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[Linux] HOW-TO achieve perfect playback at 23.97 or 59.94 Hz with NVIDIA GPU hardware - Printable Version

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- danz0l - 2010-09-13 19:59

Superorb Wrote:Don't I need 1920x1080_60_0 for 59.97fps content?

Well its my understanding that 59.94 is actually used for 29.97 (29.97x2) which could be your issue and why xbmc is switching to that for your content instead of the others.. I'd disable it, reboot and see what happens with the switching. I have to use 59.94 but only because my tv does not i have a native 29.976 option. Certainly worth a shot.


- Superorb - 2010-09-13 20:32

danz0l Wrote:Well its my understanding that 59.94 is actually used for 29.97 (29.97x2) which could be your issue and why xbmc is switching to that for your content instead of the others.. I'd disable it, reboot and see what happens with the switching. I have to use 59.94 but only because my tv does not i have a native 29.976 option. Certainly worth a shot.
Well that's weird... I removed the 1920x1080_60_0 mode but 25fps content is still being run at 60hz. I don't even see how that's possible if I removed that mode from the xorg file.


- danz0l - 2010-09-13 21:26

Superorb Wrote:Well that's weird... I removed the 1920x1080_60_0 mode but 25fps content is still being run at 60hz. I don't even see how that's possible if I removed that mode from the xorg file.

Are your other ones running at the correct rates ? i.e 23.97 and 29.97 and the tv is adjusting the refresh accordingly ?

If so I'm going to assume your running xbmc at 60hz and as you don't appear to have a 50hz setting on your tv that will likely be the closest match. Its likely that not having a res to switch to it will run at default hz of xbmc. Does that sound logical ?

BTW i'm far from an expert on this stuff so just trying to offer some suggestions that may or may not help.


- Superorb - 2010-09-13 22:07

danz0l Wrote:Are your other ones running at the correct rates ? i.e 23.97 and 29.97 and the tv is adjusting the refresh accordingly ?

If so I'm going to assume your running xbmc at 60hz and as you don't appear to have a 50hz setting on your tv that will likely be the closest match. Its likely that not having a res to switch to it will run at default hz of xbmc. Does that sound logical ?

BTW i'm far from an expert on this stuff so just trying to offer some suggestions that may or may not help.

Yeah, this makes sense. So, all 720p content I throw at it switches the TV to 24p and xbmc is reporting 23.97fps and 24hz, but all my HD stuff seems to be 24fps so I can't test for other rates. The newer SD stuff switches the TV to 24p correctly, but the older SD stuff reports 25fps and 60p on the TV. I wish I could find some HD content at a frame rate of other than 23.97 but I can't. I have a rather large library but everything I've tried has been 23.97. I found an SD movie at 29.97 that still triggers 60hz even though my TV supports 30p.

Ok, so I tried setting the xbmc to 1920x1080@30hz and set "adjust refresh rate" to unchecked. ALL content then plays at 30p, and the TV correctly displays 30p. So, if the TV can correctly do 30p then why doesn't xbmc automatically switch to 30p if it correctly switches to 24p?


- danz0l - 2010-09-14 07:10

I have an issue not dissimilar to yours really. I do have a 29.97 option on my TV

# "1920x1080_30" : 1920 x 1080 @ 29.97/30 Hz (CEA-861B Format 34)

But when using that, xbmc refuses to switch to that mode. I tried setting it through xbmc as the default mode though and get a blank screen (even though the edid reported it supported it).

So no idea mate to be honest.


- Superorb - 2010-09-14 15:49

danz0l Wrote:I have an issue not dissimilar to yours really. I do have a 29.97 option on my TV

# "1920x1080_30" : 1920 x 1080 @ 29.97/30 Hz (CEA-861B Format 34)

But when using that, xbmc refuses to switch to that mode. I tried setting it through xbmc as the default mode though and get a blank screen (even though the edid reported it supported it).

So no idea mate to be honest.
If I set xbmc to default to 30p (a supported mode) the TV will switch fine, but for some reason it will only switch to 24p and not 30p even though it is supported when playing content.


- X3lectric - 2010-09-15 14:32

I have noticed that many files of the similar extension say mpeg4 from a tv series compared to other tv series mpeg4 files, that I have some play always varying dynamically from 23.976/24fps @ refresh 24, some @ 24/25fps @ refresh 25 some at 23.976/24fps @ refresh 50, so really its odd but I found that the final fps and refresh rate is determined by something other then just the file extension.

This could explain why you find that xbmc "refuses" to change to a expected or supported fps and refresh rate maybe that specific file just wont do that. My TV and modelines range from 60/50/30/25/24 while they all supported and when playing back a file you expect to see at that specific value is not gonna play ball, if its because of diff audio or encoding options despite file extension, i cant say.

I'm still to monitor other file extensions that may play at diff fps/refresh but I'm pretty sure this happens, if its considered a issue or not idk. Maybe you guys can monitor your file extensions from different tv series or other completely different files that have a same extension.

Something else I know to be true is that 23.976/24 is always dynamic in between the two values same applies to higher refresh rates like 49.94/50 and 59.94/60 you never get a solid value its forever changing during playback.


- Superorb - 2010-09-15 16:00

^^ Frame rate has nothing to do with file extension Wink


- X3lectric - 2010-09-15 16:40

Maybe not extension in itself but something in the files is a reason for the different fps and refresh they get played, it and its only apparent to me in the way described. Please read what I posted, If it is a problem, like I said idk.


- Superorb - 2010-09-15 16:57

X3lectric Wrote:Maybe not extension in itself but something in the files is a reason for the different fps and refresh they get played, it and its only apparent to me in the way described. Please read what I posted, If it is a problem, like I said idk.
Frame rate is determined by source material. Any video file [extension] can have any frame rate.


- danz0l - 2010-09-15 17:09

X3lectric Wrote:Maybe not extension in itself but something in the files is a reason for the different fps and refresh they get played, it and its only apparent to me in the way described. Please read what I posted, If it is a problem, like I said idk.

I think you could be on to something here. I've had some issues with 29.97 rates and they usually result in choppy video. I'm in the UK so both 29.97 and 23.97 are not native here although like a great many UK tv's, mine supports both.

Now 23.97 works, for the most part, with maybe 4 very quick jerks through an entire movie if its going to happen.

Today i'm watching a show downloaded that aired on ABC and i honestly thought it was 23.97 as it played back without any issue. To my surprise however it was 29.97. The show was Jamie Olivers Food Revolution. I'd gone through 4 episodes before checking and never had any issue with any of them.

Now in comparison, another ABC show i watch through XBMC, again at 29.97, mellisa and Joey, runs pretty dire with both lipsync issues and jerking. Both files are avi xvid but it could be keyframe issues within the encoding perhaps ?

What i'm trying to suggest is that different shows obviously don't force the full correct refresh rates always or could just be badly encoded.


- Superorb - 2010-09-15 17:13

^^ I'm going to go with badly encoded. Xbmc should detect the framerate and then switch output to correct refresh rate. If, for whatever reason, xbmc cannot correctly detect the rate it won't change anything.

I'm still trying to figure out why it only changes to 24p and not 30p or 25p even though my TV supports them.


- danz0l - 2010-09-15 17:22

The thing is it does change the refresh rate for the abc one that runs like a bag of spanners, but its not smooth. Likely is encoding mind ....


- Superorb - 2010-09-15 17:24

danz0l Wrote:The thing is it does change the refresh rate for the abc one that runs like a bag of spanners, but its not smooth. Likely is encoding mind ....
Well if it does change the rate than the only problem lies within the file itself and not xbmc or your TV. Be happy, my xbmc only changes 24p Wink


- groggycl - 2010-09-16 06:26

just wonderfull man, thanks!!