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• 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>

• FFMPEG to remove audio but keeping background sound

  17 octobre 2022, par Sushil

  I am trying to add voice over to the existing video which has some audio in English and some background sound. I am trying to add other than English audio on top of it and keeping background sound. But when I add new audio it removes all the background sound and when it adds new audio which makes it robotic as original background sound is lost.
When I add new audio by using amix filter, it keeps all sound like English and new language both, and both plays together.

  


  

  1. Is there any way to separate background sound and speaking audio from video separately ?

  


  2. Is it possible to mute or remove audio from only parts of video like offset between time frames ?

  


  


  Command that I am using for add new audio
ffmpeg  -i independance_speech.mp4  -i 01.mp3 -filter_complex "[1]adelay=10000[s1];[s1]amix=inputs=2[a]" -map 0:v  -map "[a]" -c:v copy result.mp4

  


• Subtitles added to MKV with ffmpeg doesn't show

  15 avril 2023, par Efraín

  I've a weird problem, that I don't seem to understand what's happening. Basically, I've an MKV with 2 subtitle tracks, and I want to add a new one, so after searching a little, I worked this command

  


  ffmpeg -i "file v.mkv" -i "file s.ass" -c copy -map 0 -map 1 -metadata:s:s:2 language=eng -metadata:s:s:2 handler_name=English -metadata:s:s:2 title=English-dl output.mkv


  


  But when I opened output.mkv, and selected the 3rd sub track, It doesn't show the subtitles. I used MKVExtract to extract the track, and it correctly is the same .ass file that I merged, so I don't know why they don't show.

  


  I used this other command as example to make the previous one

  


  ffmpeg -i "file v.mkv" -i "file s.ass" -c copy -map 0 -dn -map "-0:s" -map "-0:d" -map "1:0" "-metadata:s:s:0" "language=eng" "-metadata:s:s:0" "handler_name=English"  "-metadata:s:s:0" "title=English-dl" "output.mkv"


  


  And this one correctly show the subtitles, but it erase the 2 original tracks of the MKV(Which I don't want to happen). What is the difference here that makes the second one show the subtitles, but the first one don't ? Do I have to lose the original subs for this ?