Frame rate & refresh rate question

[madhatter300871]

After a lot of searching here, reading and experimenting I now understand a lot more clearly about frame rates and refresh rates and the reason we get subtle jerky playback.

And so to my question .....

My display supports 50Hz and 60Hz input. From what I can tell 50Hz really is 50Hz and 60Hz is really 59.96Hz, reclock reports these values and also madVR reports these values.

QUESTION 1 : Is it possible that the graphics card has set itself to 59.96Hz (when I asked for 60) but the display really does have a 60Hz refresh rate, or can I trust the graphics card and believe that the display, when it says 60Hz, really means 59.96Hz.

If I play my 25fps sources at 50Hz everything is great.

If I play my 23.976fps sources at 50Hz I get the classic NTSC judder.

If I play my 23.976fps sources at 60Hz it's a lot better but there is still a subtle jerk in motion.

If I play my 24fps source at either rate, I get subtle jerk in motion.

QUESTION 2 : is the 23.976fps source having pulldown applied somewhere to play at 60Hz, if so any ideas where this is likely to be done ?

It dawned on me that probably the best thing for me to do with my backups is simply convert them all to 25fps, just like PAL DVD, and set the display to 50Hz. I can speed up my 23.976fps source to 25fps easily :- avisynth, or matroska stretch, or reclock for example BUT I cannot easily speed up the audio without re-encoding it : either off line or on the fly.

QUESTION 3 : Is it possible to speed up a DTS (for example) audio track without re-encoding it, what I mean is just send it to my amp 'faster' to match the video 25fps ?

EDIT : Removed a question regarding 24i

Many thanks in advance for any help.

[Ghitulescu]

Is there anything like 24i?

[madhatter300871]

Very good question .... I was surprised what the display was telling me as well. Ignore this anyway, I never set my output to this resolution, I only ever set 1280x720 (native resolution) @ either 50Hz or 60Hz. In fact I'll scrub this from my original post ..

[PetitDragon]

@madhatter300871

You can refer to my past post here:

http://www.avsforum.com/avs-vb/showthread.php?p=20121196#post20121196

[madhatter300871]

Well .... it seems the projector manual is not giving me the full picture. I decided to ignore it and try a few things anyway with great results.

It seemed the answer was quite simple.

I configured a custom resolution in the Nvidia control panel of 1280x720@71.928Hz. The projector accepts it, and shows the horizontal refresh rate of 71.9 (it can't display 3 decimal places). MadVR shows a refresh rate of 71.926 (pretty darn close) and I have to say the result is pretty darn smooth and judder free playback.

I played with 72Hz as well and got equally good results. I also played with 23.976Hz and while the projector had no problem with this setting and the playback was smooth, I experienced tearing. Bizzare ! I also set a 24Hz refresh rate, but nvidia insists on setting this as 24i and not 24p. Again, bizzare !

I have now set MPC-HC to select either 72Hz, 60Hz or 50Hz depending on the content being played. So it seems my projector accepts pretty much anything I throw at it.