Remove/reduce B-VOPs without reencoding?

[jaffaman]

Is it possible to remove or reduce the B-VOP count to 1 in XviD without reencoding the whole file? My Pioneer 575-A is playing such files with lags (frame changes only every 5 seconds or so).

Tried unpacking the file with MPEG4 Modifier, but the result is the same.

I've heard something about "header modification trick", but never seen any further description about it.

Any ideas?

[Ark]

No, it's not possible to remove/reduce bvops, you have to reencode.

[bond]

where do all these "i want to change the used encoding tools after encoding without having to reencode" questions come from lately? :D

[jaffaman]

that's couse the divx hardware players get more and more popular :)

[unskinnyboy]

And also because people keep downloading more and more stuff without knowing the specs beforehand..:D

[Prettz]

Think of it this way: your question is exactly equivalent to asking if you can reencode a JPEG image to a smaller file size without reencoding it.

[SeeMoreDigital]

What would happen if somebody was to create a tool that can scan thru' an entire Mpeg4 B-VOP encode and re-write the frame sequence, so that anything that says "B" could be changed to "P"?

Is such an idea too stupid to work. Has anybody tried it?


Cheers

[Ark]

Mmm, i don't know if it will work...
I mean, b-vops work in a different way, so simply change their "flag" or name so that the decoder identifies they as p-frames isn't enough to make it work i think...

[akupenguin]

The only thing you can do to B-frames without reencoding is to remove them (not replace them, just drop the frames). And I don't know of an existing tool to do even that.

Originally posted by Prettz
Think of it this way: your question is exactly equivalent to asking if you can reencode a JPEG image to a smaller file size without reencoding it. I know what you meant, but: http://compression.ca/act/act-jpeg.html :)

[Prettz]

Originally posted by akupenguin

I know what you meant, but: http://compression.ca/act/act-jpeg.html :)
Bah!!

[b0b0b0b]

Thanks to moitah's mpegmodifier, I think testing zany ideas like this have become very possible. it's gpl, so you can just try your idea out.

However, I assume that if you just flip the flag on the field, very bad things will happen.

My own idea of transcoding directly from mpeg-2 to mpeg-4 got a shot in the arm after I found moitah's mpeg4 modifier.