PAL Speedup - DVD - Some Eps Sound Normal Despite Shorter Length

[rustyshackleford]

Greetings,

I purchased the Quantum Leap DVD set from the UK since it has all the original music intact. I'm familiar with the PAL speedup issue since I have other UK DVDs that I've successfully converted via avidemux. However, I've been ripping the Quantum Leap DVD eps and some sound normal and others sound like they're sucking helium despite them ALL being shorter in length than their USA counterparts.

For example, Season 2, episode 8 ("Jimmy") is 46m on the DVD but it should be about 47m 50s. I checked this by playing the Netflix version. I also did this with several other episodes from season 1 and 5. In all cases the UK DVD eps are shorter than they should be. Some of the UK DVD eps when converted sound fine and the length is correct. Others turn out to the the right length (Jimmy ends up at 47m 47s) but sound like they're talking in slow motion despite the sound being in sync with the video.

It's like some episodes are sped up but the audio pitch somehow stayed what it should be and others both the video and audio are sped up. Has anyone experienced this? I was hoping to batch convert all the eps. Now I have to go through one by one and see if they sound normal or not. I was just wondering if this is common. Thanks for any advice.

[hello_hello]

In my experience, when film is sped up to 25fps for PAL, the audio is usually just sped up to match, and not pitch corrected, so if you're re-encoding you can just slow the frame rate down to 24fps and slow the audio to match. Usually all the episodes would be the same. Given the age of the series and the horrors that are often inflicted on video on it's way to DVD though, anything's possible.

If you're sure all episodes are simply film sped up to 25fps, and I assume you're slowing it down to 24fps when re-encoding, you might need to pitch correct the audio again for the appropriate episodes. I don't think Avidemux can do it. It can be done using Avisynth (pitch correcting stereo audio is fine but there's potential issues for multi-channel audio). The only GUI I know of off the top of my head with audio pitch correction is MeGUI. No doubt there's others, but MeGUI is the only one I know of for sure.

Pitch correcting the audio in Avisynth is pretty easy if you're familiar with Avisynth (by pitch correcting I mean slowing the audio down without changing the pitch). When slowing Pal down to 24fps without changing the pitch.
http://avisynth.nl/index.php/TimeStretch
TimeStretch(tempo=(2400.0/25.0))

Normally you'd just slow it down which does change the pitch.
TimeStretch(rate=(2400.0/25.0))

Although MeGUI slows it down like this. Maybe SSRC is technically better quality when simply changing speed. I'm not sure.
http://avisynth.nl/index.php/SSRC
SSRC(Round((AudioRate()*25.0)/24.0)).AssumeSampleRate(AudioRate())

If each episode is sped up film, there's probably no reason why you can't still slow them all down, but I assume you'll have to work out how to deal with the audio in different ways.

[rustyshackleford]

hello_hello,

Thanks for the response. I am 100% certain that some of the eps are film and audio sped up whereas some are simply film sped up and the audio pitch is unchanged. It looks like the whole disc is one way or the other. I haven't found any discs where some eps are film/audio sped up and some are film sped up only. All the eps on one disc are encoded the same way. I don't know why that would be but it's very noticeable. I may only convert the ones I know are film/audio sped up. It bothers me that the episode is 2 minutes shorter than usual, but it's the pitch that bothers me the most. For my region 4 Greatest American Hero DVDs I knew something was off immediately since I know what show backwards and forwards. I automatically assumed that's what I'd be dealing with with the Region 2 Quantum Leap DVDs. I won't have them ripped to my NAS as quickly as I thought.

[johns0]

Please do not cross post,one thread is enough,continue in this thread.

https://forum.videohelp.com/threads/378377-PAL-Speedup-DVD-Some-Eps-Sound-Normal-Despit...Shorter-Length

This thread is closed.