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Old 9th October 2012, 17:31   #1  |  Link
benwaggoner
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Real-world support for full range and greater color depths

I am doing some playing around with 0-255 luma range and 10-bit encoding.

I was wondering how good real-world player support is for those modes. I know that there are certaninly good software players for those. But how about GPU accelerated playback? Or ASIC-based playing in living room and handheld devices?

I imagine 0-255 is more broadly supported, since it's part of the original profiles. I know there's been plenty of talk about 10-bit support in ASICs, but I'm not sure if those are in the wild yet, or if the devices's media software will support correct playback of those if provided with files in Hi10P. Let alone Hi422P or Hi444PP.

So, can anyone offer any tips for what players and devices are or are not known to work? I'd love to be able to see what kind of quality differences I can get outside of computer monitors.
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Old 11th October 2012, 05:51   #2  |  Link
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I'm not aware of a single consumer grade hardware player.

There are plenty of hardware players for the pro market, but even those are few and far between in my experience. AVC-Intra is about the only common implementation I'm aware of...
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Old 11th October 2012, 15:48   #3  |  Link
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I could be wrong, but xvYCC looks like fullrange and AVCHD supports it (and there are a lot of players that support it)...
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Old 11th October 2012, 17:38   #4  |  Link
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Originally Posted by Blue_MiSfit View Post
I'm not aware of a single consumer grade hardware player.
You mean for the 10-bit and higher profiles?

I'd think that there should certainly players out there that can handle High Profile using a 0-255 luma range. Or is even that not broadly supported?


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I could be wrong, but xvYCC looks like fullrange and AVCHD supports it (and there are a lot of players that support it)...
Link?

I'm sure that plenty of things that can play AVCHD out over HDMI can use xvYCC, but I don't believe the AVCHD bitstream itself can be anything beyond 8-bit 4:2:0. So it'd have to use post-decode upsampling in the player itself.
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Old 18th June 2013, 21:27   #5  |  Link
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--range full needed for xvYCC?

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I could be wrong, but xvYCC looks like fullrange and AVCHD supports it (and there are a lot of players that support it)...
Coming back to this some months later.

Are you saying that xvYCC would require --range pc and not --range tv?

My understanding of xvYCC is that it wouldn't have luma our of the 16-235 range. But does it need --range pc in order to allow the broader chroma range for xvYCC?

It seems like we'll need the xvYCC flag for playback to not get black levels wrong in this case.
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Old 19th June 2013, 10:42   #6  |  Link
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http://www.sony.net/SonyInfo/technol.../xvycc_01.html
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With 8-bit quantization of luminance and color-difference signals, definition formula are set and the color gamut is expanded by using values between 1 and 15 and between 241 and 254 as picture signals. Definitions over 8 bits are also used to support precise gradation.
My understanding is that besides using luma and chroma values outside of the TV range you would still set the encoder to TV range for compatibilty with non-xvYCC devices.
This is assuming the encoder does not clip the input levels to TV and encodes the full range. I think x264 handles it this way as long as input and output range are the same.
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Old 19th June 2013, 16:57   #7  |  Link
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Although there are some GPU's that support vxvYCC colour, they need to be connected to a display device that also supports vxvYCC... And currently these are only manufactured by Sony
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Old 24th June 2013, 18:00   #8  |  Link
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I had a quick look at the histogram of the "Mastered in 4K" Ghostbusters BD and levels seem to be within the regular video range!? This is not what I expected...
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Old 11th October 2012, 19:02   #9  |  Link
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Right. I'm sure any hardware player could PLAY full range, but whether it would display it correctly is another story entirely

In any case, I have no experience in this matter whatsoever!
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Old 13th October 2012, 13:05   #10  |  Link
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Full range has no effect on the bitstream. The only difference is that with TV range, the "contrast" of the image is bad, and there's a flag that says whether this should be compensated for or not.
I can imagine some players just ignoring this flag and automatically compensating for it even if they shouldn't, so the blacks and whites will be crushed in the final displayed image, but it will be decoded correctly in any case.
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Old 25th June 2013, 23:37   #11  |  Link
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But then it's not a Blu-ray Disc ?
Sure it is. Hence the Blu-Ray logo and Sony calling them "Mastered in 4K Blu-Ray titles".

SONY PICTURES HOME ENTERTAINMENT ANNOUNCES "MASTERED IN 4K" BLU-RAY TITLES TIMED WITH SONY 4K TVs

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Old 25th June 2013, 23:42   #12  |  Link
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If the official Blu-ray Disc specifications do not allow xvYCC encoded video, then how can a disc containing xvYCC encoded video be a Blu-ray Disc?
It doesn't disallow it.
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Old 25th June 2013, 23:50   #13  |  Link
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So xvYCC encoded video is guaranteed to be fully backwards-compatible with all Blu-ray Disc players?
Yes the discs are compatible with all players you just get regular gamut if it doesn't support xvYCC.
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Old 26th June 2013, 20:29   #14  |  Link
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Yes the discs are compatible with all players you just get regular gamut if it doesn't support xvYCC.
So how does it work then? The extended primaries get truncated or something? Or is it some kind of an enhancement layer? Multiple encodes?

I suppose it's time to transcend whatever latent remnants of HD DVD bitterness I have and pay more attention to Blu-ray .
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Old 26th June 2013, 20:31   #15  |  Link
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So how does it work then? The extended primaries get truncated or something? Or is it some kind of an enhancement layer? Multiple encodes?
I don't think anyone has analyzed a stream yet to know exactly. I assume it's some form of custom signaling or metadata that their players can read and is ignored by others. There's no way it can be multiple encodes when the other point of these discs are to increase the average bitrate.
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Old 26th June 2013, 20:33   #16  |  Link
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To add from here:

Quote:
Other Blu-rays have been sourced from a 4K master, so what’s the big deal with these? A few things. First, the video bitrate has been upped considerably to ensure a solid, artifact-free picture: The new, Mastered in 4K Spider-Man maintains a steady 35 Mbps, as compared with the high-20 Mbps bitrate typical with other discs, including the 2012 Spider-Man Blu-ray. (Unfortunately, the increased video data rate means there’s no space for extra stuff like features and commentary tracks.) Second, Mastered in 4K discs incorporate something Sony calls Expanded Color, which otherwise goes by the name x.v.Color or xvYCC. To briefly sum up, discs with x.v.Color incorporate data describing colors outside the standard Rec.709 HDTV color space. When a Mastered in 4K disc is played on an x.v.Color-compatible BD player (according to Sony, only its own player line plus the PlayStation 3 can reliably be called compatible) and displayed on a TV capable of x.v.Color reproduction — Sony’s new W900A series HDTVs (look for my review in the June/July/August issue of Sound&Vision) and XBR-X900A Series 4K Ultra HD TVs, for example — you get the option to view this expanded range. And displaying it shouldn't involve any shift in the TV’s color points — the disc simply instructs the TV to “retrieve” those extra colors without distorting the set’s overall color balance.
There's not a whole lot of specifics though from what I've seen.
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Old 26th June 2013, 21:43   #17  |  Link
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To add from There's not a whole lot of specifics though from what I've seen.
There really aren't.

The only obvious way I see for them to do what they're doing would be to have a stock Rec. 709 encode and then some kind of enhancement later that added the (relatively small delta) of xvYCC data. Since it's mostly in chroma, that wouldn't be that many samples and they can be quantized quite coarsely. Perhaps using something like Scalable Video coding. I'd think the PS3 would likely have the horsepower to do something like this.

I am now very intrigued by this!

Also, other than Sony BD players, are there any known devices capable of xvYCC playout? It seems support is way more common in TV than it is in any way to play back the content. Can decoders internal to the TVs do the right thing with xvYCC bitstream?
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Old 26th June 2013, 23:00   #18  |  Link
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From what I understand Sony use the 1-15 and 241-254 chroma values to represent higher saturation colours. When you do the normal YUV->RGB translation you can end up with normalised colour values less then 0.0 or greater than 1.0, normal decoders clamp these values, advanced decoders map these values into a wider gamut colour space. The luma range is still 16-235.
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Old 26th June 2013, 23:14   #19  |  Link
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From what I understand Sony use the 1-15 and 241-254 chroma values to represent higher saturation colours. When you do the normal YUV->RGB translation you can end up with normalised colour values less then 0.0 or greater than 1.0, normal decoders clamp these values, advanced decoders map these values into a wider gamut colour space. The luma range is still 16-235.
That makes sense. But if chroma is getting clamped at those values, I worry we'll see posterization of chroma levels when the extended colors get clamped. A gradient of "very red" could turn into a flat area of just red without any detail. If there is some texture in the luma channel that might mask things, but still. It seems like it would be hard to make a "best of both worlds" encode like this.
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Old 27th June 2013, 01:25   #20  |  Link
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The out of gamut high saturation colours considered here would have been clamped in normal processing anyway, either by the source camera and/or the display device. The system just gives the opportunity to not clamp the very saturated colours when a high gamut source and display are available.
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