Video Size - .avi files - Autosize - Oh My!

[awsedr]

I use ffmpegx exclusively to re-encode avi and other formats to work with my DVP642. The XviD[.AVI](mencoder) setting works quite well. What does not work well is resizing the video using any of the Autosize settings. I always set the width first and need the height to follow. In order for this to work I have to open D-Vision to the "re-encode avi/mpg" section and plug in the width and use the "calculate height respecting ratio" under Dimensions to get the new calculated height to preserve the original aspect ratio, then I plug this into ffmpegx. Is there any way in ffmpegx to calculate a new height without screwing things up using "Autosize" and "keep height"? Thanks

[Case]

The Autosize button will help you if you know the aspect ratio
(and if the a.r. is listed in the ffmpegX settings).

Set target width. Set aspect ratio in Autosize. The new height will be calculated based on the former two.
The "a:b (keep height)" options are for the reverse: calculate the width based on height and aspect ratio.

[awsedr]

Thanks Case. I believe thats my problem, I usually don't start out with a standard aspect ratio and usually want to bump the width up to the next size and need the height to follow which never matches 16:9 or 4:3 numbers like 640x352 or 640x480 etc. They typically are 640x328 after D-Vision calculates or something. It just looks better sized to fill the TV screen up with as little black box fill as possible.