Refresh Rates in Media Center

In this weeks Media Center Show I will have a couple of emails on refresh rates and Windows Media Center, so I wanted to create a discussion on refresh rates.

In the show (out Thursday 18th) one mailer from Sweden asked about a way of automatically switching Vista to the correct refresh rate to match the content, eg PAL 50hz and NTSC 60hz as he couldn't live with the mismatch of refresh rates.

Another email came in asking about whether the Xbox 360 supports 50hz output for HD content as 60hz refresh rate was making content broadcast at 50hz look very jerky on his TV.

This is not the first email I have had on the subject so I have created this thread to discus the issue and would love to hear your thoughts on it.

So how do you find the refresh rates in Media Center and Extenders?
Do you find the mismatch in rates a problem or do you think there is no problem?
Do you have a workaround?

I've never noticed a refresh rate option in MCE2005 (which I'm still using).

However, I'm UK based and need a 50Hz refresh rate (or more accurately 25Hz interlaced).

My solution was to configure a custom resolution of 1080i x 25Hz for my Radeon X1300 in the ATI Catalyst Control Centre.  This resolution appears to be respected by MCE and works well for broadcast material and DVDs with no flickering.  I've also used 720p x 50Hz successfully, but my LCD TV panel just looks better at 1080i

Hope this helps.

 

Hi Ian,
To answer your questions:

1. So how do you find the refresh rates in Media Center and Extenders?
Have the Media Center as office PC only, and use the 360 extender for all TV watching. I find that despite confirming in the Xbox setup that that TV is able to display 50Hz OK it will always revert back to 60Hz in HD modes. With the switch on the AV cable set to std TV it refreshes correctly at 50Hz. I think the table below summarises the modes available with the 360 Extender software:

Resolution   |  50Hz | 60Hz
480               |  yes     |   yes
576               |  yes     |   yes
720               |  no      |   yes
1080             |  no      |   yes

2. Do you find the mismatch in rates a problem or do you think there is no problem?
Some people in my family find there is not a problem - they get used to the judder of the News 24 ticker, or the judder as the camera pans horizontally in sports. I personally cannot get used to it and it drives me mad!
As I understand it, most of the worlds (inc UKs) TV footage is shot at 25 frames per second  (this is historically to make the frames in phase with the power grid frequency of 50Hz, to elimenate visible pulsing of studio lights, and to elimenate problems in early TV sets with 50Hz ripple appearing on screen). So with 25 fps you need to play back at say 50Hz, so that either each frame is shown twice (progressive mode) or once (interlaced mode, it does odd lines then even lines). As I understand it when you play back 25fps footage at 60Hz the system will be displaying the frames to quickly. The audio is being played at the correct speed, and as in video playback audio rules, the system has to regularly correct the video to match the audio. Hence the judder that we see.

Yes it is a problem, and it is a basic of video playback that the refresh rate of playback matches the frame rate. Most of the world outside of North / South America need 50Hz.

3. Do you have a workaround?
No, only to use standard definition and get the correct 50Hz setting on the 360.

I wonder if this is a question you could put to Microsoft: Perhaps to Jessica Zahn or perhaps the chap you interviewed from MS Media Center team based in Ireland?

Please, please Microsoft fix this bug!!

James

It's a major issue for users in 50Hz regions because almost all downloaded content is encoded as 24p (sometimes 23.976) or 60i, and all of this plays a lot better at 60Hz than 50Hz. Any of the HD trailers/samples from Apple and MS being a good example.

Of course, we have the option to manually change the refresh rate for any particular content, but I find that this is quite painful - it requires me to change it in both the Nvidia Control panel and also the VMC TV settings. And most of the time, the change doesn't stick at the first attempt. Changing the refresh rate is also a process that has zero WAF.

I'm planning to soon add a Bluray drive to my HTPC soon. Seeing as how the movies are encoded at 1080p24, I presume that this will be another reason for wanting to be able to easily switch from 50 to 60Hz. 

I don't have any workaround, but have been looking to write my first media center add-in to address this very issue because I am heartily sick of it. For anyone who is serious about video quality, the current situation is just not acceptable.

Of course, it's even worse for those PAL folk using the Xbox 360; the lack of 50Hz HD means that the Xbox is simply not viable as an extender for the main (HD) screen in a PAL household. IMO at least. I have one connected to an old CRT (so SD 50Hz) in the secondary location in my house, but would never commit the travesty of using an Xbox for my 70" SXRD. The Xbox situation is particularly frustrating since all available evidence suggests that the hardware is probably capable of 50Hz HD. Instead of fixing this, we have all these pokey Dashboard updates farting around with really useless stuff.

To top it all off, Linksys have told me that their new V2 extenders will likely be 60Hz only. Yes, I have already sent a ranting e-mail to them.

I would love to see this issue resolved. If the XBox 360 can do SD at 50Hz why the heck can't it be enabled to do it for HD content? Surely this cannot be so difficult to implement. It would solve a lot of issues for those of us in non 60Hz countries. The problem is annoying to say the least especially as my CRT TV (Panasonic) is totally incapable of using a 60Hz signal. Please get those in charge to look at and address this major problem, how hard can it be? You'll please a lot of folks if it's fixed. 

Do you find the mismatch in rates a problem or do you think there is no problem?

Definite problem since I notice the judder usually when watching Region 1 DVDs (60hz) and I've set VMC to be 50Hz.

 

Do you have a workaround?

Yes. AnyDVD has a function which will run a program depending on what type of disc you have loaded i.e insert a Region1 DVD and you set AnyDVD to run a program that will change the refresh rate to 60Hz. As part of AnyDVD there is a program called setdisplayfrequency and you set the correct parameter for this and upon insertion (and/or on eject) of a disc the desktop refresh rate is set. However, in VMC the resolution and refresh rate are independent of the desktop resolution so this dos not work (also a huge problem if you have two displays at different resolutions).

To workaround this I have used autohotkey to create two .exe's that loads registry settings, one for 60Hz and the other for 50Hz in VMC. I then point AnyDVD to the appropriate program to change the refresh rate. Works for me and the refresh rate is now set automatically for NTSC and PAL DVDs.

 
I'll post more details if anyone is interested.


 

Someone asked me for instructions, so here goes:

NOTE: Use at your own risk, messing with registry like this could have bad effects on your PC. 

Download autohotkey - http://www.autohotkey.com/

Create two registry files (.reg) for each refresh rate, mine are 50Hz.reg:

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Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Media Center\Settings\DisplayService]
"RefreshRate"=dword:00000032

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and 60Hz.reg:

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Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Media Center\Settings\DisplayService]
"RefreshRate"=dword:0000003C

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Then create two autohotkey scripts to load these registry files, my 50Hz.ahk file looks like this:

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if WinActive("ahk_class eHome Render Window")
WinClose
Run, RegEdit.exe /S C:\Users\paul\Documents\50Hz.reg
Run, C:\Windows\ehome\ehshell.exe

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Some explanation of the above, first 2 lines check if MCE is running and close it if it is. Third line loads the 50Hz registry file. Fourth line starts MCE back up again.

60Hz.ahk file:

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if WinActive("ahk_class eHome Render Window")
WinClose
Run, RegEdit.exe /S C:\Users\paul\Documents\60hz.reg
Run, C:\Windows\ehome\ehshell.exe

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Then use autohotkey to convert your ahk script files to exe's. You'll now be able to use AnyDVD to point to these exe's and run them as necessary.