720P,60 FPS to 24FPS

[LockoNH]

Hi, kinda new to AVIsynth, so hopefully I can express my problem coherently.

I recorded ABC's 'Lost' at 720P, 60 fps. I am planning on reducing it back to it's original 24 fps.

I use VideoRedo to edit out commercials, output it as an MPEG2 file, AC3 audio, direct copy,no re-rendering.
From there is DVD2AVI-->VFAPIconv-->AVIsynth-->Virtualdub (for now--eventually I might use Nero's Recode H.264 in place of Virtualdub/X.264)


It's not a nice neat 3/2 pattern, so I was forced to use FDecimate.
I used the FDecimate plugin pretty successfully except I noticed an occasion stutter in the video.
I stepped through VFAPI avi with Virtualdub and noted each original frame.

My problem is that I am finding that the source seems to be actually yielding 24.281 fps instead of 24 (or 23.976). I basically counted unique frames until the time indicated 20 plus seconds, divided number of unique frames by exact time and got 24.281 FPS.

If I go back into the script set it up for FDecimate(rate=24.281,threshold=3) I get pretty good video, no repeating frames, no missed unique frames. I can then use AssumeFPS() to set it up for 24 fps. I guess I'll have to monkey around with the sound to make it fit (for some reason it doesn't seem to be set for 23.976 or 24 fps either).

At this point I'm trying to understand why I'm getting such oddball results. What's causing this desync? I assume it's just a timebase issue (if that's the right word for it)
Also, does anyone have a tip to stretch or shrink AC3 5.1 channel audio? My only convoluted thought right now is to take the AC3 and convert it to wav 5.1, and then use WavSource() and adjust it in AVIsynth, then mux it with the video (Nero needs the audio and video to be muxed)

[Pookie]

Really? I record it OTA and it doesn't seem to have any strange characteristics. Might you have an incorrect setting in DGIndex - like the ForceFilm button checked?

This works great for me:

SelectEven()
Tdecimate() #Latest TIVTC.DLL works nicely with this source

No reason to change the AC3 file once you're set with the above. You can just mux it with your new 23.976 video file :)

[Awatef]

Wow! They broadcast 24fps video at 60fps?? Isn't 24fps part of the HDTV specs?! such a bitrate waste...

[LockoNH]

I record it via firewire from my Comcast motorola DCT6200 STB. I could upload a sample if someone can recommend a good free upload/filesharing service for a 200MB file.
I don't have force film checked, and it's definately a weird pattern, not straight 3/2 3/2 etc.

Almost forgot, the file I'm currently looking at is an episode from last season, I haven't tried converting any of this season's yet. Maybe they've changed format a bit since you're finding it to be a straight 3/2 pattern. Either that or it's something that happens with Comcast?

[LockoNH]

Wow! They broadcast 24fps video at 60fps?? Isn't 24fps part of the HDTV specs?! such a bitrate waste...

I totally agree.

[pandy]

I record it via firewire from my Comcast motorola DCT6200 STB. I could upload a sample if someone can recommend a good free upload/filesharing service for a 200MB file.
I don't have force film checked, and it's definately a weird pattern, not straight 3/2 3/2 etc.

"HQV Automatic Film Mode Cadence Processing A quantum improvement in automatic handling of film and video sources such as 3:2 and 2:2 sequences common to broadcast and DVD. HQV processing provides industry-first support for "Vari-Speed" cadences such as 3:2:3:2:2 commonly used for movies broadcast on television, as well as 5:5, 6:4, and 8:7, cadences used for the many different styles of animation. HQV cadence processing ensures that users will always be viewing film and video sources in the original format without loss of resolution. HQV technology is first to offer 3:2 insertion at HD, an important requirement of the new HD Blu-Ray and HD-DVD formats coming soon to the consumer market."

http://www.siliconoptix.com/chipProducts/Realta/Realtaarticles/ResidentialSystems/
http://teranexlive.dimentians.com/

:eek:

[*.mp4 guy]

Try
Tdecimate(slow=2, CycleR=3, Cycle=5)
If that doesn't work try.
SetMemoryMax(512)
Tdecimate(slow=2, CycleR=36, Cycle=60)

If the first one doesn't give you smooth video you are dealing with a botched cadence pattern, and If the second doesn't work you are dealing with a more or less irreparable source. You shouldn't end up with anything other then 23.976 fps video, becuase that is what lost is shot at, anything other then ~24 fps means the source has been screwed up in some way.

[Pookie]

Just upload 10-15 seconds, no audio required. Megaupload, Rapidshare, etc.

[LockoNH]

Try
Tdecimate(slow=2, CycleR=3, Cycle=5)
If that doesn't work try.
SetMemoryMax(512)
Tdecimate(slow=2, CycleR=36, Cycle=60)

If the first one doesn't give you smooth video you are dealing with a botched cadence pattern, and If the second doesn't work you are dealing with a more or less irreparable source. You shouldn't end up with anything other then 23.976 fps video, becuase that is what lost is shot at, anything other then ~24 fps means the source has been screwed up in some way.
Honestly, I believe that the source is correct at 23.976 fps, I think its the way Virtualdub is dealing with timestamps or whatever is off. I will upload a sample tonight (of the raw source) and maybe a divx version of what I'm seeing on output.

[LockoNH]

I've uploaded the clip, my avs script, etc:
http://www.megaupload.com/?d=3PLMZFGN

I think I found the exact problem though, VideoRedo *is* listing the file as the wrong length in time.
It lists the clip as being 1869 frames, length of 31.11 seconds.
At 59.940 fps the time should be 31.18.
Virtualdub gets it right (after the AVIsynth filter frameserves at 23.976 fps).
It may seem like a trivial difference, but it does throw the fps off exactly in the manner I'm seeing. I just need to way to change the length of time on my mpg files created with VideoRedo. I'm going to try the Tdecimate though and see if it ignores the stated length of the file (I have no idea how files mark off time).