[alsa-devel] basic question on .pointer function

Harsha priya gupta harshapriya at gmail.com
Fri May 9 20:21:17 CEST 2008

Thanks a lot for this pointer. A quick question;

For the .pointer function, it says " This callback is called when the PCM
middle layer inquires the current hardware position on the buffer."

Does the word "PCM middle layer" mean that the MMF like Helix / Gstreamer is
continuously querying for hardware position on the buffer? Or does the
player keep querying?

I also see that this function gets called quiet a number of times. Is there
a way to reduce these calls? My guess is that to reduce the number of calls
to .pointer, MMF or player needs to be modified. Am I thinking right?


On Fri, May 9, 2008 at 4:26 PM, Takashi Iwai <tiwai at suse.de> wrote:

> At Wed, 7 May 2008 09:10:00 +0530,
> Harsha priya gupta wrote:
> >
> > Hi,
> > It would be really helpful if someone can help me understand why do we
> need
> > to implement .pointer and what does it need to do? I am facing an issue
> to
> > write a driver in this .pointer function. Please help
> >
> > Also if someone can point me to a document where all the playback_ops are
> > defined, it would be really helpful
> Did you check the page below?
> http://www.alsa-project.org/main/index.php/ALSA_Driver_Documentation
> Takashi


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