SDL-mixer and SDL-sound: Problem with mp3 support

[Vincent Prat]

Hello

As you suggested, I have reported the bug [1].
What seems odd to me is the fact that everything worked fine with the 
previous stable version of the package (with the same mp3 files).

[1] http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=708297

Cheers,
Vincent

Le 12/05/2013 17:13, Manuel A. Fernandez Montecelo a écrit :
> 2013/5/12 Vincent Prat<vinceprat at free.fr>:
>> Hello
>>
>> Thank you for your answer.
>> After some investigations, it appears that libmad and sdl-mixer work fine.
>> It is in fact sdl-sound that is unable to handle correctly mp3 files.
>> I used sdl-sound to compute the duration of the sound file I wanted to play
>> and if the duration was zero, nothing was played by sdl-mixer. Sorry for
>> having misled you.
>>
>> Anyway, there is still a problem with sdl-sound. The duration of mp3 files
>> is largely underestimated whereas the result is correct for other formats.
>> And using sdl-sound to play a mp3 sound through Mix_QuickLoad_RAW and
>> Mix_PlayChannel gives a very short and unpleasant sound.
>> Besides, for a valid mp3 file, the flag of the corresponding Sound_Sample
>> used to be different from SOUND_SAMPLEFLAG_NONE, which is not the case now.
> The relevant options of sdl-sound are:
>
>    --enable-smpeg             enable MP3 decoding via smpeg default=yes
>    --enable-mpglib            enable MP3 decoding internally default=yes
>
> both of which are enabled in debian/rules.
>
> They seem to have been built in my system (amd64) when I uploaded the
> package.  mpglib seems to be internal code, but smpeg is not and the
> library doesn't link against it (it does for ogg or others).  I don't
> know very well what's going on.
>
> On the other hand, smpeg is old (almost 10 years old) and I think that
> mostly abandoned upstream (although I didn't check).  Maybe recent
> changes in compiler options, for example the hardening flags, are
> causing troubles.  Since libmad looks a much better alternative, I did
> the switch in sdl-mixer, but this one doesn't support it.
>
> I compiled "playsound" (from sdl-sound sources), which after a small
> modification needed to get it compiled (adding<signal.h>), can play
> some .mp3 that I have around, but only ~20% of them.
>
> Many of the produce a bad sound for a fraction of a second and abort with:
>
> Error in decoding sound file!
>    reason: [MPGLIB: Free format not supported.].
>
> My guess is that sdl-sound's internal "mpglib" are not up to date and
> cannot play many .mp3 files, for one reason or another (maybe they are
> e.g. with VBR, some "advanced" features, or newer variations of the
> standard).
>
> Maybe you can submit a bug report to the package with a minimal test
> case (instructions plus small mp3 file) so we can forward it upstream
> or somebody can produce a patch.  You can try also with other .mp3
> that you have around, to see if you can get at least some of them
> played.
>
>
> Cheers.
> --
> Manuel A. Fernandez Montecelo<manuel.montezelo at gmail.com>
>