Roland Vlaicu, Dolby Labs consumer imaging VP.
The format for high dynamic range (HDR) known as Dolby Vision is gaining momentum with a growing library of content available via over-the-top streaming of 4K Ultra HD movies and television programs carrying metadata for the system to an expanding field of supporting televisions.
But thus far, one of the best delivery methods available for 4K Ultra HD and HDR information – the new Ultra HD Blu-ray format – has lacked the necessary hardware to bring Dolby Vision titles to the optical-disc system. The format delivers one of the more robust delivery methods available with bit rates of up to 100 Mbps. Instead, Dolby Vision must rely on adaptive bit-rate streaming content from services including Vudu, Netflix and Amazon, with rates generally running under 20Mbps.
It has been suspected that a brewing format war between Dolby Vision and the baseline HDR standard format for the Ultra HD Blu-ray spec. — known as HDR-10 — had kept Samsung, the first manufacturer to deliver an Ultra HD Blu-ray player to market, from supporting Dolby Vision. The same goes for the two other UHD Blu-ray players now in the market or coming soon from Philips and Panasonic, respectively.
Like some of our readers, we were curious, so, we decided to ask Dolby Labs, Dolby Vision’s developer, what the hang up seems to be? In addition to developing Dolby Vision, which is used today in select advanced professional movie theaters, Dolby contributed to developing the electro optical transfer function (EOTF) [also known as perceptual quantitizer (PQ) gamma] on which both the Dolby Vision and HDR-10 systems are based. This is now part of the Society of Motion Picture & Television Engineers (SMPTE) ST.2084 EOTF standard.
It turns out that Ultra HD Blu-ray support for Dolby Vision is on the way and awaits completion of a special system on a chip (SoC) to properly handle the single.
We submitted some questions to Roland Vlaicu, Dolby Labs consumer imaging VP, to find out when we might expect Dolby Vision-supporting Ultra HD Blu-ray discs and players to be available.
Read his response to us after the jump:
Vlaicu pointed out the Blu-ray Disc Association, which developed the Ultra HD Blu-ray standard, recognizes Dolby Vision as part of the new UHD Blu-ray specifications. Dolby Vision is, in fact, one of the HDR formats that can be used on Ultra HD Blu-ray disc and decoded by an Ultra HD Blu-ray player, but that support is left to the voluntary discretion of the player manufacturer. Similarly, support for Dolby Vision HDR is left to the discretion of Hollywood studios on Ultra HD Blu-ray titles.
The HDR-10 format, on the other hand, is specified for mandatory support in players, and on Ultra HD Blu-ray discs that carry HDR, although studios are not required to support any 4K Ultra HD titles with HDR, but if they do, one of the formats must be HDR-10.
Vlaicu told us that Dolby Labs is “working closely with Hollywood studios, vendors of authoring tools and OEMs to incorporate Dolby Vision in future UHD Blu-ray discs and players to provide end-consumers with an astonishing viewing experience at home. At NAB, ATEME announced the addition of Dolby Vision into its TITAN solution, a video transcoding software for live and file applications. In addition, last year Sony Pictures Home Entertainment announced its plan to use the Dolby Vision mastering process for the release of 4k Ultra HD titles in the home. Both Scenarist and Sony DADC are working on integrating Dolby Vision into their disc authoring tools for UHD Blu-ray.”
Vlaicu explained that on UHD Blu-ray, “Dolby Vision is an enhancement layer on top of the generic HDR-10 layer. In order to read the Dolby Vision enhancement and to reconstruct the full fidelity 12-bit master, certain decoding blocks are needed on the chipset in the UHD Blu-ray player. These chips are forthcoming from Mediatek and will ultimately enable players with Dolby Vision.”
In addition, supporting hardware must be included in the Dolby Vision display, in order to communicate with the player and tell it the playback capabilities of the display so the correct signal can be sent.
Thus far, LG and Vizio sell Dolby Vision-supporting televisions, but not all of the 4K Ultra HD sets from these manufacturers do, so it is important to look for Dolby Vision support specifically on the product to ensure you are getting a product that can play it back, if that’s what you are looking for. Similarly, not all of HDR TVs from these manufacturers will support the baseline HDR-10 format, so it is important to make certain the display can handle this as well, or your set won’t playback some of the HDR content available in the market.
Dolby Vision and HDR-10 are similar in the benefits they deliver, but there are some differences. Which one is better ultimately will be up to each viewer to decide. For mastered content, the maximum target for Dolby Vision is 10,000 Nits of peak brightness, but this is well beyond what any consumer displays can achieve.
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Dolby has specified a target of up to 4,000 Nits of peak luminance, although even this is adjusted down for commercially available displays, which generally top out between 1,000 and 1,400 Nits. As mentioned, Dolby Vision-mastered content also specifies up to a 12-bit color depth, and up to a Rec 2020 color gamut, the latter of which is part of the Ultra HD Blu-ray spec, and a 4K Ultra HD resolution. The player will down convert the higher specs to meet the requirements of supporting displays.
Like Dolby Vision, the HDR-10 format is based on PQ gamma, ST.2084 EOTF. For mastering content, HDR-10 uses very similar specs to Dolby Vision for brightness and color. The standard for Ultra HD Blu-ray, however, only calls for 10-bit color compared to Dolby’s 12-bit color. Most consumer displays top out at 10-bits. Ultra HD Blu-ray content today is generally mastered to the capabilities of the professional monitor used in the mastering process.
Vlaicu said that currently, no Dolby Vision encoded discs for UHD Blu-ray exist in market, but that will be changing.
Another rumored potential handicap to Dolby Vision support has been Dolby Labs’ licensing royalties for the technology. Vlaicu acknowledged that Dolby does require an added fee to support Dolby Vision, and said that “our business model charges a nominal royalty on all devices that perform Dolby Vision processing. At this point, availability is mostly influenced by the timing of the supply chain, specifically the Mediatek SoC [system on a chip] which is forthcoming.”
As for when we might expect a Dolby Vision-supporting Ultra HD Blu-ray player and discs, Vlaicu said: “Both Scenarist and Sony DADC are working on enabling their authoring tools for Dolby Vision.”
Stay tuned.
By Greg Tarr
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