Re: New PCM API extension

[Abramo Bagnara <abramo.bagnara@libero.it>]

Jaroslav Kysela wrote:
> 
> On Mon, 24 Feb 2003, Abramo Bagnara wrote:
> 
> > Jaroslav Kysela wrote:
> > >
> > > I think that I have one present problem. It was not possible to write,
> > > something like the dmix plugin does (in the server/client model): Transfer
> > > data to different areas in the ring buffer. Imagine that client1 wants to
> > > write data at the end of the ring buffer (assume that server don't change
> > > the r/w pointer). Then client2 comes with some data to be placed at the
> > > start of the buffer later (server rewinds the stream position). Then
> > > hardware processed a period and client1 wants to continue (server forwards
> > > the stream position at the end of the ring buffer).
> > >
> > > I can imagine more examples where "later" samples might be wanted to be
> > > processed before "quick" ones.
> >
> > Your examples appears a little confused at my eyes, but if I've
> > understood correctly don't you think this might be solved by
> > snd_pcm_rewind done by server?
> 
> And you'll need to commit the same samples later which seems to me quite
> ineffective (extra copy + processing (if required)).

Yes, this is definitely true.

> I probably don't explain clearly my point:
> 
> We have data for time T, T+1 and T+2. The application might want to write
> data in this order: T+1, T, T+2. While we going back to T position, we can
> use snd_pcm_rewind(), but going to T+2 (without changing T+1 data)
> requires writting (or commiting) of same samples now. That's exactly what
> I want to eliminate.

Now I understand perfectly.

When in past I analyzed this I was unable to imagine a real scenario
where this might happens.

To tell you the truth now too I've some difficulties... can you help me?

-- 
Abramo Bagnara                       mailto:abramo.bagnara@libero.it

Opera Unica                          Phone: +39.546.656023
Via Emilia Interna, 140
48014 Castel Bolognese (RA) - Italy


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