How to convert with Variable Frame Rate? (VFR, H.264)

[21420]

Hello,

which software is needed to convert movie clips (Quicktime H264) with a constant frame rate (CFR) to clips with a variable frame rate (VFR)?


(I already searched the forums and the internet)


Thanks in advance!

[tetsuox]

Why do you want to convert a CFR source to VFR anyway?

[21420]

I am recording my computer screen. Often there will be no movement in the video while I am explaining something in the audio track.*

Basically I want to end up with a video like this:
http://www.lynda.com/home/Player.aspx?lpk4=51616


edit:
* using a VFR should decrease the file size significantly

[Ghitulescu]

edit:
* using a VFR should decrease the file size signifiantly
So will a GOP-based algorithm do ;), since B-frames, which keep the differences, would need less space if no changes in image are present.

[21420]

So will a GOP-based algorithm do ;), since B-frames, which keep the differences, would need less space if no changes in image are present.

Great!
...so which program/codecs may I use to convert the files?

I am on Mac OS X / Win XP.

[Ghitulescu]

Well, one of them is h.264, which seems to be your original codec. Aren't you happy with its size? Reduce then the bitrate and/or the screen size.

I'm not very expert in VFR, the only one I (accidentaly) heard of was RMVB, which belongs to RealMedia (Real Networks) formats.

[Guest]

His source is already H.264. The salient point now is does it use B frames already.

21420, post a link to a small unprocessed sample of your source.

[21420]

I just recorded the video I posted in the link above so I can compare the recorded with the original one.

It is currently encoding the video with H.264, 16fps, 30 Kbyte/s*, multipass

* QuickTime indicates that the original video has a bitrate of about 240 Kbit/s




The finished video is about 16.8 MB (235 kbit/s; no audio), while the original file was 16.5 MB (232 kbit/s WITH the audio track (AAC)).

In my video the frame rate never drops. The original file's frame rate often drops to 1 or even 0.14 fps




In my "Compression Settings" I can select
- Key frame every X frames
- Frame reordering


What is a good setting to use for recording applications?

[Guest]

I'm checking out as you won't post what I asked for. Bye!

[microchip8]

How big may a file be for attaching it in this forum?

don't attach to this forum! just cut a small sample, say ~30 MB, and upload it to mediafire or such service, then post link to it here

[21420]

See here:
http://www.mediafire.com/?sharekey=5f2db0440ec24eacb64026cfc0611236e04e75f6e8ebb871


edit: about 500 kb

edit2:
16fps, 30 KBytes/s, Multi-pass

I'm not really satisfied with the quality. Also I don't know how to create a clip with VFR instead of CBR (the program's codec does not offer such an option).