minaust
10th January 2012, 23:31
I had a strange problem getting chapters from a DVD while ripping with DVD Decrypter. I had a need to rip a single chapter from one episode of a NTSC episodic DVD. Bring up DVD Decrypter in IFO mode, uncheck all but the desired chapter, rip, encode, & run. No problem – I had what I wanted.
When I got back home, I decided to rip the whole disc, each episode one chapter at a time. I have DVD Decrypter set up to output chapter information, so I ripped each episode in its entirety and used the chapter info to generate trims for avisynth scripts. Using that, I was off by a few seconds – and it was cumulative - the higher the chapter number, the further I was off.
Hours * 3600 + minutes * 60 + seconds = the time in seconds. Then multiply that by the frame rate (29.97 in my case), and I have a frame number. No good. Then I discovered that if I output the chapter info in IFOEdit format, I got the chapter info in frame number format. Maybe my math was off – no need to convert. No good – I got the exact same numbers I got the first way.
Then I went back to doing a time conversion, but this time I used 30 fps as the frame rate instead of 29.97. Bingo - now I'm spot on, all the way through, every chapter. Now I get the exact same thing either way. Actually, I'm off by one frame – rounding error I guess.
Now I'm like Christopher Columbus: Problem solved, but I don't know where I am or how I got there....
Admittedly, this is something I'll probably never need to do again, but now I'm not sure I can trust DVD Decrypter's chapter information – or can I? Why did I need to lie about the frame rate? Bug in DVD Decrypter, mastering error, or conceptual error on my part?
Any clues anybody? :confused:
When I got back home, I decided to rip the whole disc, each episode one chapter at a time. I have DVD Decrypter set up to output chapter information, so I ripped each episode in its entirety and used the chapter info to generate trims for avisynth scripts. Using that, I was off by a few seconds – and it was cumulative - the higher the chapter number, the further I was off.
Hours * 3600 + minutes * 60 + seconds = the time in seconds. Then multiply that by the frame rate (29.97 in my case), and I have a frame number. No good. Then I discovered that if I output the chapter info in IFOEdit format, I got the chapter info in frame number format. Maybe my math was off – no need to convert. No good – I got the exact same numbers I got the first way.
Then I went back to doing a time conversion, but this time I used 30 fps as the frame rate instead of 29.97. Bingo - now I'm spot on, all the way through, every chapter. Now I get the exact same thing either way. Actually, I'm off by one frame – rounding error I guess.
Now I'm like Christopher Columbus: Problem solved, but I don't know where I am or how I got there....
Admittedly, this is something I'll probably never need to do again, but now I'm not sure I can trust DVD Decrypter's chapter information – or can I? Why did I need to lie about the frame rate? Bug in DVD Decrypter, mastering error, or conceptual error on my part?
Any clues anybody? :confused: