KVCD: Good Idea to Increase Compression?

[Gaudi]

Some time ago I posted this, and this post remained lost. But the other day I came across with the same idea. Is it feasible?

Would like the gurus in here to give some hint on this idea.

Quote:

Originally Posted by Gaudi

I have come across a good idea, despite the fact I am not proficient in programming.

Perhaps someone out there can do something with it.

First of all. I know very little about compressing and the like. But I think that the bitrate of a scene, provided CQ_VBR is a good index of its action or complexity. Perhaps there are some other methods.

Ok, here is then the idea:
Why don´t encode small clips of the movie, lets say 10 seconds every 1 to 3 minutes (perhaps we could impement some scene change detection here to include complete scenes in each clip avoiding splitting). We can easily do this with a small soft that automates a creation of an avisynth script, sends the commandline to TMPEG, waits for the encoding to complete, and then checks the file size.
We can do this for every sample in the movie, and can the build a "complexity" vs time graph. If we account for the sample to be representative of every clip, then we will have some idea on how to set CQ (or bitrate) for different parts of the movie.

We can then repeat the encoding but this time for each clip (not just the sample) setting different CQ and/or bitrate settings for each one. We will the come to a series of clips or "parts" that will have to be joined together.

No problem with that. And the audio will be ok because it uses CBR.


Perhaps someone can do a small test to check results. I myself will try to do something in excel this weekend to check what comes out.


Another aproach could be to use bitrate viewer and export the data for each clip after encodign the whole movie.


Hope this idea is a good one to trigger some development in this area.


Gaudi

Many thanks

Gaudi

[jorel]

Gaudi,
yes i remember,i read this before...
but don't have knowledge to do some.
waiting with you,maybe it could be usefull!

[Gaudi]

With some little help on how to control TMPGEnc from command line, I might be able to do something.

Anyhow, I will be waiting for some post with more info.

Thanks.


Gaudi

[rendalunit]

Quote:

Originally Posted by Gaudi

Why don´t encode small clips of the movie, lets say 10 seconds every 1 to 3 minutes (perhaps we could impement some scene change detection here to include complete scenes in each clip avoiding splitting). We can easily do this with a small soft that automates a creation of an avisynth script, sends the commandline to TMPEG, waits for the encoding to complete, and then checks the file size.

This is what ACP does

[Latexxx]

Have you guuuys heard about 2-pass vbr??? Exact the filesize you want. The only disadvantage is that it tooks two times more time than encoding single pass.

[Gaudi]

Quote:

Originally Posted by rendalunit

Quote:

This is what ACP does

Sure, only it does that for the whole movie. I mean aplying different CQ/BR to different parts according to their complexity.

[kwag]

Quote:

Originally Posted by Latexxx

The only disadvantage is that it tooks two times more time than encoding single pass.

And also looks worse
Here: http://www.kvcd.net/forum/viewtopic....=asc&start=195 and the screenshots are on the following page

-kwag

[kwag]

Quote:

Originally Posted by Gaudi

Sure, only it does that for the whole movie. I mean aplying different CQ/BR to different parts according to their complexity.

That's exactly what CQ does. It changes bit rate in different parts of the movie based on a "quality" treshold. That's the definition of "Constant Quality"

-kwag

[Gaudi]

Quote:

Originally Posted by kwag

That's exactly what CQ does. It changes bit rate in different parts of the movie based on a "quality" treshold. That's the definition of "Constant Quality"

So, what about then on changing the bitrate. Wouldn´t that help compress more the low detail parts and less, with better quality the high action/high detail scenes?
We could even apply different GOPs perhaps to different parts. Or use the LBR selectively.

Gaudi

[kwag]

Quote:

Originally Posted by Gaudi

We could even apply different GOPs perhaps to different parts. Or use the LBR selectively.

Gaudi

VBR + VGOP
Not so sure that DVD players will like that

-kwag

[Latexxx]

Quote:

Originally Posted by kwag

Quote:

And also looks worse
Here: http://www.kvcd.net/forum/viewtopic....=asc&start=195 and the screenshots are on the following page

-kwag

Didn't know that! I just tought it would be the same thing than with cce.

[GFR]

Quote:

Originally Posted by kwag

Quote:

VBR + VGOP
Not so sure that DVD players will like that

-kwag

I guess if you check "scene detect" you end with VGOP - altough the number of B's is fixed the total GOP length is variable as you may insert an I anytime needed.

[kwag]

Quote:

Originally Posted by GFR

Quote:

I guess if you check "scene detect" you end with VGOP - altough the number of B's is fixed the total GOP length is variable as you may insert an I anytime needed.

Yes, that's true. But I think some players (wrongly designed) might have sync issues with scene change detect and a long GOP. Maybe, that's just a guess

-kwag