Re: [alsa-devel] safe support for rewind in ALSA

On Mon, 15.02.10 11:03, Raymond Yau (superquad.vortex2@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