[alsa-devel] safe support for rewind in ALSA

Lennart Poettering mznyfn at 0pointer.de
Wed Feb 17 16:46:56 CET 2010

On Mon, 15.02.10 11:03, Raymond Yau (superquad.vortex2 at gmail.com) wrote:

> For USB case , the driver cannot give accurate hw pointer position , hw
> pointer increase in steps for the current implementation, (i.e. the graph is
> a stepping fuction if you plot the position of hardware pointer against time
> elasped ) .

The granularity of write transfer blocks and of playback pointer
updates is currently not quriable nor configurable in ALSA. We only
have periods which tries to cover both in a way.

For the use in PA it is really important to get better APIs for
this. Ideally both for querying the latency and the transfer
granularityand configuring it, but most importantly for querying it.

This has been discussed before on this mailing list, btw.


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

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