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Bug 26463 - -march=pentium4 causes hissing/white noise in OGG audio playback
Summary: -march=pentium4 causes hissing/white noise in OGG audio playback
Status: RESOLVED FIXED
Alias: None
Product: Gentoo Linux
Classification: Unclassified
Component: [OLD] GCC Porting (show other bugs)
Hardware: x86 Linux
: High minor (vote)
Assignee: Gentoo Sound Team
URL:
Whiteboard:
Keywords:
Depends on:
Blocks:
 
Reported: 2003-08-11 23:50 UTC by Hypnos
Modified: 2003-08-16 08:34 UTC (History)
0 users

See Also:
Package list:
Runtime testing required: ---


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Description Hypnos 2003-08-11 23:50:19 UTC
I recently upgraded to GCC3 (3.2.3), and rebuilt libvorbis in the process, going
from ebuild 1.0-r2 to 1.0-r3.  The latter does not filter out "-march=*" flags,
and this caused a problem with rock music, which has some jarring higher
frequency sounds like cymbal crashes and electric guitar harmonics.  So I
changed my CFLAGS from "-march=pentium4 -Os -pipe" to "-mcpu=i686 -Os -pipe" and
now my OGG tracks sound nominal.

My recommendation is to retain the "-march=*" filter in the libvorbis ebuilds.


Reproducible: Always
Steps to Reproduce:
1. (see "Details")
Comment 1 Martin Schlemmer (RETIRED) gentoo-dev 2003-08-12 06:48:59 UTC
Whoever does libvorbis please.
Comment 2 J. Ellis (RETIRED) gentoo-dev 2003-08-15 23:39:01 UTC
Can you retest with -r4. If it is still an issue we can filter pentium4 out.
Comment 3 Hypnos 2003-08-16 02:50:14 UTC
There is some improvement, but still not acceptable.  Going from "-march=pentium4" to "-march=pentium3" doesn't help; "-mcpu=*" is works fine, as before.

This Forums thread suggests that "-march=*" is untenable for AMD architectures as well:

http://forums.gentoo.org/viewtopic.php?t=73292&highlight=libvorbis
Comment 4 J. Ellis (RETIRED) gentoo-dev 2003-08-16 03:37:29 UTC
Understood. I'll add something to filter march in r4. Thanks.
Comment 5 J. Ellis (RETIRED) gentoo-dev 2003-08-16 04:38:34 UTC
Now filtering -march=pentium?. Let me know if this works.

I'm not convinced that the athlon-zp problem is the same. Reading into the forum post i'd guess that -sse +3dnow results in the simd patch not being applied and consequently everything being okay.

If this is the case then perhaps the patch could be applied if (sse || 3dnow), but i have no idea if that will result in any improvement on althon-xp.

Anyway, that bug will wait for another day; i don't have an athlon box to experiment with.
Comment 6 Hypnos 2003-08-16 04:54:36 UTC
Where are you filtering?  I'm not seeing any changes after "emerge rsync" nor through the CVS browser on Gentoo.org.

Anyway, I'm hitting the sack soon -- let me know when you commit the changes, and I'll try out the ebuild to make sure it works.
Comment 7 Hypnos 2003-08-16 08:34:13 UTC
Revised -r4 has propagated, and works fine.