Slashdot Mirror
The History of the CD-ROM
Gammu writes "The inventor of the compact disc, the most popular medium in the world for playing back and storing music, is often disputed as one individual did not invent every part of the compact disc. The most attributed inventor is James Russell, who in 1965 was inspired with a revolutionary idea as he sketched on paper a more ideal music recording system to replace vinyl records; Russell envisioned a system which could record and replay sounds without any physical contact between parts."
4-8GB of mp3 space vs 800MB for a CD-R.
However, Sony vice-president Norio Ohga, who was responsible for the project, did not agree. "Let us take the music as the basis," he said. He hadn't studied at the Conservatory in Berlin for nothing. Ohga had fond memories of Beethoven's Ninth Symphony ('Alle Menschen werden Brüder'). That had to fit on the CD. There was room for those few extra minutes, the Philips engineers agreed. The performance by the Berlin Philharmonic, conducted by Herbert von Karajan, lasted for 66 minutes. Just to be quite sure, a check was made with Philips' subsidiary, PolyGram, to ascertain what other recordings there were. The longest known performance lasted 74 minutes. This was a mono recording made during the Bayreuther Festspiele in 1951 and conducted by Wilhelm Furtwängler. This therefore became the playing time of a CD. A diameter of 12 centimeters was required for this playing time.
In this way the specifications of the CD were determined by means of intensive contact between Philips and Sony.
http://www.research.philips.com/newscenter/dossier /optrec/beethoven.html
Just thought you'ld like to know
qz
Just to pick at a nit here, Gregg's work was an analog recording, not digital. If you look at the direct derivitive of Gregg's work - the LaserDisc - you'll find that the data is encoded in a Pulse Width Modulation format. This allowed for NTSC signals to be directly recorded to discs long before the invention of digital encoding technologies like MPEG.
In fact, the microprocessor technology necessary to decode a digital datastream into television quality video cost millions of dollars back when the LaserDisc was introduced to the market. During development of the format, the necessary framebuffer devices were still in development and wouldn't reach truecolor capabilties until the New York Institute of Technology experiment in 1977. (They took three 8-bit, grayscale framebuffers manufactured by Evans & Sutherland and wired them together to create a 24-bit display.)
So as you can imagine, an analog design was far superior to a digital video format back when Laserdiscs were introduced.
Javascript + Nintendo DSi = DSiCade
If I recall correctly it was Ron Kok, a Dutch entrepreneur, who came up with a *MUCH* more efficient production method to make them cheaper. He put the separate components inline and improved the sequence, thus taking away a lot of the media handling which caused quality issues. Quality went up, volume went up, price came down.
Did the guy get rich off it? No, because in those days he was naive and thus had it stolen and copied from right underneath his nose. He's fared better since, but he's the guy that's responsible for CDs being so dirt cheap (AFAIK, been a while since I heard this).
Insert
As many audiophiles will tell you, though humans cannot generally perceive tones above 20kHz, they are able to use high-frequency information for things like localization, and an entire high-resolution sound recording market, based on 96 and 192 kHz recording formats is built around it. The quote from the website above sort of tries to reason the 44.1 issue backwards: why didn't they just do 44.0 or (44.2 even?) if they were trying to find a sample rate that didn't convert so well? Particularly when the best analogue formats, like 30 ips 2 inch tape, can record up to 30 kHz?
Here's the story my recording engineering teachers passed down to me, accept it if you wish:
A long time ago the only way you could make a digital recording (without building a cleanroom or spending $10 grand on a 1 Gig hard drive) was to take your digital bit-stream and record it on some kind of helical video tape. Sony was the first company to sell these devices, which were basically black boxes with audio in on one side, and video out on the other; you would then take this video signal (which looks like "checkerboard" noise on a TV) and send it to a VCR to record. The best commonly-available video recording format at the time was 3/4" U-Matic.
U-Matic can record the full 525 lines of an NTSC image at (nominally) 30 frames/sec. In tests, the Sony engineers found they could squeeze about 47,040 bits into a frame. (There's some way this worked out into an integer number of bits per an integer number of lines, but I can't remember the math right now. It averages about 90 bits per line.)
So, if you have 47,040 bits per frame, you have 1,411,200 bits per second, which is 176,400 bytes/sec, which is the data rate of 44.1 kHz stereo PCM. The system also works for PAL, which only runs at 25 video frames per second, but has 625 line to record on, making up the difference.
Don't blame me, I voted for Baltar.
CD was not the first technology to read discs without physical contact. RCA had a turntable capable of "reading" vinyl records with a light-beam in the late 1930s.
s g_0000018187.shtml
The RCA Magic Brain Victrola/Radio "was advertised as being able to play both sides of a record without turning it over and used a jewel-lite scanner that eliminated the needle and you could stack up to 15 records at a time."
Sometimes seen advertised on RCA 78rpm record labels of the period.
http://www.phonoland.com/archives/mboards/18100/m
"You must try to forget all you have learned. You must begin to dream." -- Sherwood Anderson
"Slashdot - News and Chat Sites Deviant". (Click "homepage" link above for details).