when to edit? before demuxing, encoding, or authoring?

[Questmark]

I have an ogm that I've demuxed to avi and ac3. It has subtitles. I want to cut some sections from it.

I don't know whether it's best to edit before I've finished demuxing in VirtualDubMod, just before I've encoded in tmpgenc, or just before I author the dvd in DVDAuthor.

I've read around, and I feel like there are conflicting answers. I was hoping someone could explain to me why it's best to edit video and audio at a certain point.

[greymalkin]

ok..you definitely want to edit first..cutting out the sections you don't want...then you should be able to do a stream copy to get your edited file.

if you demux first you'll end up with too much audio and never be able to get it sync'ed up.

Once you have the edited file you will have to demux I belive then render the video portion only to mpeg2 in TMPGenc Xpress (I don't think it allows importing ac3?), author in TDA (it will mux the new m2v and ac3 streams)..then burn.

I'm assuming that virtualdub will allow you to import the ac3 audio with the video stream and edit them together. If it will not then you will have to do some more trickery.

[Questmark]

I can see your point re: editing before demuxing-- for timing, which makes good sense. I guess I'm curious because I've done this once already and I just edited in DVDAuthor, and it seemed to work out fine.

I followed some of the guides in here-- demuxing, encoding seperately, and then remuxing in the authoring program... where I proceeded to edit the whole shebang.

I know there's more than one way to skin a cat, but I wasn't sure if there was some benefit to editing before demuxing, or whether it was all about the same in the end. One thought that had occured to me was that if you edit it after you've encoded (i.e. in the authoring program), then if you decide your editing was wrong, you've encoded the full file (rather than the edited file), and thus don't have to go through the long encoding process all over again.

I just thought that perhaps editing before demuxing, encoding, etc. might give better/different results re: quality of picture, etc.

Also, I might as well throw in here what I'm planning on doing in general to the file, as it might change some of the suggestions--

I also want to edit the subs a bit, here and there, and if I can (I dont' know how hard this is), try and take out a section of the audio to make it silent for a little. Thus, perhaps with changing the .srt file and changing the audio, it really __is__ better to edit before demuxing, since I really can't edit those things while authoring the DVD. Re: those two editing processes-- does anyone have good guides they could link me to (for editing sound and subtitles)? I've been hunting around, but haven't been able to find much on the editing of a bit of audio, and the guides/threads on editing just a section of the subtitles are really simple/vague.

Also, if I edit the video/audio in VirtualDubMod, will it also appropriately edit the srt file as well, to fit the now edited video/audio? I guess it must, huh? I just haven't tried that yet.