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• no audio after mp3 + jpg with ffmpeg

  31 octobre 2019, par YongJiang Zhang

  I have a mp3 file. I checked. It has audio. After run command

  ffmpeg -i 31.mp3 -i cover.jpg -c:a copy -s 1280x720 -pix_fmt yuv420p 31.mp4

  I got 31.mp4 but it has no audio.

  I use macbook pro and ffmpeg version 4.1

• ffmpeg produced .wav reads only zeros with scipy.io.wavfile

  8 janvier 2015, par question_mark

  Hi everyone and thanks for reading.

  I wanted to do some analysis on a song using Python’s scipy.io.wavfile. Since I only have the song as .mp3 I converted the file to .wav using ffmpeg the following way :

  ffmpeg -i test.mp3 test.wav

  The .wav file plays perfectly well with vlc player, but wavfile shows only zeroes when reading it :

  from scipy.io import wavfile as wf
  
  
  
  data = wf.read("test.wav")
  
  C:\Program Files\Anaconda\lib\site-packages\scipy\io\wavfile.py:42: WavFileWarning: Unknown wave file format
  
    warnings.warn("Unknown wave file format", WavFileWarning)
  
  
  
  data
  
  (44100, array([[0, 0],
  
          [0, 0],
  
          [0, 0],
  
          ..., 
  
          [0, 0],
  
          [0, 0],
  
          [0, 0]], dtype=int16))

  I tried getting the data with Python’s built-in wave module before to the same effect (only zeros).
  I am using the 64bit version of ffmpeg (ffmpeg-20140218-git-61d5970-win64-static).

  Any help is appreciated :-)

  Edit : Included .wav header and tried forcing ffmpeg output format

  I guess the header information of the .wav file is included here :

  ffmpeg -i .\test.wav
  
  Guessed Channel Layout for  Input Stream #0.0 : stereo
  
  Input #0, wav, from '.\test.wav':
  
    Metadata:
  
      artist          : Joe Cocker
  
      copyright       : (C) 1987 Capitol Records, Inc.
  
      date            : 1987
  
      genre           : Pop
  
      title           : Unchain My Heart
  
      album           : Unchain My Heart
  
      track           : 1/10
  
      encoder         : Lavf55.33.100
  
    Duration: 00:05:04.33, bitrate: 1411 kb/s
  
    Stream #0:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 44100 Hz, stereo, s16, 1411 kb/s

  If I try to specify the ffmpeg output format explicitly for the .mp3 conversion :

  ffmpeg -i .\test.mp3 -f s16le -ar 44100 -ac 2 test.wav
  
  Input #0, mp3, from '.\test.mp3':
  
    Metadata:
  
      title           : Unchain My Heart
  
      artist          : Joe Cocker
  
      album           : Unchain My Heart
  
      genre           : Pop
  
      composer        : Bobby Sharp
  
      track           : 1/10
  
      disc            : 1/1
  
      album_artist    : Joe Cocker
  
      copyright       : (C) 1987 Capitol Records, Inc.
  
      date            : 1987
  
    Duration: 00:05:04.35, start: 0.025056, bitrate: 240 kb/s
  
      Stream #0:0: Audio: mp3, 44100 Hz, stereo, s16p, 235 kb/s
  
      Stream #0:1: Video: mjpeg, yuvj420p(pc), 600x600 [SAR 1:1 DAR 1:1], 90k tbr, 90k tbn, 90k tbc
  
      Metadata:
  
        title           :
  
        comment         : Cover (front)
  
  Output #0, s16le, to 'test.wav':
  
    Metadata:
  
      title           : Unchain My Heart
  
      artist          : Joe Cocker
  
      album           : Unchain My Heart
  
      genre           : Pop
  
      composer        : Bobby Sharp
  
      track           : 1/10
  
      disc            : 1/1
  
      album_artist    : Joe Cocker
  
      copyright       : (C) 1987 Capitol Records, Inc.
  
      date            : 1987
  
      encoder         : Lavf55.33.100
  
      Stream #0:0: Audio: pcm_s16le, 44100 Hz, stereo, s16, 1411 kb/s
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (mp3 -> pcm_s16le)
  
  Press [q] to stop, [?] for help
  
  video:0kB audio:52425kB subtitle:0 data:0 global headers:0kB muxing overhead 0.000000%
  
  size=   52425kB time=00:05:04.32 bitrate=1411.2kbits/s

  But in this case (forced format), both ffmpeg and wavfile are not able to read the file :

  ffmpeg -i .\test.wav
  
  .\test.wav: Invalid data found when processing input

  and

  data = wf.read("test2.wav")
  
  ---------------------------------------------------------------------------
  
  ValueError                                Traceback (most recent call last)
  
   in <module>()
  
  ----> 1 data = wf.read("test2.wav")
  
  
  
  C:\Program Files\Anaconda\lib\site-packages\scipy\io\wavfile.pyc in read(filename, mmap)
  
      152 
  
      153     try:
  
  --> 154         fsize = _read_riff_chunk(fid)
  
      155         noc = 1
  
      156         bits = 8
  
  
  
  C:\Program Files\Anaconda\lib\site-packages\scipy\io\wavfile.pyc in _read_riff_chunk(fid)
  
       98         _big_endian = True
  
       99     elif str1 != b'RIFF':
  
  --> 100         raise ValueError("Not a WAV file.")
  
      101     if _big_endian:
  
      102         fmt = '>I'
  
  
  
  ValueError: Not a WAV file.
  
  </module>

• Celery task execution never stops

  2 janvier 2015, par Dmitry Mikhaylov

  I don’t know why but my task never stops executing, it just starts from the beginning.

  Here’s the code :

  @task
  
  def create_screenshots(video_id):
  
      from videos.models import Video
  
  
  
      video = Video.objects.get(id=video_id)
  
      filename = os.path.join(settings.MEDIA_ROOT, video.file.name)
  
      cmd = ["ffprobe", "-of", "json", "-show_format", "-show_streams", filename]
  
      info = json.loads(check_output(cmd))
  
      streams = info['streams']
  
      frames = 0
  
  
  
      for stream in streams:
  
          if stream['codec_type'] == 'video':
  
              frames = stream['nb_frames']
  
              break
  
  
  
      rate = int(frames) / (settings.FRAMES_NUMBER + 1)
  
  
  
      output_filename = os.path.join('/tmp', '%s_tile.jpg' % os.path.basename(video.file.name))
  
  
  
      # create thumbnails tile
  
      cmd = ["ffmpeg", "-i", filename, "-vf",
  
             "select=not(mod(n\\, %d)),scale=231:160,tile=1x10" % int(rate), "-y",
  
             output_filename]
  
      call(cmd)
  
      video.screenshots_sprite.save("%d.jpg" % video.id, File(open(output_filename)), save=False)
  
  
  
      # create cover
  
      output_filename = os.path.join('/tmp', '%s_cover.jpg' % os.path.basename(video.file.name))
  
      cmd = ["ffmpeg", "-i", filename, "-vf", "select=gte(n\,%d)" % (int(frames) / 2,),
  
             "-vframes", "1", "-y", output_filename]
  
      call(cmd)
  
      video.cover.save("%d.jpg" % video.id, File(open(output_filename)), save=False)
  
      video.save()

  What I do here is just run ffmpeg to get video thumbnails and cover file. I don’t see any loop here.