Why Don't PAL dvdrips slow down the film and audio to film

[drmuffin]

PAL dvds are made by speeding up film by ~4%. Why then when ripping and encoding the video is the film and audio not slowed down as part of the process?

Film has a framerate of 24000/1001
PAL has a framerate of 25

TO go from PAL to film you'd have to perform a stretch on audio (resample to alter the pitch as well) and video of (24000/1001)/25, simplifying to 960/1001

How come this isn't done? Is there any particular reason?

[setarip_old]

Hi! PAL dvds are made by speeding up film by ~4%. Why then when ripping and encoding the video is the film and audio not slowed down as part of the process?...To go from PAL to film... If you're asking why existing "ripping" programs don't include such a feature, it's probably because the intended purpose(s) of the DVD "ripping" programs is to make backups of DVDs that you own - and with VERY rare exception (DVD released as PAL but not NTSC, or vice versa) there would be no reason to convert from one format to the other...

[Ghitulescu]

TO go from PAL to film you'd have to perform a stretch on audio (resample to alter the pitch as well) and video of (24000/1001)/25, simplifying to 960/1001

How come this isn't done? Is there any particular reason?

For video:
there are extremely few devices that can play native 24fps, especially in the PC world
not all PAL movies have been sped up

For audio:
the second resampling may hurt the quality

[drmuffin]

With a NTSC DVD, care is taken that if the source is film, it should be IVTC'd to return it to the original framerate, while those shot for ex: on video stay at the video framerate. Why shouldn't this be done with PAL DVDs: those that were originally film be slowed down to the original speed, those not be left alone.
Regarding the audio: I've performed a test myself, and the audio was fine.

[sneaker_ger]

Why shouldn't this be done with PAL DVDs: those that were originally film be slowed down to the original speed, those not be left alone.

No one says that it shouldn't be done. But by the time people developed programs like GuardianKnot etc. displays and players weren't capable of displaying 24(/1.001)Hz anyways, so keeping it at 25Hz prevented judder. This also allowed to keep the sound completely untouched. (As Ghitulescu already pointed out.)
Plus there is no easy way of figuring out how to handle the audio pitch.

Now that displays and players are 24Hz capable we have the Blu-Ray and we don't have to take care of such things anymore.

[manono]

How come this isn't done? Is there any particular reason?
I do it myself. You can do it yourself. What do you care how others do it?

[hello_hello]

To my way of thinking the main reason for converting would be to correct the audio pitch as a 25fps video doesn't look sped up to me (I can't tell it's running slightly faster).
These days a lot of PAL content seems to have pitch corrected audio (the NTCS and PAL DVD audio sounds exactly the same, ignoring the small speed difference) so in order to convert it I assume you'd have to time stretch it and pitch correct it again, which doesn't seem worth the effort (to me).