View Full Version : ProRes Confusion


Alex Hawt
January 4th, 2010, 01:08 PM
I keep hearing people talk about ProRes. I have have a raw 6 second video shot with my 5d that is a file size of 35 megabytes. I use compressor 3.5 to convert that clip to ProRes. My new ProRes Version of the clip is 124.6 megabytes...

Isn't compressing your raw video to ProRes 422 suposed to make your file smaller? The ProRes file seems to have a slightly better image quality however. Im sorry if I sound like a video N00B, but can someone please shed some light on this for me?

Raymond Tsang
January 4th, 2010, 01:15 PM
You are not compressing the video - In fact, ProRes is decompressing it (not sure if that's the correct term). And yes, transcoding to ProRes will make your file sizes considerably larger.

Raymond Tsang
January 4th, 2010, 01:17 PM
On that note, the h.264 files straight out of the 5D Mark II is a highly compressed format and generally not ideal for editing.

Mike Watson
January 4th, 2010, 01:46 PM
I say "uncompress".

Furthermore, a directly converted video clip will not look any different (theoretically) after conversion than before. You can't get MORE information from a compressed clip, you can only uncompress the information that is there. However, once you start to edit it, if you apply filters (e.g. color correction), the color correction is done in the greater color space of ProRes 422, rather than H.264.

Also, editing in ProRes will be infinitely easier than H.264. Less processor stress leads to less dropped frames and shorter render times.

Alex Hawt
January 4th, 2010, 02:10 PM
Thank you for clearing that up for me.

Steve Maller
January 5th, 2010, 10:29 AM
The most significant difference with respect to editability between H.264 (what comes out of the camera) and ProRes (and other, similar formats) is that ProRes compresses the individual frames as separate frames, whereas H.264 uses an "inter-frame" method which makes it complicated for editing software to work in a frame-accurate mode. For example, playing an H.264 clip backwards is an amazingly complicated thing (read: processor-intensive).

Alex Hawt
January 5th, 2010, 10:48 AM
you guys are awesome. thanks.

Perrone Ford
January 5th, 2010, 11:03 AM
I keep hearing people talk about ProRes. I have have a raw 6 second video shot with my 5d that is a file size of 35 megabytes. I use compressor 3.5 to convert that clip to ProRes. My new ProRes Version of the clip is 124.6 megabytes...

Isn't compressing your raw video to ProRes 422 suposed to make your file smaller? The ProRes file seems to have a slightly better image quality however. Im sorry if I sound like a video N00B, but can someone please shed some light on this for me?

You were not the target audience. The target audience were professionals who were faced with dealing with uncompressed HD, like they had been dealing with uncompressed SD. Uncompressed SD clocks in around 80Mbps. Uncompressed HD clocks in at 1500Mbps. ProResHQ is 220Mbps and this was a GODSEND to people who were looking at 2.5 hours per Terabyte for uncompressed HD. Back then, 1TB drives were $1k each.

Your 5D shoots 40Mbps. AVCHD is 24Mbps. HDV is 25Mbps, the GH1 is 17Mbps.

You're playing in a different league.