Mobile HDR got off to something of a false start. When Samsung announced the Galaxy Note 7 in 2016, it also announced that it had equipped the super-sized smartphone with an HDR display and that glorious movies would be streamed to your phone for enjoyment anytime, anywhere.
Fast-forward to 2017, and mobile HDR is back on the agenda, spearheaded by the launch of the LG G6.
Here's everything you need to know about the latest step in mobile entertainment.
What is HDR?
HDR stands for high dynamic range and it's been a buzzword in TV for the past couple of years. If you bought a top tier 4K television in 2016, it's likely that it will also be HDR capable.
HDR means that the display is able to produce a wider range of colours, bringing greater authenticity, and you'll often hear talk about 10-bit or 12-bit colour. But it's also about brightness.
On televisions, HDR is about using the display's peak brightness to give amazing highlights, while still maintaining fidelity in darker areas of a scene. For example, a typical HDR scene is a sunset, where you have searing oranges across the sky, a detailed shadowed foreground and perhaps the blazing sun dipping over the horizon.
Mobile HDR aims to create the same stunning visuals: in reality, it's about making content look better, and specifically movies or games.
We've written a lot about HDR, so for the nitty gritty, make sure you read up on that feature.
What is mobile HDR?
Mobile HDR is specifically about bringing this experience from your 55-inch TV to your smartphone or tablet. Again, it's all about using the skills of the display, giving amazing colours and controlling the backlight to give you a better experience.
It also has a great deal to do with brightness, because it's the ability of the display to push the brightness in areas that are supposed to be bright that really makes a difference. Many mobile devices have displays that are under-utilised and HDR can make much better use of the display's ability to show content.
As we mentioned, the Samsung Galaxy Note 7 attempted to kickstart the mobile HDR movement, but the biggest hitter is now the LG G6. The LG G6 offers HDR10 and Dolby Vision support, just like LG's televisions.
There are several different standards for HDR on mobile that you'll hear about: there's HDR10 which is a common standard and there's Dolby Vision, which Dolby is pushing as an enhanced HDR experience.
Dolby Vision aims to achieve much the same results as HDR10, but uses frame-by-frame metadata to ensure that the display you're watching is showing you the best results. HDR10, by comparison, uses metadata less often, so technically isn't as potent a solution.
Dolby Vision has been slightly rarer up till now, but in 2017 that position seems to be changing, with a big push to expand the Dolby Vision ecosystem.
What is Mobile HDR Premium?
In February 2017, the Ultra HD Alliance announced a new standard for mobile devices, called Mobile HDR Premium. The Ultra HD Alliance is made up of movie producers and technology companies looking to establish a standard for next-gen entertainment. The UHDA is best known for the Ultra HD Premium badging that it applies to televisions - as seen on Samsung, LG and other sets.
For mobile devices, the Mobile HDR Premium badging means that the device adheres to a particular standard too, designed to ensure that you're getting a great experience from mobile HDR entertainment.
The specifics include:
- Resolution: 60 pixels/degree
- Dynamic range: .0005-550nits
- Colour space: 90 per cent of P3 colour gamut
- Bit depth: 10
These standards apply to smartphones, tablets and laptop computers, meaning that the Mobile HDR Premium badging could be applied to all those devices which offer HDR content, but not necessarily at 4K resolution.
How does Dolby Vision on mobile work?
The LG G6 is the first mobile device to support Dolby Vision and the message from TV has changed slightly. On mobile devices, Dolby Vision is a software solution, rather than hardware-based. On the first run of TVs to support Dolby Vision, you needed the correct hardware to decode the information; now you'll be able to do this with software.
Dolby Vision (or HDR10) doesn't apply to all your content, only the content that's encoded for HDR, like Luke Cage on Netflix, for example. Unlike something like Sony's X-Reality image processing that attempt to improve everything you see on your device, Dolby Vision/HDR only swings into action when you're watching the right content.
With this in mind, you can't turn it off or on: it just works, taking the content you're watching and using the metadata to control the backlight of your device to give you the best colour, great contrast and those characteristic dazzling highlights.
What about variable bitrate services?
One thing that's helped services like Netflix and Amazon Video offer a great services is using variable bitrate. This means that the stream of data is scaled, so on a slow connection you get less data and watch at a lower resolution - without the video stopping or buffering. This also allows almost instant starting of videos too.
We asked Dolby what happened to Dolby Vision content in a variable bitrate situation and the reply was that it very much came down to the content provider. Technically, HDR and resolution aren't intrinsically linked, so you can have that HDR effect even if you're not watching the highest quality stream.
One thing is clear though: you don't want to be jumping from HDR to non-HDR, because the colours will be changing and that doesn't make for a good viewing experience.
What about auto-dimming on your display?
This is something of a potential problem for HDR on mobile devices. The TV in your front room probably doesn't change its brightness. It's likely you set it to your preference and then it stays at that level. However, mobile devices use auto-brightness to change the display to suit the environment - it's darker in dark conditions, brighter in bright conditions.
This will have an impact on how HDR content is displayed. Talking to Dolby, the company confirmed that they took into account these sorts of hardware factors with the aim of always delivering the best visual experience when watching Dolby Vision content.
But you can mess with it. If you turn auto-brightness off and turn the display brightness all the way down, then you get a fairly dull result. The long and short of it is that you're best leaving your device on auto-brightness to get the best effect.
What devices support mobile HDR?
There have been a couple of big announcements for mobile HDR support in 2017.
The LG G6, as we said, is really the highest-profile device that's supporting a wide-range of HDR content. It fits LG's positioning for its televisions, so it makes sense, and the company offers a wide range of Dolby support. The LG G6 supports both Dolby Vision and HDR 10.
The Samsung Galaxy Tab S3 also supports HDR. This 9.7-inch tablet is the company's answer to the iPad Pro and has a lovely AMOLED display, so it's great for a slightly larger entertainment experience. There's no mention of Dolby Vision support though.
The Samsung Galaxy Book 12-inch is also HDR ready. This is a Windows 2-in-1 device and it again supports HDR content, although the smaller 10.6-inch Galaxy Book doesn't.
The Sony XZ Premium supports HDR, although the phone isn't launching until June 2017. This flagship device takes a step up over these other listed devices as it also carries a 4K display, meaning you should get that HDR content paired with extreme levels of detail too - whether mobile streaming will be in 4K is a separate argument.
What does mobile HDR content look like?
We've been fortunate enough to see demos of HDR working on Samsung devices, as well as the Sony XZ Premium. We've also seen the LG G6 playing a Dolby Vision demo.
If you've seen HDR content on TV, then you know what to expect: colour are richer, there's better contrast and brighter highlights. HDR makes everything look better and this is certainly an exciting evolution: if you watch Netflix on your tablet or smartphone in bed, it's going to look better.
What HDR content is available?
This is where technology often falls over, when there's no actual content to support the abilities of the devices.
In the case of HDR and Dolby Vision, it's already on Netflix and Amazon Video and streaming to your TV. Both services are going to be offering this content to mobile devices too, but there's no word on exactly when.
We've heard mutterings of April 2017, but that's unconfirmed: there's likely to be phased roll-out across the globe, so don't be surprised if it comes to the US before the UK.
The important message is that it is coming - but of course you need to have a device that supports it.
YouTube also offers HDR content and we'd expect this to be enabled on mobile devices at some time in the future and this is likely to be one of the best sources of free HDR content. The only barrier, perhaps, is creation, as currently there are few consumer devices that can capture HDR video - the Panasonic Lumix GH5 is one such camera.
Can my old phone support mobile HDR?
This is a good question. Technically, if the display is good enough, then there could be some scope to enabling viewing of HDR content on existing devices. When talking to Dolby, we were told that Dolby Vision isn't restricted to a specific set of specifications and that the aim was to make the display work to its maximum potential.
As Dolby Vision on mobile devices is a software solution, it's really down to the manufacturer to work with Dolby to enable support. For a manufacturer this is likely to involve licensing fees, so we suspect that some won't take the Dolby path for this reason.