Re: [PATCH 00/17] audio: improve callback interface for audio frontends

[Mark Cave-Ayland]

On 28/01/2023 09:03, Volker Rümelin wrote:

> Am 22.01.23 um 19:13 schrieb Mark Cave-Ayland:
> > On 15/01/2023 13:45, Volker Rümelin wrote:
> >
> > > Am 15.01.23 um 14:08 schrieb Volker Rümelin:
> > >
> > > Ccing a few more people who might be interested in this patch series.
> > >
> > > @Mark:
> > > After this patch series, the code in your out of tree ASC audio device (and a few 
> > > in tree audio devices) could be simplified. write_audio() and the loops calling 
> > > write_audio() could be removed.
> >
> > Hi Volker,
> >
> > I know we have discussed this in a separate thread off-list, but this is 
> > fantastic!
> >
> > Just out of interest, if the available bytes wraps the circular buffer will the 
> > audio core call the audio callback twice to maximise the ability of the guest to 
> > generate samples before the next audio timer? Or does that not make much difference 
> > in practice?
>
> Hi Mark,
>
> I guess with circular buffer you refer to the mixing engine buffer. The audio system 
> calls the callback once on every audio timer event. If the available bytes wrap the 
> mixing engine ringbuffer, the audio_pcm_sw_resample_out() function uses two writes to 
> write all available bytes. Compared to the unpatched version, nothing has changed in 
> this regard. Of course the audio frontend devices are still free to write 'avail' 
> bytes with multiple calls to AUD_write().
>
> With best regards,
> Volker

Yes that makes sense, thanks for confirming this. I'm sorry that I'm not familiar 
enough with the audio side to do a proper review but obviously the A-B still stands 
and I would certainly be keen to see this merged.


ATB,

Mark.