Color Space/Colorimetry/x.v.Color on Sony HD Camcorders

cbstryker · 11-26-09, 06:43 PM

So I've been trying to find out some info about the camera I bought about 2 years ago now. It's the Sony HDR-SR11, it has x.v.Color, records at a maximum of 1920x1080i @ 16Mbps.

What I've been trying to find out is what the exact color space options are for this camera. The reason is that I've been trying to do some chroma keying lately and I've been having a really hard time with color separation. Normally I record at 1440x1080 @ 7Mbps with great results. There is virtually no artifacts that can be seen and despite what I've read today about the problem of editing low bitrate AVCHD videos, I've NEVER had a problem and have successfully edited two wedding videos for friends.

I did a test shoot today by setting everything to the highest quality, and manually white balanced the shot. I have a very green wall in my kitchen and I had very bright daylight coming in, I have successfully used such a setup with a old compact VHS camcorder before, but this time the green with just impossible to key out. Using MediaInfo on the file it told me that it has a 4:2:0 color space, but many websites report that this camera can do 4:2:2 via HDMI out. But what does it mean "via HDMI out"? Do I need to record to a separate device?

Anyone that can help shed some light on this issue would be appreciated. I am not a novice when it comes to chroma keying. I just haven't been able to do it well with this camera yet (plus I don't have the money to buy my own proper lighting equipment).

ericjut · 11-27-09, 10:57 AM

Your VHS cam was probably NTSC color space (aka REC601), HD cams are all ATSC color space (aka REC709) which requires a different transform matrix to do RGB conversion.

Most HD consumer cams record in either YUV420 or 411 (4:1 luma vs color), but that technically doesn't have any effect on the color space, just how blocky your color info is.

Your Sony also support xvColor (as your title implies), which is also call "deep color" and is yet another color space, which most TVs don't support. I'm pretty sure most softwares supporting chroma keying will have a harder time with xvColor too, so I would personally stay away from that mode to do chroma key stuff.

Your HD cam has an HDMI output, which will be in 422 (2:1 luma vs color). That means you could grab an HDMI capture card (like the blackmagic) and "capture" the data live with potentially more color data and less compression. Again, the color space is unchanged when using this, so I doubt very much it'll make much difference.

I'm no chroma key expert, but I think it's probably time for you to upgrade your chroma key software.

cbstryker · 11-27-09, 12:58 PM

@ericjut:

Thanks for the reply. I find it interesting that you say xvColor would likely cause problems for chroma key software, I assumed the extra color info would simply help. I'll try another test with it turned off.

Also, I use After Effects CS4 for 99% of my compositing, I know it's not the #1 choice for industry professionals but I'd expect that it could handle simple chroma keying operations without too much trouble. Would you suggest trying something else? I have access to Autodesk Combustion 2, which I personally feel is leaps and bounds more superior to Adobe's line, but I initially learned compositing on AE so I'm more used to it's workflow.

Is there perhaps another program you would recommend?

As for the the whole color space topic, I know that 4:4:4 is technically "full" quality and 4:2:2 is ok and 4:2:0 is lower, etc. But I haven't been able to find any reliable resource online that will explain in depth the technical details of how it all works. Is there any website you could suggest?

Thanks again.

cbstryker · 11-27-09, 01:14 PM

Well just a quick update. I did the same shot with the xvColor setting turned off and there was an improvement, although it was far from workable. With my C-VHS camera I was able to get away with A LOT but this camera clearly needs generous (read: accurate) lighting on a chroma key background to get any sort of usable results.

Again, I did the keying in After Effects and I tried most of the keying tools to try to get the best result.

ericjut · 11-27-09, 04:30 PM

If you don't read xyColor data specifically as xyColor, you'll read the wrong colors (it won't get mapped correctly). Does your software enable you to select xyColor at the input? If not, I suggest you keep that option turned off.

Is there a variance or tolerance setting you can change so it accepts more shades of green? You C-VHS cam probably used a CCD sensor, which typically has less color noise than the current crops of HD cams which use CMOS sensors. This probably triggers more errors off of your chroma key software algorithm.

I unfortunately don't have better suggestions for you software-wise, sorry.

As for learning more about 444, 420 and 411, wikipedia is your friend: http://en.wikipedia.org/wiki/YUV

11-26-09, 06:43 PM	#1 \| Link
cbstryker New Member Join Date: Dec 2008 Posts: 8	Color Space/Colorimetry/x.v.Color on Sony HD Camcorders So I've been trying to find out some info about the camera I bought about 2 years ago now. It's the Sony HDR-SR11, it has x.v.Color, records at a maximum of 1920x1080i @ 16Mbps. What I've been trying to find out is what the exact color space options are for this camera. The reason is that I've been trying to do some chroma keying lately and I've been having a really hard time with color separation. Normally I record at 1440x1080 @ 7Mbps with great results. There is virtually no artifacts that can be seen and despite what I've read today about the problem of editing low bitrate AVCHD videos, I've NEVER had a problem and have successfully edited two wedding videos for friends. I did a test shoot today by setting everything to the highest quality, and manually white balanced the shot. I have a very green wall in my kitchen and I had very bright daylight coming in, I have successfully used such a setup with a old compact VHS camcorder before, but this time the green with just impossible to key out. Using MediaInfo on the file it told me that it has a 4:2:0 color space, but many websites report that this camera can do 4:2:2 via HDMI out. But what does it mean "via HDMI out"? Do I need to record to a separate device? Anyone that can help shed some light on this issue would be appreciated. I am not a novice when it comes to chroma keying. I just haven't been able to do it well with this camera yet (plus I don't have the money to buy my own proper lighting equipment).

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11-27-09, 10:57 AM	#2 \| Link
ericjut AVS Special Member Join Date: Aug 2002 Location: WA Posts: 1,769	Your VHS cam was probably NTSC color space (aka REC601), HD cams are all ATSC color space (aka REC709) which requires a different transform matrix to do RGB conversion. Most HD consumer cams record in either YUV420 or 411 (4:1 luma vs color), but that technically doesn't have any effect on the color space, just how blocky your color info is. Your Sony also support xvColor (as your title implies), which is also call "deep color" and is yet another color space, which most TVs don't support. I'm pretty sure most softwares supporting chroma keying will have a harder time with xvColor too, so I would personally stay away from that mode to do chroma key stuff. Your HD cam has an HDMI output, which will be in 422 (2:1 luma vs color). That means you could grab an HDMI capture card (like the blackmagic) and "capture" the data live with potentially more color data and less compression. Again, the color space is unchanged when using this, so I doubt very much it'll make much difference. I'm no chroma key expert, but I think it's probably time for you to upgrade your chroma key software.

11-27-09, 12:58 PM	#3 \| Link
cbstryker New Member Thread Starter Join Date: Dec 2008 Posts: 8	@ericjut: Thanks for the reply. I find it interesting that you say xvColor would likely cause problems for chroma key software, I assumed the extra color info would simply help. I'll try another test with it turned off. Also, I use After Effects CS4 for 99% of my compositing, I know it's not the #1 choice for industry professionals but I'd expect that it could handle simple chroma keying operations without too much trouble. Would you suggest trying something else? I have access to Autodesk Combustion 2, which I personally feel is leaps and bounds more superior to Adobe's line, but I initially learned compositing on AE so I'm more used to it's workflow. Is there perhaps another program you would recommend? As for the the whole color space topic, I know that 4:4:4 is technically "full" quality and 4:2:2 is ok and 4:2:0 is lower, etc. But I haven't been able to find any reliable resource online that will explain in depth the technical details of how it all works. Is there any website you could suggest? Thanks again.

11-27-09, 01:14 PM	#4 \| Link
cbstryker New Member Thread Starter Join Date: Dec 2008 Posts: 8	Well just a quick update. I did the same shot with the xvColor setting turned off and there was an improvement, although it was far from workable. With my C-VHS camera I was able to get away with A LOT but this camera clearly needs generous (read: accurate) lighting on a chroma key background to get any sort of usable results. Again, I did the keying in After Effects and I tried most of the keying tools to try to get the best result.

11-27-09, 04:30 PM	#5 \| Link
ericjut AVS Special Member Join Date: Aug 2002 Location: WA Posts: 1,769	If you don't read xyColor data specifically as xyColor, you'll read the wrong colors (it won't get mapped correctly). Does your software enable you to select xyColor at the input? If not, I suggest you keep that option turned off. Is there a variance or tolerance setting you can change so it accepts more shades of green? You C-VHS cam probably used a CCD sensor, which typically has less color noise than the current crops of HD cams which use CMOS sensors. This probably triggers more errors off of your chroma key software algorithm. I unfortunately don't have better suggestions for you software-wise, sorry. As for learning more about 444, 420 and 411, wikipedia is your friend: http://en.wikipedia.org/wiki/YUV