To Whom It May Concern: The Mayhem Of 10bit DIY Conversion

[christoph]

[...] but there is a small benefit - isnt it?

well, without getting too technical here:
yes, exporting as uncompressed 4:2:2 (8 bit is perfectly enough since your DV source is 8bit) will slightly alter the footage, at least if you export it out of FCP. the reason for this is that it trys to smooth the chroma losses of the DV material. however, this is not something you can easily see by pure eye and you need to use an video analysis program to really see what's going on. there are also special chroma reconstruction filters that get even smoother results, but the effect on the luminance is very very small. so for your b/w sample there really shouldnt be any difference (if there is, most likely something with your export settings is weird).

in short, the only reason to export your footage to uncompressed is if you want to ploay it out to digibeta or if you already applied some effects and need to import it into another application to do effect work/color correction.
++ christoph ++

[S8 Booster]

to be fair ive added Evan to the list of "correctors" as he was the first to mention it.


there is a difference in greyscale and contrast definition isnt it?
at least it looks so on my mac?

A: 10 bit 4:2:2 uncompressed.


B: MiniDV standard


C: 10 bit 4:2:2 uncompressed.


D: MiniDV standard




s8hôôt

[mattias]

apple's dv codec is a gamma correcting codec, which means it tries to look as it would on a tv when viewed on a mac display which has a different gamma, but the uncompressed codec isn't. so for the exact same image data the dv version will always look darker on the screen. on tape it's the same again, and conversion between them is handled properly as well, something which isn't true with all codecs unfortunately.

/matt

[christoph]

actually quicktime does correct for gamma on uncompressed 4:2:2 clips (i just checked).

anyway, exporting a dv clip out of quicktime player to uncompressed 4:2:2 results in exactly the same quality as far as the eye can see (if you make a difference mask and crank up the brightness by factor 10 you can see slight variation, but that's a non-issue here)

and still boosters dv stills look definitely more blurry and blocky than the uncompressed ones, which i'm absolutely sure is an export or display problem.

++ christoph ++

[mattias]

'actually' i also just tried it, and it doesn't. I'm using the 'apple uncompressed 4:2:2' codec. Maybe final cut applies its own magic or something. I've only checked it in quicktime player. And i'm not commenting on the blurriness, just the gamma. The blur is definitely a high quality setting issue. /matt

[christoph]

'actually' i also just tried it, and it doesn't. I'm using the 'apple uncompressed 4:2:2' codec.

weird, must be a configuration missmatch.
i'm getting no gamma change with the "uncompressed 4:2:2" (both 8 or 10bit) codecs, even if i export directly qt player (qt automatic gamma correction can be a real bummer sometimes though)..
but i still dont really understand what you meant, i don't see a gamma change on the above stills...

with no gamma applied, the detail shot would look something like this:

video gamma:


no gamma correction:


but i just i realized that the detail screenshots are different size, so definitely an export problem. enough of the techno babling.
++ christoph ++

[mattias]

no it seems like i was off topic a little. i was posting from my cell phone and didn't look at the images, just read the line about different brightness.

i maintain that uncmpressed footage is displayed at the native gamma on screen though. at least on my system. and there doesn't seem to be any configuration mismatch either since converting back and forth between it and the dv codec doesn't create any gamma shifts, as some codecs do, which you've noted. it handes the gamma issue gracefully, it just doesn't display at the darker gamma of the dv codec. i'll look into it when i get back to work in a couple of days. i've taken some time off after a couple of weeks of post production madness.

/matt

[mattias]

i'm getting no gamma change with the "uncompressed 4:2:2" (both 8 or 10bit) codecs

me neither. i think you misunderstood. it just looks different on the cmputer screen. maybe that's what you mean it does on your system, but can we conclude that there's no gamma change, which is what's important? ;-)

even if i export directly qt player

no, that's not what i'm saying. i'm *watching* it in qt player.

/matt

[mathis]

i was posting from my cell phone

You´re too cool! 8O

[mattias]

haha, yeah, and i'm too confused too. apple uncompressed is in fact gamma correcting. i was using the black magic codec, which isn't. i tested the two against each other and completely mixed up the results. sorry.

/matt

[Cheezy]

Beware of Quicktime Player ! It always plays DV in the lowest quality, thus giving you that blury picture that lacks definition. If you look at the same shot in Final Cut Pro in high quality playback it's ok. It's just the QT Player playback of dv. Never rely on this to judge your dv shots.

[mattias]

Beware of Quicktime Player ! It always plays DV in the lowest quality

well, not always. once you've checked the high quality box it doesn't. and if you save the movie after that it will always open in hq on all computers from then on.

/matt