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Possible to add a new refresh rate? - Printable Version

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+--- Thread: Possible to add a new refresh rate? (/showthread.php?tid=74214)



Possible to add a new refresh rate? - Sunflux - 12-16-2014

I have a fair bit of media in 25/50hz, but my North American TV does not report that as a compatible refresh rate. But I know that in many cases it isn't that the set isn't capable of supporting the rate, just that ithey choose not to report rates not supposedly appropriate for your area (the set actually does report 25hz compatibility for one resolution).

Is it possible to "add" a refresh rate to an existing resolution? This would be on a Chromebox running latest OE stable (Gotham), so we're talking Intel video.


Possible to add a new refresh rate? - chewitt - 12-17-2014

http://myit-solutions.blogspot.ae/2010/09/how-to-add-and-set-custom-display.html


Possible to add a new refresh rate? - Sunflux - 12-17-2014

WTH? Sitting on this screen for a while working up my response as I follow instructions and experiment, and then when I try to post it says "Your session has expired, please log in again" and then promptly LOSES everything I typed - and of course doesn't actually need me to log in again at all! What is WITH this forum? It's like a total usage nightmare (too "smart" for its own good), and I've been developing forum software since the late 90's! This isn't my first "problem" with it either: http://openelec.tv/forum/103-infared-remotes/73274-adding-missing-mce-functions-doesn-t-work#119678

Anyways, back to the point, and I'd better type fast. OpenElec doesn't seem to have the referenced "cvt" command, so I based my modeline on the 50hz one already posted here: http://wiki.openelec.tv/index.php?title=Configuring_a_Custom_xorg.conf#tab=Intel

Added the appropriate lines to my autostart.sh file, and it seems to work just fine. Only catch is Kodi's "System Info" screen still says it's outputting 1920x1080@60hz, but my A/V receiver confirms it's receiving and passing 50hz, and in A/B tests motion on my 25p files is silky smooth without any of the 50-60hz judder. My 24p and 60p files continue to switch refresh rates fine. So, as I suspected, the TV does support it!


Possible to add a new refresh rate? - chewitt - 12-17-2014

The forum software has sucked arse for several years; the current project staff are excellent at kernel fettling but very average webmasters, and despite the interstellar growth in our user numbers in recent years nobody has ever come forward to volunteer time and effort to evolve things. Until that situation changes, don't expect changes.

cvt is installed in /usr/bin/cvt on my test box (an old AppleTV) but it might vary with other builds. The main thing is you have a working modeline so you can investigate a custom xorg.conf to add the required mode to the Xorg modepool - the process for this depends on the GPU you have but there are examples on the wiki. Once you add the mode via Xorg (after a reboot) it will it will be selectable within Kodi settings.


Possible to add a new refresh rate? - Sunflux - 12-17-2014

I did a "find" on cvt and there wasn't anything (I can check that path a bit later when I'm beside the box again). But, adding xrandr addmode/newmode commands to autostart.sh did make the new modeline selectable within Kodi - I can rotate through "50hz" as an available refresh rate for 1080p. And it auto-selects it fine; it just seems that reporting that it's been selected is a bit off.

Is there some reason to want to use xorg.conf versus the xrandr route?


Possible to add a new refresh rate? - chewitt - 12-17-2014

I'd argue xorg.conf is less hacky.. but it ultimately gets you to the same place.


Possible to add a new refresh rate? - nickr - 12-17-2014

+1 on the forum software. The number of quite complex replies I have prepared only to have lost it because my "session expired" or some such. I have taken to delecting and copying my posts before pressing submit, in case I have to redo it. Boring.

EDIT: having said that I don't have the skills to fix it, and this is not a complaint, merely an encouragement for improvement!

Perhaps Sunflux needs to be on the team? *hint*


Possible to add a new refresh rate? - Sunflux - 12-17-2014

Heh - well, my first suggestion would be to ask for the reasoning behind a session timeout that seems to do nothing but prevent posting to pages that have been open a moderate amount of time, and if the feature is deemed dubious, then modify the code to extend the timeout such that it is no longer an issue. I would also re-evaluate any "soft" errors that result in the loss of created content, as that is at no time acceptable.

Anyways, back on topic, I guess I can ignore the reported refresh rate, as that never changes even when it's in 24hz mode either. But, xrandr shows it switching properly between my desired refresh rates. Must say true 50hz looks SO much better than trying to play it back at 60hz.


Possible to add a new refresh rate? - Sunflux - 12-18-2014

Question on the xorg.conf route - if I were to do that, would I have to recreate the modelines for every resolution and refresh rate I would want supported? And if so, where would I find that information?


Possible to add a new refresh rate? - chewitt - 12-18-2014

Depending on the GPU type it may be possible to completely disable EDID and define your own mode pool, but 99% of the time you're just appending your mode to the dynamic pool which is based on the EDID data from the TV over HDMI.