[Jack-Devel] S24_3LE

Dear list,

I'm writing a full-duplex program (2in/2out) which will output something,
record it as a block of data (1024-3268 samples), analyze it and decide
what to output next. I'm on Ubuntu, at the moment with a UA-25ex USB audio
interface, speaking S24_3LE.

The Jack API looks fantastic except for one thing: I prefer working with
integers and not float. In ALSA I can set the sample format to
SND_PCM_FORMAT_S24_3LE and then I can give it data in that format directly,
3 bytes per sample per channel. On the capture side, I receive nice 24-bit
integers.

In Jack, there appears to be one available format, "32 bit float", even
though the driver is ALSA. My jackd looks like this:
atc@atc-nb:~$ jackd --name dpoae -d alsa -d hw:1
<snip>
JACK server starting in realtime mode with priority 10
control device hw:1
control device hw:1
audio_reservation_init
Acquire audio card Audio1
creating alsa driver ... hw:1|hw:1|1024|2|48000|0|0|nomon|swmeter|-|*32bit*
control device hw:1
configuring for 48000Hz, period = 1024 frames (21.3 ms), buffer = 2 periods
ALSA: final selected sample format for capture: *24bit little-endian*
ALSA: use 2 periods for capture
ALSA: final selected sample format for playback: *24bit little-endian*
ALSA: use 2 periods for playback

and I stumbled upon some format-converter functions in the jack source.

I'm sure that jack is very capable of converting between the format, but is
there a way that I, as a user, can get to work with the 24-bit host format
directly?

Thanks for your time.

Best, Anders

1376219493.9502_0.ltw:2,a <CAMeZe4HYCo_gJ0JnY4Ays+_175DnGKvFsekGyzj_r3jpETrfaQ at mail dot gmail dot com>