Re: [LAU] USB audio interfaces >= 8 channels

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To: Clemens Ladisch <clemens@...>
Cc: Brian Quandt <brian.quandt@...>, A list for linux audio users <linux-audio-user@...>
Date: Tuesday, May 15, 2012 - 11:24 pm

On 05/15/2012 08:03 PM, Clemens Ladisch wrote:
[..snip..]

All right. All systems go.
`jackd S -d alsa -d hw:1 -p 64 -n2` works great!

that's jackdmp 1.9.9 -- git f82ec715
Linux 3.2.0-2-rt-686-pae #1 SMP PREEMPT RT i686 on an Atom CPU dev-kit
board: Genuine Intel(R) CPU @ 1.00GHz (!) running debian/wheezy
(alsa/libasound 1.0.25-2).

jack_lsp lists 18 inputs and 18 outputs (so SPDIF and analog I/O seem to
work simultaneously, but I have not tested SPDIF I/O -- Brian was kind
enough to patch analog output channels 1-8 to their respective inputs
for me to runs some tests.)

`mplayer | patch-cables | jack_capture -c 8` works fine and
`jack_capture -c 18` does too, but the additional 10 channels are of
course silent.

`jack_delay` measured round-trip latency:
286.903 frames 5.977 ms
286.540 frames 5.970 ms
292.858 frames 6.101 ms
292.902 frames 6.102 ms
291.903 frames 6.081 ms
291.903 frames 6.081 ms
291.903 frames 6.081 ms
286.898 frames 5.977 ms
288.124 frames 6.003 ms

Despite the slow system there were no x-runs. CPU utilization was around
70-80%.

As for device configuration:

jackd starts with either -r 48000, -r 44100, -r 96000 and -r 88200. The
1818VSL switches the sample-rate automatically. very neat! See attached
`cat /proc/asound/VSL/stream0`.

The clock-sources can be queried and set using `amixer` or `alsamixer`.
The labels are somewhat misleading but that does not really matter: In
`amixer` all names start with "AudioBox 1818 VSL Clock Selector" - even
the Volume controls (but those end in "Playback V" and "Capture Vo").
`alsamixer` labels them "Front*2, Rear*2, Center, Woofer, Side*2, N/N*1,
and then repeats that for 9 more channels (while in fact it's 8 analog +
2 SPDIF + 8 ADAT -- not sure about SPDIF/ADAT order), but that's just
/usr/share/alsa/pcm/* trying to be smart.

With -r96000 the device only worked with -p256 -n2 or larger periods -
due to CPU limitation (-r 96000 -p128 or -p64 maxed out this weak CPU)
`jackd -S -d alsa -d hw:1 -p 256 -n2 -r 96000`
measured round-trip latency: 887.173 frames ~ 9.241 ms -- not bad!
..but I'll happily stick with 48k.

FWIW. the device also runs fine with -p 32 !!
`jackd -S -d alsa -d hw:1 -p 32 -n2`

jack_capture recorded merrily w/o xruns, but jack_delay maxed out the
CPU and caused xruns on this dev-board.

Many thanks to Brian Quandt for making these tests possible.

> Please show the output of "lsusb -v" for this device.

attached. since this ML limits emails to 30K, files are bziped:

#lsusb -v
1818vsl/1818vsl.lsusb
#amixer -c 1 contents
1818vsl/1818vsl.amixer.contents
#amixer -c 1 controls
1818vsl/1818vsl.amixer.controls
#cat /proc/asound/VSL/stream0 while running at 44.1 and 48k
1818vsl/1818vsl.asound-44100
1818vsl/1818vsl.asound-48000

I'm going to order one now :)
robin

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Messages in current thread:
[LAU] USB audio interfaces &gt;= 8 channels, Robin Gareus, (Tue May 15, 10:07 am)
Re: [LAU] USB audio interfaces &gt;= 8 channels, Fons Adriaensen, (Tue May 15, 4:10 pm)
Re: [LAU] USB audio interfaces &gt;= 8 channels, Robin Gareus, (Tue May 15, 6:44 pm)
Re: [LAU] USB audio interfaces &gt;= 8 channels, Fons Adriaensen, (Tue May 15, 8:59 pm)
Re: [LAU] USB audio interfaces &gt;= 8 channels, Paul Davis, (Tue May 15, 10:34 am)
Re: [LAU] USB audio interfaces &gt;= 8 channels, Robin Gareus, (Tue May 15, 10:41 am)
Re: [LAU] USB audio interfaces &gt;= 8 channels, Fons Adriaensen, (Tue May 15, 12:36 pm)
Re: [LAU] USB audio interfaces &gt;= 8 channels, Robin Gareus, (Tue May 15, 1:31 pm)
Re: [LAU] USB audio interfaces &gt;= 8 channels, Clemens Ladisch, (Tue May 15, 6:03 pm)
Re: [LAU] USB audio interfaces >= 8 channels, Robin Gareus, (Tue May 15, 11:24 pm)
Re: [LAU] USB audio interfaces &gt;= 8 channels, Paul Davis, (Tue May 15, 8:16 pm)
Re: [LAU] USB audio interfaces &gt;= 8 channels, Robin Gareus, (Wed May 16, 9:28 am)
Re: [LAU] USB audio interfaces &gt;= 8 channels, Fernando Lopez-Lezcano, (Wed May 16, 11:13 pm)
Re: [LAU] USB audio interfaces &gt;= 8 channels, Paul Davis, (Wed May 16, 2:14 pm)
Re: [LAU] USB audio interfaces &gt;= 8 channels, Fernando Lopez-Lezcano, (Tue May 15, 5:10 pm)
Re: [LAU] USB audio interfaces &gt;= 8 channels, Emanuel Rumpf, (Tue May 15, 8:52 pm)
Re: [LAU] USB audio interfaces &gt;= 8 channels, Fernando Lopez-Lezcano, (Tue May 15, 5:11 pm)
Re: [LAU] USB audio interfaces &gt;= 8 channels, Paul Davis, (Tue May 15, 11:03 am)