Friday, July 22, 2005

SageTV Results at 6Mbps

Like I talked about in "Video capture with SageTV", I switched to a 6Mbps MPEG2 capture rate on the Hauppauge card. My goal is to only fit a pair of 1-hour episodes on each 4.35GB DVD rather then my previous method of fitting (3) 1-hour episodes.

What's interesting is that I'm seeing much larger compression values then expected. The nightly files are of the expected size, but when I create the DVD, I'm getting much smaller DVDs then expected. The raw MPEG2 footage off of the PVR card is 9.83GB for 3.5 hours (up from 6.87GB for 4Mbps). That's the correct growth amount.

However, the output to DVD (conversion to AC3, no re-encoding of the MPEG2 stream) is smaller then expected. For a ~43min episode, my VOBs are anywhere between 1.65GB and 1.79GB. Some of the VOBs have come out as small as 1.33GB. The super-small VOBs are probably because those were letter-boxed shows over NTSC. Since I'm not re-encoding the MPEG2 stream, I'm not 100% sure why these files are shrinking so much. Maybe TMPGEnc DVD Author has some smarts when it packs the stream into VOBs.

So, assuming that 1.85GB is an expected maximum size for the VOBs for a 43min episode and my target is actually 2.10GB to fit better onto a DVD. That gives me another 13% or so. So I can probably boost my PVR bitrate up to 6800Kbps on the video stream, getting a bit more clarity out of the image.

Labels: 2005, VideoCapture

posted by Wuphon's at 9:25 AM