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Kona3 gamma shifts and chroma issues

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Paul Flint
Kona3 gamma shifts and chroma issues
on Jan 26, 2009 at 10:37:06 pm

I've got a problem with Kona card. Its AJA Kona 3 put into 8core MacPro on Tiger OS . I'm using Kona card with FCP environment to capture footage in 8bit uncompressed codec from Sony digibeta deck using SDI. Then I export those files into TGA for compositing. There are 2 issues, first one is gamma shift. I've attached a link to uncompressed image ( 4xzoom ) to illustrate those problems.

http://pawelk22.website.pl/AJA_QT_error.tga

As you can see there is a gamma variation compared to the actual footage that is on digibeta, we checked it twice by ingesting it using flame.

2nd, more disturbing issue are the artifacts in the RGB channels. THe are mostly visible in blue channel.

I tried all things to check out when those thing occur.
Lodead frames in motion - everything was ok until I converted to QT using AJA 8bit uncompressed, after that I get those artifacts. Tried Prores also, same thing. The only way I can work in QT is to use no compression at all - that means no realtime playback. but that solves just half of the problems.

I still need to get footage from tape and record it back. Using AJA card I can only capture/edit to tape using native AJA QT codecs.

My software is up to date, QT is updated as well as drivers from AJA.

I realy have no idea how to fix this problem, and the worst part is that I was hoping to base my work on AJA workflow. Help out.

thanks in advance
Paul



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gary adcock
Re: Kona3 gamma shifts and chroma issues
on Jan 26, 2009 at 11:15:52 pm

[Paul Flint] "My software is up to date, QT is updated as well as drivers from AJA."

first make sure the card has had the firmware updated -it is in the AJA utilities folder.

[Paul Flint] " I'm using Kona card with FCP environment to capture footage in 8bit uncompressed codec from Sony digibeta deck using SDI. Then I export those files into TGA for compositing."

Ok Why capture in only 8bit for compositing with tga files? Why not the same 10bit signal the Flame is ingesting? that alone could account for the noise difference issue -- though the vertical issue on the edges in your image.

[Paul Flint] "THe are mostly visible in blue channel. "
the vast majority of digital noise resides in the blue channel- thats the way it is- that why video is keyed with greenscreen and not blue, which is mostly reserved for film work.

The Gamma Shift is a known issue with RGB -YUV files in standard workflows.

[Paul Flint] "I still need to get footage from tape and record it back. Using AJA card I can only capture/edit to tape using native AJA QT codecs. "

Thats not true- hell that flame is using the OEM of the same AJA card you are - it ain't the card.


FYI-

Download AJA's FREE VTR exchange app to capture directly to numbered TGA files on your mac without having to go thru FCP (the part that is screwing it up)



gary adcock
Studio37
HD & Film Consultation
Post and Production Workflows

Inside look at the IoHD
http://library.creativecow.net/articles/adcock_gary/AJAIOHD.php




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Paul Flint
Re: Kona3 gamma shifts and chroma issues
on Jan 27, 2009 at 7:49:02 am

Thanks Gary for quick reply,

I did tried to capture also in 10bit in FCP with the same results.
Those artifacts are generated for sure when AJA codec comes into play.
It's hard for me to get rid of FCP in my pipeline since I use it as a sort of Hub for ingesting footage by EDL ( from AVID )for compositing department, keeping all ordered for presentations etc and outputting it back on tape at the end.

I'm in contact with AJA support as we speak, we're gonna try to pinpoint the issue with those artifacts. It does not have anything to do with footage and noise. this is some strange vertical chroma shifts - maybe related to some aliasing codec is doing since it react to edges.

As for gamma shift from YUV to RGB is there a way to get it under control ?

Paul Flint



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gary adcock
Re: Kona3 gamma shifts and chroma issues
on Jan 27, 2009 at 5:28:16 pm

[Paul Flint] "Those artifacts are generated for sure when AJA codec comes into play. "

I do not see these type of artifacts in either the AJA 10bit RGB LOG or the AJA 10bit RGB Linear codecs- which are the only 2 codecs that are AJA specifically installed.ALL other codecs are part of the FCP Suite or Quicktime and subject to question.

[Paul Flint] "It's hard for me to get rid of FCP in my pipeline since I use it as a sort of Hub for ingesting footage by EDL"

Then you need to spend a little more time to figure out your specific workflow issues as there are workarounds the gamma issue - the artifacts are something else however.




gary adcock
Studio37
HD & Film Consultation
Post and Production Workflows

Inside look at the IoHD
http://library.creativecow.net/articles/adcock_gary/AJAIOHD.php




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Jeremy Garchow
Re: Kona3 gamma shifts and chroma issues
on Jan 27, 2009 at 7:40:41 pm

[Paul Flint] "I did tried to capture also in 10bit in FCP with the same results. "

Yeah, but did you try using VTR Exchange and capturing direct to TGA files like Gary mentioned?


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Paul Flint
Re: Kona3 gamma shifts and chroma issues
on Jan 27, 2009 at 9:50:17 pm

I tried it and when I capture to image sequence those artifacts are gone. That is a good thing. that means the card itself is good. Problem occurs when I capture to AJA kona 8bit or 10bit quicktime.

Gary, yes I need to figure out how to keep that gamma shift under control. Problem is I don't know how. That is one of the reasons I am writing here. To make it work.

cheers
Paul Flint



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Jeremy Garchow
Re: Kona3 gamma shifts and chroma issues
on Jan 27, 2009 at 10:36:09 pm

Time out.

Are you capturing to the Kona codec of v210? Or are you capturing to Apple Uncompressed?

Jeremy


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Paul Flint
Re: Kona3 gamma shifts and chroma issues
on Jan 27, 2009 at 11:08:06 pm

hmmm, I'm not sure what v210 means. If I want to work on footage in FCP i need to use AJA Kona 10bit uncompressed codec ( or 8 bit ) in order to maintain the quality of the footage. And that is the codec I was using so far. My workflow is quite simple

1) Ingest footage from digibeta using EDL. (Kona10bitUncompressed mov)
2) Once I have all shots in order on timeline i check witch shots require some compositing.
3) I desired shot from sequence using export/quicktime convention to TGA sequence
4) Ppl at my studio work on the shot ( either on Nuke, AE, or Maya )
5) as a result I get finished shot in TGA seqence, I load it to Motion to convert it back into mov in order to put it into FCP.
6) record finished movie to digibeta using edit to tape.

It's pretty strait forward and should work without any problems. But I still need to solve those 2 issues in order to make it work properly. So any advice on how to improve it will be greatly appreciated. I'm not a technician, so I dont have a lot of experience with that.

Thanks in advance
Paul Flint



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Jeremy Garchow
Re: Kona3 gamma shifts and chroma issues
on Jan 27, 2009 at 11:29:51 pm

Paul, there are a cpuple of Uncompressed codecs. A few are marked AJA and one the other marked simply 'Uncompressed'. Just need to be sure that we are talking about the same thing. You say you are using Kona Uncompressed. Does that mean you are using the Uncompressed easy setups or have you created your own with the AJA Uncompressed codec?

[Paul Flint] "3) I desired shot from sequence using export/quicktime convention to TGA sequence "

This is your problem. QT conversion is horrible. You should export out of FCP as a 'Quicktime Movie' and use AE or a similar app to make a TGA sequence.




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Paul Flint
Re: Kona3 gamma shifts and chroma issues
on Jan 27, 2009 at 11:38:04 pm

I use presets provided by AJA and FCP. As for exporting using Exporting using quicktime convention in FCP does not alter the image in any way during that process. shifts in gamma and chroma problems occur at the time of encoding into mov while capturing footage from the tape. Those Mov's already got the problems I mentioned.



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gary adcock
Re: Kona3 gamma shifts and chroma issues
on Jan 28, 2009 at 12:33:06 am

[Paul Flint] "3) I desired shot from sequence using export/quicktime convention to TGA sequence "

this is where it fails....

do not do this in FCP

gary adcock
Studio37
HD & Film Consultation
Post and Production Workflows

Inside look at the IoHD
http://library.creativecow.net/articles/adcock_gary/AJAIOHD.php




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Paul Flint
Re: Kona3 gamma shifts and chroma issues
on Jan 28, 2009 at 7:28:10 am

the problem is I don't have any alternative. FCP is the tool I have to use. I know that many studios are using FCP in their pipeline. There must be a way to avoid those problems. And the only way to get image sequence from FCP is to export it that way. I can send Project to motion and export the files there but the export itself as I mentioned before does not alter images in any way so its not an issue. It is true that the problem is somewhere between AJA and FCP when the footage is being encoded.

Gary if you could shed some light onto this, how do you think I can avoid those problems I would be gratefull.

Paul Flint



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Jeremy Garchow
Re: Kona3 gamma shifts and chroma issues
on Jan 28, 2009 at 3:27:11 pm

I know this is the case with AE, but I haven't tried it with Motion. First, export a Quicktime Movie out of FCP at 'current settings'. Second, Quit FCP and Quit Motion.

Before you launch Motion, go to your Hard Drive > Library > Quicktime folder and move the AJAUncompressedcodec.component out of the folder there (say to your desktop for now). Now, launch Motion and try to make an image sequence there from your 'Quicktime Movie'.

This process works very well for AE renders and returns a near perfect render. If you have any clips that are out of range, they will get clipped to RGB/SMPTE range.

I am not saying this will work for Motion, but it works great for AE renders.

Jeremy


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Paul Flint
Re: Kona3 gamma shifts and chroma issues
on Jan 29, 2009 at 8:59:44 am

hmm this seams to complex - and it slows the process a lot. I need to find some automated way to compensate for the gamma shift while the card is converting the image from YUV to RGB while ingesting without any image quality and detail degradation. Any ideas guys ?



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gary adcock
Re: Kona3 gamma shifts and chroma issues
on Jan 29, 2009 at 3:42:45 pm

[Paul Flint] "hmm this seams to complex - and it slows the process a lot. I need to find some automated way to compensate for the gamma shift while the card is converting the image from YUV to RGB while ingesting without any image quality and detail degradation. Any ideas guys ?"

Stop using Final Cut for capture or use one of the workarounds for the issue

those are the only choices

gary adcock
Studio37
HD & Film Consultation
Post and Production Workflows

Inside look at the IoHD
http://library.creativecow.net/articles/adcock_gary/AJAIOHD.php




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Paul Flint
Re: Kona3 gamma shifts and chroma issues
on Jan 29, 2009 at 4:08:34 pm

Gary, we figured it out 10 posts before that, but what workarounds do you have in mind. Seams that you have to deal with this stuff every day so please share with me some workarounds. I do know I need a workaround but dont know how. Since I cant stop using FCP the trick need to involve FCP in its pipeline. Maybe this will help other FCP+AJA combo users.

cheers
Paul Flint



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Jeremy Garchow
Re: Kona3 gamma shifts and chroma issues
on Feb 2, 2009 at 4:56:04 pm

[Paul Flint] "hmm this seams to complex - and it slows the process a lot. "

Tell me this. If you remove the codec, launch motion and render do you get the gamma shift? If so and you don't have to keep remoivng the ocdec, ust leave it out of the Wuicktime fodler. How does that slow it down? You can send to Motion right from FCP.

Jeremy




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