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Hey all,
I've been messing about making some 3 second films and I'm confused.

When I choose MJPEG Compressor as the video compressor the final file is 14.1mb in size, if I choose DivX 5.2.0 codec the exact same movie is only 412kb in size.

If anything the DivX movie is better quality, the only downside being a small watermark in the corner.

I've not used any sound but maybe when I do the MJPEG movie will sound better.

Can anyone explain why there's such a big difference in file size.

Thanks in advance.

For most video compressors basically they use a pixel block scheme.

64x64 pixels (why you get that horrible blocky effect at low-res or high-rate compression) which basically samples each pixel around it and if it's within a certain range will then say 'well these pixels are close to X Colour' it'll then adverage them all and put the colour dword (of byte if it's paletted colour) plus the number of pixels. Often it's a 24-bit colour value with an 8-bit offset.
If it's a 16-bit compression then then the choice usually is to just drop the colour range, and deliberately use an LDR.

So you'll find those sample of colours end up being like X colour for X pixels.

This can be up to 128 pixels, so your getting a single dword = 128 pixels which normally would be a 24/32-bit colours meaning up to what, 512 byte down to 4 byte .. in the best case scenario.

Uusually it's not done to that sort of extreme and the whole block will get a single pass gzip or something as well. Then you have the whole huffman compression which just plainly confuses me.

Divx is just better at compressing video into a smaller size. Similar to how a .rar is smaller than a .zip
The technical details are complicated and beyond my understanding. With MJPEG each individual frame is compressed as a Jpeg image. Divx is a lot more sophisticated and uses methods to reduce the amount of info required to draw a frame. For instance if any parts of the previous frame are identical to the current frame the current frame doesn't need to store them, they can just be left from when the previous frame was drawn.

Thanks.