[pulseaudio-discuss] alsa pulse bugs

Lennart Poettering lennart at poettering.net
Tue May 6 12:36:17 PDT 2008

On Mon, 05.05.08 10:34, tom at dbservice.com (tom at dbservice.com) wrote:

> I reported three bugs to the alsa bugtracker:
> https://bugtrack.alsa-project.org/alsa-bug/view.php?id=3942

I though I already posted a patch like this a while back. This really
should be merged!

> https://bugtrack.alsa-project.org/alsa-bug/view.php?id=3943

This is not correct. snd_pcm_delay() is the delay that it takes until
a sample you write now to the PCM stream takes to be played. For PCI
devices this is usually the same as write_index-read_index, but not
for virtual devices like PA, and not even for USB.

This is the only way snd_pcm_delay() has any value for synchronization
purposes (i.e. syncing video to audio).

I think there's simply in invalid assumption made by the WINE devs (or
possible even the MS devs who designed the API): they assume that all
sound cards are PCI sound cards. Which ain't really true.

In short: the transport latency *needs* to be taken into account,
there is no way around this.

> https://bugtrack.alsa-project.org/alsa-bug/view.php?id=3944

This looks good to me and should also be applied.

Could you please post the patch for 3942 and 3944 to the ALSA ml? The
truth is that the ALSA devs are very good at ignoring the ALSA BTS. If
you want your stuff merged, post it to the ALSA ML, don't bother with
the BTS.

And thank you very much for your patches!


Lennart Poettering                        Red Hat, Inc.
lennart [at] poettering [dot] net         ICQ# 11060553
http://0pointer.net/lennart/           GnuPG 0x1A015CC4

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