xvYCC usage with Cineform at DVinfo.net

Anmol Mishra · February 16th, 2011, 06:00 PM

Normal YUV 4:2:2 captured via CF seem to be no problems. However, I am doing a project with 2x camcorders that output xvYCC over HDMI.

Since the output is still 0-254 I would assume even an 8-bit 4:2:2 recorder will take in this data.
How would Cinefom map the extra color data if I converted the file to 10-bit space ?

Would you consider adding a field in the GUI to make CF aware of the extra color data ?

Here is the info from Wikipedia :-
>>
xvYCC-encoded video retains the same color primaries and white point as BT.709, and uses either a BT.601 or BT.709 RGB-to-YCC conversion matrix and encoding. This allows it to travel through existing digital YCC data paths, and any colors within the normal gamut will be compatible.

The xvYCC color space permits YCC values that, while within the encoding range of YCC, have chroma values outside the range 16–240, or that correspond to negative RGB values, and hence would not have previously been valid. These are used to encode more saturated colors. For example, a cyan that lies outside the basic gamut of the primaries can be encoded as "green plus blue minus red".[3]
>>

David Newman · February 16th, 2011, 06:39 PM

We always encode full range YUV 0 to 255. So no issues.

Anmol Mishra · February 17th, 2011, 02:34 AM

Thanks for the quick answer. Now, since you have often educated your customers while answering questinos, I will press on. Hope thats OK!

YUV uses 16-240 from the chroma region. xvYCC uses 0-254.Now there is a problem if these have to be converted to RGB, since these chroma values give a negative color value. However, that can be remedied by the video editor deciding how to deal with these values.

If I understand this, CF simply copies over these values, then it is upto the editor (FCP ??) to decide how to deal with these values.

Does FCP actually consider these values during processing, or are they thrown away. I am aware that xvYCC images look REALLY strange on a standard color gamut. However, this is actually 15% extra color information, and I am keen on retaining it.

As far as I know, only the Canon 7D and the Panasonic HDc-SD9 actually output xvYCC via HDMI. I am unsure if any camera currently even captures the xvYCC color to their recording codec.

February 16th, 2011, 06:00 PM	#1
Anmol Mishra Major Player Join Date: Jun 2007 Location: Sydney Australia Posts: 401	xvYCC usage with Cineform Normal YUV 4:2:2 captured via CF seem to be no problems. However, I am doing a project with 2x camcorders that output xvYCC over HDMI. Since the output is still 0-254 I would assume even an 8-bit 4:2:2 recorder will take in this data. How would Cinefom map the extra color data if I converted the file to 10-bit space ? Would you consider adding a field in the GUI to make CF aware of the extra color data ? Here is the info from Wikipedia :- >> xvYCC-encoded video retains the same color primaries and white point as BT.709, and uses either a BT.601 or BT.709 RGB-to-YCC conversion matrix and encoding. This allows it to travel through existing digital YCC data paths, and any colors within the normal gamut will be compatible. The xvYCC color space permits YCC values that, while within the encoding range of YCC, have chroma values outside the range 16–240, or that correspond to negative RGB values, and hence would not have previously been valid. These are used to encode more saturated colors. For example, a cyan that lies outside the basic gamut of the primaries can be encoded as "green plus blue minus red".[3] >> __________________ mishra.tv Productions A Sydney-based group for dance movement-based video and film productions.

February 16th, 2011, 06:39 PM	#2
David Newman CTO, CineForm Inc. Join Date: Jul 2003 Location: Cardiff-by-the-Sea, California Posts: 8,095	We always encode full range YUV 0 to 255. So no issues. __________________ David Newman -- web: www.gopro.com blog: cineform.blogspot.com -- twitter: twitter.com/David_Newman

February 17th, 2011, 02:34 AM	#3
Anmol Mishra Major Player Join Date: Jun 2007 Location: Sydney Australia Posts: 401	Thanks for the quick answer. Now, since you have often educated your customers while answering questinos, I will press on. Hope thats OK! YUV uses 16-240 from the chroma region. xvYCC uses 0-254.Now there is a problem if these have to be converted to RGB, since these chroma values give a negative color value. However, that can be remedied by the video editor deciding how to deal with these values. If I understand this, CF simply copies over these values, then it is upto the editor (FCP ??) to decide how to deal with these values. Does FCP actually consider these values during processing, or are they thrown away. I am aware that xvYCC images look REALLY strange on a standard color gamut. However, this is actually 15% extra color information, and I am keen on retaining it. As far as I know, only the Canon 7D and the Panasonic HDc-SD9 actually output xvYCC via HDMI. I am unsure if any camera currently even captures the xvYCC color to their recording codec. __________________ mishra.tv Productions A Sydney-based group for dance movement-based video and film productions.