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Comment by mrb | Hacker News Reader

"if you take a track and play it a little bit faster or slower it still sounds great or awful as at the default speed in most cases."

Yup. Another example: in most of the world (where the television system is PAL or SECAM) movies are played on TV or released on DVD at 25 frame per second. But to achieve this frame rate, they take the theatrical film release at 24 fps and speed the video and audio up by 25/24th (4.17%). Of course almost nobody knows this because nobody notices it. https://en.wikipedia.org/wiki/576i#PAL_speed-up

For NTSC, the film release is sped down by a much smaller amount (0.1%) during the 3:2 pulldown to adjust from 30 to the exact 29.97 fps that NTSC needs.

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Another example is the kind of dastardly television trick of increasing the speed of a television program to shorten it and thus increase the amount of advertising space that can be run alongside the program.

https://www.youtube.com/watch?v=z6i1VVikRu0

This video claims that TBS is currently increasing the speed of Seinfeld episodes a whopping 9%, reducing a 25 minute episode to some 22.5 minutes.

USA network used to do this.

"mpv -speed 1.1 file.webm" ... get 10% of your watching things time back, it does pitch correction, often its unnoticeable.

Technology can work in your favor too!

VLC can do this too:

Speed up: ] key Speed down: [ key Normal speed: = key

I use that to watch slow lectures at anywhere to 1.8x to 2.3x the speed. Turns a 40 minute lecture into a 20 minute lecture.

Some people one youtube speak really slowly, or are unprepared. The 1.25x speed button is great for that.

Also, some youtubers speak way too fast. Slowing them down helps comprehension a lot, I find.

I am used to speed up things, but last weekend I suddenly realised I can also slow down engrenages (a French show recommended in another HN thread, by the way) and suddenly I can understand so. much. French. It's like magic!

Not many people are aware that this is in fact the natural way spoken French sounds like in France, because of a difference in air composition and thus the speed of sound.

Uhm, no that's definitely not true.

You absolutely see it in TBS broadcasts of Family Guy, where they can get away with speeding up the show without impacting its look and feel tremendously.

Can't skip frames when there are none.

Stanley Kubrick would have hated this. ;)

http://www.cinemablend.com/new/Message-From-Stanley-Kubrick-...

Of course almost nobody knows this because nobody notices it.

Though, I can now instantly tell if I'm watching a PAL or NTSC version of Star Trek TNG based on the the first few bars of the opening song.

Which is weird, because I don't even have pitch perfect hearing and I'm not even that musically inclined.

I'm guessing you've watched a lot of Star Trek? I figure this is just the human mind's wonderful proclivity towards learning patterns.

I was actually thinking about a similar but less subtle example: I use a transit system that involves tagging on and off with an RFID card (Clipper on Caltrain). When you tag your card, it makes one of three different noises depending on what happen—and I couldn't possibly tell you which one corresponds to what. But if I'm actually using it and I make a mistake, I notice immediately because I'm so acclimated to the pattern it normally makes!

If I hadn't realized this, the UI for the system would have looked absolutely terrible. The different beeps are the auditory equivalent of "mystery meat navigation" but even worse because they don't carry any semantic meaning at all. But because I always use the system in the same way and the noises were consistent, it actually works really well even if I never consciously learned what noise corresponds to what.

(The fact that there are wrong ways to use the system is bad design, but it's a function of how the whole train system is set up, not the fault of Clipper's designers.)

There are several different Clipper beeps:

* One beep - successfully paid fare

* Two beeps (different) - successfully paid fare, and you're about to run out of money on your card

* Two beeps (equal) - tagged off (e.g. on Caltrain or San Francisco Bay Ferry)

* Three beeps - read error or insufficient value

There might be others. Indeed, they've introduced a quieter "here is a Clipper reader" beep to help visually impaired people locate them: https://vimeo.com/183916243

I wouldn't be surprised if there was some psychology behind the choice of sounds when you tag the transit card. Just like visual "affordances" in UI design, there may be certain audio characteristics that people will associate with "good" vs. "error," for example. I recall one study showing that people almost universally feel certain shapes and word sounds are "friendlier" than others (albeit by very subtle margins). And I believe in many languages people interpret pitch inflections to tell when a sentence is continuing vs. finished - think about reading someone a serial number out loud, and how if you were to pronounce the last number the same as all the others it will sound like you left the sentence dangling, with more digits still to come.

I'd be really interested to read anything more concrete about audio affordances though, if anyone knows of links to further research, etc!

I can list at least three linked ones: with two beeps, if the second's pitch is higher, means "on" or "ok" or "up", whereas if the second's pitch is lower, the other way around.

A fantastic book on how these are all related is "metaphors we live by". I'd expand on this but I'm typing on mobile and on a hurry. But seriously: read the book. It takes a long afternoon. It's great, short, illuminating, and not excessively dense or padded.

Yeah, there's quite a lot of this but I can't think of any good references offhand. When doing audio logos I've always looked to catchphrases and famous movie quotes and tried to emulate the underlying intonation/cadences. I'm not aware of this knowledge being systematized anywhere though.

"Audio logos" - that's a fascinating concept I've never really thought about. Any recommended reading about that field?

You can train your brain to remember pitches. Try humming your favorite song, then play it and see if you picked the right key. I did this as a game with a friend one afternoon with maybe 80% success rate across 50 songs.

Does that mean you can train yourself to have perfect pitch?

That seems like a logical conclusion

As I understand, no. There's some suggestion that small children, usually under the age of 10, can acquire perfect pitch, but no adult has ever been documented acquiring it.

Source: http://www.zainea.com/absolpitch.pdf

There seems to be some controversy about this though. I've seen other papers[1] claiming that adults can acquire it, albeit only to a limited extent.

[1] e.g. http://www.sciencedirect.com/science/article/pii/S0010027715...

Might not be the change in pitch you are noticing but the speed of the music

I know what you mean, when I was living in Australia I could swear the voices sounded off on The Simpsons.

This explains the years of confusion I've suffered noticing sharp pianos in films. I could never work out what was wrong with American film pianos! Thank you, seriously.

The European (PAL) ones are sharp. The American (NTSC) ones are accurate (or very very slightly flat).

Late night error, thank you for pointing that out. European etc PAL formats go sharp when transcribed to. So American and all films transcribed into PAL go sharp, which happens a lot. So it's not the origin of the film, but the (usually) PAL format I historically watched them in that caused this.

And in cinema they were better (I seem to remember Geoffrey Rush 'playing' Rachmaninov 3rd Piano Concerto in that film, at excellent pitch in the cinema), so I knew they were sometimes right. But i think the tape, TV and DVD formats I'll have rewound most often in perplexity.

Another confounding: living in California a lot and not having incorrect pitch on local copies. And nowadays, when sources are digital, bit may have originated from analogue recordings, it's now very unclear what to expect.

> For NTSC, the film release is sped down by a much smaller amount (0.1%) during the 3:2 pulldown to adjust from 30 to the exact 29.97 fps that NTSC needs.

No. For NTSC they just drop (throw away) 1 frame from every 1000 frames, so there's no speed-up or speed-down in audio track.

There must be a speed-up since the audio track is not divided into frames. Dropping a 33ms chunk of audio would be very noticeable.

No, you don't have to alter audio in any way, you just leave it untouched.

Let's say you have 100 seconds of film material with corresponding audio duration. That would be exactly 2400 frames, because film is 24 fps. When you do 2:3 pulldown (that's one of the methods used to do telecine, i.e. film conversion to television format) you'll get back exactly 3000 video frames. But in NTSC format, (if you'll leave audio untouched, i.e. it's duration didn't change, it's still is 100 seconds) for 100 seconds of video duration you must display 2997 video frames, not 3000. So you just throw away 1 frame from every 1000 frames to get the exact 29.97 fps.

Doing this, at worst case you'll get audio/video desynchronization of 33 ms, which I don't think is noticeable (I tend to visually notice desynchronization when it's at about 100 ms or more). But if you'll drop that 1 excessive frame in the middle (not at the end) of the sequence of 1000 frames, you'll get audio/video desynchronization which only varies from -16 ms to +16 ms. Which is not worth the trouble of fixing this by going the other way around it: leaving video untouched and slowing down the audio by 0.1%.

This is incorrect. I worked for a decade as a film sound engineer. If you don't implement the 0.1% pull-up/pull-down, then sync will begin to drift noticeably.

https://www.lynda.com/Pro-Tools-tutorials/Understanding-vide...

The first time I remember hearing about this was in regard to the semi-famous "Wizard Of Oz / Dark Side Of The Moon" combination, which supposedly only works at the theatrical frame rate.

If anyone wonders where the odd NTSC frame-rate ratio originated from, Matt Parker (standupmaths) did a comprehensive video, with some original write-up on this recently: https://www.youtube.com/watch?v=3GJUM6pCpew

Whilst conversions that speed up video do happen, It's not really intentional or desirable.

A friend of mine bought the DVD of 'Rent' when it first came out in our region. A month or two after it came out, the DVD got re-issued because it's a musical, and people had been complaining that the conversion had been messed up. I think she got the re-release for free.

Rate changes are a bigger issue for musical features like Rent, as it makes them difficult to play along with. For a more typical dramatic feature, it's less noticeable.

There's a really interesting video by Matt Parker about why 29.97 is the magic number.[1]

[1]: https://youtu.be/3GJUM6pCpew

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