About 24000/10001 Framerate again...

[Libeluratio]

Hi everybody,

Sorry for my writing, I'm from France :/

By customing nvidia resolutions, I managed to get 23.97628 (says MadVr) output from my gt 430 which is also bitstreaming HD audio to my Avr.

A proper 23.976 would be 24000/1001=23.97602.....

So, when I do the math, I get 1 frame drop every 1/(23.97628-23.97602)=3846 seconds = 64 minutes, so 2-3 dropped frames per films. And the "ctr+J" option tells me the same thing after looking a 3h film: 3 dropped frames.

Believe it or not, that's annoying me a lot. Maybe I'm too sensitive but I see them every single time they appear :/

I must be mad, Ill, or whatever, but I can't believe arrived in 2012 you can bitstream HD audio without problems, but it is impossible for anyone to have a perfect 23.976 video playback from a pc...

Please tell me I'm wrong, tell me reclock with special settings, or using windows xp instead of windows 7, or anything else could enable me to get a perfect 23.97602 video while getting HD Audio out of my Avr... ?

Or, if it is really not possible at the time, does it exists hardwares (like popcorn hour etc) that do exactly what I want ?


Thank you so much !!! :)

[Ghitulescu]

It's a clock issue (quartz PLL). The PC was never designed to support fractional fps. Some graphic cards manufacturers may include the right timing (and thus clock) in their products, as a convenience, some only for the analogue (TV) out only, thus some may have good results, some not.
On the other hand, the audio, be it HD or not, was from the beginning (Adlib and Creative) supported at those sampling rates.

Another issue is the quartz drift (not being accurate, this happens also in real life non-PC products), which may force the SW/HW combination to drop frames (a better and longer explanation you can find in the capturing section, it's the "reverse").

[Libeluratio]

Thank you, I understand your clock explaination but, how could this be explainable:

My 23.976xx changes with the windows boot:
For example, I boot my pc, plays as many 23.976 movies as I want and the frequency of my graphic card displayed by Madvr will be 23.97625.


OK


Now I reboot my pc, plays as many 23.976 movies as I want and the frequency of my graphic card displayed by Madvr will be 23.97608. (Yes, I managed to get this accurate once).

Why the two last numbers are changing from one boot to another ? I know my graphic card can deliver 23.97608 because it did once, so why could not it deliver that exact frequency everytime ? I don't even know if it's windows of nvidia drivers at the origin of this change... :/

[dukey]

the films were probably all shot originally at 24fps anyway and then slowed down to fit them to NTSC TV. Personally i'd go with 24fps and not worry about bitstreaming the audio.

[Ghitulescu]

Since I don't use the PC to play movies (other as a sort of control), I don't have much experience with various graphic cards and their tweakings. I can only say that your card does not support natively 24/1.001 yet it may be "reclocked" to this (it's within the PLL error). You need therefore to instruct the drivers to force 24/1.001 each time. Another explanation might equally be that the card supports 24/1.001 natively, however if connected through DVI/HDMI it renegociate the fps with the display (in which case the EDID plays an important role, and there are many cases where the display had a wrong/"imature" EDID).