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We're In Such A Hurry That We're Even Rushing Through Recordings
from the speed-that-up,-won't-ya? dept
It's been nearly two years since a TV station got into all sorts of trouble for using some compression technology to speed up a football game so that they could add an extra 30 second commercial. The technology works by cutting out tiny, unnoticeable segments during the game. Over the course of a three-hour football game, it's pretty easy to get an extra 30 seconds without anyone noticing at all. Since then, plenty of TV stations have adopted the technology. However, the NY Times is looking at a different application for the technology: speeding up audio recordings. While using the technology for video compression, the overall effect is small, because you're trying to make it completely unnoticeable. However, with an audio recording, humans can still understand the audio at much higher speeds. The speed of our normal conversation is limited by how fast we can really talk - not how fast we can hear. In the past, speeding up audio meant increasing the pitch and getting the infamous "Chipmunks" effect. However, this new technology lets people speed up audio recordings many times over without such an effect - and it's still quite understandable. They also say that it doesn't suffer from the sort of "blurring" you get when people try to speak quickly themselves. Suddenly, people are listening to hourlong radio broadcasts in much shorter time frames - giving people back one of their most precious resources: time. In fact, some people claim that once they get used to listening to audio at high speeds, it's tough to go back to listening to people speak at normal speeds (someone compares it to the difference between dial-up and broadband). Some fear that constant use of such systems will make us all start talking much faster, like we're in some sort of Aaron Sorkin TV show, but others doubt that will ever happen. In the meantime, how long will it be until TiVo or someone like that starts advertising this technology as an additional "feature"? Forget just skipping commercials, you can now cut a few more minutes off the shows your watching and end up watching even more TV shows.
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Of course, instrumentalists have been doing this for years so that tunes come out faster and brighter sounding - they often crank things up so that the key moves up a semitone. It's a bugger if you want to play alogn though. There is a rumour that Stefan Grossman recorded his Red Pepper rag at half speed and in the first postion and then doubled it up so that it came out as though played up the neck.
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Limits
This kind of thing has been done in advertising for a long time. I suspect that when you look at this technique more closely, you will find that when speech is sped up, and the mind is more heavily occupied with comprehension, critical faculties are diminished, and therefore the ideas in the speech are received less critically -- and are more likely to be accepted without the kind of filtering one is accustomed to.
I conclude that this idea is progress, but ONLY up to a point, beyond which it is pure manipulation.
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close captioning
I remember something from "Microserfs" by Douglas Copeland where the protagonists make the most of their free time by watching videotaped films with close-captioned subtitles. Put the tape onto fast-forward/picture-search and speed read the sub-titles as they zip by.
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I have been using this at home already...
I have been using a 1.3X play feature on a Panasonic DVD recorder that has a hard drive. I just got it a week ago but have gotten used to the speeded up info. I use it mostly for chat shows and the news (Letterman, BBC news, etc).
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FX Uses This Method
I've noticed this when doing my daily morning workout to "Buffy the Vampire Slayer". Certain bits of the show, such as ends of scenes, that I remember from the network run will be cut out.
It may seem inconsequential, but sometimes they'll cut what seems to be a fragment of dialogue that actually moves the story line along. Annoying.
MLO
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The technology used to be called VOX
Radio Shack used to sell a +$115 cassette player that would do that.
A audio clipping circuit and a variable speed motor, for up to 2x speed up.
Sold in the early 1980's.
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Re: FX Uses This Method
Syndicators have been doing this for years. They're not compressing the time format but just cutting out enough material to let stations add an extra two minutes of commercials when they run it non-prime time. When the Sci Fi channel ran "Star Trek" episodes several years back they made a big deal about how they were showing the original length shows instead of the ones chopped up for syndication. The episodes weren't tremendously different but they did run several minutes longer.
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20 year old technology
I used to build systems like this for the NSA about 20 years ago. Most people can understand a 2x speed increase of a low-noise source.
First, run an autocorrelation function on the source stream to detect intervals of uniform pitch. Most pitch intervals contain many nearly identical small units of pitch or pitch periods.
Then delete as many redundant pitch periods from within the pitch intervals as needed to change the stream to the new speed. It sounds better if you blend the edges of the spliced periods. The result is pitch-normalized, i.e. doesn't sound like the speaker was breathing helium.
It only takes a few hundred lines of C code.
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Re: 20 year old technology
I train kids to read when the schools can't. When I read your article I was looking for a new source of a tape player that could be played at speeds between .75X normal to 2X normal. My last one disappeared and I went to get a new one, only to find that Radio Shack doesn't carry them anymore. What to do? It's an important part of the program.
My question is, can a computer be programmed to replay an audio source at a variety of speeds, say .7X normal to 2X normal in predetermined increments of .1X normal? Would it work on any new source or would each one have to be individually programmed?
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