Comment on shrimp colour drama
null_dot@lemmy.dbzer0.com 1 week agoOh man.
12 year old me waiting for hours to rip mp3s from cds always wondered about this.
Like why isn’t it already compressed?
The answer is that storage was available but processing wasn’t. Amaze.
T156@lemmy.world 1 week ago
Mp3 is already compressed, as is the MP2 CDs use.
If it wasn’t conpressed, you’d be looking at CDs per track, instead of tracks per CD.
deltapi@lemmy.world 1 week ago
What are you on about? CD-DA, aka audio CD, aka red book audio, is uncompressed 16-bit PCM @44100Hz. It is lossless.
MP3 (MPEG-1/2 Audio Layer III) is a lossy encoding standard commonly used for online audio distribution and steaming. MP2 usually refers to MPEG-1 Audio Layer 2, which was most commonly used in Digital Audio Broadcast.
Neither are used in ‘regular’ CD audio.
SaharaMaleikuhm@feddit.org 1 week ago
I’d like to subscribe to the format facts newsletter. Can you do VHS next?
captain_aggravated@sh.itjust.works 1 week ago
The round hole in the middle of the cassette near the tape path is designed to have a light bulb on a stick inserted into it.
Most of the tape is (approximately) opaque due to the magnetic recording media, but the very ends are transparent. If you open the cassette’s lid and look at the uncovered ends of the cassette, you’ll see a hole on each end that has a path through the cartridge to the light bulb hole, only interrupted by the tape itself. Photoreceptors in the VCR sit just outside those holes, and if light is detected it means that the clear leader is starting to unwind from the spool meaning the tape is over, so this is how the VCR knows to stop the tape. This is why so many VCRs and rewinders glow inside.
Later hardware swapped it for an infrared LED and detectors but still did the job optically.
WhiskyTangoFoxtrot@lemmy.world 1 week ago
Each frame of video on VHS actually occupies a diagonal section of the tape. That allows the width of the tape to be effectively longer which means it can store more information. It’s also why the image will jitter a bit when the tape is paused since there’s multiple frames of data under the read head at any given time.
captain_aggravated@sh.itjust.works 1 week ago
I’m not sure that’s the right word for uncompressed digital audio, because it’s lossless compared to what? Presumably an analog recording or the original input signal? Because Shannon-Nyquist, with CD audio you can’t get anything higher than what? 16kHz out of it, but within that limitation you can reproduce any arbitrary waveform within a speaker’s ability to produce given the laws of physics regarding inductance and inertia.
MP3 does use a lossy compression, but you can maintain listenable quality while cramming about 10 times as much audio into a given space. You can get just over an hour of Red Book audio on a CD, and about 11 hours of mp3s, give or take. You might get lower audio bandwidth or various kinds of artifacts but it’ll still sound pretty good, it’s way more practical to store and transmit over the internet. We didn’t Napster no .wav files.
FLAC and similar formats use lossless compression, kind of like a .zip file. If you rip a CD to FLAC, and you were to then burn a CD from that FLAC, the data on the new CD would be identical to the old one. So you get as-perfect-as-we-can-do digital audio, but only 5 or 6 hours worth would fit on a CD. Someone somewhere on this earth has filled a compact disc with FLAC files, I’m sure.