On Tue, 18 Nov 2003, Giuliano Pochini wrote:
>
> On 15-Nov-2003 Jaroslav Kysela wrote:
> > On Sat, 15 Nov 2003, Giuliano Pochini wrote:
> >
> >> My hardware can start/stop multiple indipendent substreams at the same time.
> >> Does the ALSA driver API support that feature ?
> >
> > Yes, use snd_pcm_set_sync() function in open() callback and add necessary
> > code to the trigger() callback. See to alsa-kernel/pci/ens1370.c code for
> > more details (this hardware has three streams which can be controlled
> > simultaneously) as a good example.
>
> Fine.
> Is that feature used by the upper ALSA driver to create multichannel
> substreams when the hw hasn't this capability ?
It can be used in alsa-lib (for example in multi plugin which does exactly
what you want).
> Older Echoaudio
> soundcards can only do mono and stereo operation, while newer series can
> manage mono and any even number of channels. Since all cards can run any
> number of substreams at the same time, I can emulate large substream on
> older cards by starting several mono substream simultaneously
> (MMAP_NONINTERLEAVED in this case). If the upper layer already has this
> feature, I can avoid wasteing my time :)
Don't do this. Our goal is describe hardware in the driver not create
another abstraction layer.
Jaroslav
-----
Jaroslav Kysela <[EMAIL PROTECTED]>
Linux Kernel Sound Maintainer
ALSA Project, SuSE Labs
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