MythTV-light not changing display mode for recordings/video

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mr_smidge
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MythTV-light not changing display mode for recordings/video

Post by mr_smidge » Mon Dec 31, 2018 12:29 pm

Hello all,

I have noticed that when playing recordings and videos, MythTV-light does not appear to change the display resolution/refresh rate when watching a video that is different from the default display mode. I have enabled the "Separate video modes for GUI and TV playback” setting in the menu.

One thing I notice is that xrandr does not appear to have any effect on the latest raspbian:

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$ DISPLAY=:0 xrandr --output default --mode 1920x1080 --rate 24
xrandr: Failed to get size of gamma for output default
$
(I had to install xrandr by hand through the x11-xserver-utils package... the invocation succeeds but doesn't do anything.)

However, the tvservice utility works perfectly:

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$ tvservice -e "CEA 32 HDMI"
$
(Mode 32 is 1920x1080 24Hz.)

This sets the new mode without issue. I would really like to enable this, as it would (I hope) result in judder-free playback for 24Hz material, and allow me to use my TV's deinterlacing capabilities (the RPi doesn't seem to have enough processing power to handle yadif) for interlaced broadcast recordings.

For reference, I am using a RPi 3 Model B running Raspbian 9, connected to a TV that definitely supports all the modes I'm trying, via an AV receiver.

Any ideas? Many thanks!

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pgbennett
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Re: MythTV-light not changing display mode for recordings/video

Post by pgbennett » Mon Dec 31, 2018 5:14 pm

MythTV only supports changing display modes using xrandr, which is not supported on raspberry pi.

When decoding with openmax, raspberry pi supports openmax advanced deinterlace, which works well, so you should not need to try anything different. Is there a problem with that? There is an issue that if you use a new build of mythtv-light with an old raspbian version (prior to 2016-02-09) the deinterlace does not work, perhaps you need to upgrade your raspbian version.

mr_smidge
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Joined: Tue Nov 06, 2018 9:25 pm
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Re: MythTV-light not changing display mode for recordings/video

Post by mr_smidge » Tue Jan 01, 2019 4:03 pm

Hi pgbennett (& Happy New Year!),
pgbennett wrote:
Mon Dec 31, 2018 5:14 pm
MythTV only supports changing display modes using xrandr, which is not supported on raspberry pi.
Ah, that explains it!
pgbennett wrote:
Mon Dec 31, 2018 5:14 pm
When decoding with openmax, raspberry pi supports openmax advanced deinterlace, which works well, so you should not need to try anything different.
I have a recent Raspbian build, but will investigate openmax advanced deinterlace more closely.

Many thanks,

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