PhotoJPG Bug in FCP 6

[Rafael Amador]

Hi Tate,
The truth is that I never heard of this bug, but I never work with PhotoJPEG and I really don’t find people, here in the Cow, using that codec.
Do that problem happens when you force rendering in YCbCr? Is not a problem of rendering RGB transitions?
If you want I could try to reproduce the issue. I’m in FC 6.0.3

Mac OX 10.5.2-FC 6.02-QT 7.4.1
G5 2x2Gh 4GbRAM-BlackMagic Extreme
PMBP 17″Core2Duo 4GbRAM-AJA ioHD
JVC DTV-17″
SONY EX-1 . SONY PD170
..and always a big mess on top of the table.

[Tony Young]

Thanks for the reply, Rafael. I know it’s not a common codec, but it worked well for us in SD for the past couple of years. Very low file sizes for the quality–far better visual quality than DV, about the same as DV50, which ran about 7mb/sec.

The only other stuff I’ve been able to find about this issue is on the LAFCUG forum — https://www.lafcpug.org/phorum/read.php?4,192516,192516
That guy has about the same problem I do, but I’ve been lurking here for years, so I thought I’d ask.

Good question about the YCbCr. I do remember messing with that years ago, and we went back to RGB.

Hey, if you could digitize a couple clips in PhotoJPEG in 6.0.3 and try rendering a transition in YCbCR, that would be fantastic. Maybe there’s some other setting in 6 that we missed. Maybe a sequence setting? I wonder if there would be someone at Apple we could talk to directly about an issue like this?

Honestly, I haven’t had many issues in the past few years that I haven’t been able to fix by dumping prefs or a simple restart, so a major issue like this is all new. Thanks for any ideas.

[Rafael Amador]

Hi Tate,
Sorry I came back this late. I’m leaving next week in holidays and I’m a bit busy.
I’ve been making some simple tests.
I’ve transcoded some DV and Proress HQ to PhotoJPEG 75%. Then I made some simple dissolves.
I really haven’t see any change in gamma in the beginning or end of the transition. I’ve ben looking for that last frame that so many times ruins a beautiful transition. Nothing. Dissolves start and ends OK.
About the gamma-shift between play-stop, sure it is over there.
What is clear is that the correct gamma is the one you get on play.
However, I this gamma shift I think is an issue only for Color Correction. You can not correct with the play-head stopped.
I think this is a behaving of the codec. May be because PhotoJPEG, the same than his relative MJPEG, use a certain temporal compression ( https://codecs.onerivermedia.com/ ).
In This case to read properly a frame, you need read more than one. That would explain why the image looks different when stop or in play.
I have the same story with Sheer (Probably is the best codec in the market). Is what is call a “Gamma Independent Codec”.and shows the same behavior. The truth is that I don’t care anymore about the shift. What its really matters is what you get in your external monitor in play.
The real problem is understand all the story of the gamma. The way each application, each QT version or even each codec manage it is a real mess. At least for me.
I like PhotoJPEG. I have use it in the past mainly to archive things in RGB 8b. I prefer it than Animation. But now I think there are better options. As i commented, i use Sheer. Is 100% uncompressed and you get files halve the size of Apple Unc. 8/10b, RGB/YCbCr, 422[4]/444[4]. Always with Alpha channel available.
Cheers,
rafael

Mac OX 10.5.2-FC 6.02-QT 7.4.1
G5 2x2Gh 4GbRAM-BlackMagic Extreme
PMBP 17″Core2Duo 4GbRAM-AJA ioHD
JVC DTV-17″
SONY EX-1 . SONY PD170
..and always a big mess on top of the table.

[Tony Young]

Thanks, Rafael. That’s interesting. Perhaps it’s the way we digitized it? Or maybe there was an adjustment between 6.0 and 6.02?

I certainly noticed the same issues with PhotoJPEG between the running gamma and the playhead stopped gamma–in Final Cut 5.1. So that must be a standard function of the codec.

Hmm. We brought our footage in on a blackmagic card through SDI. I believe we’re at QT 7.4 as well. Maybe that’s different than transcoding from DV or Prores. Maybe it’s a blackmagic photojpeg issue?

Maybe it’s a timeline setting in 6 that we didn’t adjust when we tried to go to that version? Tough to tell.

I phoned Apple and discussed with a tech yesterday, sent him some QT samples, so he was going to try a few tests and see what he could come up with. He had never heard of folks using PhotoJPG as an online codec. Anyhow, hopefully that yields a few answers.

Sheer sounds like a great option. Actually, it sounds terrific. So–it’s completely lossless at half the file size? What kind of mb/s do you get for standard def?

Anyhow, thanks for all your help!

[James Tully]

We are using FCP5 and have been experiencing the same issue with the gamma. By now I am sure you figured a work around, I wanted to post in the event someone else gets affected by this same issue.

We believed that the issue stems from Photo Jpeg not being 100% dedicated to RGB. FCP has issues with the gamma, even if Quicktime does not.

The fix may require some extra rendering in the beginning but i have found it does fix the problem and you can go on with your editing as normal.

Simply export your original file in Quicktime to a Planar RGB. This forces the video to full RGB. You can export it back to Photo JPEG after and you should no longer experience the gamma shifts.

A lot of render time but if you have a file that needs fixing at least you can, without going insane.

By the way if you don’t see the Planar RGB codec option, goto ‘Quicktime Preferences” then advanced and check off “Show Legacy Encoders”

Hope this helps =D