Change resolution without recompressing?

[StoneGold]

I have some Xvid and Divx files I want to play in my Divx player. The problem is, they surpass the resolution of my player. I want to reduce the resolution to 720xwhatever, but preferably without having to run the Divx file through the Divx filter a second time. Is there any way this is possible?

[Baldrick]

Nope, you must reconvert. You can use autogk, avi recomp or virtualdub.

[StoneGold]

Crud. Are there any suggestions on how to do it with the least amount of compression artifacts? I gave it a shot, and for the most part it looked OK, but you could tell in things like the credits that things had been altered.

[zedalis]

I use MPEG4 Modifier program frequently and it works well - I think I found it on this forum initially.

You can find it here: http://www.moitah.net/

From the site:

"Modifies a MPEG-4 ASP video (XviD, DivX) without re-encoding (change aspect ratio, edit userdata, remove or add packed bitstream, and change interlaced field order). It can also show information about the video such as the amount of I/P/S/B-VOPs used, whether or not QPel/GMC were used, etc. The video must be in an AVI container. More information can be found in this thread. There is also a command line version sharing most of the same features which even runs in other OSes with Mono."

Hope this helps.

[Ai Haibara]

MPEG4Modifier won't let you change the resolution (with or without re-encoding), which is what the OP wants. It does let you change the aspect ratio - but that isn't the same as changing the resolution.

There isn't a way to change the resolution of a video file without re-encoding, unfortunately.

[StoneGold]

I don't mean to ask again, but is there a preferred method for re-encoding an Xvid file so as to avoid artifacting as much as possible? Should I de-encode, then re-encode? Is that even possible?

[Baldrick]

Nope, you can't "deencode". You will lose a bit quality, best would be to convert from a better source but try increase the bitrate a bit and use 2-pass encoding. What tool did you use?

[StoneGold]

Virtualdub.

[guns1inger]

Use quality based encoding and take whatever file size it creates. You should get near-as-damnit to the original quality.

[jagabo]

VirtualDub:

File -> Open Video File
Video -> Filters -> Add -> Resize, set size and Lanczos3 filter
Video -> Compression... -> Xvid -> Configure... -> single pass, target quantizer = 3
File -> Save as AVI.