Re: [Alsa-devel] Re: [OT] ALSA userspace API complexity

Hannu Savolainen
2006-01-10T02:17:03Z

On Tue, 10 Jan 2006, John Rigg wrote:

> On Tue, Jan 10, 2006 at 02:48:35AM +0200, Hannu Savolainen wrote:
> > On Mon, 9 Jan 2006, John Rigg wrote:
> >
> > > Yes, but the CPU has plenty of other work to do. The sound cards that
> > > would be worst affected by this are the big RME cards (non-interleaved) and
> > > multiple ice1712 cards (non-interleaved blocks of interleaved data),
> > ice1712 uses normal interleaving. There are no "non-interleaved blocks".
>
> With two ice1712 cards I had to patch jackd for MMAP_COMPLEX
> support to make them work together. My understanding was that the
> individual cards use interleaved data, but when several are combined
> the resulting blocks of data are not interleaved together. I realise the
> usual way of dealing with this is to use the alsa route plugin with
> ttable to interleave them, but I couldn't get it to work with these
> cards.
Right. If you use two cards then both of them have independently
interleaved blocks. However if this kind of mapping belongs to the lowest
level audio API or not is yet another API feature to argue about. Higher
level libraries like Jack could do this themselves.

Best regards,

Hannu
-----
Hannu Savolainen (hannu@opensound.com)
http://www.opensound.com (Open Sound System (OSS))
http://www.compusonic.fi (Finnish OSS pages)
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