Reducing file size

[MunkyB]

What is the best way to reduce the size of huge video files without sacrificing too much quality? I'd like to reduce 640x480 to maybe half that resolution, but maintain the color and sharpness, and if the audio is AC-3 or something ridiculous like that- reduce that, too. I want to make them about 100 megs (there is no good reason why some of these are so large). I'm pretty good at using TMPGEnc, but haven't found an AVI counterpart to it.

[xo]

[Tyreal]

As he said before, virtualdub is excellent. As far as mpeg-4 codecs go, I like xvid. Xvid has a lot of the mpeg features for tweaking. Personally, I like working with the quantanization matricies. The intra frame matrix would be the keyframe matrix the inter frame matrix would be the delta frame (P) frame matrix in a setup similiar to IpppppIpppppIpppppI. P would be the delta frames (ie, the fillers for the keyframes). Xvid is currently beta with the bframes as we see in normal mpeg GOP's (ie. IBBPBBPBBPBBPBBPBBP). I wouldn't recommend using those. The inter matricies are mainly what you want to go after. intra matrix should be set to all 32 and left at that. This is the default matrix for cgi and animation. The inter matrix is defaulted at 16. By increasing the values, you can increase the compression but the quality is decreased. Around values of all 10 can give you a file size of 150 - 250MB, depending on what your bitrate, quality, or quantanizer values are set to. I used to use divx, but, they use blurring instead of macroblocks, something I think looks really bad for those resizing. If you're pulling the size down, the quality naturally increases. If you pull down a 640X480 video, I believe that you could most likely set the inter matrix quantanizers to all 10 and the 1-pass quantanizer method in xvid to about 3 or 4. Experiment with those values. A difference of 1 in your quantanizer can be a difference of about 20MB file size. As for your audio, I recommend using mpeg layer 3. If you want the better compression, 96kbs compression should suit you fine. If you want medium compression, as in compressing, but still keeping quality, go for 128kbs. If you still have a good amount of space, keep going up. 320kbs is super quality but can really push up your file size. That's about it.

Tyreal
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