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  1. Member
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    I have a 50 fps PAL video in MKV format. I know you can add multiple audio streams in MKV, so I've extracted/converted the audio from a NTSC 29.970 fps video; because it's in the language that I want, to AC3 and added the file to the MKV. As it's to be expected the audio doesn't match. The audio I'm trying to add is about 4 minutes longer than the original, probably because of the 50 fps, and it eventually gets out of sync. Someone suggested a program called AC3to, which is supposed to help me sync and convert the 29.970 fps audio to 50 fps audio. Most of the AC3to tutorials I've found online, help people fix audio/video sync issues when the fps are not that far off... 29.970 fps to 30 fps, 29.970 fps to 24 fps etc. But 29.970 fps to 50 fps is a huge difference. I successfully ran the audio through AC3to, but it results in a Chipmunk effect, very fast audio. Is it even possible to sync the audio from a 29.970 fps video after extraction, to a 50 fps video?. I'm going to post the thread in the audio and video conversion section because I don't even know if it's an audio problem of a video issue.
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  2. Film is shot at 24 fps. When broadcast as 29.97 fps video (really 59.94 fields per second) it is slowed to 23.976 fps and 3:2 pulldown applied. When broadcast as 50 fps PAL it is sped up to 25 fps and each frame displayed twice. So the real difference in running time between NTSC and PAL broadcast is about 4.271 percent (23.976 / 25).

    But beware, releases of movies in different countries often differ because shots are cut or added. So simply adjusting the length of the audio often won't work.
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    Hello,

    thanks for responding. I'm not very good with audio and video. I only took on this project because a friend of mine wanted to watch some movie with the original audio that she remembered when she was little. Based on your expertise, what do you suggest I do. Convert the extracted audio with AC3to to 25 fps instead of 50 fps like I was trying to before, Convert the video, find a way to remove frames since they're been displayed twice?. I know that it's difficult to explain something to someone that knows nothing about the subject, but I'm just trying to get this done and if you could give me a few pointers, at least I'll have something to build on.
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  4. Originally Posted by Merazomo View Post
    Someone suggested a program called AC3to...
    You mean eac3to and, as jagabo suggested, your best chance to get it to synch up is to go from 23.976fps to 25fps.
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    Originally Posted by manono View Post
    Originally Posted by Merazomo View Post
    Someone suggested a program called AC3to...
    You mean eac3to and, as jagabo suggested, your best chance to get it to synch up is to go from 23.976fps to 25fps.
    I posted my comment just after noticing that you posted yours, sorry. So converting to 25 fps is an option, ok thanks.
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  6. I don't use it but I believe there's a film to PAL or 25fps option, or a speedup option or some such. Shouldn't be hard to figure out, as long as you know 29.97->50 isn't the way to go.
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  7. Some containers let you specify the audio playback speed too. MKV for example. Not all players support that though.
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    Hello guys, I extracted and converted the NTSC 29.970 fps video's audio to 25.000 fps, and it's a little closer to the original. But it's still a little off. I watched most of the movie, and all the scenes are pretty much the same. Would converting the MKV PAL video from 50 fps to 25.000 fps help at all? Or is the key to the problem the audio. Most of the tutorials I see in the forum are PAL>NTSC, not NTSC>PAL.
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  9. Originally Posted by Merazomo View Post
    Hello guys, I extracted and converted the NTSC 29.970 fps video's audio to 25.000 fps, and it's a little closer to the original. But it's still a little off. I watched most of the movie, and all the scenes are pretty much the same.
    If the sync is off by the same amount over the entire movie all you have to do is add a delay (or a negative delay to advance the audio) to the audio when you mux new new audio with the video.
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    Whether is NTSC > PAL, or PAL>NTSC, the method is the same, either speed up or slow down the audio.
    50 fps or 25 fps, should have the same running time. I don't see it making any difference.

    I have done this a few times myself, my general method is make sure it is in sync close to the start of the movie,
    then navigate to some dialogue close to the end and see how it is there. Adjust as necessary.
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    Thank you guys so much, I was finally able to sync and add the audio I wanted, to the MKV movie that I wanted to use. I'm going to explain everything I did, so that other people with the same problem get some kind of idea on how to fix the issue.

    I found a MKV movie online for a friend of mine, that had amazing quality. The video was PAL 50 fps, but it was in a language she didn't want. I finally found the movie with the language she wanted which was NTSC 29.970 fps, just to find out the quality was crap. So here is what I did to merge the good quality video, with the desired audio track.


    1. I used Bigasoft Total Video Converter to extract the audio I wanted from one of the movies, and convert it to AC3 audio.


    2. I then used the program eac3to to convert the audio from 29.970 fps to 25.000 fps, thanks to the guys here which explained to me that 50 fps or 25 fps was pretty much the same when it came to the audio running speed. After the conversion, the AC3 audio file was slowed to match 25 fps and the running time was longer for the same reason.


    3. To match the video running time to my audio, I used a program called AudioDirector3 which stretched the audio to the specific running length of the video.


    4. The last step was to pretty much merge the video and audio with mkvmerge GUI, and adding a -150 ms delay to the audio because it was still a little off.


    jagabo, manono, and davexnet. Thank you so much for your help, to think that a week ago I knew nothing about all this kind of stuff. The slightest suggestion can make a world of difference. I had been wanting to do this project for a while now. The threads on the forum are very helpful as well. Just reading through some of them can give you the answers you're looking for. So thank you very much, blessings.
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