composite out signal distortion

[mad4pi]

Hello one and all,

I've been trying to get composite / AV video working on the Raspberry Pi 4, but all I seem to be able to get is a wildly distorted image; coloured diagonal stripes dancing over the screen with the TTY console and / or X11 login screen (depending on attempt) showing vaguely in the mix being the best I have gotten so far.

I have tried:

* 2 different Raspberry Pi 4 units
* Raspbian, Ubuntu, Manjaro
* 4 different cables AND different colour combinations (yellow to yellow, red to yellow, white to yellow)
* different televisions and even an AV capture card hooked up to 'tvtime' on another computer
* different framebuffer sizes
* different television standards
* different aspect ratios
* turning progressive scan on / off
* enabling / disabling fkms
* ...

All to no avail. The same cables and output devices worked fine with a Raspberry Pi 3B and Raspberry Pi 3B+ in the past.

I've Googled myself silly looking for posts describing similar issues, but all I seem to be able to find are people not being able to get the signal up in the first place (i.e. forgot turn on enable_tvout=1, experimenting with the tvservice command).

Those solutions don't match my problem however as I do get a signal - just not a very functional one...

Can anyone offer any insight?

[klricks]

Maybe you need to update firmware? See: viewtopic.php?f=28&t=271154

[mad4pi]

Maybe you need to update firmware? See: viewtopic.php?f=28&t=271154

Thank you for the reply - much appreciated

I did actually consider that it might be a firmware issue and did see a mention of the RPi team regressing something in order to fix something in the composite video department. I updated both Pi's to the April 16 stable / critical release prior to posting my help request, but to no avail.

My problem is similar to the one mentioned in the link you posted, although in my case the OS does boot - and the distortion does show a very vague console and lightdm login screen behind the distortion at their respective moments in the boot up process.

[mahjongg]

Sounds like this problem (inverted video signal)

viewtopic.php?p=653422#p653422

[mad4pi]

Maybe you need to update firmware? See: viewtopic.php?f=28&t=271154

I tried running kernel 5.4.x that is available through rpi-update, but that didn't change anything either

[mad4pi]

Sounds like this problem (inverted video signal)

viewtopic.php?p=653422#p653422

I wish the screen output was that good - the distortion is actually a lot worse than that. When I say vaguely visible login screen - I mean the basic shape, logo and some text can more or less be made out but not as good as in the link you sent.

I've tried about 5 different cables at this point - 3 of which worked perfectly fine with the Raspberry Pi 3B & 3B+.

It's only my 2 Raspberry Pi 4B's that have this problem.

I thought it might be a firmware or kernel issue, but I've updated both and no change.

[Burngate]

Sounds like this problem (inverted video signal)
viewtopic.php?p=653422#p653422

I wish the screen output was that good - the distortion is actually a lot worse than that.

Can we see a photo of it?

[mad4pi]

Sounds like this problem (inverted video signal)
viewtopic.php?p=653422#p653422

I wish the screen output was that good - the distortion is actually a lot worse than that.

Can we see a photo of it?

Ah yes, apologies - I should have thought of that

In PAL mode it will stay like this for a brief while:

pal.jpg (219.71 KiB) Viewed 306 times

Which then quickly becomes:

pal_2.jpg (226.99 KiB) Viewed 306 times

NTSC mode however never gets any better than:

ntsc.jpg (161.94 KiB) Viewed 306 times

For the record:

The pictures listed above are from the Raspberry Pi's composite out being fed into an analogue capture card + 'tvtime' (a GNU/Linux analogue capture card viewer which supports both PAL and NTSC). I have tested said capture card + 'tvtime' with an external HDMI to AV converter box connected to the Pi and that worked just fine.

Note: The output above is exactly the same on the 2 different televisions I have tried with the Pi 4.

[hippy]

Similar issues in the following thread. As noted there I have never got Raspberry Pi composite video to work with my PVR, which is in essence a capture card. PI composite works with other things. Other composite sources work with the PVR.

viewtopic.php?f=28&t=273498

[mad4pi]

Similar issues in the following thread. As noted there I have never got Raspberry Pi composite video to work with my PVR, which is in essence a capture card. PI composite works with other things. Other composite sources work with the PVR.

viewtopic.php?f=28&t=273498

The image in the link you sent is still a lot better than what I get in my setup though. It's not actually a PVR but a very simple minimalistic UVC chip on a USB stick - which works fine with the Raspberry Pi 3 and 3B+. The behaviour is exactly the same when I hook up the Pi 4 to a television set (I've tried 2 different ones).

The problem must be something else...

I'll try reverting to an old firmware and raspbian installation and see if that works. If it does, then at least I'll know there is still some firmware issue lurking about.