Where to post HDMI hardware Q?

[Esc_Jim]

Hi all - I'm new here and unsure of the best place to post this.

I'm looking for a (cheap) way to derive a V sync pulse from an HDMI signal. I'm aware of the Analog Devices decoder chip, but it's way too expensive.

There are $20 HDMI --> VGA adapters that have H+V sync on the VGA output, but they're locked to certain standards. You can only use them with 1080p/60, for example. Not surprising, since there are no 24fps VGA monitors (-:

I'm open to something using a fast micro with HDMI-in. Programming wouldn't be a problem (he says)

Any ideas, or a better place to post this?

Thanks!

[pandy]

I'm looking for a (cheap) way to derive a V sync pulse from an HDMI signal. I'm aware of the Analog Devices decoder chip, but it's way too expensive.

There are $20 HDMI --> VGA adapters that have H+V sync on the VGA output, but they're locked to certain standards. You can only use them with 1080p/60, for example. Not surprising, since there are no 24fps VGA monitors (-:

I'm open to something using a fast micro with HDMI-in. Programming wouldn't be a problem (he says)

Any ideas, or a better place to post this?

HDMI doesn't carry H and/or V sync pulses - contrary to DVI where H and V sync pulses are transmitted jointly with video data - this is fundamental difference between HDMI and DVI - HDMI use VBI (Video Blanking Intervals) to carry auxiliary information (for example audio samples). You need HDMI receiver to recreate H and V sync pulses (if your HDMI sink require such pulses).
HDMI transmit video data + auxiliary data and they are sent with structure described by signaled, particular video mode (HDMI sink sent EDID signal with information about supported video modes, HDMI source interpret EDID and set video mode accordingly to signaled).

[Esc_Jim]

>> HDMI doesn't carry H and/or V sync pulses -

Sorry for not being perfectly literal. I want to create V sync pulses based on the timing information in the HDMI signal. What I'm looking for is a way to do it without needing an entire receiver or an expensive 'receiver on a chip' like the AD. I may have found something in the $30 TFP401 decoder breakout from Adafruit. I'm waiting for confirmation that it can do its decoding at any supported HDMI frame rate.

[pandy]

>> HDMI doesn't carry H and/or V sync pulses -

Sorry for not being perfectly literal. I want to create V sync pulses based on the timing information in the HDMI signal. What I'm looking for is a way to do it without needing an entire receiver or an expensive 'receiver on a chip' like the AD. I may have found something in the $30 TFP401 decoder breakout from Adafruit. I'm waiting for confirmation that it can do its decoding at any supported HDMI frame rate.

TFP401 doesn't support HDCP. It should decode any format where pixel clock is between 25 and 165MHz. To set desired video mode you need EDID source - https://learn.adafruit.com/adafruit-tfp401-hdmi-slash-dvi-decoder-to-40-pin-ttl-displa...iting-the-edid

[Esc_Jim]

TFP401 doesn't support HDCP. It should decode any format where pixel clock is between 25 and 165MHz. To set desired video mode you need EDID source - https://learn.adafruit.com/adafruit-tfp401-hdmi-slash-dvi-decoder-to-40-pin-ttl-displa...iting-the-edid

Thanks, yep, I saw that but I'm hoping that, since the video itself is of no interest, it will provide the V sync info from the original HDMI signal regardless of its resolution and the EDID won't matter. On order, I'll see if my dreams come true...

[pandy]

TFP401 doesn't support HDCP. It should decode any format where pixel clock is between 25 and 165MHz. To set desired video mode you need EDID source - https://learn.adafruit.com/adafruit-tfp401-hdmi-slash-dvi-decoder-to-40-pin-ttl-displa...iting-the-edid

Thanks, yep, I saw that but I'm hoping that, since the video itself is of no interest, it will provide the V sync info from the original HDMI signal regardless of its resolution and the EDID won't matter. On order, I'll see if my dreams come true...

Once again - you need to understand how HDMI works, EDID is crucial as receiver tells to video source what kind of display mode (video format) should be used - HDMI source can't output video until process of handshake between HDMI source and HDMI sink will be complete - technically HDMI source will output video in format required by HDMI sink if HDMI source is capable to output such video format.