Cutting/Splitting .VOB

[erzane]

Hi, I'm used with DVD Decrypter to RIP my DVDs, then I keep the files on .VOB.
I'd like to cut and split those files, so actually I use Mpg2Cut2 but this one is not precise enough. I'd like a more frame precision tool, and free.
Thanks!!

[jagabo]

There are no free, frame accurate, smart MPEG 2 editors.

[erzane]

There are no free, frame accurate, smart MPEG 2 editors.

Ok, so if I have no choice I'm able to pay. Which are the bests?

[jagabo]

I've used VideoRedo in the past. There's also TMPGEnc MPEG Smart Renderer (maybe some of the other products) and SolveigMM Video Splitter.

[erzane]

Ok, thanks. And what about Virtual Dub, is it less accurate (maybe obsolete?) than the ones you listed?

[jagabo]

VirtualDub is frame accurate but it will have to reencode the entire video if the input is VOB. If you don't mind reencoding (and losing quality) you can use any editor that can read VOB files.

With high compression codecs like MPEG2 the problem is that most frames only contain the changes from prior frames. They start with a keyframe -- a frame encoded much like a JPEG image. The second frame only includes changes from the keyframe. The third frame only includes changes from the second frame. Etc. Until (about 15 frames later with DVD MPEG2) another keyframe is encoded. (It's actually more complex than that but that's the general idea.) The keyframe and all the frames that depend on it are called a GOP (Group Of Pictures). If you trim away the keyframe the rest of the GOP can no longer be reconstructed. So editors that don't reencode can only cut on keyframes. Smarter editors allow you to cut on any frame but must reencode the cut GOPs. So only a few frames at the cuts lose quality. Other editors will let you cut on any frame but will reencode the entire video.

[abolibibelot]

For such purpose I've used DVBCut and Avidemux, both were accurate enough for my needs (15 frames is about half a second). DVBCut seemingly allows to cut with a 1 frame accuracy, but I'm not sure if it reencodes when the cutting point is not a key frame (which is called “smart rendering”, and which would be surprising considering that it's free and small), or if the cut is actually made on the next key frame and thus less accurate than it appears to be.

[jagabo]

For such purpose I've used DVBCut...

The description of the program here says:

the input video and audio data is mostly kept unchanged, and only very few frames at the beginning and/or end of the selected range are re-encoded in order to obtain a valid MPEG file.

So it falls into the smart editor class.

[erzane]

Ok, thanks!