[alsa-devel] Maximum buffer size on HDA

Lennart Poettering mznyfn at 0pointer.de
Mon Jun 16 14:37:41 CEST 2008

On Mon, 16.06.08 14:29, Jaroslav Kysela (perex at perex.cz) wrote:

> > > > It's rather a silly constraint, and I think it'd be better cut off.
> > > > OTOH, this makes the system safer (e.g. avoiding page allocations for
> > > > too large buffers), and there is a proper workaround, too.
> > > > So, I'm open about this change, so far.
> > > 
> > > Which workaround you're talking about?
> > 
> > Reset a proc file manually like the above.  Without this, you cannot
> > allocate the buffer over the pre-allocated size.
> I'm not quite sure what you like to change. Make 1MB limit smaller? Or 
> change the default preallocated size? Or remove preallocation? I think 
> that it might make sense to increase the default preallocation value to 
> 128KB or 192KB.

For PulseAudio it would be of big benefit if we could change the
default in a way the for the highest sensible sampling rate/number of
channels/sample type we'd always be able to get a two-second
buffer. Windows and Mac use 2s of buffer by default, and I think it
would make sense for PulseAudio to do that too. 

i.e. if the soundcard can do 2ch/16bit/44100hz at best I'd like to
have a buffer size of up to 344KB; if the soundcard can to
5.1/32bit/48000 at best then i'd like to have a buffer of up to 2.2MB
or so.


Lennart Poettering                        Red Hat, Inc.
lennart [at] poettering [dot] net         ICQ# 11060553
http://0pointer.net/lennart/           GnuPG 0x1A015CC4

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