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Visitor simontheu
Visitor
253 Views
Registered: ‎09-15-2019

HDMI Without AVI Infoframes

Hi,

I have been developing a custom HDMI core on Xilinx Artix-7, and with some devices it does not show any video at all or it is very intermittent, but on other devices the signal is solid.

I do NOT currently implement any AVI Infoframes. Could this be the reason? Or should I be more worried about things like phase drift between TMDS lanes?

Any help appreciated.

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7 Replies
Scholar watari
Scholar
241 Views
Registered: ‎06-16-2013

Re: HDMI Without AVI Infoframes

Hi @simontheu 

 

What kind of HDMI do you implement ? HDMI Rx or HDMI Tx ?

 

If Rx, you must implement DDC/CI and use suitable EDID.

If Tx, you can only output suitable video signal without AVI infoframe.

 

Best regards,

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Visitor simontheu
Visitor
223 Views
Registered: ‎09-15-2019

Re: HDMI Without AVI Infoframes

It's HDMI TX. The video content is RGB444 so is the base format for when info frames are not present, but the compatibility is very poor. Do you think no AVI info frames could be the cause?

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Scholar watari
Scholar
194 Views
Registered: ‎06-16-2013

Re: HDMI Without AVI Infoframes

Hi @simontheu 

 

Why don't you use RGB888 instead og RGB444 ?

 

Also, do you use correct protocol ?

 

It seems protocol issue.

I suggest you to make sure HDMI protocol, first.

 

Best regards,

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Moderator
Moderator
144 Views
Registered: ‎11-21-2018

Re: HDMI Without AVI Infoframes

@simontheu 

If your question is answered or your issue is solved, please kindly mark the response which helped as solution (click on "Accept as solution" button below the reply).

 

If this is not solved/answered, please reply in the topic giving more information on your current status.

 

Thanks and Regards,

Aoife
Product Application Engineer - Xilinx Technical Support EMEA
**~ Don't forget to reply, give kudos, and accept as solution.~**
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Visitor simontheu
Visitor
140 Views
Registered: ‎09-15-2019

Re: HDMI Without AVI Infoframes

RGB888? Double samples. I dont think we have the bandwidth for that. It was my understanding that RGB444 was the default standard if no AVI Infoframes are present? 

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Scholar watari
Scholar
106 Views
Registered: ‎06-16-2013

Re: HDMI Without AVI Infoframes

Hi @simontheu 

 

There are TIPS for you about HDMI.

 

- HDMI uses TMDS protocol to reduce/minimize DC component.

  -> Must use correct encoding/decoding pattern. which known as K code.

- Don't need AVI infoframe, if you don't concern compatibility.

  -> Some HDMI signal and pattern generators can turn off AVI infoframe.

  -> It is hard to decode TMDS signal without negotiation in HDMI sink side, if you use specific clock frequency and/or specific resolution.

- There is YUV444 as default format. Also, there are YUV422, YUV420, RGB88 and so on.

 

So, I suspected it's protocol issue...

 

Best regards,

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Visitor simontheu
Visitor
87 Views
Registered: ‎09-15-2019

Re: HDMI Without AVI Infoframes

Hi Watari,

Thanks for your input.

When you say negotiation, I take you are referring to the i2c EDID part of the protocol?

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