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List:       kde-multimedia
Subject:    Re: mpeglib's handling of signed and big audio?
From:       Stefan Westerfeld <stefan () space ! twc ! de>
Date:       2001-04-01 22:10:21
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   Hi!

On Sun, Apr 01, 2001 at 05:51:48PM +0200, Martin Vogt wrote:
> On Sun, Apr 01, 2001 at 12:05:34PM +0200, Carsten Griwodz wrote:
> > After a longer pause, I have revently tried to use mpeglib on AIX again,
> > and the sound was quite garbled until I made some changes.
> > 
> > Was there any change in the signed and endianness handling in the last,
> > say, 3 months?
> > 
> > The flags for signedness and for endianness that are passed to audioSetup
> > do not reach the platform-specific audio code. The AIX audio devices wants
> > this information for initialization. Why is this not important for other
> > platforms???
> >
> 
> IIRC we made a bad hack for PPC support in the splay mp3 decoder
> for KDE 2.0.
> This broke AIX.
> The problem was that aRts always wanted little endian data, even
> on big endian machines. So we made the hack to convert the
> big endian output by mpeglib on PPC to little for arts.
> But this broke the mpeglib audio output layer (yaf-xxx players)
> Maybe we should pass the audio stream info really to the
> audio subsys.
> Before this the assumption for the mpeglib audio subsys was: 
> 
> decoder endianess == machine endianess.

I know - in KDE2.0/KDE2.1, aRts COULD NOT deal with big endian support at all.
The uni_convert_stereo_2float routine really didn't support it. Now, as in
CVS, current version (HEAD), it does support it, properly. So basically the
hack can be reverted and be replaced by

  int format;
#ifdef WORDS_BIG_ENDIAN
  format = uni_convert_s16_be;      // signed 16 bit, big endian
#else
  format = uni_convert_s16_le;
#endif
  uni_convert_stereo_2float(...,format,...);

in the mpeglib_artsplug part. Martin, what do you think? Can you have a look
at unbreaking it? ;)

   Cu... Stefan
-- 
  -* Stefan Westerfeld, stefan@space.twc.de (PGP!), Hamburg/Germany
     KDE Developer, project infos at http://space.twc.de/~stefan/kde *-         
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