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• how to extract multi frame with ffmpeg exact and fast

  24 février 2018, par Questioner

  i want extract frame from video with ffmpeg

  for example

  ffmpeg.exe -an -r 21 -ss 00:17:50 -i "K :\test.mkv" -t 00:00:30 -s 560x314 -q:v 1 "T :\GIF\test_%05d.png"

  the command what i intend is

  extract frame from K :\test.mkv(O)
  start at 00:00:30 (O)
  extracted image size is 560x314 (o)
  output path and file name format T :\GIF\test_%05d.png (O)

  extract 30seconds from start point -t 00:00:30 (X)
  with frame rate 21(so if video’s original fps is 24fps, then it reduced to fps22)(maybe ? X)

  anyway this is not collect

  i got 660 images, image number is collect but this is not 30seconds video data
  only 15seconds data
  too large error, so i can’t ignore it

  i think i can fix it by -ss move to after -i
  but this need really a lot of time..

  how can i solve this problem
  1 5second error is ok but error is too large

• Streaming converted movie with mp4 container in NodeJS, movie playing very fast

  20 septembre 2016, par Mustafa

  I have used stream-transcoder module to convert a file make it a stream. So the file is not stored, it is on the fly.

  app.get("/video", function(req,res){
  
      res.writeHead(200, {'Content-Type': 'video/mp4'});
  
      var src = "movie.avi";
  
  
  
      var Transcoder = require('stream-transcoder');
  
      var stream = fs.createReadStream(src);
  
      new Transcoder(stream)
  
          .maxSize(1280, 720)
  
          .videoCodec('h264')
  
          .videoBitrate(800 * 1000)
  
          .fps(25)
  
          .sampleRate(44100)
  
          .channels(2)
  
          .audioBitrate(128 * 1000)
  
          .format('mp4')
  
          .on('finish', function() {
  
              console.log("finished");
  
          })
  
          .stream().pipe(res);
  
  });

  It works nicely, it is fast, but too fast, the audio is played at the same speed, however the video does not respect the frame rate, whatever is recieved from ffmpeg is immeidately shown, fastly. Additionally, it does not show the total time, I believe it is the problem. I need to somehow specify the length, framerate, but I could not find enough information on that. I thought the stream recieved from ffmpeg should contain that. And I could not find respective headers for that in HTTP.

  Here are the flags that this stream-transcoder module uses for MP4 :

  [ '-i',
  
    '-',
  
    '-vf',
  
    'scale=min(trunc(1280/hsub)*hsub\\,trunc(a*720/hsub)*hsub):min(trunc(720/vsub)*vsub\\,trunc(1280/a/vsub)*vsub)',
  
    '-vcodec',
  
    'h264',
  
    '-b:v',
  
    800000,
  
    '-r',
  
    25,
  
    '-ar',
  
    44100,
  
    '-ac',
  
    2,
  
    '-ab',
  
    128000,
  
    '-f',
  
    'mp4',
  
    '-movflags',
  
    'frag_keyframe+faststart',
  
    'pipe:1' ]

  When I use VP8 encoder and WebM, it works nicely, the time is displayed, video plays normal speed.

• libavcodec/mpeg12 : Remove "fast" mode

  29 octobre 2023, par Kieran Kunhya

  libavcodec/mpeg12 : Remove "fast" mode
  

  • [DH] libavcodec/mpeg12dec.c