i]->codecpar;

        if (pLocalCodecParameters->codec_type == AVMEDIA_TYPE_AUDIO) {
            avCodecContext = avcodec_alloc_context3(avCodec);
            if (!avCodecContext) {
                
                LOGE("FFmpegExtractor avcodec_alloc_context3 failed!");
                return FAILED_TO_LOAD;
            }

            if (avcodec_parameters_to_context(avCodecContext, pLocalCodecParameters) < 0) {
                
                LOGE("FFmpegExtractor avcodec_parameters_to_context failed!");
                return FAILED_TO_LOAD;
            }

            if (avcodec_open2(avCodecContext, avCodec, nullptr) < 0) {
                
                LOGE("FFmpegExtractor avcodec_open2 failed!");
                return FAILED_TO_LOAD;
            }
        }

        while (av_read_frame(pFormatContext, avPacket) >= 0) {
            
            sendPacketResult = avcodec_send_packet(avCodecContext, avPacket);

            
            receiveFrameResult = avcodec_receive_frame(avCodecContext, avFrame);

            // TODO: Get frames PCM data from the decoder, 
        }
    }


  


  I am stuck on the last part. I want to get the decoded data of the current frame as a float between -1 to +1 for all the channels the audio has but I have no idea how to. I looked at the official documents but I could not understand them. How can I get the data from the decoder on the line

  


  


  // TODO : Get frames PCM data from the decoder,

  


  


• Concatenate multiple video php ffmpeg

  3 mai 2017, par Angus Simons

  I have multiple files that are already been encoded (they have the same format and size) I would like to concatenate on a single video (that already exist and has to be overwritten).

  Following the official FAQ Documentation I should use demuxer

  FFmpeg has a concat demuxer which you can use when you want to avoid a
  re-encode and your format doesn’t support file level concatenation.

  The problem is that I should use a .txt file with a list of files using this command line

  ffmpeg -f concat -safe 0 -i mylist.txt -c copy output

  where mylist.txt should be :

  file '/path/to/file1'
  
  file '/path/to/file2'
  
  file '/path/to/file3'

  How can I do with PHP ?

  ---

  Also tried with concat protocol

  I tried using also the concat protocol that re-encode videos with these lines of code :

  $cli = FFMPEG.' -y -i \'concat:';
  
  
  
  foreach ($data as $key => $media) {
  
    $tmpFilename = $media['id'];
  
    $tmpPath = $storePath.'/tmp/'.$tmpFilename.'.mp4';
  
  
  
    if ($key != ($dataLenght - 1)) {
  
      $cli .= $tmpPath.'|';
  
    } else {
  
      $cli .= $tmpPath.'\'';
  
    }
  
  }
  
  
  
  $cli .= ' -c copy '.$export;
  
  exec($cli);

  that generate this command line :

  /usr/local/bin/ffmpeg -i 'concat:/USER/storage/app/public/video/sessions/590916f0d122b/tmp/1493768472144.mp4|/USER/storage/app/public/video/sessions/590916f0d122b/tmp/1493767926114.mp4|/USER/storage/app/public/video/sessions/590916f0d122b/tmp/1493771107551.mp4|/USER/storage/app/public/video/sessions/590916f0d122b/tmp/1493771114598.mp4' -c:v libx264  /USER/storage/app/public/video/sessions/590916f0d122b/tmp_video_session.mp4

  but I got this error :

  [mov,mp4,m4a,3gp,3g2,mj2 @ 0x7fc8aa800000] Found duplicated MOOV Atom. Skipped it