8-bit 4:2:2 Component Y'CbCr Compressor

[dalelpaq]

I'm curious, in the export movie menu, the subject compressor as well as a 10-bit compressor is offered. Under what circumstances would these be used? Dale

[Bob]

As far as I know, all consumer class video equipment and video for distribution is 8-bit 4:2:0. Professional camcorders can record in 4:2:2 8-bit and some can record in 10-bit. Some analog capture cards can produce 10-bit as well.

4:2:2 captures more chroma information and can produce cleaner green screen work. Converting 4:2:0 to 4:2:2 does not improve anything because the data is already lost. 10 bit is generally used in intermediate codecs where there will be a lot of compositing or effects used because expressing the quantities as 10-bit numbers instead of 8-bit numbers gives a higher quality result when lots of calculations are involved --10 bits allows 1024 levels compared to 256 levels using 8 bit numbers. However, in that case, the nle software must be capable of using 10-bit values on the timeline to take advantage of that.

Don't confuse 10-bit with high definition. They are two different things. The HDV spec, for example, calls for 8-bit 4:2:0.

[dalelpaq]

Thanks Bob, I get it. I have one more question. I'm under the impression that consumer HDV cams store the video on tape in the Y'CbCr format and support brightness values to 110 IRE units. (Super brights above 100 IRE.) Stu Maschwitz's DV Rebel's Guide indicates that this extended brightness range is retained when the video is downloaded to a PC but is then lost when input to an NLE that doesn't support it. He suggests some techniques to retain super brights to aid in effects and compositing until the final render. He's not clear, though, as to which NLEs but suggests Premiere Pro does. As I understand it, PE4 is a "dummed down" version of Premiere - I would guess the basic editing and compositing "engine" is much the same but with the bells and whistles removed - but I don't know. Are you familiar with this and how it all works? Thanks again. Dale

[Bob]

Yes, HDV uses MPEG-2 which in turn uses 4:2:0 Y'CbCr.

Strictly speaking, IRE is an analog brightness unit defined in terms of the analog composite video signal used in analog television. An IRE value of 0, for example, corresponds to zero voltage during the blanking period of the analog composite signal. But, the idea is the same. There is a reference black and a reference white and you can have super whites and super blacks outside that range. You generally wanted to avoid signals outside the reference range if they were to be broadcast as they could cause problems. TV broadcasters would either reject such material or clamp the brightness levels themselves. Premiere Elements shares the same engine and, like it's big brother, supports super brights. However, Elements does not contain the other tools, e.g. waveform monitor; vectorscope, manual levels etc., to manage them.

[dalelpaq]

Bob, I kind of thought so. I'm poking around with Premiere Pro 2.0 to see what all this looks like - just can't get it to open my video files. I'll call back later if after I run that one to ground, no joy. Dale

[Chuck Engels]

Dale,
What type of files are you working with?
Version 2 did have some limitations.

[dalelpaq]

Chuck, I have 2.0. I've tried both mpeg2 (m2t) as well as uncompressed avi. Same problem regardless of the project settings. When I open footage, I get the yellow icon filled with foreign language. PPro recognizes the files, tells me all about them (frame size, frame rate, etc.) and plays them - just won't show the imagery to me!!

I'm wondering, if I open one of these files in After Effects, and apply Color Finesse, I'll have access to a waveform monitor and vector scope. Will I have already lost access to any super whites that may have been in the original footage?

Dale

[Chuck Engels]

Can you open the uncompressed AVI in Movie Maker or Windows Media Player?

[dalelpaq]

I need to do a little more testing, but so far, I located some project presets on adobe.com for Canon 30p and installed per adobe.com. I tried opening an m2t (mpeg2) previously downloaded to my PC from my Canon HV30 using HDVSplit. The info panel reads perfectly - 29.97 1440 X 1080 (1.33) but all I can see is the yellow icon. I opened a new project set to 1280 X 720 30p and again, imported an mpeg2, and the info panel described it perfectly but no pix. As for the uncompressed avi, it opens in PE4 as well as WMP but not in PPro 2.0. I'm stymied at the moment! Dale

[Chuck Engels]

You may want to do a reinstall of Premiere Pro 2.
Sounds like it got some codecs screwed up.
Version 2 was the first version to support HDV natively, so you shouldn't have these problems.
Did you install all of the updates?