[alsa-devel] Master Plan on rewinding

[Alexander E. Patrakov]

13.09.2014 17:33, Raymond Yau wrote:
>
> 2014-9-13 下午6:43 於 "Alexander E. Patrakov" <patrakov at gmail.com
> <mailto:patrakov at gmail.com>> 寫道：
>  >
>  > 13.09.2014 14:57, Raymond Yau wrote:
>  >>
>  >>
>  >>  >>
>  >>  >>  >
>  >>  >>  > On my desktop PC, on snd-hda-intel with analog outputs for S16LE
>  >>  >> stereo, the granularity is 32 bytes (= 8 samples), and I get the
> pointer
>  >>  >> granularity of 64 bytes (=16 samples) over HDMI. The minimum
> period size
>  >>  >> is 32 samples in both cases.
>  >>  >>
>  >>  >> Do you mean hda-Intel does not support arbritray period size
> when you
>  >>  >> say the granularity is 32 bytes ?
>  >>  >>
>  >>  >> However the granularity of the emulated hda sound card inside any VM
>  >>  >> depend on the vm and the backend audio system and sound card
>  >>  >
>  >>  >
>  >>  > The precise meaning is defined here:
>  >>  >
>  >>  >
> http://mailman.alsa-project.org/pipermail/alsa-devel/2014-May/076475.html
>  >>
>  >> Do you mean the different hda controllers may have different
> granularity ?
>  >
>  >
>  > Yes. My two hda controllers have different granularity.
>  >
>  >
>  >> Do your two hda controllers have different Fifo size ?
>  >
>  >
>  > If you mean the result of snd_pcm_hw_params_get_fifo_size(), then
> both cards return 0. I call this function after snd_pcm_hw_params(), as
> recommended by the documentation.
>
> Do your hda controllers OSDnFIFOS register match the granularity ?

I don't know. Please send a program or a kernel patch that prints this 
value (including units - samples or bytes), otherwise I won't be able to 
answer.

-- 
Alexander E. Patrakov