VDub, Key frames and syncing...

[takearushfan]

Hi all,
I've noticed that when I use VirtualDub I can make a cut anywhere I want, but if I save the edited file and play it back, the cuts won't remain where I made them; instead they'll stick to and are kind of "forced" to the key frames. Again, bad wording, so I hope you'll understand what I mean. Is there a way to be sure that when saving the edited file it'll remember the *exact* frame(s) that were cut, rather than "snapping" to a key-frame?
Also, here's something the occurred to me when using AutoGK. Even if the log claims that there's no A/V delay/skew, how do you know that it's accurate? For all I know, the application might be completely screwed up and there actually is some sort of delay, despite it claiming that there isn't any.
Thanks,
Justin

[redwudz]

If you were able to cut a Xvid, for example, anywhere other than a keyframe you would just get video garbage as the keyframe is the only complete frame. The editor will just jump you to the next keyframe instead. If you use one of the newer versions of Vdub, you can use the 'Smart rendering' option and it will fix those partial frames, letting you cut where you want. It re-encodes at the cut, restoring the keyframe.

Most highly compressed formats like Divx/Xvid only have keyframes about every 300 frames by default. The problem is with the codec, not the editors. Those codecs were designed as a end product, not for frame accurate editing.

If 'Smart rendering' doesn't work for you, you can re-encode the file with lossless codecs like HuffyUV or Lagarith and every frame is a keyframe. It makes frame accurate editing very easy. The downside is you will have huge files, so you need a lot of hard drive space. After editing, re-encode the file back to Xvid and delete the lossless file after checking the finish product.

Not sure about AGK and how it determines audio offsets, but someone here may be able to give you an answer.

[takearushfan]

If you were able to cut a Xvid, for example, anywhere other than a keyframe you would just get video garbage as the keyframe is the only complete frame. The editor will just jump you to the next keyframe instead. If you use one of the newer versions of Vdub, you can use the 'Smart rendering' option and it will fix those partial frames, letting you cut where you want. It re-encodes at the cut, restoring the keyframe.

Most highly compressed formats like Divx/Xvid only have keyframes about every 300 frames by default. The problem is with the codec, not the editors. Those codecs were designed as a end product, not for frame accurate editing.

If 'Smart rendering' doesn't work for you, you can re-encode the file with lossless codecs like HuffyUV or Lagarith and every frame is a keyframe. It makes frame accurate editing very easy. The downside is you will have huge files, so you need a lot of hard drive space. After editing, re-encode the file back to Xvid and delete the lossless file after checking the finish product.

Not sure about AGK and how it determines audio offsets, but someone here may be able to give you an answer.

You mean that all this time there's been the potential to encode in a lossless format? Now that is something I want to try! Unfortunately I always post these questions shortly before going to bed, so I won't be able to report my results 'til later.
Thanks for the advice ... of course I wouldn't mind if others would chime in as well
- Justin

[jagabo]

You mean that all this time there's been the potential to encode in a lossless format?

Yes, but lossless encoding usually doesn't compress much. Expect an hour of standard definition video to consume 20 to 40 GB of disk space.

[takearushfan]

You mean that all this time there's been the potential to encode in a lossless format?

Yes, but lossless encoding usually doesn't compress much. Expect an hour of standard definition video to consume 20 to 40 GB of disk space.

Yikes! Compression it is ... I don't have that kind of space