SDI -> HDMI converter with HDR metadata override

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peter_a

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SDI -> HDMI converter with HDR metadata override

PostWed Sep 28, 2022 10:05 am

I'm trying to find a 12G SDI to HMDI converter with the capability to override the HDR metadata flags coming in on the SDI.

In my specific use case, I have an SDI feed carrying HDR (PQ / 2020) but with no HDR metadata being carried. I need the converter to add the flags to the HDMI signal, so the TV correctly interprets its input.

Does anyone know of a Blackmagic converter with this feature?

I know AJA product has users setting to do this (e.g. the Hi5-12G) but I can't see any Blackmagic converters advertised with this function.
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Dave Del Vecchio

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Re: SDI -> HDMI converter with HDR metadata override

PostSun Oct 02, 2022 8:52 am

I believe only the Teranex Mini SDI to DisplayPort 8K HDR has any kind of HDR output metadata override feature. And it doesn't have the fine control over various parameters like on the AJA Hi5-12G, but does have several common presets that can be set through a Dynamic Range Override option, these include:
  • Auto (detect from the input signal)
  • Rec. 709
  • Rec. 2020 SDR
  • HLG
  • ST2084 (PQ)
  • ST2084 300
  • ST2084 500
  • ST2084 800
  • ST2084 1000
  • ST2084 2000
  • ST2084 4000
You'd also need an DisplayPort to HDMI adapter to use it with an HDMI display.

Oddly enough judging from the manual, the very similar Teranex Mini SDI to HDMI 8K HDR doesn't seem to have the output override option that the DisplayPort model has (although I believe that model will output HDR metadata if the SDI video input signal is flagged as such).
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Andrew Kolakowski

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Re: SDI -> HDMI converter with HDR metadata override

PostSun Oct 02, 2022 9:45 am

HDFury Dr HDMI 4K should Vertex/Integral do it at relatively low price.
Don't think any BM device offers such a functionality (except mentioned one).
Last edited by Andrew Kolakowski on Sat Oct 08, 2022 10:40 am, edited 1 time in total.
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peter_a

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Re: SDI -> HDMI converter with HDR metadata override

PostSun Oct 02, 2022 5:23 pm

Hadn't looked at the HDFury stuff! Will have to check it out. Thanks!
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Dave Del Vecchio

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Re: SDI -> HDMI converter with HDR metadata override

PostMon Oct 03, 2022 8:43 am

I think the Dr. HDMI 4K is just an EDID emulator device, but I'm not sure that it includes HDR metadata injection support.

Which would mean that the Dr. HDMI could be used to advertise the HDMI source device as HDR capable to the HDMI sink device (such as a monitor), but my understanding is that the HDMI source device is supposed to send a Dynamic Range and Mastering InfoFrame with each field of the video stream (the HDMI Dynamic Range and Mastering InfoFrame includes the HDR metadata such as the transfer function, luminance range, etc.).

So if the actual source video stream does not include HDR InfoFrames, then I'm not sure just overriding the EDID table alone will accomplish that much.

I think you would probably need to use something like the HDfury Integral 2 or HDfury Vertex if you want to inject HDR metadata via an HDMI InfoFrame override. And then you'd also need a 12G SDI to HDMI converter (a Micro Converter 12G might work) since the HDfury devices are HDMI in and out.
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Andrew Kolakowski

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Re: SDI -> HDMI converter with HDR metadata override

PostMon Oct 03, 2022 8:47 am

It should (won't, you need Vertex/Integral) to inject HDR metadata. It’s the cheapest option in HDFury range.
At the end HDR metadata is just few static values, nothing that complicated.
To be sure best to ask HDFury support. Other options allow to directly use any metadata you want, where in Dr HDMI you save presets and then just use them (as far as I understand).
Dr HDMI can be also useful when you have typical BM HDMI compatibility issue between TV and BM card.

I assumed Peter has HDMI signal, but he has just SDI, so he needs converter. AJA is good choice, but not cheap.
Last edited by Andrew Kolakowski on Sat Oct 08, 2022 10:42 am, edited 4 times in total.
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Andrew Kolakowski

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Re: SDI -> HDMI converter with HDR metadata override

PostMon Oct 03, 2022 8:58 am

Actually depending on what TV you have, you can force HDR mode directly in TV. Some offer such an option ( Sony, Panasonic I think) as a standard for others, eg. LG it’s hidden feature, but people found out shortcuts to enable it.
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Dave Del Vecchio

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Re: SDI -> HDMI converter with HDR metadata override

PostFri Oct 07, 2022 6:48 am

Andrew Kolakowski wrote:It should inject HDR metadata. It’s the cheapest option in HDFury range.
At the end HDR metadata is just few static values, nothing that complicated.
To be sure best to ask HDFury support. Other options allow to directly use any metadata you want, where in Dr HDMI you save presets and then just use them (as far as I understand).
According to the specs and documentation, the HDfury Dr. HDMI 4K is primarily just an EDID override device. EDID is used by the HDMI sink device (such as a display) to communicate to the HDMI source device what video formats it supports and what its preferred video format is. And then in principle the HDMI source device will send a video format that is compatible with one of the formats in the EDID table presented by the sink device.

So by inserting an EDID override device like the Dr. HDMI in-line between the source and sink device, the Dr. HDMI can now send a different EDID table to the source device than the actual sink device (monitor, TV, etc.) would have sent. So this allows for overriding the allowed or preferred video formats to modify what would have otherwise been communicated to the source device.

Applying one of the HDR EDID presets in Dr. HDMI just indicates to the source device that the sink device supports HDR. It does not guarantee the source device will actually send such a signal. This is the same way EDID works with other aspects of the signal format such as resolution, refresh rate, color space, bit depth, etc. For example, even though the preferred video format of the sink device's EDID table might be 3840x2160 @ 10-bit 4:2:2, if the source device can only generate a 1920x1080 @ 8-bit 4:2:2 signal, then that is what it will send.

In order for an HDMI source device to indicate to the sink device that the video stream contains HDR content, as well as what the HDR format of that content is (HLG, PQ, etc.), the source device should send a Dynamic Range and Mastering InfoFrame with each field of the video data (the HDMI Dynamic Range and Mastering InfoFrame includes the HDR metadata such as the transfer function, luminance range, etc.). More details on the HDR InfoFrame in this spec document:
https://www.avsforum.com/attachments/hd ... f.3191945/

Without these HDR InfoFrames, the HDMI sink device (display) does not know how to interpret the video metadata that is actually being sent. Now, if you have some out-of-band way to tell the display how to interpret the incoming content (such as by supplying the HDR format information through some menu setting of the display), then that could certainly work.

But if your display does not have this capability and the HDMI source device does not send these HDR InfoFrames with the video data, then you need some way to inject this information into to the HDMI video stream. An EDID override device like the Dr. HDMI 4K does not have this capability (nor does HDfury claim it does, nor is there any interface to configure the content that would need to go into the HDR InfoFrames for that matter).

In contrast, the higher end HDfury devices like the Integral 2 and Vertex are capable of modifying the data in the HDMI video stream (which is why they are more expensive). Both of those devices claim to have HDR InfoFrame injection/replacement capabilities as does the AJA Hi5-12G.

Anyway, hope this is helpful in better understanding some of the HDMI signal format details.
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peter_a

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Re: SDI -> HDMI converter with HDR metadata override

PostFri Oct 07, 2022 8:18 am

Dave Del Vecchio wrote:Anyway, hope this is helpful in better understanding some of the HDMI signal format details.
That is a BRILLIANT summary. Thanks for taking the time.

My source device has no way of inserting the info frames necessary, so something like the Integral 2 seems to be necessary. If I get a solution working I'll report back.
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Andrew Kolakowski

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Re: SDI -> HDMI converter with HDR metadata override

PostFri Oct 07, 2022 10:32 am

Dave Del Vecchio wrote:
Andrew Kolakowski wrote:It should inject HDR metadata. It’s the cheapest option in HDFury range.
At the end HDR metadata is just few static values, nothing that complicated.
To be sure best to ask HDFury support. Other options allow to directly use any metadata you want, where in Dr HDMI you save presets and then just use them (as far as I understand).


In order for an HDMI source device to indicate to the sink device that the video stream contains HDR content, as well as what the HDR format of that content is (HLG, PQ, etc.), the source device should send a Dynamic Range and Mastering InfoFrame with each field of the video data (the HDMI Dynamic Range and Mastering InfoFrame includes the HDR metadata such as the transfer function, luminance range, etc.). More details on the HDR InfoFrame in this spec document:
https://www.avsforum.com/attachments/hd ... f.3191945/

Without these HDR InfoFrames, the HDMI sink device (display) does not know how to interpret the video metadata that is actually being sent. Now, if you have some out-of-band way to tell the display how to interpret the incoming content (such as by supplying the HDR format information through some menu setting of the display), then that could certainly work.

But if your display does not have this capability and the HDMI source device does not send these HDR InfoFrames with the video data, then you need some way to inject this information into to the HDMI video stream. An EDID override device like the Dr. HDMI 4K does not have this capability (nor does HDfury claim it does, nor is there any interface to configure the content that would need to go into the HDR InfoFrames for that matter).

In contrast, the higher end HDfury devices like the Integral 2 and Vertex are capable of modifying the data in the HDMI video stream (which is why they are more expensive). Both of those devices claim to have HDR InfoFrame injection/replacement capabilities as does the AJA Hi5-12G.

Anyway, hope this is helpful in better understanding some of the HDMI signal format details.


If you sure it doesn't have this ability then cool.
If I remember well I did ask them if Dr HDMI can insert HDR metadata, but I'm not 100% sure for the answer, so I said best to ask support.

You don't even need actual metadata (Resolve doesn't send real values either), just most basic HDR flagging which allows for TV to go into HDR mode. As far as I understand HDR metadata is part of EDID, so tool which allows to alter EDID should be enough (it's not as EDID is on the display side and we need extra info on the transmission side). Dr HDMI 4K has support for EDID CEA861 extension which carries HDR metadata, so you can do a lot by creating own presets (but only for display emulation). It may just not be as user friendly as eg. AJA or Vertex, but it's way cheaper.
Last edited by Andrew Kolakowski on Sat Oct 08, 2022 10:44 am, edited 2 times in total.
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Andrew Kolakowski

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Re: SDI -> HDMI converter with HDR metadata override

PostFri Oct 07, 2022 11:28 am

peter_a wrote:
Dave Del Vecchio wrote:Anyway, hope this is helpful in better understanding some of the HDMI signal format details.
That is a BRILLIANT summary. Thanks for taking the time.

My source device has no way of inserting the info frames necessary, so something like the Integral 2 seems to be necessary. If I get a solution working I'll report back.


If you have SDI which needs to go into HDMI TV then converter like AJA is probably overall best way to go. AJA is reliable as well.
If you already have some SDI to HDMI converter (without HDR insert) then you may think what will work better for you: new converter or hardware like HDFury.
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Andrew Kolakowski

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Re: SDI -> HDMI converter with HDR metadata override

PostFri Oct 07, 2022 2:38 pm

According to HDFury you can add HDR metadata by providing correct EDID (which you can generate with 3rd party tool), but not necessarily trigger HDR mode. I think they don't want people to use DR HDMI 4K for things which they provide in higher-end devices. If you want user friendly approach then Vertex 2 does it in simple web interface, so in very convenient way:

Image
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Dave Del Vecchio

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Re: SDI -> HDMI converter with HDR metadata override

PostSat Oct 08, 2022 6:57 am

As I mentioned earlier, EDID is used by the HDMI sink device (such as a display) to tell the HDMI source device what video formats it supports. So the primary direction of the information flow with EDID is in the opposite direction that the video data will eventually be sent.

So if you use an inline EDID override device like the HDfury Dr. HDMI 4K that device can now present a different EDID table to the EDID source device (this EDID table will be sent out of the Dr. HDMI's input port). But just changing the EDID table does not by itself alter the actual video content sent by the source to the sink device (and sent through the output port of the Dr. HDMI).

The reason changing the EDID table presented to the source device sometimes helps with HDMI signal format issues is that it will cause the source device (plugged into the Dr. HDMI input) to change the video content it actually sends. But EDID cannot cause a source device to send video data in a format it does not support.

It's true that there is an HDR related section of EDID, but this works like all the other video format sections of the EDID table and is used to communicate to the source device what the supported and preferred HDR formats are. So the sink device (display) can indicate which Electro-Optical Transfer Functions (EOTF) it can handle, what its preferred luminance range is (e.g. max brightness of the display), etc.

But EDID guarantees nothing about the video content that the actual source device will send. If the source device is not capable of generating video data in a particular resolution, then setting that as the preferred resolution in an EDID table will not help. Similarly if the source device cannot generate video with HDR infoframes, presenting an EDID table to the source device that says what HDR format is preferred will not solve anything.

The HDR metadata describing the HDR format of the video data that the source device is actually sending is in the Dynamic Range and Mastering InfoFrame. These InfoFrames are sent as a packet that is part of the video stream. InfoFrames are also used to describe other aspects of the video format such as resolution, refresh rate, color space, etc. (AVI InfoFrames). There are also Audio InfoFrames to describe the format of the audio data (channels, sample rate, etc.) being sent by the source device.

But it's InfoFrames (not EDID) that is the mechanism used by the source device to communicate information about the video content being sent. The extensions to InfoFrames (and EDID tables) to communicate HDR-related information are both described in the spec document I referenced earlier.

Just to recap, here are the signal flows used to communicate preferred and actual video format information between an HDMI source and sink device:
HDMI Source <--- EDID (preferred video format) --- HDMI Sink (display)
HDMI Source --- InfoFrames (actual video format) ---> HDMI Sink (display)


This is why an EDID override device (like the Dr. HDMI 4K) is not sufficient to communicate HDR metadata to an HDMI sink device (like a display). You need something that can actually add HDR InfoFrames into the video stream sent to the sink device. And some of HDfury's other devices (like the Integral 2 or Vertex) are capable of injecting or replacing HDR InfoFrames in the output video stream.

HDfury is not charging more for these other devices (like the Vertex, etc.) because they are easier to use, it's because they have additional processing capabilities that modify the actual video data stream flowing through the device. Which is not something that can be done via EDID overrides alone.

Anyway, just trying to clarify how HDMI signals work as I know there is often a lot of confusion about this. It's more complicated than something like SDI where the information only flows in a single direction (from source to sink) without any negotiation between devices.
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Andrew Kolakowski

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Re: SDI -> HDMI converter with HDR metadata override

PostSat Oct 08, 2022 10:38 am

We don't need to change any data in our case- it's already HDR signal just not flagged as HDR.

I think it's (at leats for me) clear now. It's metadata in InfoFrames which are transmitted "next to" video/audio data which trigger HDR mode. Dr HDMI 4K has no ability to alter InfoFrames (it can just alter EDID, but this is for other side of the chain), where other products do (so they cost more as they provide more features including web interface). Thanks for explanation.

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