[pulseaudio-discuss] avoid increase watermark for low latency capture

Colin Guthrie cguthrie at mandriva.org
Mon Jul 25 02:34:45 PDT 2011

'Twas brillig, and xing wang at 25/07/11 02:27 did gyre and gimble:
> Hi Pierre, Colin,
> Any comments?

No specific comments from me as I'm not super clued up on that area.

Pierre any specific comments at your end?



> 2011/7/22 xing wang <wangxingchao2011 at gmail.com>
>> 2011/7/23 pl bossart <bossart.nospam at gmail.com>
>>>> When meet Overrun or Underrun, PA will increase watermark. Due to some
>>>> hardware limitation, the hw_ptr will not be updated in PA's request latency.
>>>> So there maybe some cases "faked overrun/underrun". Take capture for
>>>> example, when Pulseaudio was waken up to read new capture data from driver,
>>>> and find the "available" area is much more than the record space. Although
>>>> it's fast enough to read out all data in short time, PA regard that as
>>>> "overrun" and increase watermark/latency step by step, that's really
>>>> useless.
>>>> So attached patch used to avoid such case and only increase
>>>> watermark/latency in real "overrun" case.
>>> Humm, it's not clear what problem you are trying to solve and on what
>>> platform. Looks like a very old MRST firmware/driver?
>>> If your driver doesn't update the hw_ptr, then how can you know if
>>> this is a real or a fake overrun?
>> In fact it's a solution for such firmware hasing  low hw_ptr updating rate.
>> Pulseaudio use hw_unused field to track the unused buffer, the real overrun
>> means the "avail" space is geting close to hwbuf_size.
>> --xingchao
>>> -Pierre
>>> _______________________________________________
>>> pulseaudio-discuss mailing list
>>> pulseaudio-discuss at lists.freedesktop.org
>>> http://lists.freedesktop.org/mailman/listinfo/pulseaudio-discuss


Colin Guthrie

Day Job:
  Tribalogic Limited [http://www.tribalogic.net/]
Open Source:
  Mageia Contributor [http://www.mageia.org/]
  PulseAudio Hacker [http://www.pulseaudio.org/]
  Trac Hacker [http://trac.edgewall.org/]

More information about the pulseaudio-discuss mailing list