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Re: [Gap-dev-discuss] Cynthiune on Linux/ppc

From: Sebastian Reitenbach
Subject: Re: [Gap-dev-discuss] Cynthiune on Linux/ppc
Date: Sat, 12 May 2012 17:09:25 +0200
User-agent: SOGoMail 1.3.14

On Saturday, May 12, 2012 15:01 CEST, Riccardo Mottola <address@hidden> wrote: 
> Hmm,
> Alsa backend.
> I confirm that I can play MP3 files on ppc, but WAV file sound garbage.
> If I play this file I get garbage (alsa in LE mode)
> Record Take 20.wav: RIFF (little-endian) data, WAVE audio, Microsoft 
> PCM, 16 bit, stereo 44100 Hz
> However if I set Alsa in BE mode, it plays fine. It appears thus that 
> the WAV library returns the stream in the correct endianness of the 
> computer, while the MP3 library returns it alwas little endian.
> Checking in the alsa header one can set LE, BE or not specified. Not 
> specified is then the correct endianness of the computer.
> Furthermore if I play this file,
> Windows XP Ding.wav: RIFF (little-endian) data, WAVE audio, Microsoft 
> PCM, 16 bit, mono 22050 Hz
> I get:
> ALSA lib pcm.c:7482:(snd_pcm_set_params) Unable to get period size for 
> PLAYBACK: Invalid argument
> Thus it appears that to make this thing portable the media type needs to 
> set endianness and playrate in the backend.

I also think we need to propagate such information to the output backend.


> The OSS backend suffers similar problems, it is set to LE at the moment 
> it appears.
> The AO backend plays instead only WAV files so it is set to big-endian..
> Riccardo
> Riccardo Mottola wrote:
> > Hi,
> >> Should we add a -dataEndianness method to the Format protocol ?
> >>> I still don't know if it is file-format dependent or not, it depends
> >>> how the libraries handle it
> >> Maybe inspection of other players is in order ?
> >>
> > Checking other code on the network, I found that while our backend 
> > initialized the backend to 16bit PCM, others initialize it as 16bit 
> > LittleEndian PCM.
> > By reading around, this appears to be a sound-specific setting and not 
> > a hardware specific setting. Thus more than a configure script, we 
> > should have an endianness property for the media type. However, the 
> > library used for reading the media might already do a conversion, 
> > however since we decode one file type always with the same library, it 
> > still would work. I tried it only with MP3 files, I will try other 
> > files like WAV.
> > I commited the change to little-endian since I think it is the safer 
> > bet (I guess that o n x86 my change has no effect) please try.
> >
> > Riccardo
> >
> >

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