Blackmagic Design DeckLink for Macintosh v5.0.1 software

[Felix Mack]

Thanks for checking into it.
I’ve tried some more stuff, and you are right – the new codecs preserve the gamma of video files originating from FCP5, but not rgb files from AE. I made a ramp in FCP, and added a grayscale made in PS. AS you can see below, while the video has the correct gamma, the RGB is too bright in BM10bit. The opposite is true for DV10, where the RGB is handled correctly, but the video is now too dark.

My issue is that I use AE to add titles and other graphics to video daily, so both of these don’t work for me.

Now if only we could get DV10s RGB handling with BM10s video handling, we would be happy like we were with FCP4.5

[Felix Mack]

Hi –

thanks for trying it out.

However, both BM10bit and the Apple codec introuce the gamma shift to rgb material from what I can tell.

If you go try the same test on a FCP 4.5 system, you will see that the apple codec still does a gamma boost, but the Black magic 10bit codec does not. It’s new as of FCP5.0 that the BM10bit also has a gamma shift.

https://www.kenstone.net/fcp_homepage/video_levels_nattress.html

Check out the link above and see how FCP kindly introduces a gamma boost to all the stills you import into FCP.

[Florian Hirschmann]

You are right. I did another test. I imported the still image of the ramp created in after effects in shake an rendered it with the apple 10 bit uncompressed codec – the resulting gamma was linear. To me it seems to be a problem of quicktime (since version 7?) and the conversion from rgb to yuv or something like this. Even rendering the ramp in DV-Codec in After Effects showed the same strange curve… only shake seems to know what to do ;-(…

Florian

[Chris Tomberlin]

Early on in this lengthy gamma trouble shooting process, I did a gamma test and included Motion into the mix. I’ll have to do the test again, but at one point, Motion handled the curves correctly too – at least to the video preview output. See this thread:

https://forums.creativecow.net/cgi-bin/new_read_post.cgi?forumid=124&postid=855644&theadid=855577&pview=t

Florian mentioned that only Shake “seems to know what to do”. If Motion handles it correctly as well, then we can be sure that Apple has made a change and expects developers to adapt. We’ll have to move all these threads over to the After Effects forum..

Chris Tomberlin
OutPost Pictures

[Felix Mack]

I think I remeber trying to render the grayscale I made in PS from Motion with the same gamma shift. I’ll have to try it again to verify that, though.

I just think that this is an awesome ‘feature’ built in to quicktime. For people who use DVDSP, you’ll notice if you import a still menu you get the same gamma shift as in FCP. So it’s probably more of a global quicktime issue.

More on Motion after I test it out.

[Felix Mack]

About Motion –

the ramp you can make in Motion seems to be very S-curvey, so it’s hard to say, but the RGB grayscale I have gets the same boost in gamma. What about your findings?

[Florian Hirschmann]

As I am working on visual fx for a movie right now, I got very nervous after reading your messages tonight. Because my footage are DPX-Files and so the conversion between RGB and YUV happens in After Effects. So today I did another test. I took a quite dark sequence of the movie and looked very closely to it on my video monitor. I rendered it with den Decklink 10 Bit 422 Codec and imported it in Final Cut. I switched several times between After Effects and Final Cut and there seems to be no difference in gamma between the videooutput of After Effects and the imported rendering in Final Cut. Unfortunatly I have no scope that I could connect to the SDI Output of my Decklink Card. So to me it seems that the wrong gamma is also displayed on the videooutput of After Effects.

Florian

[Chris Tomberlin]

Florian,

Where did your DPX files originate? What system were they captured on?

Thanks
Chris Tomberlin
OutPost Pictures

[Florian Hirschmann]

Hi Chris.

The DPX files are 2K scans (Kodak Vision 2 Super 16) scanned by a Northlight scanner.

Florian

[Chris Tomberlin]

If you could send me a single full resolution frame, or a link to a frame, I could run it through the same tests I’ve done with the ramp and see if the gamma changes at all on the scope…

FYI, AE was displaying gamma incorrectly with the original 5.0 BMD drivers. You would see a difference between the AE video preview and the FCP video out, but the render would be correct. That has been fixed in the 5.01 drivers.

Chris Tomberlin
OutPost Pictures
outpostpictures(at)mac.com