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View Full Version : Is xvYCC color space supported in avisynth?


tedkunich
28th November 2007, 16:08
Just bought a new Sony HD handy cam and it has the option of recording in this new extended color space - my TV does not support HDMI 1.3 so it does not play on that, wondering if avisynth can process footage shot in that color space.


Thanks

T

sh0dan
28th November 2007, 18:15
First of all, if you don't change colorformats, anything colorspace you put in comes out the same.

In principle there is nothing holding AviSynth back for supporting conversion to/from it, but I cannot find any conversion matrices for it online.

IanB
28th November 2007, 22:55
xvYCC is a new international digital video color space standard published by the IEC (IEC 61966-2-4). It is based on the ITU BT.601 and BT.709 standards but extends the gamut beyond the R/G/B primaries specified in those standards.gamut is the sub-triangle of displayable colours from absolute colour.

Avisynth is currently 8 Bit, any conversion will downgrade the image to the current quality of 24bit RGB limits.

However I have added some infrastructure to the API in 2.6 to be able to define 16bit and 32bit per channel formats. So some time in the future there can be actual code that implements these extended formats.

Mug Funky
29th November 2007, 00:58
is this just YUV with 0-255 ranges? in this case avisynth should support it already.

wikipedia is a bit light on the details about this, apart from the marketese sounding "deeper colours".

tedkunich
29th November 2007, 06:13
is this just YUV with 0-255 ranges? in this case avisynth should support it already.

wikipedia is a bit light on the details about this, apart from the marketese sounding "deeper colours".

From Answers.com

xvYCC uses the full range of values (1 to 254 in an 8-bit space) to represent colors. In BT.601 and BT.709, RGB colors are represented only by 8-bit values from 16 to 235. This limited range was established to allow for undershoot and overshoot, attributes of analog TV signaling. With digital TV signaling, there is no undershoot or overshoot, and the values from 1-15 and 235-254 can be used to represent real colors. In order to maintain backward-compatibility with earlier standards, the red (R), green (G), blue (B) and white standard colors are still calculated at the same indices in the color space. The wider ranges of digital values allow representation of deeper greens, deeper reds, and deeper blues - and of course intermediate colors previously beyond the boundary limit in the CCIR 601 color space.

Full article here http://www.answers.com/topic/xvycc

foxyshadis
1st December 2007, 09:47
This is BT.709 Gamut (pretty close to 601 and NTSC) with the fullrange exposed. The primary reason 16-235 was chosen for digitization was because of the expectation that wider gamuts would shortly come into use; turns out they were about 20 years too early.

You can process it all you want in Avisynth, as long as it can read the container format, just don't convert it into 8-bit RGB or you'll lose all the extended range. You need a tool to convert it to 16-bit or higher RGB to be useful.

Despite what wiki sez, most cheap LCDs have a gamut limited to sRGB or at most approaching NTSC, though, so don't expect it to automatically translate to vibrance unless you have something like a new Bravia or another LED backlit set.

Fizick
2nd December 2007, 13:15
doc is not free.
http://webstore.iec.ch/webstore/webstore.nsf/artnum/035442

Preview:
http://webstore.iec.ch/preview/info_iec61966-2-4{ed1.0}en.pdf

Correction 1:
http://www.iec.ch/cgi-bin/getcorr.pl/yab/iec61966-2-4-cor1{ed1.0}en.pdf?file=iec61966-2-4-cor1{ed1.0}en.pdf

HDMI 1.3
http://www.eetchina.com/ARTICLES/2006AUG/PDF/HDMI_Spec_1.3_GM1.pdf?SOURCES=DOWNLOAD

See slide 17 of this:
http://www.jeita.or.jp/japanese/hot/2006/0830/0830.pdf
Seems, luma is not extended.

2Bdecided
4th December 2007, 12:17
That Japanese presentation is interesting, even for a non-Japanese speaker!

I wonder how they got those extended colour demonstrations to display on my sRGB PC display! ;)

Cheers,
David.

Balling
25th December 2020, 12:37
>on my sRGB PC display

Even sRGB display should be able to present superwhite values...

TheFluff
25th December 2020, 16:44
>on my sRGB PC display

Even sRGB display should be able to present superwhite values...

I'm not sure if the person who posted that thirteen years ago cares anymore, especially since their last activity on this forum was five years ago.