[alsa-devel] [alsa-lib, dmix] Support for S24_3BE

Takashi Iwai tiwai at suse.de
Mon Dec 24 10:51:49 CET 2012

At Sat, 22 Dec 2012 01:43:13 +0100,
Vincent Vinel wrote:
> Hello,
> The bugtracker seems to be down, so I'm posting here instead.
> I was trying to use software mixing with my Native Instruments USB
> soundcard (snd-usb-caiaq), but all attemps to use the dmix pcm ended
> up with the rather unhelpful error :
> ALSA lib pcm_dmix.c:1311:(_snd_pcm_dmix_open) Unsupported format
> When using the hw pcm, however, aplay was kind enough to display the
> list of available formats, which in my case was limited to S24_3BE.
> A quick check confirmed that dmix doesn't support that format, which
> happens to be the only format available for NI USB soundcards (as
> defined in snd-usb-caiaq).
> Is it worth writing a patch for 24bit big-endian support in dmix ?

If you find it's useful, it's worth, yes ;)

The patch won't be that big, it's just adding swapped version of
generic_mix_areas_24() and generic_remix_areas_24().

> External soundcards like these ones are usually used for realtime
> effects processing and low-latency audio, things for which dmix
> proably isn't suited anyway.


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