Ultra HD Blu-ray Is On The Way
What some look to as the holy grail of source devices – Ultra HD Blu-ray™ continues to move closer to completion this week as members of the Blu-ray Disc Association (BDA) resolve remaining elements for the format’s specifications.
More on what to expect in the final Ultra HD Blu-ray spec. after the break:
The group wasn’t ready to formally disclose any of the newer elements just yet, but a few niggling issues remained to be settled before the final specifications are released. Samsung’s Dan Schinasi, who chairs the BDA’s U.S. promotions group, said the goal is still to have the full specs completed and released around the middle of the year.
At the recent International CES 2015, BDA members disclosed a number of additional issues that had been agreed to since last fall’s IFA Show, where a substantial portion of the specs were first disclosed. Like earlier Blu-ray specifications, Ultra HD Blu-ray will encompass a range of both mandatory and voluntary standards.
The format will be compatible with 4K Ultra HDTV display device characteristics as defined by the Consumer Electronics Association’s 4K Ultra HDTV Working Group. Players will also be backward compatible with previous generation Blu-ray Discs, but manufacturers will have the option of whether or not to include Blu-ray Disc 3D support, as well as support for older disc formats including DVDs and CDs.
As representatives for various companies have said to us in recent weeks, nothing is final until the final spec is released, but here’s what’s been disclosed so far:
Not By Any Other Name
Victor Matsuda, BDA global promotions group chairman, revealed at CES that the official name for the new Blu-ray format will be “Ultra HD Blu-ray™” – adding Ultra HD on the front end and dropping “Disc” from the back end.
Spokesmen for the BDA have said that if final specifications are released around mid-year as expected, the first Ultra HD Blu-ray players could start appearing on the market by the holidays or early 2016. Panasonic already showed a prototype model Blu-ray player supporting 4K UHD resolution video and high dynamic range (HDR), which is expected to be a big part of the next-generation standard.
The format will support 3840×2160 pixel resolution found in today’s consumer 4K Ultra HDTV displays.
New players will include HDMI 2.0 outputs with HDCP 2.2 copy protection, as called for in the Consumer Electronics Association’s latest definitions for 4K Ultra HDTVs. Dan Schinasi could not tell us what form of additional content protection the spec will include to encrypt digital files.
3D Or Not 3D?
Schinasi confirmed that offering 3D content in 4K Ultra HD resolution has not been part of the discussions for the new Ultra HD Blu-ray specification so far, but as mentioned earlier, manufacturers will have the voluntary ability to include support for current HD Blu-ray 3D discs.
Ultra HD Blu-ray players will support both the H.264 compression codec of today’s Blu-ray players as well as the new more-efficient H.265 High Efficiency Video Codec (HEVC) used for streaming 4K Ultra HD videos.
New Disc Capacities
Plans currently call for new 66GB (dual layer) and 100GB (triple layer) Ultra HD Blu-ray discs, at data rates of 108 mbps and 128 mbps, respectively. The extra layers will provide space for additional data some studios might wish to include, without the need to add extra discs.
Beyond delivering four times the resolution of Full HD 1080p video, the Ultra HD Blu-ray spec will include support for high dynamic range (HDR) video in a mandatory single layer solution. Studios will have the option to add on any of the optional HDR formats.
The HDR information will be signaled using static metadata, and supporting televisions will be able to read this and utilize it to improve visual detail in dark and bright white segments of an image, for a more life-like experience.
Color Me Wide
Ultra HD Blu-ray players must include support for color gamuts ranging up to ITU BT.2020 with 10-bit resolution, which covers about three quarters of the visual color spectrum. This means Ultra HD Blu-ray movies connected to supporting 4K Ultra HDTVs will be able to present richer and truer shades of colors that exist outside of the range covered by today’s ITU Rec.709 format used for HDTV sets. For comparison, today’s HDTV sets supporting Rec.709 produce about 30 percent of the visual color spectrum.
What is actually put on the disc will be at the option of the studios, however. Blu-ray Disc Association representatives said BT.2020 was selected with future capabilities in mind, since no consumer displays today can achieve it. Some experts argue that a nearer-term color space would be the Digital Cinema Initiative’s DCI-P3 color, which was the target set when designing some of today’s better 4K Ultra HDTVs. The BDA said that DCI-P3 color is not a formally defined color space or color gamut, which is why it is not included in any formal standards documentation or in the next-generation Blu-ray specifications. It is a recommended practice for cinema projectors which is why it is not included in any formal standards documentation or in the next generation Blu-ray. Both consumer and cinema display systems are targeted to support BT.2020 as a goal in the future.
Interestingly, the Blu-ray spec. also calls for 4:2:0 chroma subsampling, Schinasi confirmed. This is used in the AVCHD compression standard as well as in version 1 of the newer HEVC standard. However, the second version of HEVC was approved last year and published in recent weeks including range extensions supporting higher bit depths with 4:0:0, 4:2:2 and 4:4:4 chroma subsampling formats, scalable coding extensions and multi-view extensions. Current version 1 decoders will not handle higher chroma subsampling bitstreams. Some argue that 4:2:0 chroma subsampling loses data and adds image noise compared to the 4:2:2 or 4:4:4 approaches, (the latter of which is found in professional video cameras), which also should be included for the sake of forward compatibility. The BDA said the primary reason for selecting 4:2:0 subsampling was data savings and ease of compression, which allow for longer content to be stored on the disc media.
The new specs will also add high frame rate support for up to 60 frames per second (fps). With supporting content (studios again have the option to decide what frame rates they wish to use on a disc), the higher frame rates should eliminate blurring that is sometimes seen in fast-moving action scenes of movies shot at the traditional 24fps.
All This And Audio Too
All Ultra HD Blu-ray players will also play all of the audio formats in today’s Blu-ray Disc players and will be able to pass-through the bitstreams for today’s newer object-oriented, immersive-audio formats, including Dolby Atmos, Auro-3D and the forthcoming DTS:X. Signals are not decoded by the player but passed on to an external decoder or A/V receiver equipped to decode the formats. These systems allow placement of more speakers around the listener (including overhead) to create the illusion of objects moving around the audience. Remaining to be seen is how studios will opt to support these new advanced audio formats.
Digital Copy Part 2?
One of the more interesting optional features reportedly being considered for the spec is called Digital Extension or Digital Bridge. This will allow transferal of a disc’s title to some form of internal memory and then transferring it to an external playback device. Schinasi could not confirm for us if this will be included in the final spec or how it would be implemented, but the idea is to simplify today’s Digital Copy capability for Blu-ray Disc players. As with that system, it will allow studios to decide if or how it is applied.
By Greg Tarr
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