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Old 13th December 2001, 12:57   #1  |  Link
resonator
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Timestreching NTSC Audio to sync with PAL

Hi!

I guess the topic pretty much said it all. I'm trying to sync an NTSC audio stream to a PAL video stream. The movie is "Requiem for a dream". I rented the DVD and dumb as I am I forgot to look at the box, so I didn't get that it's missing the english audio track. I hate german dubs, but I want to watch this movie.

Anyway, I borrowed a 1-CD DivX-version that a friend of mine had, which has a very, very crappy picture (deinterlaced, 29,97fps, the ripper probably used flask), but an OK audio track. So, just for fun I guess, I figured I could time-compress the bastard so it fits to my PAL video, and make a nice SVCD of it.

Btw, the two of them doesn't start with the same frame. I found a matching keypoint in a studio logo though, at NTSC it's 5,372 sec, at PAL speed it's 6,840 secs. The ratio between these points should be 0,95904 (23,976 / 25), but as you can see it's not. From that initial keypoint I checked some other keyframes during the movie, and it seems that the ratio between them, measured from time in seconds, is pretty much overall somewhere near 0,95904 (0,959 always matched, the rest differs).

Would it be easier to reduce the framerate back to 23,976 with the PAL video? Although I want to keep the PAL resolution.

Anyway, if anyone can offer advice on how to imply such a project, please let me know.
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Old 13th December 2001, 14:19   #2  |  Link
manono
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Hi-There are several ways to match them up (you already stripped the audio from the 29.97fps movie, right?). I think you should go find Doom9's Virtual Dub Procedures Guide in the Guides area where he outlines the different ways to do it. It'll involve some work, but it's doable.
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Old 13th December 2001, 14:29   #3  |  Link
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It's not that I don't understand VDub, I do, really, it's just that, even if I use the theoretical conversion ratio of 95,904 % (Progressive NTSC / Progressive PAL) for the time-streching (I use Prosoniq EZTimeStrech, a pro-audio tool) it just won't sync properly, and I wanted to know if anyone has an advice for me.
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Old 13th December 2001, 16:38   #4  |  Link
smok3
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1st option:

audio has NO frame rate and it should be the same for pal and ntsc versions of the movie, there could be a different cut in movies for region 1 and region 2 tho

2nd option:

different telecine transfer, 4 example, ntsc was done with pulldown to keep original lenght and pal was done 24 to 25 (straight), this will give u a 4% speed increase.

Last edited by smok3; 13th December 2001 at 16:49.
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Old 13th December 2001, 16:52   #5  |  Link
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Hmmm... pretty confused at your posts.

To make PAL (S)VCD from NTSC DVD usual way is: Force Film or IVTC to get 23.976 fps. It can be done in DVD2AVI (Force Film), or IVTC in TMPGenc. Then frameserve it to VDUB, there set 25 fps and again frameserve to MPEG 1/2 encoder.

Audio must be stretched by factor what you said - before all this, or you may mux it later.

Problem is that you can't do it with DivX source. Can't perform IVTC, only framedrop. It will cause choppy movement. And you must it in DivX case also perform in 2 steps: first ensure 23.976 fps with framedrop and then speed up with Virtual Dub to 25 - multiple frameserving...
Simpler: you can try to make it in TMPGenc by setting framerate to 25.
I don't know how choppy result will be, try it if you have no other choice.
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Old 14th December 2001, 13:23   #6  |  Link
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ppera2 - you wouldn't be confused if you'd read my first post entirey.

I have a PAL DVD without an english audio track
I have an NTSC DivX-AVI with an english audio track
I wanna make a PAL-SVCD with an english audio track
I wanna time-strech (or compress in this case, as the ratio is 95,9somewhat% - 23,976 / 25) the audio track so it'll match to the video.

And of course audio has no framerate, but the framerate goes along with the time, and PAL DVDs are generally faster than NTSC DVDs.

My problem is that, even when I use the theoretically exact conversion rate, the audio won't sync properly.
What I wanted to know is, if anybody ever tried this and has any advice. Maybe I've just forgot to take something into account.

Quote:
different telecine transfer, 4 example, ntsc was done with pulldown to keep original lenght and pal was done 24 to 25 (straight), this will give u a 4% speed increase.
Every PAL DVD I know (I own about 30, I've rented 100+) is authored this way, progressive 25fps, speeded up from a 24fps master. I think only 0.05% of all PAL DVDs are truly interlaced. (Documentaries and stuff...)
And almost every NTSC DVD (I own about 40) I know is telecined 23,976fps.

Maybe just my crappy english...
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Old 14th December 2001, 15:51   #7  |  Link
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OK, I see it now. Sorry... Ratio what you mentioned should be 100% OK.
Also what you said about way how making PAL or NTSC DVD-s.

Because you checked start point, I have only one 2 idea: version of film is not 100% same. Or DivX isn't made accurate.
You should check some exact point of movie near to end. See time in Vdub for 'NTSC' DivX and in your rip too. Then calculate ratio.
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