Low resampling quality in OSS4

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Low resampling quality in OSS4

Postby fly-away » Sun Feb 20, 2011 10:58 pm

vmix with 48000 rate and preset "HIGH" sounds worser than alsa 'samplerate' plugin.

Test sound: http://traffic.ihome.ru:8088/udial.wav
At the second part of track you can hear high frequency noise if resampler isn't good enough.
With alsa its ok but noise really annoyng with oss. Its important for sound tract quality.

.asoundrc for alsa:
Code: Select all
pcm.!default {
        type rate
        slave {
            pcm  "hw:0,0"
            rate 48000
        }
        converter "samplerate"
}
Last edited by fly-away on Sun Feb 20, 2011 11:23 pm, edited 1 time in total.
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Re: Low resampling quality in OSS4

Postby fly-away » Sun Feb 20, 2011 11:17 pm

After reading this http://www.opensound.com/forum/viewtopic.php?f=3&t=3730
as I can see, I need to choose more vmix-src quality.
But I cant.

Code: Select all
$ ossmix | grep vmix0-src
vmix0-src <Fast|High|OFF> (currently High)


The only place where I find definition of CONFIG_OSS_GRC_MAX_QUALITY is
oss-v4.2-build2004-src-gpl/kernel/framework/include/grc3.h
And its already set to 6.
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Re: Low resampling quality in OSS4

Postby igorzwx » Sun Feb 20, 2011 11:25 pm

fly-away wrote:After reading this http://www.opensound.com/forum/viewtopic.php?f=3&t=3730
as I can see, I need to choose more vmix-src quality.
But I cant.

Code: Select all
$ ossmix | grep vmix0-src
vmix0-src <Fast|High|OFF> (currently High)


The only place where I find definition of CONFIG_OSS_GRC_MAX_QUALITY is
oss-v4.2-build2004-src-gpl/kernel/framework/include/grc3.h
And its already set to 6.


You can also find a special PKGBUILD for OSS4 on this forum (if you need "Production quality")
http://www.opensound.com/forum/viewtopi ... =30#p15711
It seems that "Production quality" resampler is buggy, it may produce strange results (dowsampling).

There is also the Russian "exact scientific resampler" (standalone, very old version).
The ALSA plugin with "exact scientific resampler" is available on the Russian forum.
There is also "pcm_play" (ALSA/OSS4) and a special OSS4 plugin for the Russian Ultimate Player (deadbeef).
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