MPG2 size reduction for Laserdisc

[Sexmoron]

I have a laserdisc I'm trying to put on DVD so I can sell the LD. (I guess it's worth about $120.00). The problem is it is 140 minutes long and I want to get it on one disc. I've encoded it at 4.1 Mb/sec and I really would like to get a higher bit rate.

So, I considered IVTC thinking that would save me about 20% of disc space and I could probably encode at a bit rate of 6Mb/sec. Which I'd be pretty happy with. The thing is I don't think this material was filmed. I think it was videotaped and put on Laser. This is my guess just by the appearance of it. It LOOKS like video. Plus I think it was originally done for TV, not cinema.

So, am I just stuck with the choice of low bit rate or two discs?

[int 21h]

Lets ponder this for a second...

The total size is ((video bitrate * duration) + (audio bitrate * duration)). While a lower FPS will mean more bits per frame, and while IVTC is generally a good idea for a telecined source, it most certainly will not gain you any additional bitrate.

[Sexmoron]

...that always did confuse me. But I was under the impression that reducing the 30 telecined frames to 24 frames would reduce the number of frames 20%. That would mean 20% fewer frames encoded, thus a smaller file size.

So, I figured by flagging the process in TMPGenc the dvd player automatically converted the IVTC to 30 again. I guess that was why I thought I could gain by a encoding a smaller file size with a higher bitrate.

Hmmmm... But, I admit I never did fully understand the IVTC process.

[jggimi]

If you IVTC, you will lower the number of frames. But if your bitrate will remain unchanged, you will have more bits per frame. Confusing, I know, but the duration remains unchanged when you IVTC. If you want the same bits/frame, you must also lower the bitrate.

For more on IVTCing, and whether or not it's appropriate, check out www.doom9.org/ivtc-tut.htm

[Sexmoron]

Hey, thanks. I didn't know about this tutorial. There was another I read that had more to do with converting Mpeg2 to other formats and retaining audio synch. It really did'nt address my situation.

I'll read this one the minute I have time.