[Ffmpeg-devel] [BUG] garbled sound when playing 8kHz MP3s

[Stefan Gehrer]

Hi list,

I found that 8kHz mp3 files sound a bit garbled when decoded with ffmpeg.
I also get error messages like

foo at bar:~$ ./ffplay ../s8000.mp3
invalid new backstep 95
overread, skip -7 enddists: -1 -1
overread, skip -7 enddists: -5 -5
overread, skip -7 enddists: -1 -1
overread, skip -6 enddists: -4 -4
invalid new backstep 130
overread, skip -6 enddists: -1 -1
overread, skip -7 enddists: -6 -6
overread, skip -9 enddists: -7 -7

The same happens when playing back in mplayer or mpg123, but the error 
message are different:

mpg123: Can't rewind stream by 5 bits!1%
mpg123: Can't rewind stream by 144 bits!
mpg123: Can't rewind stream by 3 bits!1%
mpg123: Can't rewind stream by 22 bits!%
mpg123: Can't rewind stream by 46 bits!%

But if I decode the file with lame, it sounds OK.
To reproduce, it should be sufficient to encode your favorite piece of music
with 'lame --resample 8' (note that this is not a general recommendation to
encode good music at 8kHz :) ).
But if anybody is interested I can upload a sample where this happens.

Regards
Stefan Gehrer