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Date: Sat, 27 Dec 2003 12:12:54 -0800
From: "Martin J. Bligh" <mbligh@aracnet.com>
To: Jaroslav Kysela <perex@suse.cz>
cc: Edward Tandi <ed@efix.biz>, azarah@nosferatu.za.org,
       alsa-devel@lists.sourceforge.net,
       Linux Kernel Mailing Lists <linux-kernel@vger.kernel.org>,
       Rob Love <rml@ximian.com>, Andrew Morton <akpm@osdl.org>,
       Stan Bubrouski <stan@ccs.neu.edu>
Subject: Re: OSS sound emulation broken between 2.6.0-test2 and test3
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>> --- compile/sound/core/oss/pcm_oss.c.old	Mon Nov 17 18:29:43 2003
>> +++ compile/sound/core/oss/pcm_oss.c	Sat Dec 27 10:32:30 2003
>> @@ -814,7 +814,7 @@
>>  			xfer += tmp;
>>  			if (substream->oss.setup == NULL || !substream->oss.setup->wholefrag ||
>>  			    runtime->oss.buffer_used == runtime->oss.period_bytes) {
>> -				tmp = snd_pcm_oss_write2(substream, runtime->oss.buffer, runtime->oss.buffer_used, 1);
>> +				tmp = snd_pcm_oss_write2(substream, runtime->oss.buffer, runtime->oss.period_bytes, 1);
>>  				if (tmp <= 0)
>>  					return xfer > 0 ? (snd_pcm_sframes_t)xfer : tmp;
>>  				runtime->oss.bytes += tmp;
> 
> It's not a good fix. 

OK you know the code far better than I ... but it sounds a lot better ;-)
So *something* around there is broken. It sounds horrible in 2.6.0 virgin.

> The problem might be that the rate convert plugin is 
> activated. When small chunks are passed to this plugin, the quality drops.
> You can check it with this command (and compare native and OSS rates):
> 
>   cat /proc/asound/card0/pcm0p/sub0/*

OSS rate: 44100
rate: 48000 (48000/1)

However, test2 worked fine - and it works fine with whole-frag turned on ...
has the rate conversion changed?

> Also, we fixed some OSS emulation errors in our latest code which is 
> available here:
> 
>   bk pull http://linux-sound.bkbits.net/linux-sound
> 
> or
> 
>   ftp://ftp.alsa-project.org/pub/kernel-patches/alsa-bk-2003-12-05.patch.gz
> 
> I will prepare new patch for recent kernel soon.

I tried the above patch - doesn't help.

Thanks,

M.