[mythtv-users] CX88 "Blackbird" audio razziness

[Rod Smith]

Hi,

A while ago I picked up a cheap used AVerMedia AVerTV M150-D card to use as a 
backup tuner. This card is based on the Conexant 2388x chip and the 23416 
MPEG-2 encoder chip using the "Blackbird" reference design. It uses the Linux 
cx88, cx88-blackbird, and related drivers (it's reported to NOT work with the 
ivtv drivers, so I've not tried them). After struggling for some time, I 
finally got the card working in Linux and MythTV, but not completely. The 
main issue is an audio "razziness" problem that crops up occasionally. When 
this problem surfaces, it sounds as if people are speaking with kazoos in 
their throats, making a recording pretty much useless. The problem is, as far 
as I can tell, 100% certain to occur after changing channels in the live TV 
viewer, but is much less likely to occur when doing a scheduled recording or 
when entering live TV after the tuner has had a few minutes to "rest." I'm 
using a 64-bit 2.6.19.1 kernel on an AMD Athlon-64 3000+ running Gentoo. I 
don't see any obvious differences in /var/log/messages or in dmesg output 
when the problem occurs vs. when it doesn't, but I do get a "cx8802_timeout" 
message whenever MythTV tunes the card.

So, has anybody run into anything like this before? I may start futzing with 
using v4lctl and various options as a channel-change command if I don't get 
any replies, but if somebody's got a ready-made solution, or even a 
better-educated guess at a solution, I'd love to hear it!

Once I solve the problem or give up on trying to solve it I'll upload a 
description of the card, and the steps needed to get it working in MythTV, to 
the wiki.

Thanks for any replies.

-- 
Rod Smith
http://www.rodsbooks.com