Color/gamma shift on exported video

David Newman · July 1st, 2007, 09:47 PM

Try Aspect HD v5

K. Tessman · July 1st, 2007, 10:36 PM

I tried the Aspect 5 trial just now, and the Prospect trial while I was at it. Same thing: VirtualDub plays it back "right", while the image is a little washed out and brighter in WMP.

David Newman · July 1st, 2007, 11:52 PM

Please stick with your AE issue, as video levels in Media Player is an NVidia bug handling the overlay surface. That has been discussion in great depth on this forum -- it is your AE issue that no one else has reported.

K. Tessman · July 2nd, 2007, 11:38 AM

I have an ATI video card.

What I've been trying to diagnose, on and off, for a few months

http://www.dvinfo.net/conf/showthread.php?t=73069
http://www.dvinfo.net/conf/showthread.php?t=35671

is why it seems that an exported CFHD AVI does not play back with the same color/gamma rendition as in AE (or Premiere Pro) from which I exported it. I have been using Windows Media Player to judge this. I used to think of it as the Adobe apps being incorrectly darker. I have suspected alternately that this was happening either at display time in the application or at export time via the CFHD encoder. Given recent tests with TIFF sequences and uncompressed AVI and playback in other applications like VirtualDub, however, I'm leaning toward it being a WMP (or general DirectShow) playback issue.

I'm not sure the AE issue in my initial post is in fact the issue. I didn't make particularly detailed notes on my test for that post and I've since re-rendered the files several times, so the real valid starting point is probably my post #6, involving TIFF, uncompressed, and CFHD output. You note that on your computer the two AVIs play back identically: but that's not the case for me in Windows Media Player (although it seems to work fine in VirtualDub). That is what I'm now trying to get to the bottom of.

Given that it seems to play properly in VirtualDub, I'm reassured for the most part that the proper image is being exported. I'd just like it to play back properly in applications such as WMP.

It may still be an overlay issue of some sort, so I've tried playback with every combination of renderer and/or overlay on/off combination that's user-available in both WMP and VirtualDub (or selectable via DShow interface in my own applications), to no effect.

It may be that this is not a Cineform issue at all. It may well be that WMP/DShow use entirely different pipelines to render CFHD and uncompressed AVIs, and somewhere in that architecture is the problem that manifests solely on this setup, but I don't know.

David Newman · July 2nd, 2007, 12:11 PM

Sounds like we are down to an overlay issue -- and that isn't CineForm. The overlay screws-up as each graphic card vendor has there own YUV to RGB mapping that is completely non-standard. So when play a compressed YUV file and an uncompressed RGB file, they will look different on the overlay when in fact they are the same. You can prove the fault of the overlay by playing the same compressed clip in two windows at the same time, one clip will get the only overlay, the other will not (use a tool like MediaPlayer Classic which can be run twice.) If they are the same, you have one for the few GFX cards that get this correct (e.g. Matrox Parahelia), ATI normally gets the overlay correct, but the desktop YUV to RGB conversion wrong, NVidia is the other away around. Tools like VirtualDub are get for testing as they don't use the overlay.

K. Tessman · July 3rd, 2007, 08:57 AM

Thanks for all your help and feedback on this, David.

July 1st, 2007, 09:47 PM	#16
David Newman CTO, CineForm Inc. Join Date: Jul 2003 Location: Cardiff-by-the-Sea, California Posts: 8,095	Try Aspect HD v5 __________________ David Newman -- web: www.gopro.com blog: cineform.blogspot.com -- twitter: twitter.com/David_Newman

July 1st, 2007, 10:36 PM	#17
K. Tessman Regular Crew Join Date: Jun 2005 Posts: 66	I tried the Aspect 5 trial just now, and the Prospect trial while I was at it. Same thing: VirtualDub plays it back "right", while the image is a little washed out and brighter in WMP. Attached Thumbnails

July 1st, 2007, 11:52 PM	#18
David Newman CTO, CineForm Inc. Join Date: Jul 2003 Location: Cardiff-by-the-Sea, California Posts: 8,095	Please stick with your AE issue, as video levels in Media Player is an NVidia bug handling the overlay surface. That has been discussion in great depth on this forum -- it is your AE issue that no one else has reported. __________________ David Newman -- web: www.gopro.com blog: cineform.blogspot.com -- twitter: twitter.com/David_Newman

July 2nd, 2007, 12:11 PM	#20
David Newman CTO, CineForm Inc. Join Date: Jul 2003 Location: Cardiff-by-the-Sea, California Posts: 8,095	Sounds like we are down to an overlay issue -- and that isn't CineForm. The overlay screws-up as each graphic card vendor has there own YUV to RGB mapping that is completely non-standard. So when play a compressed YUV file and an uncompressed RGB file, they will look different on the overlay when in fact they are the same. You can prove the fault of the overlay by playing the same compressed clip in two windows at the same time, one clip will get the only overlay, the other will not (use a tool like MediaPlayer Classic which can be run twice.) If they are the same, you have one for the few GFX cards that get this correct (e.g. Matrox Parahelia), ATI normally gets the overlay correct, but the desktop YUV to RGB conversion wrong, NVidia is the other away around. Tools like VirtualDub are get for testing as they don't use the overlay. __________________ David Newman -- web: www.gopro.com blog: cineform.blogspot.com -- twitter: twitter.com/David_Newman

July 2nd, 2007, 11:38 AM	#19
K. Tessman Regular Crew Join Date: Jun 2005 Posts: 66	I have an ATI video card. What I've been trying to diagnose, on and off, for a few months http://www.dvinfo.net/conf/showthread.php?t=73069 http://www.dvinfo.net/conf/showthread.php?t=35671 is why it seems that an exported CFHD AVI does not play back with the same color/gamma rendition as in AE (or Premiere Pro) from which I exported it. I have been using Windows Media Player to judge this. I used to think of it as the Adobe apps being incorrectly darker. I have suspected alternately that this was happening either at display time in the application or at export time via the CFHD encoder. Given recent tests with TIFF sequences and uncompressed AVI and playback in other applications like VirtualDub, however, I'm leaning toward it being a WMP (or general DirectShow) playback issue. I'm not sure the AE issue in my initial post is in fact the issue. I didn't make particularly detailed notes on my test for that post and I've since re-rendered the files several times, so the real valid starting point is probably my post #6, involving TIFF, uncompressed, and CFHD output. You note that on your computer the two AVIs play back identically: but that's not the case for me in Windows Media Player (although it seems to work fine in VirtualDub). That is what I'm now trying to get to the bottom of. Given that it seems to play properly in VirtualDub, I'm reassured for the most part that the proper image is being exported. I'd just like it to play back properly in applications such as WMP. It may still be an overlay issue of some sort, so I've tried playback with every combination of renderer and/or overlay on/off combination that's user-available in both WMP and VirtualDub (or selectable via DShow interface in my own applications), to no effect. It may be that this is not a Cineform issue at all. It may well be that WMP/DShow use entirely different pipelines to render CFHD and uncompressed AVIs, and somewhere in that architecture is the problem that manifests solely on this setup, but I don't know.

July 3rd, 2007, 08:57 AM	#21
K. Tessman Regular Crew Join Date: Jun 2005 Posts: 66	Thanks for all your help and feedback on this, David.