Why 24 fps Mr's Guide writers

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Why 24 fps Mr's Guide writers

Postby gypsy » Thu Nov 14, 2002 7:11 am

Right...

Loooooo all :)

I've Read ErMaC & AbsoluteDestiny's Friendly AMV Guides and in it sais your not allowed, sorry... You CANT make a 23.976fps movie. I know this and am very aware of this fact. Not quite sure why this is such a bad thing but I'll take their word for it and will not use 23.976 fps source in premiere. They suggest that you (or me or anybody :lol: ) convert the framerate of the movie to 24 fps and then speed up the audio source as well to 24 fps.

I have no problem with using AVS files but I'm just wondering... Why dont you convert the fps of your source to 23.98 using an AVS file and then leave your audio as is. The only reason I am asking is when I put my audio file into BeSweet it is @ 25000 so I have to slow it down for my editing. This sounds really weird and I'm scared that it wont sync up when I convert back to normal speed.

Why should one change the speed of your sound file if it get's interleaved with your video on precise increments anyway... Dont fully understand this.

An explenation would be nice by anybody that understands this better than myself.

Lets see how many responces I'll get before the Allmight Forum replyer, Klinky get's his fingers on this one. he he he. :lol: :lol:

Cheers vir eers.
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Postby AbsoluteDestiny » Thu Nov 14, 2002 7:33 am

I knew this one would cause problems.

Audio doesnt have an fps, really. (it sort of does but it makes no difference to you what it is when making an amv).

What we are suggesting is, to make a 23.976 fps amv:


1) Make sure all source footage is 24fps

2) Make a 24fps video in premiere

3) Change the video frame rate to 23.976 when it is finished.


However, if you follow those steps you will notice that the audio will be ever so slightly out of synch.

You can just leave it as 24fps. If you are just doing internet distro then that will be fine.

If you want to have 23.976 fps video without messing with your audio then you make a slightly faster version of your audio stream which you use on the timeline when editing. When you are done, you change the video frame rate back to 23.976 and attach the original audio. What this does is it cancels out the speed changes and everything will be in synch like it should be.

If you don't understand it, then don't do it. If you don't need 23.976 then don't do it.

Audio frame rate doesn't matter - we put in a frame rate ratio in order to change the speed of an audio for editing. That's all. All it's doing is making sure that an audio file that fit the video at 23.976fps fits the same video played at 24fps. It's not really a property of the audio, its just some numbers that allow us to change the audio to fit things. We are actually resampling the audio, not playing it faster (like you do with video frames).

It doesn't make any sense to talk about 25fps audio.


As for why you shouldn't do 23.98fps, as it is said in the guide there is no timebase for 23.98, only 24. Timebase is important to ensuring things synch up.

I hope that helps.
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Postby ErMaC » Thu Nov 14, 2002 7:41 am

OK there are a lot of things to answer here:

The problem with editing something close-to-but-not-quite 24fps in Premiere is that you will run into timebase problems. Premiere measures a lot of preview events and keyframe effects based on a timecode. This timecode's relation to the frame # is based on the timebase you choose. Premiere has a 24fps timebase, which means when your video is 24fps and your timebase is 24, then they sync up and you don't run into problems.
When you edit with something that isn't 24fps and set your timebase to 24 (since it's the closest number) you wind up with events and previews which are not in sync with what they should look like on the timeline. This is why we recommend using the 24fps method and not anything 23.98 or whatnot.

Now what confuses me about what you're saying is that your audio is at "25000". That makes very little sense, as your audio has no FPS or whatnot, audio's measured in totally different increments.
If you mean you're sticking your WAV file into BeSweet and it says 25000 there, that's because that's the default value for that field (i.e. when you install the program that stick that # in there automatically) and it has nothing to do with how fast your audio is.

If you are editing from PAL source (which is in 25fps) you should disregard a lot of the information in the guide because it's written for NTSC video sources (America, Japan, Canada, etc) and not for PAL video sources (England, Western Europe). PAL video sources can be made progressive at 25fps by simply running Telecide() on your video source, and that's it. Then you can edit 25fps video in Premiere with a 25fps timebase with no problem.

Your profile says you're in South Africa, and so I googled for what standard your country uses and found this which says South Africa uses PAL, so I'll assume you're using PAL stuff.

If you are using PAL stuff, do not worry about slowing down things to 23.976fps or whatever, since PAL is in 25 to begin with and all you have to do is Telecide() the stream in AVIsynth to make it progressive. Then edit in Premiere using the PAL presets.

As for your question about interleaving audio - the relationship of audio to time in a video file is not related. An audio stream is not bound to a video stream except by the way it's packetized and interleaved, and the way that gets interleaved is based upon the information specified in the AVI headers.

When you're speeding up a song to match up with a new video framerate, you're not changing the audiofile's framerate or anything. Those numbers in between are just there for convenience - what it does is it divides the two numbers, multiplies that factor by the total length of the audio file, and then stretches or shrinks the file to that length, which is very different than telling a video file to be 24fps instead of 23.976 fps, because there you're not stretching anything, you're literally telling each frame to be played closer together, as opposed to the audio where you're changing the whole waveform.

Hope that made sense, if you have more questions feel free to post.
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Postby ErMaC » Thu Nov 14, 2002 7:43 am

Looks like we cross posted there AD! :D

Hopefully all that information there will help you gypsy.
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Postby gypsy » Fri Nov 15, 2002 6:52 am

I am not worthy.... I am not worthy.... :) :lol:

WOW. :shock: 2 |33t replies in one question. I like that one. :)

Thanx for the replies. Both of you. It really helped. I will use my new found knowledge to the best of my abilities. :twisted:

I'm hoping to complete my current project on or before the 30 November. Maby you could check out my profile around this time as this AMV will be sort of an "AMV made to THE guide" and tell me what you think. lol :D

Oh, and about the South Africa part... :roll:

Being down here in the bundoes (jungle) where there is but 2 lights when viewed from sattelite (Cape town and Johannesburg) SA is VERY behind the rest of the world with everything. :evil: (We still pay for internet calls and for local calls adn cellphone charges are through the roof !!!). :evil: Unfortunately whis includes Anime. To get a DVD down here will take a miricle and about 4 weeks of waiting after order has been placed.

I am currently working from a DivX Princess Mononoke source converted to Huffyuv. I know I shouldn't use it. I don't have a choice though. Don't dispare. I will replace the clips with DVD source (which I will borow from a friend) before distributing it on the internet. This is why I was enquireing on the 23.976 fps thing).

Thanx for all the help. I hope other people asking this question will first search the forum and check this one out as I think I'm not the only one that isn't 100% clear on the subject (Though I am now :P )

Cheers vir eers.
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Re: Why 24 fps Mr's Guide writers

Postby Sub0 » Fri Nov 15, 2002 2:11 pm

gypsy wrote:see how many responces I'll get before the Allmight Forum replyer, Klinky get's his fingers on this one. he he he. :lol: :lol:

wow klinky's got a nooby fan ;-p
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Postby Sub0 » Fri Nov 15, 2002 2:16 pm

AD wrote:If you want to have 23.976 fps video without messing with your audio then you make a slightly faster version of your audio stream which you use on the timeline when editing. When you are done, you change the video frame rate back to 23.976 and attach the original audio. What this does is it cancels out the speed changes and everything will be in synch like it should be.

thas what I do, never trust Premeir with my audio...
AbsoluteDestiny wrote:If you don't understand it, then don't do it. If you don't need 23.976 then don't do it.

:D
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Postby OhMyBelldandy009 » Fri Nov 15, 2002 4:59 pm

Wow, I now have a yearning desire to go read every guide and find out what the heck FPS means, AND |33t... WHAT is that?! People say that all over the org and I am a totally clueless little girl! :oops: Ahh!! I just want to LEARN! Like Golden Boy, except without all of the horny women. :wink:
"Hurry up and go to sleep so I can ravish your body in ways you can't even imagine." -Paizuri
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Postby AbsoluteDestiny » Fri Nov 15, 2002 5:58 pm

There's a glossary in the guide that will tell you what fps is.

There isn't an entry for l33t but I can tell you if you really want to know :)
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Postby RadicalEd0 » Fri Nov 15, 2002 11:40 pm

444|-| 1337 = 73|-| |<001y |-|@x0|2z 1!|<3 4|) 4/\/c| 3|2|\/|@C
:O :O :O
NMEAMV: PENIS
NMEAMV: IN
NMEAMV: YO
NMEAMV: MIXED
NMEAMV: DRINK
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Postby klinky » Fri Nov 15, 2002 11:50 pm

I saw it was already answered when I got here :evil:


BASTARDS YOU ERMAC! & AD!



-smittens-

~klinky
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Postby RadicalEd0 » Fri Nov 15, 2002 11:52 pm

me too klink, i almost posted what you just did, but then i was like naah
:\
NMEAMV: PENIS
NMEAMV: IN
NMEAMV: YO
NMEAMV: MIXED
NMEAMV: DRINK
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Postby Sub0 » Fri Nov 15, 2002 11:53 pm

l33t l33t 1337 leet 1337 l33t

fyi 'case your fast l33t means 1337 means leet or elite. It comes from CS and the elite is the best or the best (most skilled or luckyest... in CS it's the same thing...) and haxXephons have borrowed the phrase (and don't think they're gonna give it back...
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Postby ErMaC » Sat Nov 16, 2002 12:29 am

l337 came from Counterstrike?!?!?!


HAHAHAHAHAHAHAHAHHAHAHAHAAHHA

:lol: :lol: :lol: :lol:

OMG that's good.

Little boy, I was using the phrase l337 10 years ago on AOL when you needed Trumpet-f@#$ing-Winsock to play Quake.
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Postby klinky » Sat Nov 16, 2002 12:35 am

ErMaC wrote:l337 came from Counterstrike?!?!?!


HAHAHAHAHAHAHAHAHHAHAHAHAAHHA

:lol: :lol: :lol: :lol:

OMG that's good.

Little boy, I was using the phrase l337 10 years ago on AOL when you needed Trumpet-f@#$ing-Winsock to play Quake.



If only quake was out ten years ago.

Plus I was hacking away with the DOS Kloss PPP stack f000l way back wif Kali n' d00m and shit! Well actually my computer was shit and I had to use the DOS version since nothing worked in win3.1 at the time... this was in like '97.



~klinky
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