change video bitrate

[Ogilvy]

Ive just converted an AVI file to MPEG2 using TMPGEnc. I made a mistake in video bitrate, can somebody advise me if there is a simple software facility out there (maybe like MPEG modifier) to change said bitrate or do I have to spend hours again to re-encode? Much obliged

[manono]

You'll have to spend hours again to reencode.

[Baldrick]

Yes, you must reencode/transcode. If you are making a dvd you can author it and then use dvd shrink or use rejig directly on the mpeg video. But best would be to reencode from the avi file.

[guns1inger]

You can use something like DVD Patcher to alter the number that appears in the stream as the bitrate, which can fool some authoring tools (or correct bad values put in by some encoders), however it doesn't actually alter the true bitrate. As has been pointed out by my learned colleagues, you have to encode again to alter the true bitrate.

[AlanHK]

Ive just converted an AVI file to MPEG2 using TMPGEnc. I made a mistake in video bitrate, can somebody advise me if there is a simple software facility out there (maybe like MPEG modifier) to change said bitrate or do I have to spend hours again to re-encode? Much obliged

What do you mean by "mistake"?

If you encoded an MPEG at a too high a rate, you can use Rejig to shrink it. You can choose any level, but naturally the more compression the lower the quality.
I use it occasionally to shrink an MPEG by 1 or 2% when I overshoot the size slightly. This is pretty fast, a few minutes for a 800 MB file.

There is no way to usefully increase the bitrate though.

[Ogilvy]

The mistake I made was in leaving a TMPGEnc setting on “auto” and it chose a bitrate way lower than it should have been (at least according to the bitrate calculator). All this is part of a larger problem…in AVI to DVD conversion (using also VirtualDub, DVDAuthor, and/or Nero Vision) I get perfect video on PC but on video player theyre almost always “grainy”, even from a good quality AVI and with various codecs, so Im trying to track down cause. Maybe some of you people can help me here, if there are known issues in this area. And one other question here please….I downloaded newer codec XviD 1.0.2, do I manually import it into VirtualdubMod or just continue to choose compression XvidMPEG4?

[AlanHK]

in AVI to DVD conversion (using also VirtualDub, DVDAuthor, and/or Nero Vision) I get perfect video on PC but on video player theyre almost always “grainy”, even from a good quality AVI and with various codecs,

Not a codec problem, if you can see it at all you've got the right codec. (Making AVIs is another thing than displaying).

You want more control, you need to use separate tools.

1) Make an appropriate AVS file (eg use FitCD to generate). At a minimum, this will scale it to a correct resolution.

2) Load this AVS into an MPEG encoder (eg HCenc). Choose the maximum bitrate you can fit on a disc.

To test various settiigs, just encode a few minutes and see how it looks on screen.