ffmpeg creates invalid odd-byte length wav files

[dave rice]

Summary of the bug:

When I copy the audio data with ffmpeg from wav to wav and the source has an odd-byte-length data chunk then the resulting file is invalid because the output file is missing the required padding byte. In the command below this results in a 144,485 byte wav file (odd length RIFF chunks are not allowed). I can manually make the output valid by appending a padding byte to the end.

I'm attaching a sample source file: a valid wav file with mono 24 bit audio. The file has an odd-byte data length (this happens about half the time when recording 24 bit mono).

How to reproduce:

ffmpeg -i oddbytedatalength.wav -c copy copied.wav
ffmpeg version 1.1.git Copyright (c) 2000-2013 the FFmpeg developers
  built on Feb  6 2013 22:00:51 with Apple clang version 4.1 (tags/Apple/clang-421.11.66) (based on LLVM 3.1svn)
  configuration: --prefix=/usr/local/Cellar/ffmpeg/HEAD --enable-shared --enable-pthreads --enable-gpl --enable-version3 --enable-nonfree --enable-hardcoded-tables --enable-avresample --cc=cc --host-cflags= --host-ldflags= --enable-libx264 --enable-libfaac --enable-libmp3lame --enable-libxvid --enable-ffplay --enable-libopenjpeg --extra-cflags='-I/usr/local/Cellar/openjpeg/1.5.1/include/openjpeg-1.5 '
  libavutil      52. 17.101 / 52. 17.101
  libavcodec     54. 91.101 / 54. 91.101
  libavformat    54. 61.104 / 54. 61.104
  libavdevice    54.  3.103 / 54.  3.103
  libavfilter     3. 35.101 /  3. 35.101
  libswscale      2.  2.100 /  2.  2.100
  libswresample   0. 17.102 /  0. 17.102
  libpostproc    52.  2.100 / 52.  2.100
Input #0, wav, from 'oddbytedatalength.wav':
  Metadata:
    encoder         : Lavf54.61.104
  Duration: 00:00:01.00, bitrate: 1153 kb/s
    Stream #0:0: Audio: pcm_s24le ([1][0][0][0] / 0x0001), 48000 Hz, mono, s32, 1152 kb/s
Output #0, wav, to 'copied.wav':
  Metadata:
    ISFT            : Lavf54.61.104
    Stream #0:0: Audio: pcm_s24le ([1][0][0][0] / 0x0001), 48000 Hz, mono, 1152 kb/s
Stream mapping:
  Stream #0:0 -> #0:0 (copy)
Press [q] to stop, [?] for help
size=     141kB time=00:00:01.00 bitrate=1152.8kbits/s    
video:0kB audio:141kB subtitle:0 global headers:0kB muxing overhead 0.070645%

[dave rice]

source file, a valid wav file with odd-byte-length data chunk and required padding byte

[dave rice]

invalid output from -c copy with ffmpeg, the output is odd byte length but without padding byte

[Carl Eugen Hoyos]

Fixed by Paul B Mahol.

[Carl Eugen Hoyos]

Interestingly, FFmpeg (still) claims that the original file is invalid:

$ ffmpeg -i oddbytedatalength.wav -f null -
ffmpeg version N-49708-ga92816c Copyright (c) 2000-2013 the FFmpeg developers
  built on Feb  9 2013 01:34:27 with gcc 4.7 (SUSE Linux)
  configuration: --enable-gpl --disable-indev=jack
  libavutil      52. 17.101 / 52. 17.101
  libavcodec     54. 91.102 / 54. 91.102
  libavformat    54. 61.104 / 54. 61.104
  libavdevice    54.  3.103 / 54.  3.103
  libavfilter     3. 35.101 /  3. 35.101
  libswscale      2.  2.100 /  2.  2.100
  libswresample   0. 17.102 /  0. 17.102
  libpostproc    52.  2.100 / 52.  2.100
Input #0, wav, from 'oddbytedatalength.wav':
  Metadata:
    encoder         : Lavf54.61.104
  Duration: 00:00:01.00, bitrate: 1153 kb/s
    Stream #0:0: Audio: pcm_s24le ([1][0][0][0] / 0x0001), 48000 Hz, mono, s32, 1152 kb/s
Output #0, null, to 'pipe:':
  Metadata:
    encoder         : Lavf54.61.104
    Stream #0:0: Audio: pcm_s16le, 48000 Hz, mono, s16, 768 kb/s
Stream mapping:
  Stream #0:0 -> #0:0 (pcm_s24le -> pcm_s16le)
Press [q] to stop, [?] for help
Multiple frames in a packet from stream 0
[pcm_s24le @ 0x2c713e0] Invalid PCM packet, data has size 2 but at least a size of 3 was expected
Error while decoding stream #0:0: Invalid data found when processing input
size=N/A time=00:00:01.00 bitrate=N/A
video:0kB audio:94kB subtitle:0 global headers:0kB muxing overhead -100.022856%

[dave rice]

@cehoyos. I see the invalid error is a fault with my sample and that ffmpeg's warning is correct. I was replicating a odd-byte-length 24 bit mono file with a hex editor rather than send the 2 gig original and I made an error. I'm going to upload a proper odd-byte-length data chunk wav if anyone is someday interested. Thanks for the fix.

[dave rice]

valid version of oddbytedatalength.wav