? Re-encoding Just Part of a Video

[Synetech]

Hi,

I’ve got a bunch of videos that just barely fit on a disc, so I need to cut them down by just a little. I cannot cut anything out, but the beginning and end of each video is unimportant, so I would like to re-encode those parts to a lower quality/bitrate. Is this possible? How?

Thanks.

[poisondeathray]

I think it would be very difficult to do this, and hope to keep it in sync.

How much "over" are you? You can overburn on most CD's, some DVD's

Is this DVD or CD?

[Synetech]

The total of all the videos comes out to about 60MB too much for a standard DVD5 disc.

[manono]

These are DVD movies with chapters? Then extract and reencode one or more of the chapters and stick it back in.

If these are videos in some other format, why can't you just reencode one or more of them, maybe the ones you don't like as much?

[Synetech]

There’s a dozen videos, each one between 330-400MB. Each one has a lead-in and lead-out that are not important, but cannot really be removed either. All videos are equally important.

I no longer have the uncompressed originals—I thought I was done and wanted to free up the massive amount of space they took—so I don’t want to re-encode them if I can avoid it (re-encoding a lossy format is not a good idea).

[Ollie6431]

There’s a dozen videos, each one between 330-400MB. Each one has a lead-in and lead-out that are not important, but cannot really be removed either. All videos are equally important.

...

The total amount of videos would be around 5 Gb. One way to fit all the videos in one DVD would be to:
-Author a DVD-Video project using various softwares (many are bundled with purchased PC). The total size of all your videos in the project (including menu) would be more than 5 Gb
-Use DVDShrink to fit the video into a DVD-5. The compression would not be that much
-Burn the DVD using a burning software of choice

[Synetech]

Actually it’s 4.43GB—oh so close. Just to be clear, they are AVIs.

I am going to see if maybe I can remove the header and footer, it would be easier, quicker, and I’d be more comfortable.

So for the record, it’s not really possible to reencode part of video is it? It’s not like MP3s where they can encode each frame at a different rate (VBR)?

[manono]

So for the record, it’s not really possible to reencode part of video is it?

Sure it is. Extract the audio. Cut the remaining AVI into 3 pieces, the beginning, the middle, and the end. Reencode the beginning and end, using the same settings (except for the bitrate) as the originals. Append the 3 pieces, 2 of them newly reencoded, and then add back the audio. Do that for as many of the AVIs as necessary until you've saved the required 60 MB. Kind of a lot of work, though, to save a little bit of space.

[Synetech]

So for the record, it’s not really possible to reencode part of video is it?

Sure it is. Extract the audio. Cut the remaining AVI into 3 pieces, the beginning, the middle, and the end. Reencode the beginning and end, using the same settings (except for the bitrate) as the originals. Append the 3 pieces, 2 of them newly reencoded, and then add back the audio. Do that for as many of the AVIs as necessary until you've saved the required 60 MB. Kind of a lot of work, though, to save a little bit of space.

Ah, I see. You’re right, it would probably just be easier to see if I can cut out the lead-in and out. Perhaps I can leave in just the lead-in from the first video and the lead-out from the last video.

[AlanHK]

If it's only 60 MB in 4 GB, you might be able to do this just by reencoding the audio.

First use something like AVIcodec to scan your AVI files and see how they're encoded.

It will tell you how much of the file is video, and how much audio.

If you have a total of a few hundred MB as audio, you can demux, reencode the audio at a lower rate, remux. The video will be unchanged. The audio quality will take a hit, but you can judge for yourself how important that is.

[Synetech]

GSpot is showing that the videos each have at least 3.5MB of “AVI Overhead”. I don’t suppose there is a way to shrink that is there?

[AlanHK]

Another method: Avi Recomp.

[Synetech]

Another method: Avi Recomp.

Hmmm, this line from the AVI Recomp description is interesting:

AVI ReComp can be very useful for users who want to clear their AVIs out of GMC or Qpel functions to prepare the clips for standalone DVD players.

I shouldn’t need it since my DVD player is supposed to be able to handle them, but I guess that it’s still a good idea for compatibility and future use and to be safe. Of course I don’t need AVI Recomp to do that; the XviD encoder comes with GMC and QPEL disabled by default, so everything I encode with it should be fine.