[alsa-devel] [PATCH 0/20] ASoC: rsnd: add Synchronous SRC and U/O error salvage support

[Kuninori Morimoto]

Hi Mark

> > I think I have not got comment/response about these patches.
> 
> >        17. ASoC: rsnd: add Synchronous SRC mode
> >        19. ASoC: rsnd: add salvage support for under/over flow error on SRC
> 
> > Can you give me feedback ?
> 
> The problem with those is that they add the first patch adds explicit
> controls for the rates which look awfully like the sort of thing people
> are supposed to be doing using DPCM (I've said before these drivers
> should be using that...).  I need to figure out if we have existing
> controls which do this sort of thing in the driver at which point this
> isn't so bad but still not good or if this is a new thing for the
> driver.

Thank you for your feedback.
I need to explain more about this. Yes, I know you are requesting to use
DPCM for rate convert.
Our sound device has 2 type of rate convert. 1st is "static" rate convert,
and, 2nd is "dynamic" rate convert.

1st "static" rate convert is used to convert rate to fixed sampling rate
which is based on codec device. And I will implement it as DPCM.
This is no problem.

2nd "dynamic" rate convert which is this patch is used as revision.
I don't know detail of use case, but, according to HW team,
sound clock has small accidental error.
Because of this, if we used 48kHz sound in long term,
but, the real sound can be 48001 Hz or 47999 Hz or something like that.
So, if we use it without revision in long term, the sound will has
small noise. This will be problem for TV or radio (?).
Thus, sound player wants to revise it by "dynamic" rate convert.
I guess DPCM is good match for "static" rate convert, but not good
for "dynamic".

Best regards
---
Kuninori Morimoto