frame by frame splitting filesize growth

[the.rephaim]

Hello everybody,

Ive tried doing some music-dvd backup xvid encodes of my own, but I also wanted to split the resulting 700mb file into individual songs. Framerate didn't change (25fps), so I opened up the appropriate .ifo file with Ifoedit and used the framecodes for individual chapters to split the file in Nandub, frame-by-frame exactly. But to what surprise, finding out the resulting 20 files are in total 9mb bigger than the original, 700mb one file encode!

I hardly understand this. At max what I can think of is that there's one file "duped" (at the end of one file and at the beginning of another = with 20 chapters, that gives 19 "duped" frames, and that's still not even 1 second of videp = hardly 9mb). Ive encoded my file a regular 2-pass, with max I-frame at 300. Could this be the reason why? Or is it some leading/trailing bytes per file that make the size grow?

Thanks for any help, I'm really curious about this.

[communist]

Just to get you right you've encoded from DVD to an 700MB xvid avi and tried to split it at 'random' points?

You can only cut at keyframes - if you pick a P/B it will cut at the next or last (dont know exactly) keyframe. I havent used Nandub for ages but if there is a option but in VirtualDub you can jump from keyframe to keyframe so you can see where you can cut.

[the.rephaim]

Hmm, yeah, that's a good point. What is a way around this, is it possible to e.g. pre-define keyframes before the encode? Because I know at what exact frames I have to split the file.. so setting I-frames to lower numbers won't do either (even if it were 10, it still wouldn't be "precise"). Or maybe it's possible to go through the resulting file and "flag" the appropriate frames, make them I-frames, and then split? Thanks in advance!

[Didée]

is it possible to e.g. pre-define keyframes before the encode?
Surely. For each frame you want to have an I-frame, you set up a new "zone" in XviD's GUI, and configure each of them to start with an I-frame.

Or maybe it's possible to go through the resulting file and "flag" the appropriate frames, make them I-frames,
No. Not possible.