[alsa-devel] pointer callback question

Tim Blechmann tim at klingt.org
Thu Feb 12 19:04:10 CET 2009

Takashi Iwai wrote:
> At Thu, 12 Feb 2009 18:55:49 +0100,
> Tim Blechmann wrote:
>>>> the brief log is (4 periods of 64 frames):
>>>> stream_pointer at 64
>>>> stream_pointer at 128
>>>> stream_pointer at 192
>>>> stream_pointer at 256
>>> This is invalid.  The pointer callback must return 0 in this case.
>>> The value the pointer callback returns is between 0 and buffer_size-1.
>> sry, typo, 5 periods of 64 frames
> Then it must be OK.  If the stream is stopped, it's likely by the
> buffer underrun detection or so...

is there any way to compile alsa to get some debugging information about

> BTW, you should be sure that the buffer size is aligned to the period 
> size if such a design is assumed.  Without the extra constraint, it
> could be unaligned as default.

hm, afaict alignment should be ok ...

thnx, tim

tim at klingt.org

A good composer does not imitate; he steals.
  Igor Stravinsky

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