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Help, need to sync DVD NTSC soundtrack to 24 fps

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  • Help, need to sync DVD NTSC soundtrack to 24 fps

    I know this had been discussed many times, but I didn't find thee right answer. I want to sync my projector to the audio soundtrack in spanish extracted from a DVD. My DVDs are usually NTSC 29.976 fps but I also have some PAL @ 25 fps. Sound projectors run at 24 fps. I can use audio software as Audacity or Audition to change the length of the soundtrack file. PAL to 24fps seems OK slowing the speed to 96%. But the same conversion does not work with NTSC because it gives me 80% of the original speed and that is none sense. Can somebody tell me what is the right percentage of the original soundtrack speed I must use to get the NTSC soundtrack to run at 24 fps.

  • #2
    This may be more information than You want Julian, but maybe you'll find your answer.

    http://javierzumer.com/blog/2019/4/2...io-pull-updown

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    • #3
      Dear Janice, thank you very much for the article. Everything is there. For future people searching for how to sync audio from DVD or video in NTSC or PAL. Here is the list of variation in time for audio. This can be done in any audio software as Audactiy, Audition, Protools, etc:
      1. NTSC to FILM: speed up by 0.1%
      2. PAL to FILM: slow down by 4%
      3. FILM to NTSC: slow down by 0.1%
      4. FILM to PAL: speed up by 4%
      5. PAL to NTSC: slow down by 4.1%
      6. NTSC to PAL: speed up by 4.1%
      For example:
      1. If I extracted the audio sound track from a NTSC DVD 29.976 fps and want to sync it to my FILM 24 fps. I have to change the speed in my audio software to 100.1%.
      2. If I extracted the audio sound track from a PAL DVD fps and want to sync it to my FILM 24 fps. I have to change the speed in my audio software to 96%.
      Take into account that this process changes the pitch of the audio, being more noticeable in PAL than NTSC. You can repitch the audio using a pulldown process similar to that used to convert film to video.

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      • #4
        Originally posted by Julian Baquero View Post
        Take into account that this process changes the pitch of the audio, being more noticeable in PAL than NTSC. You can repitch the audio using a pulldown process similar to that used to convert film to video.
        But PAL transfers of movies are 4% higher in pitch anyway, so changing back to 24 fps would restore the correct speed and pitch. Unless it had been pitch corrected of course in the PAL conversion, of course.

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        • #5
          Julian,
          what type of projector are you using? Mark

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          • #6
            Dear Mark,
            I will be using a 16mm ELMO 16AL to screen CASABLANCA, the film has the soundtrack in English, but I will try to sync the soundtrack in Spanish from a computer or digital player.

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            • #7
              Originally posted by John Armer View Post

              But PAL transfers of movies are 4% higher in pitch anyway, so changing back to 24 fps would restore the correct speed and pitch. Unless it had been pitch corrected of course in the PAL conversion, of course.
              Mark if the process has been done correctly to PAL the sound pitch could have been corrected using a pull down audio plugin, the article Janice shared is about this, many people just won't care about a 4% pitch increase, but audio engineers certainly do.

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              • #8
                Julian Baquero Glad the article had the answer to your syncing question. It helped me sync sound with my frame-by-frame capture system. I'm anxious to hear how your sound syncing turns out.

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                • #9
                  Julian
                  I think you'll struggle to keep it in sync with that machine as it's a fixed speed, you could modify it to variable speed which would help, you have no control if the machine slightly drifts out of sync which it will at certain times. Also splices if any need to be considered ,Mark

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                  • #10
                    Dear Janice and Mark, the projection went OK. But it required a lot of effort from me, because as you noted the movie drifts out of sync constantly, the print I have has very slight differences from the DVD so it's not perfect. I used a DAP (portable digital audio player) which was of great help. I don't know if the ELMO 16AL can be sync frame by frame, but I will certainly try with the ELMO GS1200. Some images and videos of the screening in the following link: https://photos.app.goo.gl/EMZ9NcMWF7iStXw46

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                    • #11
                      I'm impressed Julian. Not an easy task especially when you are dealing with combining analog with digital media.

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                      • #12
                        Thanks Janice for your compliments. Next saturday I will screen SUNSET BLVD. I will do the same exercise but this time I will upload the film audio track files split into the equivalent two reels so my neighbors can hear the audio in there sound system or computers in their apartments. I use an guitar amplifier for the sound amplification, some complain it is to loud, others complain they don't it's not loud enough!

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                        • #13
                          Julian Baquero Last year while screening a film in my backyard for my grandsons someone called the cops complaining it was too loud By the time a policeman showed up at my door we had already wrapped up the projection and was bringing everything back into the house. Maybe after the quarantine is over I'll have to invite the neighbors also to my next outdoor screening

                          I think it's really nice what you are doing for your neighbors and I'm sure they don't have a clue to the effort you are putting into the sound syncing. Have fun!
                          Last edited by Janice Glesser; April 07, 2020, 07:11 PM.

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                          • #14
                            Dear Janice,
                            Next time invite the police and the complaining neighbors to the event! This community activities have shown to be very rewarding. I have spend a lot of time, effort and money in this hobby which I usually only share it with my wife and kid, so sharing it with a greater public has added a new dimension to the experience, people have reacted very positively to it and that brings me a lot of joy.
                            Today I made an experiment, I ran a complete reel and timed how much it took to its end, then I compare the resulting time with the soundtrack. I found out my ELMO 16AL drifts about 2.2 percent. So I extended the soundtrack by that percentage to make a better sync tonight with SUNSET BLVD. screening.

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