Audio glitches in Linux with Edirol UA-25 USB sound device

I’m trying out Ultramixer 2.3.8 and have been so far fairly impressed with the improvements, since I last tried it a while back. One thing that is broken though, is my Edirol UA-25 sound device now has lots of audio clicks at fairly regular intervals. This makes it unusable for live playback and pretty annoying for previewing. I tried ALSA as well as OSS (emulated through ALSA). I believe this device worked OK in the last version I tried, which was probably over a year ago. My laptop’s internal sound device works fine.

I tried the device at 48KHz and 44.1KHz (its hardware switchable). It uses the format S24_3LE (24 bit 3 byte little endian).

One other issue I have noticed is that the bottom line with the Menu, Quit buttons, etc is cut off about half way (so you can only see the top parts of the buttons), I suspect this is because the application isn’t going full screen (the Gnome menu is above it). I tried it at a lower resolution and it works fine.

Is there any way to reduce the CPU usage of UltraMixer? I suspect a lot of the usage is related to the display updates for the track time, since when UltraMixer display isn’t visible CPU goes down quite a bit.

Any tips would be most appreciate. I haven’t really found anything comparable for Linux, so it would be nice to be able to use this. Thanks!

Josh Green

System details:
Ubuntu Linux 9.10
Kernel 2.6.31-9-rt
ALSA 1.0.20
Pentium M 1.86GHz laptop
2GB of RAM

java -version
java version “1.6.0_15”
Java™ SE Runtime Environment (build 1.6.0_15-b03)
Java HotSpot™ Client VM (build 14.1-b02, mixed mode, sharing)

did you try to raise UltraMixer’s internal buffers? See: Menu/Preferences/Audio

Yes, I just tried that. I’m fairly certain its not related to underruns. I recorded the audio with a Mic and found that the audio glitches are at regular intervals (16891 samples to be exact). The glitch consists of about 140 samples of 0 sample values. I can send you an example sound file if you’d like.