Variable framerate

[Slave01]

Wow i have just tried variable framerate realvideo and i can tell that ensures high quality improvement! Now my question is: is possible implementing this extraordinary (and not so complex) idea in xvid encoder? I know that the result will not be mpeg4 compliant but many functions are not supported. It is really good especially in anime in which frames are duplicated. I am not talking about dropped frames but frames that are not encoded (maybe it will concern only decoder).

Thanks in advance
Slave01

[haibane]

you can look at this thread...
http://forum.doom9.org/showthread.php?s=&threadid=68562
I think VFR is really container related.
Use dupdorp filter and the method mentioned in the thread above should give what u want with any codec.

[RadicalEd]

Originally posted by Slave01
I know that the result will not be mpeg4 compliant but many functions are not supported.

0 for 2 there, XviD is entirely compliant.. that's what it is. A noncompliant mpeg 4 codec is just not an mpeg 4 codec. As for VFR, it's as haibane said; the codec has no relevance. If you want a vfr mp4, delete the duplicate frames, encode what you have left normally, mux it to vfr matroska with a custom made vfr script, and then transmux to mp4 with the 3ivX muxer :|
And yes, that too would be compliant.

[HeadlessCow]

Yeah...All my vfr tests were done on xvid sources. It works very nicely in Matroska :)

Is there any mp4 muxer that takes as input some sort of vfr info file like mkvmerge does? If so I can probably add support for it pretty easily.

[shitowax]

The 3ivx mp4 muxer supports VFR. Even better the 3ivx DS video encoder supports VFR as well i.e if a frame lasts more time, it will get more bits ... ;)

[HeadlessCow]

Ah, very nice, automatic detection of duplicated frames at encode time is the way to go ;)

[Slave01]

Exactly. If it is so easy it would be relatively simple to put it as option (or automatically implemented) in xvid (expecially in cartoon mode).



Thanks for the interest
Slave01

[haibane]

Originally posted by Slave01
Exactly. If it is so easy it would be relatively simple to put it as option (or automatically implemented) in xvid (expecially in cartoon mode).



Thanks for the interest
Slave01

the problem is that currently, most people using virtualdub(which is vfw based) to encode stuff, which means it encodes to avi, and avi doens't support vfr. I am not sure what is the case on other platforms, but u need to have an xvid encoder and a muxer that will output to a container format that support vfw.

[spyder]

Doesn't xvid already code duplicate frames with a very few bytes? I remember a whole bunch of discussion about this. IIRC, that was the point of Donald Graft's Dup filter...to make the frames exact duplicates when they are very close already. Is MPEG4 really supposed to be variable framerate? I mean, it doesn't store framerate in the stream like MPEG1/2?

[bond]

MPEG-4 is able to do vfr, but as it was already pointed out not only the AVI container cant handle vfr also the vfw interface (which means also virtualdub/mod) cant handle it

i think the way the 3ivx guys chose to do vfr encodes by using dshow is very nice
dshow is a widely accepted and used interface, doesnt have problems like vfw with b-frames for example, and allows the usage of all advanced containers, namely matroska, ogm and mp4, capable of vfr, already

suxendrol is already working on the "official" xvid dshow encoder filter, lets hope that we will soon see vfr capabilites there too ;)

[Slave01]

the problem is that currently, most people using virtualdub(which is vfw based) to encode stuff, which means it encodes to avi, and avi doens't support vfr. I am not sure what is the case on other platforms, but u need to have an xvid encoder and a muxer that will output to a container format that support vfw.

ah yes it's true. But in virtualdub there is the possibility to create directly mkv files. So is it possible?

[Neo Neko]

No. Simply put Virtualdub does not create MKV files. OTOH Virtualdub-mod will create MKV files. But since it interfaces to all codecs via VFW it will not create VFR matroska files. Not without the addition of substantial code that is.