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• ffmpeg yuvj422p color movie conversion avi2ogv

  28 juillet 2017, par 7Tonin

  While converting avi video to ogv, there is a color problem in output file.
  How can I solve this issue ?
  normal colors altered colors

  Actually a part of the problem is from the player - so weak question

  Command using ffmpeg-3.3.2-1.mga6.tainted :

  ffmpeg -i dscn0146.avi -pix_fmt yuv422p -s 640x480 dscn0146_hq.ogv -y

  And input metadata :

  Guessed Channel Layout for Input Stream #0.1 : mono
  
  Input #0, avi, from 'dscn0146.avi':
  
    Metadata:
  
      encoder         : 
  
      maker           : NIKON
  
      model           : COOLPIX S3500
  
      creation_time   : 2017-07-22 12:09:06
  
    Duration: 00:00:07.33, start: 0.000000, bitrate: 11091 kb/s
  
      Stream #0:0: Video: mjpeg (MJPG / 0x47504A4D), yuvj422p(pc, bt470bg/unknown/unknown), 640x480, 10770 kb/s, 30 fps, 30 tbr, 30 tbn, 30 tbc
  
      Stream #0:1: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 22050 Hz, mono, s16, 352 kb/s
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (mjpeg (native) -> theora (libtheora))
  
    Stream #0:1 -> #0:1 (pcm_s16le (native) -> vorbis (libvorbis))

  Processes normaly, but fires a warning :

  [swscaler @ 0xd3c3a0] deprecated pixel format used, make sure you did set range correctly

  Output metadata :

  Output #0, ogv, to 'dscn0146_hq.ogv':
  
    Metadata:
  
      model           : COOLPIX S3500
  
      maker           : NIKON
  
      encoder         : Lavf57.71.100
  
      Stream #0:0: Video: theora (libtheora), yuv422p(progressive), 640x480, q=2-31, 200 kb/s, 30 fps, 30 tbn, 30 tbc
  
      Metadata:
  
        encoder         : Lavc57.89.100 libtheora
  
        model           : COOLPIX S3500
  
        maker           : NIKON
  
      Stream #0:1: Audio: vorbis (libvorbis), 22050 Hz, mono, fltp
  
      Metadata:
  
        encoder         : Lavc57.89.100 libvorbis
  
        model           : COOLPIX S3500
  
        maker           : NIKON

• Download youtube video duration using youtube-dl PHP and ffmpeg

  21 juin 2017, par user3285828

  Is there any more efficient way to download youtube videos at a specific start and end time using youtube-dl and ffmpeg in PHP.

  I currently have this, which does work, it first downloads the whole video to an mp3 file, and then crops that file to the range I set using ffmpeg, but when I only want 30 seconds or so of a 20 minute video, waiting for the full video to download doesn’t seem the best way to do it.

  <?php
  
  require __DIR__ . '/vendor/autoload.php';
  
  
  
  use YoutubeDl\YoutubeDl;
  
  
  
  $dl = new YoutubeDl([
  
      'extract-audio' => true,
  
      'audio-format' => 'mp3',
  
      'audio-quality' => 0, // best
  
      'output' => 'videoname.%(ext)s',
  
  ]);
  
  $dl->setDownloadPath('C:\youtubevideos');
  
  $video = $dl->download('https://www.youtube.com/watch?v=oDAw7vW7H0c');
  
  
  
  $start = 60; // Start 60 seconds in to the video
  
  $duration = 30; // Get 30 seconds after $start
  
  $fullVideo = "C:\youtubevideos\videoname.mp3";
  
  $shortVideo = "C:\youtubevideos\short\shortversion.mp3"; // create 30 seconds
  
  exec("ffmpeg -ss $start -i $fullVideo -t $duration -c copy $shortVideo");
  
  exec("DEL $fullVideo");

  I am using youtube dl PHP https://github.com/norkunas/youtube-dl-php

• Efficiently write a movie directly from np.array using pipes

  16 juin 2017, par Matt Billman

  I have a 4D numpy array of movie frames. I’m looking for a function to write them to a movie, at a given framerate. I have FFMPEG installed on my OS, and as I can see from these answers, the most efficient way to do so is via pipes.

  However, I have very little experience using pipes, and the explanations in the link above make little sense to me. Furthermore, very few of the answers seem actually implement pipes, and the one that does uses mencoder, not FFMPEG. I am relatively inexperienced with FFMPEG, so am not sure how to modify the command string from the mencoder answer to make it work in FFMPEG.

  WHAT I WOULD LIKE :

  A function of the following form :

  animate_np_array(4d_array, framerate) -> output.mp4 (or other video codec)

  Which implements pipes to send frames one after the other to FFMPEG, and which I can copy-paste into my existing code.

  Furthermore, it is absolutely necessary that this function never actually plots any of the frames, as calls to the matplotlib.imshow() function (as I have most typically seen used) slow things down considerably.