I currently use Cyberlink PowerDVD combined with a tool called ReClock that allows high quality slowing down of DVDs. This means I can finally watch PAL DVDs of US shows at the correct speed, rather than 4% faster that they normally play at. Does anyone know of a Linux program that allows fine adjustment of playback speed (as well as pitch of audio), or at least where you can do this to a saved file? Having to keep Windows around just for this would be frustrating, but if I can't find a Linux option I may have to! Thanks in advance

Sorry for my ignorance, but please could you explain how the different DVD formats, played through a software player and ending up on a monitor refreshing at a different refresh rate, somehow end up playing for different amounts of time?

Sure, I may be getting slight details wrong here, but the essence of it is that shows filmed over in the states are filmed at 24fps. For 50hz compatibility that is then sped up to 25fps, allowing for smooth compatibility in PAL (50hz) regions. So DVDs are manufactured at about 104% speed in PAL regions, often accompanied with higher pitched audio. To work around that, ReClock slows down DVDs playing in PowerDVD as they are playing to their proper speed. If you are interested in further details you can search PAL Speedup in google.

I ask you again to actually explain the issue you are trying to resolve.
https://en.m.wikipedia.org/wiki/576i#PAL_speed-up

Trying to find a piece of Linux software that allows you to slowdown videos, ideally DVDs, to their intended broadcast speed. Either during playback (a media player like VLC) or something that can timestretch saved video files.

To just slow it down 4%
Keep pitch, change tempo example: (150%)
Keep tempo, change pitch. Use [ ] keys to change pitch

24, 25 or 30 fps videos will play at the correct speed unless the time base has been messed up while dumping them.

Are you talking about a video DVD or a file that was dumped from a DVD? Both should play at the correct speed.

If you take a 30fps video and reencode it to a 24fps video, then some of the frames have to be thrown away. If you leave them in the video with a 24 fps time base then the video will play too fast. But you have to do that on purpose. You can reencode a 24fps video to 30fps, but you'll have to interleave some frames so that there are 30fps where there were 24fps.

Tell more about what you have.

If you want to dump a DVD to file so that you can play it from file, then look and see what title you want, and dump it
You'll need libdvdcss installed. Won't matter what fps video it is.

As I tried to explain, this is how DVDs in Europe and other PAL (50hz) countries are actually manufactured. TV shows in the US have traditionally been filmed at 24fps. Long before DVDs were frequently being played on PCs which can display any kind of framerate video, they were needing to work with 50hz PAL TVs. In this situation, displaying one frame every two refreshes (precisely 25fps) vs something like 0.96 (24fps) is going to be desirable. So they simply made PAL region DVDs display the 25th frame to sync with the 50hz refresh rate of PAL TVs, hence playing the video at effective 104% speed. If you check, you will find European releases of major TV shows and films with shorter runtimes despite being identical. I am successfully using software to rectify this on Windows. Thanks for the advice - are those all commands relating to encoding i.e. ripping the DVD, then processing the file is the only way - or it can also alter live disc playback speed using the command?

You still aren't giving any info.

Are you playing these DVD's with a media player on a computer? Are you dumping the DVD's to file to play them? Are you making copies of the DVD's and trying to play them on a Video DVD player with a fixed frame rate? Are you trying to remaster those DVD's to another framerate? Are you tring to telecline those 25fps videos to 24fps?

Rectify it how?

What are you wanting to do with those DVD's? Play them? Dump them? Dump them to file, change the frame rate and then make a new DVD?

Yes I know what NTSC and PAL was/is.

Rectify it as in play it back at the original 24fps broadcast speed, effectively at 96% speed of default playback, instead of the default 25fps it is programmed to play at.

I explained about the PAL speedup as it wasn't clear you understood, because of what you said about 24, 25, or 30 fps DVDs being played back at the correct speed unless they have been messed with - it seemed as though you didn't understand that the DVD itself had been deliberately sped up by 4% when it was manufactured for PAL region markets, and that I was trying to slow it down to the original broadcast speed.

If I don't have to rip them to slow them down, that's great. Ripping them and then processing them is a last resort. This is all about playing some DVDs at a slower [correct] tempo and the easiest way to do it on Linux. I'm assuming the commands you posted refer to processing a file rather than adjusting live playback?

Edits for clarity

My apologies, I did, indeed, misenterpret your post and the link to be the same thing.
What a strange thing to have to worry about nowadays. Glad I'm subscribed to this thread, anyhow.

So what's wrong with VLC then?

It provides this functionality via the GUI and also has a --rate command line argument that appears to provide the same.

I've occasionally wondered why the first option was 0.96/1.04 and I guess this is why...
(Not sure it explains why it has 1.18x/1.23x/1.28x instead of 1.2x and 1.25x though, since the latter is the ratio of 30:25 and 30:24 ?)

Can you provide a screenshot of the GUI? Because I've searched all over VLC to no avail. Definitely not seen any reference to 0.96/1.04 speed.

Tools > Customize Interface > Toolbar Elements, scroll to bottom > drag "Speed selector" where you want it.

Then load a video, click the 1.00x and mouse wheel up/down over the bar that appears.

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I have no idea why such functionality is so well-hidden in the interface - I mean if I hunted through every option knowing what I was looking for I would eventually find it, but anyway, thanks for showing me that. Unfortunately the audio resampling just isn't quite there - I can just about take the 4% raised pitch which is still present, but it is just a bit too... warbly. Digital artefacts coming up a bit too often. I think I've found my answer - yes it can be done, but not as high quality as I've got with ReClock, which is specifically designed to resample the source material to play at different speeds. Guess I'm going to have to hold onto a Windows install for now!