Video Compression

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Hello, helpful denizens of the techno section.

I have a mobile phone that takes video, and I want to know how I can crush the (relatively) enormous files it makes into much smaller ones, for more expedient transmission through the Internet. For free, preferably. Muchos graciasos.

Handbreak.

Thank you, IMCarnochan.

Try it spelled properly, handbrake. PC and Mac compatible.

Way ahead of you, but thanks

im just guessing but would a zip file not work?

Zip doesn't seem to compress enough. I need something to slash some of the content out. Cheers though.

Zip compression essentially works on plain data files, where every bit must be recorded and reproduced precisely. It is "lossless".

There are various flavours of lossless compression - which generally have no great preconceptions about the underlying data that they are compressing, other than hoping that there are some forms of repetition going on in the data.

The down side of lossless compression formats is that they can result in a "compressed" file that is larger than the original file! E.g. if you send a purely random bit stream to them.

For photographic data, you don't really mind if some of the bits of the data are not quite the same as the original image - as your eye won't notice the difference. Hence JPEG files can be much smaller than the "same" data in a zip file. The JPEG format exploits the idea that photographs usually consist of lots of fairly smoothly varying coloured areas, and isn't too fussy about the bit-level detail. JPEG is a "lossy" compression format.

For video data, the compression not only exploits the JPEG smooth(-ish) variations across each frame image, it also exploits the fact that, generally speaking, each frame of video is not completely different to the prior frame. I.e it expects lots of the data to be much the same, loosely, frame-to-frame. Hence the MPEG formats give even more (yet again, more lossy) compression.

try file splitter

On a related note, I have lots of VOB files, i.e. original DVD quality MPEG2 files. Does anyone have a good suggestion for compressing these? Every MP4 file I see seems to use different settings, and I have no idea which settings are good for an archival quality copy, meaning that I delete the original DVD image.

Also, does anyone have a good programme for revealing MP4 settings in Linux? GSpot in Windows tells you a lot about the settings, to match a file that looks good, or avoid settings that look bad. I haven't seen anything with as much detail in Linux.