3 ms·

I'm disappointed; I thought it would involve storing audio in analog format on a floppy disk.

by dreamlayers 6y ago

dylan604 6y ago
with a tiny little needle that would touch when the metal shield was moved out of the way?
- rob74 6y ago
  nope, magnetically, like on a cassette tape...
bittercynic 6y ago
It's been done! https://www.youtube.com/watch?v=ziVXF_tM4Gw https://www.youtube.com/watch?v=ziVXF_tM4Gw
- gambiting 6y ago
  Similarly, there have been photo cameras that used floppies for image storage, and I'm not talking about sony's Cybershoot cameras which stored photos as actual files - I'm talking cameras which just stored photos as analog signal directly on the floppy, in NTSC format! https://www.youtube.com/watch?v=4G_1uy_7B5w https://www.youtube.com/watch?v=4G_1uy_7B5w
- kevin_thibedeau 6y ago
  Or using MIDI "compression": https://www.youtube.com/watch?v=5ks3ucumilU https://www.youtube.com/watch?v=5ks3ucumilU
- rob74 6y ago
  Cool, wasn't aware it was possible to store an analog signal on a floppy using an unmodified disk drive. However, going from how often you hear the stepper motor in the video, the disk would fill up pretty quickly - I wonder how much analog music you could fit on a floppy with some optimization (slower rotation, tracks spaced more closely until crosstalk becomes an issue, maybe a spiral track like on a CD). My gut feeling is that you could fit more than 30 minutes on there...
  - adrianmonk 6y ago
    Interesting question. I'll try some rough calculations. A C60 audio cassette holds 30 minutes per side, and the tape is ~85 meters long (https://en.wikipedia.org/wiki/Audio_tape_specifications#Compact_audio_cassettes https://en.wikipedia.org/wiki/Audio_tape_specifications#Comp...). The diameter of the actual disc in a 3.5-inch floppy is 85mm (https://en.wikipedia.org/wiki/History_of_the_floppy_disk#.E2.80.8B3_1.E2.81.842-inch_format https://en.wikipedia.org/wiki/History_of_the_floppy_disk#.E2...), so the circumference of the outer track should be about pi * 0.085m or 0.25m. There are normally 80 tracks (https://en.wikipedia.org/wiki/List_of_floppy_disk_formats#Physical_composition https://en.wikipedia.org/wiki/List_of_floppy_disk_formats#Ph...), so if all tracks were as big as the outer one, that would give you about 20 meters. In reality, inner tracks are shorter. I can't easily find the inner diameter, but from pictures it looks like it's about 1/3 the outer diameter. So the track lengths (circumference) should grow linearly from 1/3 to 100% of the outer diameter, which means the total track length should be 2/3 of 20 meters or ~13 meters. To sum all that up, with 80 tracks, there seems to be about 13 meters of linear space the head can travel across, or about 15% of the length an audio cassette uses for 30 minutes. If you recorded at the same linear speed as a cassette, you'd get 15% of 30 minutes. But running a cassette at half speed is definitely practical (https://en.wikipedia.org/wiki/Audio_tape_specifications#Tape_speeds https://en.wikipedia.org/wiki/Audio_tape_specifications#Tape...), and machines were even sold with a setting for that. So double that to 30%. And there are a handful of floppy formats that use more than 80 tracks (one even uses 240), so let's assume 160 tracks is possible. So double again to 60% of 30 minutes. And that's just one side of the floppy, so using both sides means you can double again to get 120% of 30 minutes. So yeah, it seems possible! (Which incidentally is NOT the answer I was expecting.) If the 160 tracks thing doesn't work out, you could probably compensate slowing the rotation more. On a side note, the two-sided thing creates the potential problem of a gap at the 15-minute mark. Apparently there are read/write heads on both sides (https://computer.howstuffworks.com/floppy-disk-drive2.htm https://computer.howstuffworks.com/floppy-disk-drive2.htm), so I guess you could do the transition by recording a few seconds of audio on both sides, then cross-fading between them. In other words, start at the inner edge of the disk, reading from one side for 15 minutes as you slowly move the head to the outer edge of the disk, then cross-fade to the other head and continue back for another 15 minutes back toward the inner edge of the disk. You would need to have a good method for being sure you make this transition at the right time, though. Or you can always just record 15 minutes of stereo sound, reading each channel from one side of the floppy.

I'm disappointed; I thought it would involve storing audio in analog format on a floppy disk.

dylan604 6y ago

with a tiny little needle that would touch when the metal shield was moved out of the way?

rob74 6y ago
nope, magnetically, like on a cassette tape...

bittercynic 6y ago

It's been done! https://www.youtube.com/watch?v=ziVXF_tM4Gw https://www.youtube.com/watch?v=ziVXF_tM4Gw

gambiting 6y ago
Similarly, there have been photo cameras that used floppies for image storage, and I'm not talking about sony's Cybershoot cameras which stored photos as actual files - I'm talking cameras which just stored photos as analog signal directly on the floppy, in NTSC format! https://www.youtube.com/watch?v=4G_1uy_7B5w https://www.youtube.com/watch?v=4G_1uy_7B5w
kevin_thibedeau 6y ago
Or using MIDI "compression": https://www.youtube.com/watch?v=5ks3ucumilU https://www.youtube.com/watch?v=5ks3ucumilU
rob74 6y ago
Cool, wasn't aware it was possible to store an analog signal on a floppy using an unmodified disk drive. However, going from how often you hear the stepper motor in the video, the disk would fill up pretty quickly - I wonder how much analog music you could fit on a floppy with some optimization (slower rotation, tracks spaced more closely until crosstalk becomes an issue, maybe a spiral track like on a CD). My gut feeling is that you could fit more than 30 minutes on there...
- adrianmonk 6y ago
  Interesting question. I'll try some rough calculations. A C60 audio cassette holds 30 minutes per side, and the tape is ~85 meters long (https://en.wikipedia.org/wiki/Audio_tape_specifications#Compact_audio_cassettes https://en.wikipedia.org/wiki/Audio_tape_specifications#Comp...). The diameter of the actual disc in a 3.5-inch floppy is 85mm (https://en.wikipedia.org/wiki/History_of_the_floppy_disk#.E2.80.8B3_1.E2.81.842-inch_format https://en.wikipedia.org/wiki/History_of_the_floppy_disk#.E2...), so the circumference of the outer track should be about pi * 0.085m or 0.25m. There are normally 80 tracks (https://en.wikipedia.org/wiki/List_of_floppy_disk_formats#Physical_composition https://en.wikipedia.org/wiki/List_of_floppy_disk_formats#Ph...), so if all tracks were as big as the outer one, that would give you about 20 meters. In reality, inner tracks are shorter. I can't easily find the inner diameter, but from pictures it looks like it's about 1/3 the outer diameter. So the track lengths (circumference) should grow linearly from 1/3 to 100% of the outer diameter, which means the total track length should be 2/3 of 20 meters or ~13 meters. To sum all that up, with 80 tracks, there seems to be about 13 meters of linear space the head can travel across, or about 15% of the length an audio cassette uses for 30 minutes. If you recorded at the same linear speed as a cassette, you'd get 15% of 30 minutes. But running a cassette at half speed is definitely practical (https://en.wikipedia.org/wiki/Audio_tape_specifications#Tape_speeds https://en.wikipedia.org/wiki/Audio_tape_specifications#Tape...), and machines were even sold with a setting for that. So double that to 30%. And there are a handful of floppy formats that use more than 80 tracks (one even uses 240), so let's assume 160 tracks is possible. So double again to 60% of 30 minutes. And that's just one side of the floppy, so using both sides means you can double again to get 120% of 30 minutes. So yeah, it seems possible! (Which incidentally is NOT the answer I was expecting.) If the 160 tracks thing doesn't work out, you could probably compensate slowing the rotation more. On a side note, the two-sided thing creates the potential problem of a gap at the 15-minute mark. Apparently there are read/write heads on both sides (https://computer.howstuffworks.com/floppy-disk-drive2.htm https://computer.howstuffworks.com/floppy-disk-drive2.htm), so I guess you could do the transition by recording a few seconds of audio on both sides, then cross-fading between them. In other words, start at the inner edge of the disk, reading from one side for 15 minutes as you slowly move the head to the outer edge of the disk, then cross-fade to the other head and continue back for another 15 minutes back toward the inner edge of the disk. You would need to have a good method for being sure you make this transition at the right time, though. Or you can always just record 15 minutes of stereo sound, reading each channel from one side of the floppy.