Raks2003
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Joined: Thu Jul 18, 2019 8:32 pm

RPI 4 video flickering issue

Thu Jul 18, 2019 8:48 pm

Hi Guys,

Before i start, I am a first time user of the Raspberry PI (never owned any of the previous models), and am sorry if my post doesn't make sense.

A few weeks ago I purchased my first RPI4. It all appeared to work fine, booted fine etc - But, during video playback, e.g. Youtube or Kodi, there is an annoying flicker. It doesn't flicker like crazy, i can still see the image, but its distracting.

I was disappointed by this, contacted Customer Services who promptly responded, and sent back my RPI4 for a refund. Whilst emailing them i asked "If you issue me a refund, and I buy another new Raspberry Pi 4, will it be able to work as advertised? E.g. to be able to play YouTube videos correctly?".

There response was "We should not see there being an issue if you order another new Raspberry Pi 4."

So, i ordered another - and i received my second RPI4 today.

I set it up, and it has exactly the same annoying flickering issue. As previously, i have tried two different Micro HDMI cables, and two different TV's. Yet the flicker is still there. I have tried to change the resolution of the desktop screen, from 1080 to 720, and still have the same issue. Even when a youtube video is playing in windowed mode, i can still see the flicker. (even if i run the youtube video at 360p).

Am i doing something wrong here?

Thank you

pcmanbob
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Re: RPI 4 video flickering issue

Fri Jul 19, 2019 7:21 am

Hi.

So is this flickering just affecting just the actual video or all of the screen ?

please can you give use some basic info as well

which OS are you running
what power supply are you using
have you made any changes to config.txt
are you using chrome to view youtube or some other browser
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RaTTuS
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Re: RPI 4 video flickering issue

Fri Jul 19, 2019 7:51 am

can you record and show this flickering -
have you got a decent micro usb / hdmi lead
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jamesh
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Re: RPI 4 video flickering issue

Fri Jul 19, 2019 8:52 am

I suspect you are seeing 'tearing' about half way down the image, which is a side effect of running through X windows and its single buffered framebuffer. Try running full screen rather than in a window.
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Raks2003
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Joined: Thu Jul 18, 2019 8:32 pm

Re: RPI 4 video flickering issue

Fri Jul 19, 2019 1:53 pm

Firstly, thank you for taking the time to write back - i appreciate it

I've had some slight success since last night - i decided to give LibreELEC a go, and it plays Youtube videos fine (using the add-on), and other videos from my USB stick - with NO annoying flicker. :D

The issue is still there with Raspbian though :(

OS - I'm currently using Raspbian (downloaded from NOOBS_v3_2_0). I had the same issue with my previous RPI4, when using NOOBS_v3_1_1.
PSU - using the official Power Supply for RPI4, from the PiHut website.
config.txt - I've made no changes to this.
Browser - I'm using Chrome, the default browser that came with Raspbian.

Windowed/Fullscreen mode - i get the same flickering issue regardless
Micro HDMI cable - I'm not sure where my original cable came from, but i bought one from Amazon recently https://www.amazon.co.uk/gp/product/B00 ... UTF8&psc=1
(if LibreELEC plays the videos correctly, then surely it isn't a HDMI cable issue?)

I will try to record a video this evening of the flicker issue.

Thank you very much!

jamesh
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Re: RPI 4 video flickering issue

Fri Jul 19, 2019 2:31 pm

Raks2003 wrote:
Fri Jul 19, 2019 1:53 pm
Firstly, thank you for taking the time to write back - i appreciate it

I've had some slight success since last night - i decided to give LibreELEC a go, and it plays Youtube videos fine (using the add-on), and other videos from my USB stick - with NO annoying flicker. :D

The issue is still there with Raspbian though :(

OS - I'm currently using Raspbian (downloaded from NOOBS_v3_2_0). I had the same issue with my previous RPI4, when using NOOBS_v3_1_1.
PSU - using the official Power Supply for RPI4, from the PiHut website.
config.txt - I've made no changes to this.
Browser - I'm using Chrome, the default browser that came with Raspbian.

Windowed/Fullscreen mode - i get the same flickering issue regardless
Micro HDMI cable - I'm not sure where my original cable came from, but i bought one from Amazon recently https://www.amazon.co.uk/gp/product/B00 ... UTF8&psc=1
(if LibreELEC plays the videos correctly, then surely it isn't a HDMI cable issue?)

I will try to record a video this evening of the flicker issue.

Thank you very much!
Sadly, I think this is to be expected (if it is the tearing I mentioned above). This is due to the X windows system not being double buffered, so screen updates can happen during display updates, giving rise to tearing. We won't be spending the years of work required to make X double buffered. For serious video playback, use Kodi (in LibreElec) as that double buffers.
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Raks2003
Posts: 3
Joined: Thu Jul 18, 2019 8:32 pm

Re: RPI 4 video flickering issue

Fri Jul 19, 2019 7:28 pm

Sadly, I think this is to be expected (if it is the tearing I mentioned above). This is due to the X windows system not being double buffered, so screen updates can happen during display updates, giving rise to tearing. We won't be spending the years of work required to make X double buffered. For serious video playback, use Kodi (in LibreElec) as that double buffers.
Thank you very much for clarifying this Jamesh.

Is this a problem that's native to the Raspbian OS? I'm wondering if other OS's may or may not have the same issue, and may be worth a try.

gkreidl
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Re: RPI 4 video flickering issue

Fri Jul 19, 2019 8:41 pm

I'm not sure about Buster and the RPi 4 yet, but if you use VLC and the X11 MMAL Splitter output there will be no tearing, lost frames etc. when you switch to full screen mode (key "f"). VLC then switches to overlay mode.
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dom
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Re: RPI 4 video flickering issue

Thu Jul 25, 2019 1:45 pm

Raks2003 wrote:
Fri Jul 19, 2019 7:28 pm
Is this a problem that's native to the Raspbian OS? I'm wondering if other OS's may or may not have the same issue, and may be worth a try.
The problem is kodi in raspbian buster predates the Pi4, has no hardware decode support and triggers a bug in GL that causes tearing.

LibreELEC has pi 4 specific support and doesn't suffer from this.

Kodi with Pi4 patches can be built for raspbian - one user did it here: https://github.com/popcornmix/omxplayer/issues/714

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