The movie gets choppy when I cut it! (AC3)

[ToMmY]

I encode my DivX movie (going for 2 CDs). Then I interleave the AC3 with the movie, using settings that will not give me choppy playback (ex. 500/64ms) and I also add the delay (using NanDub). I test the final file and it works great (1.4Gb).
Note: when I use the default settings 500/1frame I get choppy playback.

Next, I reopen NanDub and I want to cut the movie to two parts using exactly the method that Doom9 recommends, BUT I try the following variations:
1.I leave the interleaving settings at default (500/1frame/0)
2.I deactivate the option “enable audio/video interleaving”
3.I use as settings the same I used for the first mux (500/64ms/delay)

The first two tests give me choppy playback!!, exactly the same performance as if I muxed the video/audio using settings of 500/1frame. Though the file sizes are not the same.
The third option gives me smooth playback.

-Am I doing something wrong?
-It seems that the interleaving settings affect the cutting. Does NunDub remux the video and audio when it cuts the file?
-If so, should I use the same settings as I used for the first mux?
-What about the delay? Should I leave it at 0 or reenter the AC3 delay for the cutting?

And something else I wanted to know…
Is the video renderer filter (WMP 6.4) correct in counting the average frame rate?
When I play the video ONLY (PAL) it varies from 24.90 to 24.99
When I play the muxed video, it gets high for the first couple of minutes. Then it stabilizes between 25.02 and 25.10. Is this a normal behavior?

Thanks…

[cult]

every time u cut a movie u have to set interleaving again with the settings u used for muxing and yes use the delay again and not set it at 0.

[Zhnujm]

DONT set the delay again - it stays in the file.

[MaXtor-Man]

I thought one only has to check "audio -> direct stream copy" and not to worry about interleaving options any more. (when cutting the movie)

[Zhnujm]

its like saving a complete new file - the video and audio is muxed again. the delay stays the same because vdub adds silence / cuts the audio the first time you save the file.

[ToMmY]

I see that I am not alone...
lots of people must have been doing this wrong

#Doom9, where are you... you must get this straight in your guides because at least I have been confused#

So what we must do is:
1. Do the first mux using the correct preload, interleave AND delay (for ex. 500/64ms/-80)
2. Cut the muxed file using nandub (doom9's guide) but insert the correct preload and interleave values ONLY, and leave the delay as 0 (for the same ex 500/64ms/0)
3. We are done... :)

Are the above correct?
PLEASE, someone verify this and most of all the Delay thing, because it is not really easy to notice for a small value.

[Zhnujm]

you can easily test this if you use a very high delay (1000ms) then reload the file and save it again with 0ms delay.
the files will be the same. dont think it would be different with a small delay value ;)

[ToMmY]

Nice tip...

But I would like a straight answer...

The first mux... I USE the delay value
During the cut... I DO NOT USE the delay value(put it to 0)
Is that correct YES or NO?

I may sound like a d**k, but sorry, I just want to clear this out once and for all!

[Emp3r0r]

here is your answer: after you have your 1.4 gig video with AC3 open that in Nandub and select the first half (700 megs) of your movie and make sure DIRECT STREAM COPY IS SET FOR BOTH AUDIO AND VIDEO and save your avi. There is no need to worry about interleaving and such when simply splitting the files. Your only worry should be splitting on keyframes.

[ToMmY]

Emp3r0r…
People that have a problem playing back muxed movies with the default settings of 500/1frame (like me. Maybe the OGM you are using prevents you from such issues), if they do not reset the interleaving values (and leave them at the default settings of 500/1 frame) during the cut, they will get avi’s that will playback choppy (as if they did the mux using 500/1frame).
I have tried this lot’s of times and that is it. NanDub REDOES the muxing during the cut. I just do not know if it keeps it sync.



After some testing, I found out something interesting…

Let’s say I have a movie with a delay of 0 (Driven). I do the first mux (a test) using a delay of 1000, and the audio is playing 1 sec later (lets call this file: A). Everything fine. Now, I cut the movie two times, using a delay of 0, and a delay of 1000. I also compare them with the first mux and I expect the one with the delay of 0 to be the same as the first mux (1 sec delay) while the other to have a 2 sec delay, but I use two different methods of doing that…

1.After doing the first mux, I DO NOT CLOSE NANDUB. I load file A, change the delay to 0 (the other values stay the same) and save the parts. Then, I reload file A, change the delay to 1000 and save the parts again.

2.After doing the first mux, I CLOSE NANDUB and REOPEN IT. I load file A, change the delay to 0 (and also the other values) and save the parts. Then, I reload file A, change the delay to 1000 and save the parts again.

Results…
METHOD 1:
Delay=0 gave me two parts that are perfectly sync (0 sec delay)!!
Delay=1000 gave me a 1sec delay!!

METHOD 2:
Delay=0 gave me a 1 sec delay (WHAT I WAS EXPECTING)
Delay=1000 gave me a 2 sec delay (that’s ok too)

-So this little “mistake” can really screw up everything.
-I thing that is why some people say we MUST use the delay again, while others say we MUSTN’T. There are two “different” methods of doing this.
-Maybe this is a bug of NanDub. It seems to redo the mux from scratch is you do not restart the program. Has anybody else experienced that?

[cult]

thats why when a movie has dealy and I am gonna split it to 3 or files i use a prog called ac3delayfix.I set the delay for ac3 to 0 so dont have to worry.Saved me alot of times,especialy with tigerland.Couldnt make it get synch no matter what.

[Zhnujm]

i think the reason why your first method dont give the results you expected are simple:
if you only reload the avi file, the audio stays at "ac3 audio". so you mux your ac3 audio file with the video instead of using the "delay correctet" audio of the avi file.
you have to switch to "avi audio" if you dont close nandub.

[ToMmY]

Zhnujm...

That is correct, but there may be people (like me) that have not noticed this in time.

cult...

It would be nice if you could tell me where to find this "ac3delayfix" program

[cult]

sorry, its called AC3 delay corrector ,and u can find in the downloads section under audio tools

[ToMmY]

cool utility but if my AC3 has a delay of -111 ms, this tool cuts it at 125 ms (4 frames).
This way it introduces a new "delay".
OK, 14 ms are almost impossible to notice, but...

[cult]

I only use it in emergency situatons when all else fails.