Tried your converter but i find handbrake easy and better (keep same aspect of original source) tried 2 more video converters and a gui for ffmpeg!
So far handbrake converts so much faster.
Only problem with handbrake is the video out puts are only MP4 (MPEG4 Video) and AAC Audio, or M4V (H.264 Video).
for some reason in Handbrake i cant get it to out put Mp3, i select option but out file has no sound.
I guess Handbrake will do the job, because
a) MP4 still plays on Dingoo so does not matter that its not Xvid/AVI
b) AAC Audio at 128br sounds as good as originals MP3 at 141br
c) It can reduce exactly 50% video screen size, i.e 624X352 when set to output to 320X240 will output 312X176 which is 50% of original size if i keep Aspect Ratio option selected.
Other converters out pit to 320-240 and the video looks stretched, but if i force 16-9 aspect in my PC Video player it looks same as handbreakes 16-9 312X176 file.
So i guess even if i found a program that keeps the same Video/Audio Codecs i.e Xvid/Mp3 and converts to 320X180 (keeping aspect ratio). Then i guess whats the difference if Handbrake does the job fast (2min) but outputs a MP4 with AAC that looks and sounds the same.