linux-kernel - Re: Is it time for remove (crap) ALSA from kernel tree ?

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Date:	Mon, 25 Jun 2007 09:11:09 +0530
From:	"Nobin Mathew" <nobin.mathew@...il.com>
To:	"Carlo Wood" <carlo@...noe.com>,
	"Alan Cox" <alan@...rguk.ukuu.org.uk>,
	"Tomasz Kłoczko" <kloczek@...y.mif.pg.gda.pl>,
	linux-kernel@...r.kernel.org
Subject: Re: Is it time for remove (crap) ALSA from kernel tree ?

> I sent a patch to the ALSA developers 4 years ago.
> It was never included in the kernel :/

ALSA maintainers are very open to patches. try sending this again

>
> Here's the comment from a script that I once wrote to
> make some closed-source dinosar code run (speech recognition)
> on modern linux:
>
> # Note that ALSA (Advanced Linux Sound Architecture), the sound drivers that
> # replace the older OSS as of kernel 2.5, also introduce a problem for some
> # soundcards: unlike the OSS drivers, the ALSA drivers limit the recording
> # buffer to the hardware limit of your sound card.  For example, the SB Live!
> # only has two 'period' buffers (called fragments before), and although
> # viavoice requests an 'arbitrary number of periods, size 1024 bytes', it
> # only gets two periods of 1024 bytes: 2048 bytes in total!  The ViaVoice
> # engine however doesn't even process sound until it sees at least 6102 bytes.
> # The 'solution' for this is to increase the buffer size (from 1024 to say
> # 8192), this script also takes care of that.  Unfortunately, also that is
> # possibly not enough: the sound is read from the hardware in chunks of
> # 'period size' and having only two buffers this is often causing an underrun.
> # When ALSA sees an underrun... it stops the sound stream.
>

native ALSA drivers has all these required features.

> My (four year old) patch can be found here:
>
> http://www.xs4all.nl/~carlo17/alsa/index.html
>
> I STILL think that ALSA should restart the stream after an underrun,
> but I am not someone who asks twice :p usually.

If it is native ALSA driver then it will restart after each underrun
and overrun. It is the applications job to do this, alsa-lib provides
all support for this. I have no idea of OSS and OSS emulation in ALSA.

If you have any queries please try sending to alsa-devel.
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