Totally and Utterly Confused!!!!!!!!!!!!!!!!!!

[Sacraven]

ok first off i must say that i have tried using the 'how to convert' menu on this site but i still havent been able to figure out a few things...
1) which format eg. .mov .avi .mpeg is the best to use in terms of compression/quality
2) i want to convert a 500mb .dat movie into a 160mb .avi without loosing any noticiable quality in both video/audio, like the ones that i seem to always download off the net.
3) ive used virtualdub to try this conversion however even with the video quality set to 20% i end up with a 750mb file!!!!
4) is there a best ratio for quality/size???
can someone PLEASE tell what im doing wrong, how to do it right and what program best to use!!!!!!! It would all be much appriciated!!

[ktnwin]

Your questions are too general. Let's me try to answer.

1) which format eg. .mov .avi .mpeg is the best to use in terms of compression/quality
A: Divx is the best in term of compression/quality IMHO. The output file is also an .AVI file. It can only be played by PC with the MPEG-4 decoder installed.

2) i want to convert a 500mb .dat movie into a 160mb .avi without loosing any noticiable quality in both video/audio, like the ones that i seem to always download off the net.
A: it depends on how you want to play back the final format (PC, DVD player, etc..). MPEG-1 is the most commonly used format (for PC and DVD player). However, to cut down to 160MB file, you need to shrink the size to about 160x120 for example and lower the bit rate. This way, it can be watched on PC with good quality. Divx is another format you can encode with 160x120 resolution.

3) ive used virtualdub to try this conversion however even with the video quality set to 20% i end up with a 750mb file!!!!
A: Either you did not select a compression algo. That's why the size is big. What resolution did you encode at ?
Or the resolution and the bitrate are still close to the original file. You have to
- lower the resolution (160x120 suggested)
- lower the bit rate (300 kbps)

4) is there a best ratio for quality/size???
A: tough to answer this one. Got to try and judge for yourself.