Subject: Re: [linux-audio-dev] USB Souncards
From: tapio.laxstrom_AT_iptime.fi
Date: Tue Mar 05 2002 - 13:18:21 EET
Brad Bowman wrote Fri Jan 18 2002:
>So, in short, what are the issues with USB sound cards
>under Linux? In particular, does it effect latency and
>realtime reliability?
I purchset Emagic's EMI 2|6 low latency USB audio interface
to may laptop (fancy box with 2 inputs, 6 outputs, 1 digital
in and 1 digital out).
All it needed was firmware loader, which I made (I will publish
it as soon as Emagic gives me right kind of copyright header to
the firmware file).
After firmware loading the device is handled with linux kernel
usb audio driver.
I haven't have any latency problems. EMI is fast enough to monitor
input signal, record it and monitor allready recorded tracks same
time (44.1/48kHz 16/24bit).
Emi also supports hardware monitoring of input signal (on windows),
but I haven't needed that so I haven't look how it is enabled on
Linux.
My problems have been on mixer side; OSS does not support more
than 2 channel ouput and ALSA does not support USB. I am not sure
how ALSA supports multiple channels, but I believe there is Linux
people using more than 2 output/input channels (I mean hardware
outputs/inputs).
-- best regards -- tapio laxström senior software developer / iptime oy
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