Ripping audio from DVD..Why are there two identical audio streams ?

[CooperCat]

One question I never figured out. Many commercial DVD's I come across, when I try to rip the audio there are two identical audio streams, both will be AC3 (48khz 2 channel). They will be under separate titles. For example, I'm ripping a DVD that has 3 episodes of a show. So Title 1 will be the introduction to the dvd. Title 2 + 3 will be for episode 1, title 4 + 5 for episode 2, and title 6 + 7 for episode 3. Title 2 + 3 will have identical audio, and both will be AC3 (48khz 2 channel). I don't understand why. I get it if you have a 2 channel stream and a 6 channel stream, but why the identical streams ? I'm trying to listen for some kind of difference, but I can't tell. I'm psyching myself out thinking one is a little better than the other, but audio tools show me no difference. Thanks.

Okay, I just checked the DVD out with DVD Shrink, and it's not just two separate audio streams per episode. Each episode is on the DVD twice. These sets came out 10-20 years ago and are dual layered dvd's. DVD Shrink has Titles 2+3 being the same, 4+5 the same, and 6+7 the same. I can extract each one separately. So I copied Title 3 into a folder, and Title 4 into a folder. They both play back the same. All audio and video attributes were the same during playback. So I don't get it. It's not just with this DVD. It's something I noticed on a lot of commercial DVD's. There's got to be a difference somehow, but I'm not seeing it. More experienced people who have dug into this stuff further over the years hopefully would know.

[Lord Reith]

They're not actually on the dvd twice, they are just referenced twice. It depends on stuff in the menu as sometimes there will be different options for playing the same episode.

There's also a form of copy protection which spoofs loads of different versions of the same movie or episode, each with a different running time and only one of them is the right one. But the episode is actually only present on the dvd once.

If you're not sure, play the disc in VLC Player and take note of which title is playing in PLAYBACK > Title. Then rip that one.

[CooperCat]

They're not actually on the dvd twice, they are just referenced twice. It depends on stuff in the menu as sometimes there will be different options for playing the same episode.

There's also a form of copy protection which spoofs loads of different versions of the same movie or episode, each with a different running time and only one of them is the right one. But the episode is actually only present on the dvd once.

If you're not sure, play the disc in VLC Player and take note of which title is playing in PLAYBACK > Title. Then rip that one.

I see what you're saying. I just can't tell the difference between Title 2 and Title 3. When I ripped each one using DVD shrink, they both played back with the same attributes, audio and video. I can see if one referenced a 6 channel playback and the other a 2, or different video attributes. Outside of trying to fully understand what the different references are, I just want to know that the audio is the same if they're both saying AC3 2ch 48khz. If one isn't different from the other, then I can just rip one of them for audio.

[Lord Reith]

There's no difference, they're the same.