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#21 tokyovigilante

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Posted 17 September 2010 - 06:17 AM

Next version of Plex 9 maybe?

Edit:

The new library and Plex for iOS are awesome. I'm watching Dragnet on my iPhone. :D

Yes :).

#22 belongamick

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Posted 18 September 2010 - 08:37 PM

Guys, I have a Pioneer Plasma TV - hence my interest in Plex doing auto refresh rate changing.

Would I be right in saying that Plex auto refresh rate changing is only something you would need (to avoid judder) on Plasma and CRT displays, and it is not needed on LCD displays due to how they work?

I am confused on this matter as I have read on one hand LCD TV's do not have a refresh rate, but then see 240Hz LCD's advertised - or are refresh rates and Hz different things?


Just found this on WikiPedia: "On smaller CRT monitors (up to about 15"), few people notice any discomfort below 60–72 Hz. On larger CRT monitors (17" or larger), most people experience mild discomfort unless the refresh is set to 72 Hz or higher. A rate of 100 Hz is comfortable at almost any size. However, this does not apply to LCD monitors. The closest equivalent to a refresh rate on an LCD monitor is its frame rate, which is often locked at 60 fps. But this is rarely a problem, because the only part of an LCD monitor that could produce CRT-like flicker—its backlight—typically operates at around 200 Hz."

#23 Atrus

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Posted 18 September 2010 - 10:38 PM

Guys, I have a Pioneer Plasma TV - hence my interest in Plex doing auto refresh rate changing.

Would I be right in saying that Plex auto refresh rate changing is only something you would need (to avoid judder) on Plasma and CRT displays, and it is not needed on LCD displays due to how they work?

I am confused on this matter as I have read on one hand LCD TV's do not have a refresh rate, but then see 240Hz LCD's advertised - or are refresh rates and Hz different things?


Just found this on WikiPedia: "On smaller CRT monitors (up to about 15"), few people notice any discomfort below 60–72 Hz. On larger CRT monitors (17" or larger), most people experience mild discomfort unless the refresh is set to 72 Hz or higher. A rate of 100 Hz is comfortable at almost any size. However, this does not apply to LCD monitors. The closest equivalent to a refresh rate on an LCD monitor is its frame rate, which is often locked at 60 fps. But this is rarely a problem, because the only part of an LCD monitor that could produce CRT-like flicker—its backlight—typically operates at around 200 Hz."

As I have understood it, LCD screens are also very much effected by this problem. The Wikipedia reference you added seems to be describing the discomforts of using Windows or OSX in general if the refresh rate of the screen is low. When watching a movie there are several frames showing every second to form fluid motion. If the refresh rate is not in synch with the frames of the movie you will get issues.
I am not an expert in this field, so await confirmation about this from other sources before believing my every word though :P

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#24 tokyovigilante

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Posted 18 September 2010 - 10:59 PM

As I have understood it, LCD screens are also very much effected by this problem. The Wikipedia reference you added seems to be describing the discomforts of using Windows or OSX in general if the refresh rate of the screen is low. When watching a movie there are several frames showing every second to form fluid motion. If the refresh rate is not in synch with the frames of the movie you will get issues.
I am not an expert in this field, so await confirmation about this from other sources before believing my every word though :P

It is optimal for any display device to run at the framerate of displayed content, for smooth motion. However the design of CRTs means that they cannot refresh the display fast enough below 60Hz to prevent flicker (the CRT electron beam scans each phosphor (ie pixel) in sequence). This is why we have (had) interlacing in the first place.

Plasma / LCD will not flicker at low refresh rates, as the entire frame is updated instantaneously.

#25 RobG

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Posted 17 May 2011 - 10:27 PM

Any updates?

#26 docjoe

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Posted 30 May 2011 - 08:54 PM

+1

Autorefresh is badly needed!

#27 RockStar

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Posted 30 May 2011 - 09:11 PM

im also eagerly awaiting this. any news from the devs would be appreciated.
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#28 craigdwlr

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Posted 10 September 2011 - 08:43 PM

Hey Rob,

I tried downloading this and it didn't do anything is there something else I need to do after downloading?

thanks a lot
Criag

#29 John Lockwood

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Posted 12 September 2011 - 10:58 AM

Guys, I have a Pioneer Plasma TV - hence my interest in Plex doing auto refresh rate changing.

Would I be right in saying that Plex auto refresh rate changing is only something you would need (to avoid judder) on Plasma and CRT displays, and it is not needed on LCD displays due to how they work?

I am confused on this matter as I have read on one hand LCD TV's do not have a refresh rate, but then see 240Hz LCD's advertised - or are refresh rates and Hz different things?


Just found this on WikiPedia: "On smaller CRT monitors (up to about 15"), few people notice any discomfort below 60–72 Hz. On larger CRT monitors (17" or larger), most people experience mild discomfort unless the refresh is set to 72 Hz or higher. A rate of 100 Hz is comfortable at almost any size. However, this does not apply to LCD monitors. The closest equivalent to a refresh rate on an LCD monitor is its frame rate, which is often locked at 60 fps. But this is rarely a problem, because the only part of an LCD monitor that could produce CRT-like flicker—its backlight—typically operates at around 200 Hz."

Your confusing two different things - flicker and judder.

Flicker dates back to CRT displays being used as computer monitors. With a computer image being more static, it was possible to notice at the typical refresh rates of CRT displays (50 or 60Hz) a flicker. Remember CRT displays are almost always interlaced meaning that half the image is drawn, then the other half. This results in thin horizontal lines in particular appearing to 'flicker'.

Judder is different and mainly applies to LCD and Plasma displays. It would also apply to variations on LCD i.e. LED (which are really LCD displays) but also AMOLED or OLED displays should you have one. These displays are usually but not exclusively used in progressive (non-interlaced) mode so do not suffer the flicker problem as much. They would if used in interlace mode with a computer image flicker due to the same reasons.

Before I move on to what judder is, I will just address the issue of 120Hz or 240Hz displays. These can still be interlaced but draw the same interlaced images multiple times per second, if 60Hz results in half the image being drawn 30 times a second (2 halves x 30 = 60) then at 120Hz it would be 2 halves x 60 = 120, and at 240Hz it would be 2 halves x 120 = 240. This gives the benefit of reducing the flicker effect.

Now juddering. Films are normally in one of three refresh rates, these being 24fps (progressive), 25fps (interlaced), or 30fps (interlaced). I am deliberately keeping this simple and rounding up numbers. Now if you show a 25fps (interlaced) movie on a display set to 50Hz you have a perfect match since it equates to 2 halves x 25 = 50. The same applies if you are playing 30fps (interlaced) on a 60Hz display as this is 2 halves x 30 = 60. If however you play a 30fps movie on a 50Hz display then you do not have an exact match, so in order to compensate either a frame has to be thrown away or duplicated to stretch the timing to match. This disrupts the smooth appearance and hence you get juddering. It is most noticeable when the camera is panning left or right, or when a new ticker is playing across the bottom of the screen, or when a football is moving across the screen.

Modern Plasma and LCD TVs can often support all three film speeds, and even multiples there of e.g. 300Hz. The problem is that while a domestic DVD player might auto set its output to match the rate of the film on the DVD and the TV might autodetect this and match itself, Plex does not currently set the Macs output automatically to match the rate of the film being played.

This feature has been requested dozens (possibly now hundreds) of times, and is a feature that XBMC on Linux apparently already supports. The Mac hardware can certainly do this, it is merely a matter of the Plex developers getting around to implementing it.

#30 Atrus

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Posted 12 September 2011 - 03:25 PM

<snip>
This feature has been requested dozens (possibly now hundreds) of times, and is a feature that XBMC on Linux apparently already supports. The Mac hardware can certainly do this, it is merely a matter of the Plex developers getting around to implementing it.

Only the windows version of XBMC has the refresh rate switching working. Not the Mac version. The Mac XBMC dev/devs have said that they will work on it after they have released the next big version.

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#31 John Lockwood

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Posted 13 September 2011 - 09:52 AM

Only the windows version of XBMC has the refresh rate switching working. Not the Mac version. The Mac XBMC dev/devs have said that they will work on it after they have released the next big version.

Thanks for the correction. I note however you do not comment on the likelyhood of the Plex team adding it. ;)

#32 tokyovigilante

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Posted 13 September 2011 - 09:55 AM

Thanks for the correction. I note however you do not comment on the likelyhood of the Plex team adding it. ;)

Its very likely, in fact I intend to as soon as possible. It's in fact already written, I just need to get access to a 24p TV to test it, and currently I don't have access to a 10.7 system either (Plex doesn't yet compile cleanly under 10.7, although it will run on it). Don't fret! These things always take longer than we'd like, but as always real life does get in the way...

#33 knight2001dts

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Posted 13 September 2011 - 10:20 AM

Thanks tokyovigilante!

This is great news.

I'm running 10.6.4 at present on a 24p tv if you would like me to test something for you?

Just send me a PM if you need some code tested.

CHEERS!

Knight.

#34 Soli

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Posted 14 September 2011 - 05:08 AM

Tokyo:
Will plex be able to switch to both 23.976 and 24hz, 59.94 and 60hz?
I use Plexbmc (I just set my display to 24hz at all times), and movies at 23.976 will get a little judder each 40sec. I have also tried setting 23.976hz with switchresx but I have not succeeded.. a quick fix for me is to use the video clock as A/V sync (in XBMC) and drop audio when neccesary.
Anyways, I hope you also fix the audio sync at 24hz at the same time.
I'll jump right back to Plex whenever autorefresh is coming. Heck, I'd jump back to Plex if Plex would support 24hz without lagging (and it would be nice to be able to drop audio frames like XBMC, if true 23.976 isn't possible)

#35 Atrus

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Posted 14 September 2011 - 10:20 AM

Tokyo:
Will plex be able to switch to both 23.976 and 24hz, 59.94 and 60hz?
I use Plexbmc (I just set my display to 24hz at all times), and movies at 23.976 will get a little judder each 40sec. I have also tried setting 23.976hz with switchresx but I have not succeeded.. a quick fix for me is to use the video clock as A/V sync (in XBMC) and drop audio when neccesary.
Anyways, I hope you also fix the audio sync at 24hz at the same time.
I'll jump right back to Plex whenever autorefresh is coming. Heck, I'd jump back to Plex if Plex would support 24hz without lagging (and it would be nice to be able to drop audio frames like XBMC, if true 23.976 isn't possible)

Sounds like you have been searching for some answers in the XBMC forums already, but maybe you have missed this: As I have understood it, the Sandybridge (and Clarkdale) driver can only output 24hz, not 23.976 (which is 24p). Plex can only work within the framework supplied by the hardware and software developers that supersedes them. That means that every 41.7 seconds a frame will be doubled.
XBMC has solved this by adding a feature which speeds up the movie with 0.1% (from 23.976fps to 24fps) thus ending up in the sweet-spot, right smack in the middle of Intel/Apple output of 24hz. This does however poses some other issues by the looks of it. Particularly some a/v synch issues which is noticeable during dialogue.

I don't know if Tokyo can do anything. I assume he can't patch the intel drivers, but he has always had some kinds of tricks of his sleeves. :)

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#36 Soli

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Posted 15 September 2011 - 06:04 AM

I have Mac minis with nVidia and ATI GPUs, the sandy bridge 24hz bug does not concern them. The problem is that Apple does not allow one to select 23,976hz in display settings. Only 24hz. And I can´t seem to force 23.976hz with switchresX either of unknown reasons. I will check if Windows with Plexbmc supports 23.976hz (I am most certain that it does) My monitor will handle both , as most TVs which support 24hz does, even though it will say 24hz on both.

Damn you NTSC. This little 0.1% is still the difference between a really good Blu-ray player and computer based HTPC. Although XBMC´ little fix is close enough for now. But 23.976 and bitperfect sound would still be the holy grail of course, as dropping sound samples or resampling can have a negative effect on the overall sound. I imagine that the best would be to use the sound clock as A/V sync and the have the video hz match ths movie fps for the ultimate sound and video reproduction.

I just had an experiment with some of my unsuspecting friends. We were watching some football this night, and afterwards I just put on a scene from Gladiator. Within seconds, everybody were fully involved with the movie. After a while I had to turn on the lights and switch back to TV, or we would have watched the whole movie! And that is the difference between 24hz and Plex´ stuttering 60hz mode.

ps! according to Anandtech (http://www.anandtech...c-perspective/7) it seems Intel has released a new driver (for windows) that supports 23.976hz . It does say "of some sorts", so I don´t know if that means 23.97hz (doubling frame each 1000 seconds) or 23.976hz

#37 tokyovigilante

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Posted 15 September 2011 - 09:08 AM

Tokyo:
Will plex be able to switch to both 23.976 and 24hz, 59.94 and 60hz?
I use Plexbmc (I just set my display to 24hz at all times), and movies at 23.976 will get a little judder each 40sec. I have also tried setting 23.976hz with switchresx but I have not succeeded.. a quick fix for me is to use the video clock as A/V sync (in XBMC) and drop audio when neccesary.
Anyways, I hope you also fix the audio sync at 24hz at the same time.
I'll jump right back to Plex whenever autorefresh is coming. Heck, I'd jump back to Plex if Plex would support 24hz without lagging (and it would be nice to be able to drop audio frames like XBMC, if true 23.976 isn't possible)

Plex will select the best display rate the output device supports for the playing media. If OS X presents 23.976Hz and 24Hz as discrete options, then yes. I'm not convinced this is technically possible with most consumer displays and HDMI, although I'm happy to be corrected by anyone with technical documentation.

My personal preference regarding sync is to not reclock audio, and just drop/repeat frames as necessary. Core Video in 10.6/7 makes this much easier. I find video skipping much less jarring than audio skip, particularly when it's only a frame or two.

#38 Soli

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Posted 15 September 2011 - 12:18 PM

Tokyo: There might be some displays that would either accept only 24 or 23.976hz when the "24hz" thing was in it's infancy. I mean, surely some manufacturers managed to screw this up, when even the mighty Intel managed to f*ck up a similar thing in their GPUs.
However, most manufacturers got it right, and all TV manufactured today will accept both 23.976 and 24hz. (it will still say 24hz anyways, as the "24hz" feature is for alle practical purposes really meant for films with 23.976fps. For films that are true 24hz, the "24hz" feature will still be 24hz :)

Proper plasmas will take 23.976/24hz and either triple or quadruple it, and display at 71.928/72hz or 95.904/96.

Not convinced? I just set up Win 7 with Plexbmc on my Mac mini 2011 with ATI GPU. And yes, both 23.976 and 24hz are available. The same is true for 59.94 and 60hz. And the picture is just stunning and amazing.

I will make a new thread about this..as even I was surprised at the difference it makes.. It is noticeably better than even the 24hz mode in OSX.
Don't know why 23.976 is not available in OSX, what with Final Cut and all.

#39 John Lockwood

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Posted 19 September 2011 - 02:23 PM

Deleted as I can see I had already replied.

Edited by John Lockwood, 19 September 2011 - 02:25 PM.


#40 Lundmark

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Posted 20 October 2011 - 11:55 PM

Great to hear that you guys are working on it.

When I forced my Mac to output 24p with SwitchResX to my TV, every movie played buttery smooth. However, I noticed severe A/V desync issues after a few minutes of watching. Automatic refresh rate switching will not remedy this of course. Why is this happening?




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