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• Running ffmpeg silently on NodeJS (Windows)

  5 janvier 2021, par Paulo Bertotti

  I'm trying to run FFMPEG as a child process on NodeJS to extract a snapshot of an mp4 video on Windows. But even spawning the process with the "silent" option, it stills opening the command prompt for a short period. Any idea of what might be happening ?

  


  The code looks something like this :

  


  const snapshot = spawn(
              "ffmpeg",
              [
                "-ss",
                "00:00:07",
                "-i",
                `${this.directory}\\${file.name}`,
                "-vframes",
                "1",
                "-q:v",
                "2",
                `${this.directory}\\channel${this.channelNum}_snapshot.png`,
              ],
              { silent: true }
            );


  


• ffmpeg decode gif got an error : “[gif @ 0000017ea4d9d1c0] cannot decode frame without keyframe”

  23 mai 2022, par Jeycri

  I want to decode gif when pts is greater than a certain period of time.

  


  This is my code :

  


  for(;;){
  ret = av_read_frame(in_ctx, pkt);

  if (ret != 0) {
      printf("av_read_frame errorcode %d \n", ret);
      break;
  }
        
  if (pkt->pts < av_rescale_q(3.0*AV_TIME_BASE, AV_TIME_BASE_Q, st->time_base)) {
       av_packet_unref(pkt);    
       continue;
  }

  if(pkt->stream_index == video_index){
     if (pkt) {
        ret = avcodec_send_packet(codec_ctx, pkt);
        if (ret < 0 && ret != AVERROR_EOF) break;
        while (avcodec_receive_frame(codec_ctx, frame) >= 0) {
             //do something
        }
     }
  }
}


  


  Is there any way to realize this function ?

  


  FFmpeg version is 4.3.3.

  


• How to extract the sound of a video from two timecodes to a .ts file [closed]

  22 avril 2023, par Imprevisible

  I'm trying to use FFMPEG to extract the audio from a video for a certain period of time and cut it into 5 second chunks, but it doesn't work. Instead, the chunks have different lengths and don't match what I asked for. I tried several solutions, but nothing worked.

  


  From what I understand, the problem could be with the picturerate and the treshold, but I don't know what to do with that information. Here is the command I used :

  


  ffmpeg -loglevel error -accurate_seek -ss 00:00:00 -to 00:00:05 -t 5 -i H:/Films/Tetris.mkv -c:a aac -b:a 128k -ac 4 -vn -map 0:1 -f adts pipe:1


  


  This gave me an audio file of 53s, but if I do from 00:00:05 to 00:00:10, I have an audio file of 4.6s.

  


  If anyone can help me, that would be great. Thanks in advance