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• combine three videos between specific time using ffmpeg

  9 décembre 2014, par Krisi

  I have a situation where I want to combine 3 videos

  The first video (guide.mp4) is the guide and the other 2 are small pieces that need to go inside the "guide"

  In a graphical manner, I have the following

  |         .---1.mp4---.                            .-----2.mp4-----.    |
  
  |---------+-----------+------------guide.mp4-------+---------------+----|
  
  0s        4s          9s                          18s             25s   28s

  the 1.mp4 and 2.mp4 will cover the guide between these times.
  the videos are of same size and all are .mp4 files

  I am pretty sure that this is covered, but I looked a lot, but since I myself am not good in english, I dont know how I could possibly look it up with success...

  Thanks in advance.

• 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 : Convert FLAC to mp3 and add album art in one step

  13 septembre 2022, par Christian Riedl

  I convert FLAC to MP3 using

  


  ffmpeg -i x.flac -f mp3 -vn -b:a 64K x.mp3


  


  and I add album art using

  


  ffmpeg -i x.mp3 -i x.jpg -map 0:0 -map 1:0 -c copy -id3v2_version 3 -metadata:s:v title="Album cover" -metadata:s:v comment="Cover (Front)" xx.mp3


  


  Is it possible to do it in one step ? Because I want to do it during "live" transcoding.