Lincoln Burrows
13th October 2011, 22:56
Folks,
I recently came across this short explanation on how we may convert any audio stream from PAL to NTSC and vice-versa.
First off, there are two NTSC versions. There is the film version which is at 23.976 fps but can sometimes be rounded up to say "24 fps" even though its really 23.976. This is what NTSC DVDs are. The other version which I guess is the TV version is 29.970 fps but can sometimes be rounded up to say "30 fps" even though its really 29.970.
-The reason putting 4.271% into audacity converts into PAL (which is 25 fps) is because it works out like this equation:
23.976 + 4.271% (1.02401496) = 25.00001496
That number is as close as you can get to exactly 25 to the thousandth of a percent. I actually worked it out and the difference between 25 and 25.00001496 in a 90 minute movie isn't even a tenth of one single frame. So the timing is only going to be off by almost literally nanoseconds from a real PAL version.
-When converting from PAL to NTSC you would use -4.096% as shown here:
25 - 4.096% (1.024) = 23.976
This one actually works out perfectly and so you would actually be more accurate if you recorded your riff in PAL and then made an NTSC version. Of course like I said, the difference is literally nanoseconds and doesn't matter one bit.
Anyways I was able to answer my own question and so I'm going to record my riff using the PAL version and then convert it to NTSC with audacity using that -4.096% number and it should be perfect. YAAAAAAAAAAAY! Using Audacity.
That's fine, but I have a problem here that is taking me a lot of time and I can't solve it.
It's apparently a NTSC file but using a PAL conversion.
Which means what exactly?
* Let's say a movie has 100 minutes in NTSC, and 96 in the PAL version.
In my case, the audio file has 100 minutes, but the source is PAL. So apparently there's no speedup, right? But there is.
However, I have seen NTSC versions with 96 minutes (that can be solved following the instructions above), and I have seen something different: a 99 minute version, so it's almost a minute shorter. But there are no cuts. It's exactly the same movie.
** In my case, I have two audio files:
The first one with:
2h14m03s
The second (I need to convert) with: 2h13m22s
What should I put in Audacity in the first and second case?
** In this scenario I have put -0.5001893047206193% (Audacity, Change Tempo) to change the time from 8002.97 to 8043s, to match the first file, but I am sure it won't work after it's finished. I have watched the 2nd stream and it's losing sync during the playback, earlier scenes have speedup (2, 5 secs before the 1st file, others have 8s). But like I said, there are no cuts or extra contents in the 1st file. They are both identical.
P.S. I have used http://www.percentagecalculator.net/ for calculating the %
Edit: I got the results from ** and the difference was shorter, but still there:
Need to add 2 secs to sync the 2nd file, but in the end (after 2 hours) the difference was 4 secs. So it's still not right, it should be 2 secs for the entire stream (and not 2 secs in the first hour, 4 secs after 2h). Oh, boy...
I recently came across this short explanation on how we may convert any audio stream from PAL to NTSC and vice-versa.
First off, there are two NTSC versions. There is the film version which is at 23.976 fps but can sometimes be rounded up to say "24 fps" even though its really 23.976. This is what NTSC DVDs are. The other version which I guess is the TV version is 29.970 fps but can sometimes be rounded up to say "30 fps" even though its really 29.970.
-The reason putting 4.271% into audacity converts into PAL (which is 25 fps) is because it works out like this equation:
23.976 + 4.271% (1.02401496) = 25.00001496
That number is as close as you can get to exactly 25 to the thousandth of a percent. I actually worked it out and the difference between 25 and 25.00001496 in a 90 minute movie isn't even a tenth of one single frame. So the timing is only going to be off by almost literally nanoseconds from a real PAL version.
-When converting from PAL to NTSC you would use -4.096% as shown here:
25 - 4.096% (1.024) = 23.976
This one actually works out perfectly and so you would actually be more accurate if you recorded your riff in PAL and then made an NTSC version. Of course like I said, the difference is literally nanoseconds and doesn't matter one bit.
Anyways I was able to answer my own question and so I'm going to record my riff using the PAL version and then convert it to NTSC with audacity using that -4.096% number and it should be perfect. YAAAAAAAAAAAY! Using Audacity.
That's fine, but I have a problem here that is taking me a lot of time and I can't solve it.
It's apparently a NTSC file but using a PAL conversion.
Which means what exactly?
* Let's say a movie has 100 minutes in NTSC, and 96 in the PAL version.
In my case, the audio file has 100 minutes, but the source is PAL. So apparently there's no speedup, right? But there is.
However, I have seen NTSC versions with 96 minutes (that can be solved following the instructions above), and I have seen something different: a 99 minute version, so it's almost a minute shorter. But there are no cuts. It's exactly the same movie.
** In my case, I have two audio files:
The first one with:
2h14m03s
The second (I need to convert) with: 2h13m22s
What should I put in Audacity in the first and second case?
** In this scenario I have put -0.5001893047206193% (Audacity, Change Tempo) to change the time from 8002.97 to 8043s, to match the first file, but I am sure it won't work after it's finished. I have watched the 2nd stream and it's losing sync during the playback, earlier scenes have speedup (2, 5 secs before the 1st file, others have 8s). But like I said, there are no cuts or extra contents in the 1st file. They are both identical.
P.S. I have used http://www.percentagecalculator.net/ for calculating the %
Edit: I got the results from ** and the difference was shorter, but still there:
Need to add 2 secs to sync the 2nd file, but in the end (after 2 hours) the difference was 4 secs. So it's still not right, it should be 2 secs for the entire stream (and not 2 secs in the first hour, 4 secs after 2h). Oh, boy...