Re: Audio recording (using ossaudio)

[Yorick Hardy <yorickhardy%gmail.com@localhost>]

Dear Tetsuya,

On 2020-03-20, Tetsuya Isaki wrote:
> At Fri, 20 Mar 2020 08:08:37 +0200,
> Yorick Hardy wrote:
> > It seems to be stuck in select (or poll, I did not check the source)
> > in portaudio.
> 
> Yeah, I'm just looking this in this week.
> poll()/select() before read() doesn't work correctly now.
> I will fix it.
> 
> > Updating audio/portaudio from portaudio-190600.20161030nb1 to portaudio-190600.20161030nb2
> > fixes the problem (maybe because of the patch to disable non-blocking I/O ?).
> 
> I looked it right now.  And it looks bad strategy.
> He should have reported it first...
> 
> > Now 44100 MHz does not sound right (I will send the example off-list), but
> > 48000 MHz is fine (this is the same behaviour as audiorecord).
> 
> I heard it but unfortunately I don't know expected status.
> It sounded like analog noise or environmental noise.
> 
> 
> Anyway, if you want to record with pure 44100Hz, you need to
> set the hardware 44100Hz mode using audiocfg(1) command:
>  # audiocfg set <index> r slinear_le 16 2 44100
> 
> On NetBSD7 (or prior), if you record 44100Hz, the kernel set
> the hardware 44100Hz, because it was single audio system.
> 
> On NetBSD9 (or later), multiple recorder apps can be run
> simultaneously.  So even if your single app want to record
> 44100Hz, the kernel can not change the hardware frequency.
> The kernel converts from the hardware frequency to your
> requested frequency (if different).
> In-kernel frequency conversion is simple (and fast and small)
> than what userland rich apps does (and I personally think that
> such rich operation should be done by userland).
> 
> You need to a)change the hardware format (by audiocfg) or
> b)record as the hardware format ("audiocfg list" displays)
> and convert it by userland rich converter.
> 
> Thanks,
> ---
> Tetsuya Isaki <isaki%pastel-flower.jp@localhost / isaki%NetBSD.org@localhost>

Thanks! I think Nia mentioned this also, but somehow
I did not fully understand the role of audiocfg.

-- 
Kind regards,

Yorick Hardy