[pvrusb2] Audio distortion - WinTV-HVR 1900

[Michael Strecke]

I'm using a Hauppauge WinTV-HVR 1900 under Ubuntu 04.10 LTS.

This device needs a 16 KB firmware, so I had to compile the pvrusb2
kernel module.

The device works reasonably well, except for the following problem:

A few weeks ago, I made my first timer-controlled recordings (from the
composite input) using crontab, simply by copying /dev/video0 to a file.

Every 20 - 30 recordings, the audio is distorted. This distortion
remains during the entire recording. The next recording (with the same
audio settings) is normal again.

I wrote a small stress test script which records small files with a
duration of 30 secs with a pause of 10 secs. The result is similar: Most
recordings are ok. Audio distortion in every 20th to 30th file.

Lowering the v4l2 volume setting had no effect.

I was able to test a second unit, with similar results.

The distortion does not sound like clipping (audio input level too
high). I presume the audio encoder in the device does not start properly
at times.

Is this a known problem? Any hints on how to prevent it?

My current work-around is a script that "records" all the time, but only
writes to disk according to a time schedule. I create a test file after
starting the script. If the distortion is present (which happens here as
well), I restart the script (thus closing and reopening the connection
to /dev/video0). If the audio is clear, all other recordings during that
session are ok, too (at least so far).

Mike