Video Encoding Question

[gideon_friedmann]

The Tivo calculates about 3 GB / Hour in best quality for video data. I noticed that in reality it is closer to 2-2.5 GB / Hour (using Tytools, I saw the capacity per program) for many programs.
On the other hand when I grab analog video using a capture card on my PC, I get about 3.5-4 GB/Hour (Mpeg II).
The video quality on the TiVo seems excellent, and the question is how come the difference. Is there a way to get similar results on my PC using Mpeg II ?
This goes true to professional DVDs as well. Although most forums on the net claim that professional DVDs can pack 2 hours of video onto a DVD because they use a 2 layer media, the fact is that many high quality DVDs still fit in the 4.4 GB restriction of a regular DVD. Can someone explain this to me as well?

In a followup (naive ) question, is there a way to transfer the Tivo video files to a PC by copying directly from the hard drive (connecting it to the IDE bus of the PC) ? Would I be able to use the Tytools then to convert to mpegII?

Thanks,

Gideon.

[zollymonsta]

It may be due to the TiVo using hardware encoding (an actual mpeg2 encoding chip) rather than software encoding (as with most PC Capture cards). Maybe the TiVo can actually squeeze the file down more due to it being hardware based encoding rather than software based.

ZollyMonsta

[gideon_friedmann]

I am not sure.
My card does much of the work in HW (most cards today do that), or it would not be able to grab and encode in real time full motion picture video. Still the question remains, how to get smaller MpegII files on the PC. If it is done in HW, it must be also possible in SW.

Gideon