119.88 fps WMV9 material?

[madoka]

I have come across several WMV9 encoded videos lately, that all have the peculiar frame rate of 119.88 fps. Then, I realized that 119.88 = 23.976 * 5, and I do not think that is a coincidence. Therefore, I looked at the video files, and they do seem to have duplicate frames; reducing the frame rate by selecting every 5th frame via AviSynth does not appear to disrupt the fluidity of the motion either.

So, are the apparently erroneous frame rate due to files corruption, did I not configure my computer correctly?

[stephanV]

its not only 5*23.976, its also 4*29.97. i believe this frame-rate is used to show hybrid material witout having to de-interlace or IVTC. but i live in PAL-country, so i dont really know...

[avih]

that's a really good solution actually for hybrid material. if the codec can recognize the dup, that it has practically zero cost. very convinient...

[bond]

hm couldnt this been also done with vfr, or am i mixing things up here?

[stephanV]

@bond: it should... and i think wmv container can actually handle vfr (but im not sure)

@all: i just saw this thread (http://forum.doom9.org/showthread.php?s=&threadid=49561&perpage=20&highlight=120&pagenumber=1) once, so thats how i got the idea...

[avih]

Originally posted by bond
hm couldnt this been also done with vfr, or am i mixing things up here?

i guess it could, but this technique allows u to use containers/players/codecs that don't allow vfr.

[bond]

Originally posted by avih
i guess it could, but this technique allows u to use containers/players/codecs that don't allow vfr.yep, thats why i wondered that such a wmv file exists, as wmv should be able to do vfr

i assume the file is maybe simply a reencode of an .avi file, which had to use this workaround (insertion of drop frames)

[madoka]

Originally posted by stephanV
@bond: it should... and i think wmv container can actually handle vfr (but im not sure)

@all: i just saw this thread (http://forum.doom9.org/showthread.php?s=&threadid=49561&perpage=20&highlight=120&pagenumber=1) once, so thats how i got the idea...
Yes, the containers are plain old AVIs. So, I only guessed half correctly, not realizing that 119.88 = LCM(23.976, 29.97), if I stretch the definition of LCM a bit...

Unfortunately, my computer's not fast enough to playback video at such frame rate, so is my only option to decimate it down to either 23.976 or 29.97 fps?

[bond]

hm with mpeg-4 streams you could bring down the framerate heavily when transmuxing to mp4 with 3ivx, but with a wmv9 stream this will not work i assume. also normal reencoding will not work i think, as than the n-vops will get coded as i/p/b-vops hurting compressibility a lot i think

[tct666]

Fortunately,ChangeFps(23.976) will drop null frames and maintain the non-null frames.However,the scene which is 30fps will be 24fps,and may not play smoothly.

Avisource("C:\120fps.avi",false)
changefps(23.976)