Need some creative thinkers regarding interlace

[Shadowmistress]

I've been looking into crunching files to REALLY REALLY small filesizes. I've been playing with the framerate, GOP, the quantization matrixes and so far have gotten about 10 hrs on a vcd of low motion low brightness source (really good quality). Unfortunately, when I try high brightness sources tmpgenc blows past my minimums and encodes to 3 hrs on a vcd. So here's what I was thinking...

Now this is only a theory.
Would it be possible to encode each frame as a sorta interlace? What I mean is that there would be no a-b frames, but frame 1 would have say only the top field visible (and the whole bottom field would be dumped), frame 2 only the bottom, frame 3 the top and so on. When looking at each frame by themselves they would all have lines, but just alternating so that all odd number frames would have top field and all even number frames would have bottom field. This would drastically save on bites if I can get it to work right.

What I need to know is how I would go about doing such a thing with tmpgenc or virtualdub. I know it will look crappy, I know it will flicker, I'll work on that part later. I just need to know how to take a non-interlace frame and put lines on it and control which frames get what. Can anyone help?

Keep in mind I'm still in the experimental stages here.

[edDV]

do you have any samples of your source material and latest best effort?

[devlynh]

This technique used to be used when digital non-linear video editing was just beginning (c 1993). Take the 1st or 2nd field throw (240 lines), then throw out half the horizontal pixels (200 or so) and then compress via JPEG. You start with 1/4 of the information and then compress the hell out of it. Works great with low contrast, low motion stuff. The files would run between 30min/GB to 90min/GB. This was needed because storage was expensive (2GB HD was US$1500, 9GB US$9000) and the fastest data rate was 5MB/sec (SCSI). Also large productions needed to store alot of video (20 to 100 Hours). Lets get to the present day...
Even DV gets 1 hour of video into 13GB of storage. Software compression to MPEG takes about 1.5x real time on a 2.8GHz P4 (depending on many other factors). Storage costs less than US$1.00/GB, and DVD-R's are less than US$0.50/ea.
Even low end video editing systems can handle multi-terabyte drive arrays and manage 100's of hours of video with no problem.
Remember that most compression schemes work better when starting with more information not less.
I don't wish to discourage your investigation however the need for such levels of compression are unnecessary any more. Just as a point of reference look what happened to drive compression software (Stacker, etc...) no one uses them anymore, drive space is cheap.

[Shadowmistress]

I don't care if storage is cheap.
How do you do interlacing? How did those old programs do it? Are there any still around? Can I mimic what they did with tmpgenc?

This experiment is part of a larger one. It's about borrowing from Paul to pay Peter. I'm on the verge of kicking Kvcd's ass here. I'm just working out how low low can go.

(And I won't be charging for my findings either. I believe in free information exchange.)

[FOO]

Recommend Avisynth.
You won't be able to do anything at the mpeg level and have
a player play it.

[bugster]

How do you do interlacing? How did those old programs do it? Are there any still around? Can I mimic what they did with tmpgenc?

Can't really help much except to say (in case you were not aware) that mpeg-1 does not support interlacing. You will have to use mpeg-2.

[bosss7]

Firstly you're out of luck (as mentioned earlier) Mpeg1 does not support interlace, hence we have Mpeg2.

Secondly what you are proposing would do absolutely nothing to the file size. If you did try to take an interlaced source and do what you suggest, it would make the video jump up and down very very quickly, resulting in motion sickness. When creating a VCD stream from an interlaced source you have to pick either the odd or even fields otherwise the image WILL jump up and down like mad.

All in all, you're theory makes no sense but keep experimenting.

10 hours on a VCD is still quite unique.

[tedkunich]

so far have gotten about 10 hrs on a vcd of low motion low brightness source (really good quality).

Too each his own, but VCD even at the maximum bitrate is unwatchable to me, nevermind the "low" bitrate stuff....

To get back on topic... as others have suggested, Avisynth will probably be your best bet...

[Shadowmistress]

Ok, I didn't know interlacing doesn't work with Mpeg-1. Switching to Mpeg-2 kinda defeats the purpose so there goes that concept. Thanks for putting up with my lack of knowledge. Guess I'll try something else then.