Virtualdubmod: Direct Stream Copy or Full Processing?

[OM2]

In Virtualdubmod what is Direct Stream Copy or Full Processing?
Is one better than the other?

The help file is very poor.
Haven't bothered with that.

Thanks.


OM

[Soopafresh]

DirectStream Copy makes an identical copy of the source Audio and/or Video track. NO processing or re-encoding happens. DirectStream copy is used if you are trimming parts of an AVI file - no quality loss because no re-encoding.

[jimmalenko]

Full Processing should only be used when you want to do some sort of alteration to the video itself - when using a filter of some sort, changing the frame rate, etc etc. As Soopafresh said, if you're just doing basic editing, then use Direct Stream Copy.

[johns0]

You can change the frame rate of an avi with direct stream copy if you want.

[jimmalenko]

ahhh OK, my bad

Certainly any filters require Full Processing, anyways ...

[junkmalle]

You can change the frame rate of an avi with direct stream copy if you want.

Because frame rate is just a number in the header of the AVI file. If that's all you want to change use a program like AVIFrate (just changes the number). It's much faster.

[gll99]

Am I missing something?
Wouldn't a true framerate change require that frames be removed or added (interpolated, duplicated or such) to make a proper change? I would think that modifying only the header information should not allow the video to play properly at it's recorded speed.
Does Avifrate or vdub do this in directstream copy?

[junkmalle]

The video frame rate in an AVI file is simply a value in the header that specifies how long to display each frame. If the value is 1/24 the file will playback at 24 frames per second. If it's 1/30 it will play at 30 frames per second. Most codecs don't include any timestamps in the individual frames so there's no problem with just changing the header.

Of course, if you change the frame rate without adjusting the audio, the audio will be out of sync.

In theory you could do the same with the audio. Say you want to change a 25 fps file with 48000 k audio to 23.976 fps. You could change the frame rate from 25 to 23.976 and the audio sample rate from 48000 to 46036 samples per second. The video will now playback slower, the audio will have a lower pitch, and they will both be in sync. Unfortunately, there is little hardware and software that supports odd audio sample rates so it's not really feasible.

[DarrellS]

It is my experience that if I make edits in the movie like cutting out unwanted frames and then try to direct stream copy that I either get an out of sync video or 9 out of 10 times I'll waste all day cutting out everything that I don't want, only to direct stream copy and save everything that I didn't want anyway so if I do alot of major editing, I use Full Processing mode.

If I cut off the frames at the end of the movie, it direct stream copies with no problem at all but if the cuts are all over the movie, There's no telling what the end product will be.

Direct stream copy seems to work best on video files that are already compressed but you want to compress the audio to make a smaller file or when joining segmented AVI files that are already compressed.