Issue with proxies files size

[Lerdouille]

Hi,

i have an issue i can't explain when i try to use proxies to deal with several huge files.

For example, when i try to convert a *.mts file (45 minutes / 4Go / 1920x1080), the converted file is larger than the original (1020x540 -> 15Go !!!)

I thought using proxies will decrease the file size, not the opposite...

Is it normal ? Am i doing something wrong ?

Regards

[Bill Gehrke]

No you are doing nothing wrong.  Proxies do increase file size to make it easy to eliminate the CPU intensive complex decoding operation.

[mattchristensen]

Bill is absolutely right and just to elaborate on what he said, you can think of it this way. The goal of a camera or recording device is to record as much as possible while keeping quality at an acceptable level. The types of compression used therefore can be complex so as to keep the file size down and allow more to fit on a memory card.

But then when it comes time to play back or edit that file the computer has to uncompress the encoded file to figure out what the image is, and that can be hard on a computer, especially to do it in real time for playback purposes.

So the point of the proxy workflow is not to make smaller files but to make easier to play files. Often that means using much less compression in the proxy files, which results in them being larger.

Note that this is not always the case, as it depends on what your source is. For example if you shoot 3840x2160 ProRes4444 you will have very large files because there isn't a ton of compression going on in ProRes4444. If you then made proxies at 1920x1080 and ProRes422 you proxy files will in fact be smaller.

Hope that helps!

Matt

[excited_Genie16B8]

I thought using proxies will decrease the file size, not the opposite...

Nope.  The purpose of proxies is to improve performance.  These days, the easy-to-edit files are larger than what comes off the camera.