Question about "Lock HPD"

Hi,

I have a question about this setting before I pull the trigger and order a Vero V to replace my 4K+

I need to enable the “Lock HPD” option to prevent my projector (BenQ TK800) losing signal when starting a 3D movie.

My main reason for upgrading to a Vero V is to support Dolby vision playback on my TCL TV which the Vero will be connected to via an HDMI matrix switch.

If I lock the HPD, I presume that the Vero won’t detect the TV’s display capabilities, including DV support, from the EDID.

If this is the case, is there a workaround through DISP files or other EDID setting or spoofing solution?

In summary.

My projector supports HDR10 and 3D but needs HPD lock enabled.

My TV also supports DV which I would want to use where available (no 3D but I can control whether movies start in 3D even if the Vero thinks is can do 3D)

Thanks.

My understanding is enabling the HPD setting just keeps the Vero from kicking off a handshake if it detects a change to its HDMI’s plug status. The display capabilities would be detected on startup and not change until the next reboot.

Thanks.

The detect on reboot is the key i guess if this is the case.
if i want to play DV on my TV, and the EDID is locked to the projector (no DV), i would need to reboot the Vero to update the EDID.

The Vero should only be connected to one or other device at a time via an HDMI matrix switch.

The HPD lock is the only way I know to get 3d working on my projector so will always be enabled.

Why not just use the Vero 4k dedicated to the projector and the Vero V dedicated for the TV?

That’s fine, you can pass an EDID (either via /lib/firmware) or a softer approach is to use disp_cap.

This can be done identically on Vero 4K+ and Vero V.

Sam

You’re right—locking HPD typically breaks real-time EDID detection, so the Vero won’t reliably see your TV’s full capabilities (including Dolby Vision).

The usual workaround is to use a fixed/custom EDID (DISP file) that advertises DV while keeping HPD locked for the projector. Some users also handle this at the HDMI matrix level if it supports EDID management per output.

So yes, it’s doable, but you’ll likely need a “best of both worlds” EDID setup rather than relying on auto-detection.

1 Like

That’s looking like a good option, especially as I’ll have the 4k spare anyway.

I can’t see a better solution which will allow each display to work properly.

I need HPD lock for 3D on the projector and pass through audio for the AVR which I can set on the 4k, and EDID detection with 2 channel audio for the TV with Dolby vision support which I can configure in the V. (Just ordered yesterday)

I still don’t understand why HPD lock is required for 3D to work from the Vero, my Bluray player switches between the TV and projector, including switching to 3D mode automatically, without any need for such workarounds.

It probably isn’t needed.

You could upload a log with HPD Lock disabled so we can see EDID.
Then you could probably use a disp_cap_3d file to bodge any missing modes if not advertised properly by your AVR/Projector.

Sam

Thanks,

Here you go.
Playback test of Ant-Man and the Wasp (2018) - 3D MVC 1080p DTSHD-MA.mkv

This in on my 4k+, I’ve ony just ordered a V but I would expect the same behaviour.

https://paste.osmc.tv/ehiruxeqad

This looks like the issue, It repeats several times before I stopped the video.
During this time the projector had no display, and no audio started either.

[WHITELIST] Searching the whitelist for: width: 1920, height: 1080, fps: 23.976, 3D: true, 3d mode flags: 0x20

I’ll need to check with HPD lock enabled, would this change the whitelest behavioiur or display mode change?

Here is the contents of my disp_cap_3d

480p60hz TopBottom SidebySide
576p50hz TopBottom SidebySide
720p50hz FramePacking TopBottom SidebySide
720p60hz FramePacking TopBottom SidebySide
1080p24hz FramePacking TopBottom SidebySide
1080p25hz FramePacking TopBottom SidebySide
1080p30hz FramePacking TopBottom SidebySide
1080p50hz FramePacking TopBottom SidebySide
1080p60hz FramePacking TopBottom SidebySide

Bump

Please enable debug logging

Sam

Sorry - it’s been a while.

Here you go.
HPD unlocked - projector loses signal, movie does not start

https://paste.osmc.tv/ayubotakoh

HPD locked - projector switches to 3D and movie starts.

https://paste.osmc.tv/omihoputud

My Vero V has arrived .

As expected it has the same issue with switching my projector to.3D, but is otherwise working well switching between my TV with Dolby Vision support detected and working, and the projector with only HDR 10.

If there’s no way to get the Vero V to handle 3D with HPD lock disabled, I will connect the Vero 4k+ for 3D use.