Here's the configuration:
KnoppMyth back end server w/ 2 Hauppauge 250's. One is hooked directly to analog cable, the other tunes through a Pioneer (model=Voyager) cable box, patched into the S-Video & stereo audio inputs of the Hauppauge 250, tuned with an IRBlaster (for digital cable).

Everything works well - except.

When HBO shows a first-run movie, they put it out in some different kind of surround sound and the volume is VERY LOW.

When I first hooked up the tuner with the cable box I was using the coax input on the Hauppauge. I quickly found out that the Pioneer cable box strips the stereo information from the signal it sends out the coax jack, so I had to switch and use the S-Video & stereo inputs on the Hauppauge to get any kind of stereo at all.

For most Surround sound content, it works fine. But HBO must be doing some other encoding for the prime-time content. I have to jack up my stereo an additional 20dB to get reasonable volume, and then I get tons of hiss.

I know this is a *really* esoteric issue, but if anyone can help I'm sure they're here! )

I *think* that the problem is only with AC3 content. The Hauppauge card is supposed to encode the AC3 content in the MPEG stream. Shows encoded with Pro-Logic appear to encode fine, but the AC3 shows have very low volume.

I've taken these MPEGs to another (windows) box, and the volume is definitely low in the recording. So, I've eliminated improper decoding as the potential issue. The only thing I can think is that the Hauppauge is doing some less-than-perfect processing on AC3 streams and saving out low volume streams.

I've been searching to see if there's a way to configure/control the way the Hauppauge does it's encoding, but so far no luck...