Please help select correct refresh rate

[riadmelb]

Hi all,

I spent hours researching on the net but couldn’t find a solution or answer. I have a small problem and was wandering if someone can help me with it please.

Video card is nVidia 8500GT connected to Panasonic TH-50PX80A via HDMI cable.

nVidia control panel recognises the TV and provides 24hz, 50hz and 60hz options.

I have a large library of video files that consist of the following different refresh rates:

23.976
24.000
24.975 (I have few of these, is this a bad encode?)

25.000
50.000

29.970
30.000
59.940

Select 24hz nVidia: I can play 24.000fps 100% smooth, but 23.976fps plays smooth except a drop frame every ~25 seconds.

Select 25hz nVidia: I can play 25.000fps and 50.000fps 100% smooth.

Select 60hz nVidia: I can play 29.970fps, 30.000fps and 59.940fps 100% smooth.

1. Is what I’m doing above correct?
2. Can some one please tell me how I can play 23.976fps 100% smooth?
3. Why do I get 100% smooth playback for 29.970fps and 59.940fps with 60hz? Is it dropping frames similar to the 24hz but I cannot see it? I’m asking this because 60hz is not a multiple of 29.970fps and 59.940fps.

I really appreciate your time and thoughts into this.

Thank you in advance,
Riado

[kutjong]

I suggest you use ReClock (http://forum.slysoft.com/showthread.php?t=19931) to properly synchronize the video with your display's refresh rate. You can speed up 23,97 material to original 24 fps and slow down 25 fps film material to 24 fps. :) Also 29,97 can be sped up to 30 fps.

[riadmelb]

Thank a lot for the tip, but before I try, will Reclock speed-up/down audio as well?

[Leak]

Thank a lot for the tip, but before I try, will Reclock speed-up/down audio as well?
That's exactly what it was made for - it'll adjust the audio speed on the fly to stay in sync with the video. :)

You can choose to either timestretch the audio or just play it faster/slower, but if it's just adapting 23.976 FPS video to a 24 Hz refresh rate the change in pitch will be negligible while timestretching might cause audible artifacts.

Reclock has a lot of options, so you should be able to configure it to your liking.

[dukey]

dont use reclock
it will change the sound ..
just set the refresh rate to 60hz, then your TV will behave exactly the same as if you had a TFT screen attached.

[riadmelb]

dont use reclock
it will change the sound ..
just set the refresh rate to 60hz, then your TV will behave exactly the same as if you had a TFT screen attached.

I was using 60hz previously for 23.976/24 fps videos using 3:2 pull down, but when I tried 24hz it was a lot smoother. Sorry I will not go back to 60hz for 23.976/24 fps videos :o

[Leak]

it will change the sound ..
A slight change in pitch (and when going from 23.976 to 24Hz it's a speed change of 1/1001th) isn't noticeable unless you happen to play the original audio alongside, as opposed to doubled/dropped frames...

(NB: Am I the only one with an evergrowing ignore list filled with perfectionist A/V nuts that do little but flood perfectly good threads about bigger problems with totally negligible tiny problems that only serve to distract from the real ones? Just watch the damn movie already, it simply doesn't matter if the audio's pitch is off by 5 Hz...)

[wozio]

What about powerstrip to try to set 23.975? If display supports 24 then it should support this also. You will probably get rid of this frame repeat.

[Steveo08]

what is if you use haali to speed up your video with 25fps (you find this under output in the splitter) and set your screen @50Hz?

i am using it with my mkv files @720p50Hz and i cann't see tearing.

[riadmelb]

Thank you everyone. :thanks:

@kutjong, I spent the past few days playing up with ReClock and have finally finished my testing.

Results are excellent! I have fixed all of the above problems by using ReClock. :D

I'm using:
24hz with 23.976/24fps videos (ReClock is doing its job here, and in case you are interested I'm using S/PDIF pass-through)
50hz with 50fps videos (I don't really need ReClock here, but it's running anyway)
60hz with 29.97/30fps videos (I never noticed a problem here, but ReClock is running anyway)

[sshd]

Why do I get 100% smooth playback for 29.970fps and 59.940fps with 60hz? Is it dropping frames similar to the 24hz but I cannot see it? I’m asking this because 60hz is not a multiple of 29.970fps and 59.940fps.

This is most likely because the refresh rate really is 59.940 Hz instead of 60 Hz. So there are probably some problems with your 30.000 fps movies, but you probably have too few to notice?

You can see the actual refresh rate by using Ctrl+J in MPC-HC (must be using 3D Surfaces on VMR9 or EVR).