1 Hour 45 Min, 1 CD or 2 CDs?

[kshawkeye]

I have a movie, that last for 1 hour and 45 minuets, and I'm torn between making it one CD or two CDs in size. If I make it one CD with a 192kB then I get a .175 Bit/(pixel*frame) amount, which is too low for my licking. The audio bitrate I would really like to stay at 192, because I feel that dropping below 192 and playing it back on speakers allows me to hear noticeable quality loss. On the other hand, if I bump it up to 2 CDs with raw AC3 audio steam coping (448kB), I get a .336 Bit/(pixel*frame) which is much to high. So I am not sure if I should just bite the bullet and drop my audio bitrate down to 128kB (which I really want to avoid), or if I should specify the Average Bitrate and just let the file be whatever size it wants. The video is 640x272 and 23.976, anyone have any ideas? Thanks! :thanks:

[prOnorama]

Bits/pixel is only a very rough estimate of the output quality it depends on the source.

Do you really need to stick to CD sizes? You can also choose a value in between 1 and 2 CD's like 1 Gb with 192 Kbps audio if you're not gonna use CD media. If you need to use CD sizes I'd pick 1 CD if the display the movie will be shown on is small and 2 CD if the display will be rather big (macroblocks etc. will be visible earlier at lower bitrates esp. on bigger screens).

[Motenai Yoda]

make a comp test, encode only 10% of the video using selectevery(200,20) at the end of script @ costant quantizer 2 (or crf 18 w x264)
the result's bitrate sould be around 120% of final bitrate (150% w x264).

[manono]

If using Gordian Knot, run its compression test. If using AutoGK, check its compression test results for a given width. Or do a one-pass quality based percentage encode and take whatever size it gives you for the quality you specified.

[jethro]

use DVDs instead

[kshawkeye]

When running a Compressibility Check in Gordian Knot, I get 55.5% for 1 CD and 106.5% for 2 CDs. So which would be best? Or should I just forget about the CD standard and stick to a constant bitrate?

[manono]

Whatever you do, don't stick with Constant BitRate (which isn't even possible using GKnot). 55.5% isn't all that good. It'll never reach the 106% size. You have several choices to bring up that 55.5% to something better. Use lower quality audio, filter the video to make it more compressible, or (the one I'd recommend) lower the resolution.

And that's if it absolutely has to be CD size (which in my opinion it doesn't in this day and age). If it doesn't, then open the AviSynth script GKnot gives you directly in VDub(Mod) and set up XviD for a Target Quantizer encode of 3.

[CWR03]

When running a Compressibility Check in Gordian Knot, I get 55.5% for 1 CD and 106.5% for 2 CDs. So which would be best?
Since "best" in this case comes down entirely to your perception of quality, only you can answer that question.

The only reason to use the "CD standard" is if you're backing up the files to CD.

[kshawkeye]

Thanks everyone for your help and comments! I decided I'm going to just go with an average bitrate, and forget about fitting it onto a number of CDs :thanks: