Technicolor/InterDigital Advanced HDR Support?

[danieljlevine]

I’m pretty sure the HDHR 4K Flex supports HDR in ATSC 3.0 broadcasts if the channel sets the right bits. Not sure which HDR that is (HDR10, HDR10+, DV, DV2, etc.). Likely it has a lot to do with the TV’s abilities. Since HDHR 4K Flex is NextGen certified, I’d expect that it’s been tested to support all the flavors of HDR that can be generated according to the ATSC 3.0 standard. But some features are optional, which means I no longer have any idea what the box is capable of handling, should a station broadcast using the feature.

I see another ATSC 3.0 tuner that is not certified as NextGen, providing an update to support Technicolor Advanced HDR. My research leads me to believe that this is related to what we often refer to here as faux HDR. And it seems like this is a transition technology on the broadcast side to make SDR recordings be faux HDR. Anyway, I wanted to learn more about this as well as whether the HDHR 4K Flex will already support this because of its NextGen certification.

I’m guessing the other tuner is seeing issues with Advanced HDR on DRM-encrypted stations and is addressing the issues its customers report back to them. So, I’m curious if we would have the same problem for a channel not using DRM encryption.

[nickk]

For HEVC content the HDHomeRun app uses the video codec support of the device you are using.

Technicolor/InterDigital Advanced HDR Support will work IF your player device supports it, and if you player device doesn't support it the video will still play fine as SDR.

[danieljlevine]

Thanks. Still not quite sure what Advanced HDR does. It seems like perhaps SDR would get faux HDR applied to it, if your display device supported an HDR format.

My understanding is that Flex 4K will send SDR broadcast video to all displays and HDR video to HDR-capable displays.

So is Advanced HDR adding any real value? I suppose if you had an HDR-capable display, all output to it from a box implementing Advanced HDR would be HDR (faux if input was SDR and passthrough HDR if input is already faux or real HDR).

[rikd]

Thanks. Still not quite sure what Advanced HDR does.

Advanced HDR is HDR input which is down converted to SDR (typically - there are 3 modes) through a particular set of Look Up Table (LUT) entries.
Because the LUT entries are known the inverse is also known and the index to the entry to reconstruct the HDR values is added to the encoded bitstream through 'registered user data' along with the converted SDR video stream.
On receiving a player will see at a minimum the SDR HEVC video and decode to SDR video.
If the player supports Advanced HDR it sees the additional data and can send that along with the decoded YUV of the SDR video and the display (assuming also has Advanced HDR support) will then recreate the HDR image.

It seems like perhaps SDR would get faux HDR applied to it, if your display device supported an HDR format.

Is not faux HDR which basically stretches the gamut detected in the video across the wider gamut of HDR.
It is true HDR input - but SDR transmission (in most cases).
There is a also a mode to use HLG as the base layer - meaning the display would have less work to do and likely less loss in HDR fidelity

My understanding is that Flex 4K will send SDR broadcast video to all displays and HDR video to HDR-capable displays.

It will send the full encoded HEVC bitstream, including the user data and base layer video, to a client app.
That app will send the received bitstream to a player - could be a self coded one, or one provided by the device vendor depending on OS, etc.
It will be that player which will check if the display can support HDR and set the appropriate bits for triggering the display to HDR mode and ensuring the user data is extracted and sent to the display.

So is Advanced HDR adding any real value? I suppose if you had an HDR-capable display, all output to it from a box implementing Advanced HDR would be HDR (faux if input was SDR and passthrough HDR if input is already faux or real HDR).

Yes it is real value - it is true HDR, but still establishes an SDR video for displays/clients that can't deal with HDR.
Could argue HLG already does this - but there are limits with HLG that Advanced HDR can overcome and is just one more tool that broadcasters can use.

[danieljlevine]

Thanks. I think I get it now. So it sounds like my HDHR Flex 4K already supports this capability, and so if my TV or tablet supported it AND a broadcaster used Advanced HDR, it would work. It also sounds like if my TV or tablet did not support Advanced HDR, it would also work as intended and just display SDR without looking funny (guessing washed out).

How would one know if a broadcast was using Advanced HDR? Does the HDHR app tell you? Does the Channels app tell you (I think their details tend to break out broadcast details)? Would the display tell you? Implementation-wise, is Advanced HDR in TVs ubiquitous in some/all brands after a certain year? Do certain tablet brands support it after a certain year on a certain OS version?

[danieljlevine]

Did a little more digging with Chat GPT.

Channels I could test with:
1. My Maryland Public Television Channels are a good source for Advanced HDR broadcasts, but do not have the HLG implemented. Also not DRM encrypted.
2. I have a number of Sinclair channels, but a decent number of the ATSC 3.0 channels in Baltimore and DC are DRM encrypted. Fox WBFF is not encrypted and doesn’t seem to use HDR. So not likely a good source to test with.

I have a Samsung TV and Apple iPad, Mac Pro, and iPhone. The TV is connected to a Google 4K Streamer running the HDHR app (and could also use a Firestick 4k Plus). However it appears that it’s well known that Samsung doesn’t support Advanced HDR, choosing the open HDR 10 and HDR 10+. Similarly, the Apple ecosystem does not support Advanced HDR. Finally, the Google 4K Streamer and Firestick 4K Plus (even the Max) don’t support Advanced HDR. If they did, I guess they could turn the Advanced HDR into HDR 10 or 10+ and then my Samsung TV would display the content in HDR. But this is not supported.

So, in my case, the local PBS station would show up in SDR on all my devices. And at best use HLG, if PBS coded that into the stream, but it does not. So SDR it is.

Which meads me back to “What value is this competitor box providing by supporting Advanced HDR?” So I think the answer to this is: They are processing the Advanced HDR and passing it through to a compatible display (like a Hisense TV) to show as HDR, just like my HDHR would do if I had a Hisense TV, which I do not. So the value they may be providing is that their box is converting the Advanced HDR to the HDR the display device is capable of displaying. So in my case, perhaps I would see the PBS station in HDR 10 with their box because they are converting it themselves in their software. I’m guessing they or their box’s OS licensed Advanced HDR to do this “trick”. So there’s the potential value for this enhancement.