Have been running various capture tests involving analog AC-3 capture, baffled by a de-synch issue.

So I ran a new test. Both PC's capping OTA HD, the Sarah Connor Chronicles. One unit with an ATI AIW, capturing MPG+Stereo audio, also a Creative X-FI capping the AC-3 thru SPDIF. Output was S-video thru a tuner box.

Second PC with a Hauppage 1600 card, direct to the antenna.

The MPG-2 video was in synch with the stereo audio, but the AC-3 was slightly short, 0.8 seconds in 56 minutes, though matched at the beginning synch being lost gradually.

The Hauppage file maintains synch throughout, same video, same time capture.

Seperated sound, converted to Wav, synched up the sound files both visually and auditorily.

The Hauppage AC-3 matches the analog capped AC-3 almost perfectly. Both are short of the MPG audio file by about 0.8 seconds.

So, why would an HD video file be 0.8 seconds SHORTER over 56 minutes than the same transmission downsampled thru S-video?

These results are consistent over multiple previous captures, this is the first tiem I've had another file for comparison.