Cropping a divX encoded movie

[big_uk_ebuyer]

Hiya everyone,

Just like to say - loving the information available on this site! Ok i'm completely new to editting movie files. Basically i have a number of .avi clips which are already encoded into DivX format - which i want to crop. Some one told me to use VirtualDub - i've got it to crop the movie using a filter fine - however after i've selected the "DivX 6.6.1 Codec (2 logical CPUs)" i noted it says width must be a multiple of 4 and Height a multiple of 2 - what does this mean?? all my videos are different sizes so i guess i cant set up a batch process?

If i pick an old number is gives me an error on saving, if i pick an even one it seems to work - guess thats just whether the dimensions a multiple of 2 / 4 correct?

Last thing - if it is already compressed in divX format is there any way program where i can just crop it instead of re-encoding it as i seem to be losing qulaity with the divX settings i've got configured - as i again have no idea what to use

Any help on cropping or encoding settings would be greatful

Many Thanks

Sion

[redwudz]

If you crop, you will have to re-encode. Why are you cropping, BTW? Think of the framesize width needing to be divisible by 4 and the height by 2 and it may make more sense.

You can minimize the re-encoding loss by choosing a higher bitrate. One way to do this is to change the 'Target quantizer' to about '2'. That may make the file bigger, but it should preserve the quality.

BTW, if your final format is to be a DVD, you may have to resize to a standard DVD framesize.

And welcome to our forums.

[big_uk_ebuyer]

Thanx for your reply - i'm cropping to remove unwated people on side of the video.

Ok i've gotta cropping sorted now - however i'm i'm still having issues with the encoding options. With the new divX configuring options there are certification Profiles - what are these? The videos are only going to be uploaded to the net - so quality doesnt need to be great - Is there any way of finding out the options / settings used the first time the movie was encoded??

many thanx

[redwudz]

Usually if you drop them in Gspot 2.70, it will tell you most information about the video. The bitrate is the main setting with any encoder. But when you re-encode you usually want to set it up a little higher to make up for some encoding losses.

I use Xvid more often, but using VirtualDub you select Divx 6.22, then you select 'Configure' in the menu and open the Divx codec page. Down near the bottom is a 'Rate control mode'. Change that to '1-pass quality-based' and change the number to the right to '2'. That should give you about the same quality as the original, if I remember the settings properly. You can also change the 'Profile' to maybe 'Portable'. Then for best quality there, go to multipass encoding. Sorry, I don't know all the settings.

What I often do is make up a short representative clip about 5 minutes or so long and try some different settings. When you find a filesize/quality you like, you can write it down or make it a preset. You can always reset it to default if you mess it up.

VirtualDub will also tell you the bitrate and other info in 'File>File Information'.

[j4gg3rr]

The profiles are to ensure that what you encode is playable on all DivX certified devices.

Namely they block the use of QPEL, GMC, Adaptive Multple Consecutive Bi-Directional Coding and Custom or MPEG Quantization Matrices so that 100% of DivX devices (new and old) can play it.
The main quality setting are changed by use of the presets whereby Balanced is the default setting.

Changing Balanced to Insane would see a higher quality video at the same bitrate. This is acheived through more extensive motion search proceedures which allows more similar block to be found therefor higher compression, and also takes alot more time to encode for that reason.
It's also the only way to get the best quality for a set file size.

In most cases you can fit 90 minutes into 700MB and get good results with the Default Balanced profile.
But for sqeezing 120 minutes into 700 MB you should probably start to think of using a higher preset and a slower encode.

Quality based encoding can produce the best results faster but the file size is completely out of your control.