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October 15, 2006 5:27 PM

What's the best video compression format for reviewing single frames?

Hi all - I take a lot of video in my research, and need to compress it down a bunch for later analysis. The compression settings I've tried (using the quite lovely MPEG Streamclip, and also Premiere) tend to garble single-frame step-through, which is somewhat important for me. In particular, I've tried MPEG-4 and a Divx/avi setting.

My videos just have one small animal running around a very static background, although there are occasional large changes in light intensity. I need the animal's movements to be clear frame-to-frame, but don't care about the background. And full quality dv is breaking the bank right now. Any hints?

posted by metaculpa to Technology (10 answers total)

Response by poster: Ah, I think I may have answered my question. Apple's MPEG/jpeg A compression looks great and only compresses individual frames (I think). I'm not sure whether the de-interlace setting I checked is the issue, though.
posted by metaculpa at 5:38 PM on October 15, 2006

Yeah, I was going to suggest Motion JPEG -- It's kinda like an MPEG with all I frames.
posted by krisjohn at 5:43 PM on October 15, 2006

First of all, on what platform are you encoding? PC or Mac?
posted by effugas at 5:55 PM on October 15, 2006

Response by poster: Either; right now I'm recording full DV on PC, and transferring to mac. For analysis, either works fine.

Motion JPEG works great, but high-quality (70%, deinterlaced) compression makes the file-size bigger than before. Interlaced compression makes everything look quite odd.
posted by metaculpa at 6:28 PM on October 15, 2006

Technically, DV is an All I frame codec, where MPEG-4 and DiVX are I + B/P codecs (smaller, good for distribution.)

MJPEG is fine....

I know people who have used huffy and sheer video (but working from uncompressed footage)

http://wiki.multimedia.cx/index.php?title=Category:Lossless_Video_Codecs
posted by filmgeek at 6:32 PM on October 15, 2006

I've got some bad news for you: what you want is going to use a lot of space. There is no magic solution here.

High degrees of video compression work because they're lossy. The MPEG committee took advantage of known characteristics of human vision in their design, and knew they could get away with a lot of noise as long as it was transient, and that's what they did.

In other words, MPEG isn't designed to be viewed as clean frames. It's going to be crummy if you're getting good compression. If you want every frame to be clean, it's going to take a lot of space.

The solution is Motion JPEG + more disk space. You're going to have to invest in hardware.
posted by Steven C. Den Beste at 7:19 PM on October 15, 2006

Seconding SDB. If you want clean frames then you'll have to go with an I-frame codec and pay the storage cost. M-JPEG is one of them; there are others, just check to see whether it is intra-frame only or also uses inter-frame compression to achieve the low bitrate. The new-ish HDV format is particularly notorious for using interframe compression.
posted by intermod at 7:31 PM on October 15, 2006

Did you try H.264/MPEG-4 AVC (I-frame only of course)? May be smaller than MJPEG, though I could be wrong, the differences in size will probably not be huge. But I agree with the others, there's just no way to significantly compress single frames without losing quality.
posted by MetaMonkey at 8:27 PM on October 15, 2006

Compressing to Xvid / DivX or AVC using the Quantiser (Quality) setting instead of constant or variable bitrate guarantees the quality of your video encoding at the expense of bloating the video size.

I personally use this for archiving computer animation footage which has a lot of noise.

I recommend using Xvid at Q4.
posted by rc55 at 4:50 AM on October 16, 2006

Response by poster: Bah, humbug! I'll try MPEG4/AVC, but I take all y'all's point that clean frames will require lots of space.

It's frustrating that so little of the image is important, but that bit has to be clean. Perhaps I should just segment out the animal and record a smaller picture; obviously, that would be an obnoxious amount of processing, so I'll just buy a few more hundred GB. Thanks for the help, all.
posted by metaculpa at 4:07 PM on October 16, 2006