Avi Shrink

[hclatwr]

I just bought a gp2x (ike a psp) it can play regular xvid files, but since the display is only 320x240 I was wondering if I could shrink my avi files without having to re-encode them
In linux I could use the transcode utility but it has not been ported to windows
Soo what i'm looking for here is a DVD Shrink but for avi (xvid) files !
does it exist ?

[Elic]

VirtualDubMod?

[celtic_druid]

Never used transcode myself but as far as I know it does re-encode. No way to resize without re-encoding anyway.

[Lil' Jer]

I just bought a gp2x (ike a psp) it can play regular xvid files, but since the display is only 320x240 I was wondering if I could shrink my avi files without having to re-encode them

You can't. That's impossible to do without re-encoding.

[hclatwr]

I was under the impression that it was possible
since you can resize your mpeg2 movies (tried it with dvd patcher)
and you can reduce the bitrate (with dvdshrink).
So with my quick mind (lol) I figured out it must be possible with Avi files ... but then again I might be way out of bounds !
here is the link to the script claiming it does not need to re-encode the file !
http://archive.gp2x.de/cgi-bin/cfiles.cgi?0,0,0,0,17,1258

[celtic_druid]

Patching a header is not resizing.

Transcode loads shared library modules that are responsible for feeding it with raw streams and encoding the frames:

If it is being fed raw video, then it must be re-encoding it.

[Lil' Jer]

I was under the impression that it was possible

No, you can't.

since you can resize your mpeg2 movies (tried it with dvd patcher)
and you can reduce the bitrate (with dvdshrink).

If you are really resizing the video or reducing the bitrate that can only be done with a re-encode.

So with my quick mind (lol) I figured out it must be possible with Avi files ... but then again I might be way out of bounds !
here is the link to the script claiming it does not need to re-encode the file !
http://archive.gp2x.de/cgi-bin/cfiles.cgi?0,0,0,0,17,1258

Except in your previous examples the files are being re-encoded. You can not resize or change the bitrate of a file without re-encoding.

[foxyshadis]

In theory Theora should be able to use bitstripping like vorbis, but I don't know if it's even implemented. Any wavelet codec should be able to resize or lower the bitrate without reencoding, if prediction methods arne't too complex. Even DCT codecs might be able to merge mvs somehow, though I've never seen research on it.

The saving grace is that 320x240 is very quick to encode even on older machines. For a tiny portable, 1-pass with vhq and me down can be hardly more noticeable than a looooong encode.