So I finally got around to doing some compression tests. My source was a 1280×720 23.98fps 10bit 4:2:2 “uncompressed” quicktime. That is a typical file that comes across my desk. I wanted to see what compression I should set my Final Cut Pro timeline to. At first, I opened the quicktime in Quicktime Player and exported to a variety of codecs. But when I opened all of the files, I noticed that they were all darker than they should have been. That indicated to me that Quicktime Player had done some sort of colorspace conversion. So I redid the same test from inside Final Cut Pro. Sequence Settings were set to the same as the source video.

For the test, I used these codecs:

• None
• Animation (100%)
• PNG
• Apple Intermediate Codec
• MJPEG-a
• MJPEG-b
• HDV
• DVCPRO HD
• Prores
• Prores (hq)
• 4:2:2 8-bit
• 4:2:2 10-bit

Results

So I noticed that None, Animation, PNG, Apple Intermediate Codec, and MJPEG went through a colorspace conversion. So I won’t be using them again.

HDV and DVCPRO HD were slightly fuzzier than the original, but also smaller than the remaining formats. DVCPRO HD also underwent a slight tonal change in image quality. DVCPRO HD also has poor cross-platform support, and both of these formats have restrictions on their frame size.

Prores lived up to its name, and was as fast to compress as the 4:2:2 “uncompressed” formats, while also yielding files over 75% smaller, with little perceptual quality loss. They also had the benefit of not causing FCP to re-render the timeline.

<needs more pics>

Conclusion

I’ll have to re-run this test with a simple filter applied to the image. I’ll probably add 8 pixels of black to the bottom or something. I think that 4:2:2 10-bit won the fps race because Final Cut Pro just copied the data instead of having to recompress as it did with all the other formats. I also haven’t figured out why Prores HQ was faster than Prores.

October 17th, 2008 | Film, Finish Writing Me Plz | No comments

Hmmm, I think that for every environment and every situation, there exists a minimum density of pens such that the average time it takes for a someone looking for a pen is less than the amount of time before frustration sets in.

1. d = minimum density of pens
2. p = density of people
3. v = average velocity of user
4. t = mean time between pen usage
5. f = time it takes for user to get frustrated
6. k = konstant

d = p • k • v² / f / t

For me, I think that d is around 0.25 pens/m² in my standard environment.

Now to calculate how the probability density function relates to the pen density function and write it up in a portable document format.

April 7th, 2008 | Finish Writing Me Plz, Nerd, pics plz | No comments