10 ms·

Floppycasts – 1.44MB Podcasts

138 points by KirinDave 7y ago

mrob 7y ago
Does the resampling and bit-depth reduction of the wav file actually help? My intuition is that a modern encoder like Opus will work better if it has more information.
- ajroach42 7y ago
  I tried it both ways with opus. More or less the same in terms of quality, but the resampled file was about 3% smaller. I imagine it would be less of a size difference and more noticable at higher bitrates.
- JensRex 7y ago
  Bit-depth reduction is counter-productive. You're just adding noise to the signal, and reducing the dynamic range. As for resampling, it depends on the specifics of the resampler used by a specific codec implementation. If a resampler is terrible, it could add artifacts like ringing and aliasing that would degrade the encoding quality. A great souce for resampler comparisons: http://src.infinitewave.ca/ http://src.infinitewave.ca/
xellisx 7y ago
http://www.rowetel.com/?page_id=452 http://www.rowetel.com/?page_id=452
- ajroach42 7y ago
  Codec 2 is on my list to investigate in the near future. Couldn't find software on the target machines that supported it, so it landed on second tier.
ehsankia 7y ago
Hmm, listening the the samples [0], the OPUS one is almost unbearably noisy, whereas the MP3 while, while clearly low quality, is still listenable. Am I missing something, why is OPUS doing so poorly? [0] http://ajroach42.com/floppycast-examples/ http://ajroach42.com/floppycast-examples/
- sigmar 7y ago
  he used the opusenc setting "tuned for speech" and music sections (like :22) sound awful. would like to know what it would sound like without that mode turned on, as it also surprises me how bad opus sounds vs mp3.
  - ajroach42 7y ago
    The opus file is at 6kbps, the mp3 at 8. Opus file is tuned for speech, mp3 isn't. The opus file sounds unbearable when the music is playing, but is clearer otherwise. Double the bitrate and opus is way ahead.
- viraptor 7y ago
  It's interesting. The OPUS one is noisy, but pretty crisp. MP3 is smooth but more muffled. (like it lacks dynamic range) Honestly, I'd rather listen to the OPUS version if these were the only choices.
- Lowkeyloki 7y ago
  That's odd. My experience was the opposite. Although the Opus one was a bit muffled and some of the low end was missing so I had to strain a little to hear, the MP3 was a cacophony of pops and whistles all the way through. It was annoying and hard to concentrate on. I'd take the Opus one every time. I will say the music part was interesting. I could mostly make out the song on the MP3. On Opus, I could barely tell there was music there. A lot of it was just missing.
- verytrivial 7y ago
  As sad as this sounds, I think based upon the slurring of "s" sounds, that I recognize those source HHGTTG encodings, having listened to them on loop for hours at a time whilst coding. I think they're the 56kb/s MP3 ones that were floating around a couple of decades ago. There are some 128kb/s ones that might be a bit fairer.
jancsika 7y ago
Perhaps you could get it smaller by making a "vector format" for podcasts and leave it to the audio player to "do it live" <bgmusic character="spooky" /> <archiveaudio year="1972" type="cop" tone="evasive" /> <foley type="tirescreech" /> <foley type="river" weight="300" />
- craz8 7y ago
  Style sheets for sound - I think BBC radio used to sell CDs for this. Now they can provide Audio Style Sheets with the acronym of... oh, wait Golly - you could make any story sound like it was a Radio 4 play
  - salutonmundo 7y ago
    Acronym already taken by Advanced SubStation Alpha subtitle files!
  - detaro 7y ago
    There actually was work on CSS additions to give hints to Text-To-Speech engines, e.g. https://www.w3.org/TR/2018/NOTE-css3-speech-20180605/ https://www.w3.org/TR/2018/NOTE-css3-speech-20180605/
  - jancsika 7y ago
    I was thinking more that one would use mechanical turk to annotate each soundfile with these tags for the set of all podcasts. Then use that as training data to a ML algorithm that gets used to render the output for each tag. So I'd use my archiveaudio tag from the example and the algo would output the band-limited frequencies of what sounds vaguely like a cop with speech patterns signaling defensiveness and irritation. It would all sound perfectly like a podcast if you were listening to it in a sleep state. Then if you concentrated on it you'd realize there's no coherent plot or even any actual natural language being spoken in the entire recording.
- xvector 7y ago
  Would be even more interesting if each sound effect were randomized a bit so you don’t feel like you are hearing the same thing over and over.
splitbrain 7y ago
when I read the title I somehow assumed that the optimization would be in the length of the recording, not the encoding. I would like a podcast format with very short episodes.
- enneff 7y ago
  Me too! I was surprised to see the target length is 30 minutes. I think there's plenty of space for even much more compact podcast episodes, under 10 minutes in length. You can say an awful lot in 10 minutes.
  - salutonmundo 7y ago
    Yeah, since a lot of people speed up podcasts anyway, why not speed it up prior to compression (or learn to talk faster)? (Of course, speeding things up 3x is a bit extreme!)
    - benj111 7y ago
      Hmm why not speak 10 times faster, then slow down by 10 times after decoding. I havent decided whether this is a serious proposition yet....
- mhd 7y ago
  Or just good sections, not just stream of concsciousness rambling. That would also be sticking perfectly to the metaphor, swapping floppy disks should be familiar to everyone who every held one in their hands. As long as the podcast doesn't approach MS Office 97 territory (50+ disks).
themodelplumber 7y ago
So, no podcast yet, right? Didn't want to miss anything. That's a pretty cool idea. I'm all for some kind of subculture where media have tiny size limits, and if that starts from retro culture then great. I love to imagine using my 4G connection to download like 60 hours of podcasts in the few minutes before leaving on vacation...
- ajroach42 7y ago
  Nah, this was just me screwing around with encoders while I was avoiding editing my podcasts. When I actually release, I'll do it at a bitrate that's more listenable, but still optimized for space.
  - themodelplumber 7y ago
    Right on, I love that you're paying attention to the space factor. I'm a casual podcaster, about 10 episodes in last I checked :) and I totally know what you mean about editing. I have to do it right after recording or I'll procrastinate for weeks!
- xvector 7y ago
  There is something beautiful about efficiency. Small computers (check out /r/sffpc), efficient codecs, those competitions where people make games/music/graphics in just a few KBs (forget what those are called - “demoscene”?). The fact that compressed Wikipedia without images fits on an 8GB USB. It all fascinates me. It is amazing to see us push the boundaries of communication under such restrictions
  - z0r 7y ago
    There's a demoscene magazine intermittently published in 'demo' form: http://www.hugi.scene.org/ http://www.hugi.scene.org/
    - kozak 7y ago
      Would be cool to make a demo that would fit on a magazine page in something like a QR code (scannable with a normal phone).
enneff 7y ago
I love the idea, because there's something to almost ideal to me about the 3.5" floppy disk format. I wish I had some reason to use them today, and so I really want this to work. However the audio quality is just terrible; it may be intelligible, but it is unlistenable IMO.
- ajroach42 7y ago
  Oh for sure. It's garbage. But opus still sounds pretty good until you get down to around 10kbps (this, iirc, is 6 or 7.)
  - baroffoos 7y ago
    If you really wanted to crunch the size you could store the podcast as a text file and run it through text to speech when you want to listen to it.
    - mgoetzke 7y ago
      that might be the next AI level of compression of just about everything. Very lossy, but very small.
    - netsharc 7y ago
      It would be.. spooky. Just like the lady who voiced Siri just had to record sounds (letters and combinations of letters) that can be combined for text-to-speech, one could do that for podcasters... But then it means you can make your podcaster say anything you want.
      - Rhinobird 7y ago
        like an audio PDF or something.
    - fsiefken 7y ago
      Combined with a good text compressor you could get > 100 hours of speech on it. http://www.mattmahoney.net/dc/text.html http://www.mattmahoney.net/dc/text.html
Scaevolus 7y ago
For super low bitrate speech, (1.44MB/30 minutes is 6.4kbps), codec2 is better than Opus, and can go to even lower bitrates. When combined with WaveNet, the audio quality is incredible, though required compute power is ridiculous. https://auphonic.com/blog/2018/06/01/codec2-podcast-on-floppy-disk/#wavenet-examples https://auphonic.com/blog/2018/06/01/codec2-podcast-on-flopp...
- microcolonel 7y ago
  > For super low bitrate speech, (1.44MB/30 minutes is 6.4kbps), codec2 is better than Opus At the top end of that, I think that's not the case. Certainly starting at 3200bps, Opus just becomes a non-option (and codec2 becomes an option). I have a trove of librivox audiobooks in codec2 from some tests I did, and I've given some of them extensive listens to get a feel for it. Without an improved decoder that isn't a WaveNet, it's still not always fun trying to understand what is said.
- est31 7y ago
  > the audio quality is incredible, though required compute power is ridiculous. LPCnet gives similar quality with much less compuation needed: http://www.rowetel.com/wordpress/?p=6482 http://www.rowetel.com/wordpress/?p=6482 https://people.xiph.org/~jm/demo/lpcnet/ https://people.xiph.org/~jm/demo/lpcnet/ https://people.xiph.org/~jm/demo/lpcnet_codec/ https://people.xiph.org/~jm/demo/lpcnet_codec/
  - fsiefken 7y ago
    Yes, amazing, but can it be played through Chrome, VLC, mpv or more importantly Android and iOS?
    - cbhl 7y ago
      Broad compatibility is important, but is there someone who has actually hooked up a USB floppy drive to an Android or iPhone or iPad and read files off of it?
_emacsomancer_ 7y ago
opus sounds amazingly good down to pretty low bitrates in general though, but this obviously pushes beyond those limits
climber604 7y ago
That feeling of nostalgia when reading about 486 DX and Sound Blaster Pro.
bArray 7y ago
I really like this idea, I was personally playing around with the idea of a bootable magazine that you could read in an emulator. Another idea was to release an entire album of music on a floppy disk. Both ideas I'm part way through, but have been incredibly busy. I prefer the sound of the MP3 in the examples, although both are really dull. I think using some modern codec like WaveNet or others, whilst sounding better, kind of defeats the point. I think MP3 is really as new a codec as I would want to go, especially as pretty much any device that can play audio that is actively used today can read an MP3 file. (I'm somebody who still uses an MP3 player.) That said, I think these floppycasts should simply be shorter, the easier they are to create, the more likely the idea won't die in the crib. I think 15 or 20 minutes is really not too bad for a start (especially a solo act), specials could come in multiple parts and still be in keeping of the theme.
Endy 7y ago
I'm looking forward to hearing the actual releases. I still use floppies when I can, and I still have a bunch of old PCs hanging around. It'll be good to have a valid reason to boot them up.
fsiefken 7y ago
Excellent, I did similar experiments in the past. RealAudio (ACELP) with Helix is also an efficient option, but Opus is the best. For more quality you can reformat your floppy with 2MF 3.0, it gives you 2 megabytes on a floppy instead of 1.44. I used it to get the bible on it and a stripped down bootable dos+win3.1.. unpack on a ramdrive and start the app. People next to me were still stuck in the University provided dos wp 5.1 wordprocessors while I could do WYSIWYG editing with true type fonts!
ChrisArchitect 7y ago
kinda was hoping for some fun pics of floppy disks..... ;) And also this all reminds of old demoscene/music tracker days when groups would release "music disks"
CharlesW 7y ago
Hey ajroach42, can you describe the AAC profile you used, and which encoder? I'm interested to see how small one could get an HE-AAC v2 encode. Would you mind linking to the uncompressed source as well?
Aser 7y ago
Note that you can only fit 1.38MB on a standard floppy.
deleted 7y ago
[deleted]
ekphrasis 7y ago
Reminds me of https://floppyswop.co.uk https://floppyswop.co.uk: "a place for sharing any files small enough to fit on a conventional floppy disc (1.44meg high density), art, media, sound, noise, its up to you, all files are hosted here for taking and swopping..".
atannen 7y ago
Regarding resampling to 8kHz, traditional telephony resampled to 300 Hz to 3400 Hz. AM (medium wave) radio was up to about 5000 Hz https://en.wikipedia.org/wiki/Voice_frequency https://en.wikipedia.org/wiki/Voice_frequency
Trixter 7y ago
LPC (think Speak'n'spell, PCjr speech adapter, etc.) and variants is really the only way to achieve this. A 1.44MB floppy has 1,457,664 bytes available after formatting. LPC at 2400 bits per second means you can store 80 minutes of speech on a 1.44MB floppy. A big flaw in the OP's testing is that he converted the audio to 8-bit PCM before feeding it to the encoders. That added 48dB of high-frequency noise and distortion for absolutely no reason. He might have found his sibilants ("s" sounds) sounding better had he not done that.
jokoon 7y ago
There is so many things you could do to make things go well on very small devices that would cost almost nothing today, if we decided to adopt interface and software standards to run on durable hardware. Meanwhile phones are always getting faster and faster and always becoming obsolete every year. Throwing software away means we are forced to throw hardware away. I wish that someday we could just decide to stick to a single system and not change things, so that system can last 10 years and work on the same durable phone. It would require making hard choices in OS and software design, but it would be really worth it. I hope a day will come where computers or smartphones will be able to last 10 or maybe 20 years and still be affordable. To be honest I don't think I want to be involved in learning how to develop apps on any phone for those reasons. At least microsoft and linux are able to maintain a minimal amount of backward compatibility. For developers that's really important. You don't have a good ecosystem or a good phone if you cannot attract developers to build apps.

138 points by KirinDave 7y ago

mrob 7y ago

Does the resampling and bit-depth reduction of the wav file actually help? My intuition is that a modern encoder like Opus will work better if it has more information.

ajroach42 7y ago
I tried it both ways with opus. More or less the same in terms of quality, but the resampled file was about 3% smaller. I imagine it would be less of a size difference and more noticable at higher bitrates.
JensRex 7y ago
Bit-depth reduction is counter-productive. You're just adding noise to the signal, and reducing the dynamic range. As for resampling, it depends on the specifics of the resampler used by a specific codec implementation. If a resampler is terrible, it could add artifacts like ringing and aliasing that would degrade the encoding quality. A great souce for resampler comparisons: http://src.infinitewave.ca/ http://src.infinitewave.ca/

xellisx 7y ago

http://www.rowetel.com/?page_id=452 http://www.rowetel.com/?page_id=452

ajroach42 7y ago
Codec 2 is on my list to investigate in the near future. Couldn't find software on the target machines that supported it, so it landed on second tier.

ehsankia 7y ago

Hmm, listening the the samples [0], the OPUS one is almost unbearably noisy, whereas the MP3 while, while clearly low quality, is still listenable. Am I missing something, why is OPUS doing so poorly? [0] http://ajroach42.com/floppycast-examples/ http://ajroach42.com/floppycast-examples/

sigmar 7y ago
he used the opusenc setting "tuned for speech" and music sections (like :22) sound awful. would like to know what it would sound like without that mode turned on, as it also surprises me how bad opus sounds vs mp3.
- ajroach42 7y ago
  The opus file is at 6kbps, the mp3 at 8. Opus file is tuned for speech, mp3 isn't. The opus file sounds unbearable when the music is playing, but is clearer otherwise. Double the bitrate and opus is way ahead.
viraptor 7y ago
It's interesting. The OPUS one is noisy, but pretty crisp. MP3 is smooth but more muffled. (like it lacks dynamic range) Honestly, I'd rather listen to the OPUS version if these were the only choices.
Lowkeyloki 7y ago
That's odd. My experience was the opposite. Although the Opus one was a bit muffled and some of the low end was missing so I had to strain a little to hear, the MP3 was a cacophony of pops and whistles all the way through. It was annoying and hard to concentrate on. I'd take the Opus one every time. I will say the music part was interesting. I could mostly make out the song on the MP3. On Opus, I could barely tell there was music there. A lot of it was just missing.
verytrivial 7y ago
As sad as this sounds, I think based upon the slurring of "s" sounds, that I recognize those source HHGTTG encodings, having listened to them on loop for hours at a time whilst coding. I think they're the 56kb/s MP3 ones that were floating around a couple of decades ago. There are some 128kb/s ones that might be a bit fairer.

jancsika 7y ago

Perhaps you could get it smaller by making a "vector format" for podcasts and leave it to the audio player to "do it live" <bgmusic character="spooky" /> <archiveaudio year="1972" type="cop" tone="evasive" /> <foley type="tirescreech" /> <foley type="river" weight="300" />

craz8 7y ago
Style sheets for sound - I think BBC radio used to sell CDs for this. Now they can provide Audio Style Sheets with the acronym of... oh, wait Golly - you could make any story sound like it was a Radio 4 play
- salutonmundo 7y ago
  Acronym already taken by Advanced SubStation Alpha subtitle files!
- detaro 7y ago
  There actually was work on CSS additions to give hints to Text-To-Speech engines, e.g. https://www.w3.org/TR/2018/NOTE-css3-speech-20180605/ https://www.w3.org/TR/2018/NOTE-css3-speech-20180605/
- jancsika 7y ago
  I was thinking more that one would use mechanical turk to annotate each soundfile with these tags for the set of all podcasts. Then use that as training data to a ML algorithm that gets used to render the output for each tag. So I'd use my archiveaudio tag from the example and the algo would output the band-limited frequencies of what sounds vaguely like a cop with speech patterns signaling defensiveness and irritation. It would all sound perfectly like a podcast if you were listening to it in a sleep state. Then if you concentrated on it you'd realize there's no coherent plot or even any actual natural language being spoken in the entire recording.
xvector 7y ago
Would be even more interesting if each sound effect were randomized a bit so you don’t feel like you are hearing the same thing over and over.

splitbrain 7y ago

when I read the title I somehow assumed that the optimization would be in the length of the recording, not the encoding. I would like a podcast format with very short episodes.

enneff 7y ago
Me too! I was surprised to see the target length is 30 minutes. I think there's plenty of space for even much more compact podcast episodes, under 10 minutes in length. You can say an awful lot in 10 minutes.
- salutonmundo 7y ago
  Yeah, since a lot of people speed up podcasts anyway, why not speed it up prior to compression (or learn to talk faster)? (Of course, speeding things up 3x is a bit extreme!)
  - benj111 7y ago
    Hmm why not speak 10 times faster, then slow down by 10 times after decoding. I havent decided whether this is a serious proposition yet....
mhd 7y ago
Or just good sections, not just stream of concsciousness rambling. That would also be sticking perfectly to the metaphor, swapping floppy disks should be familiar to everyone who every held one in their hands. As long as the podcast doesn't approach MS Office 97 territory (50+ disks).

themodelplumber 7y ago

So, no podcast yet, right? Didn't want to miss anything. That's a pretty cool idea. I'm all for some kind of subculture where media have tiny size limits, and if that starts from retro culture then great. I love to imagine using my 4G connection to download like 60 hours of podcasts in the few minutes before leaving on vacation...

ajroach42 7y ago
Nah, this was just me screwing around with encoders while I was avoiding editing my podcasts. When I actually release, I'll do it at a bitrate that's more listenable, but still optimized for space.
- themodelplumber 7y ago
  Right on, I love that you're paying attention to the space factor. I'm a casual podcaster, about 10 episodes in last I checked :) and I totally know what you mean about editing. I have to do it right after recording or I'll procrastinate for weeks!
xvector 7y ago
There is something beautiful about efficiency. Small computers (check out /r/sffpc), efficient codecs, those competitions where people make games/music/graphics in just a few KBs (forget what those are called - “demoscene”?). The fact that compressed Wikipedia without images fits on an 8GB USB. It all fascinates me. It is amazing to see us push the boundaries of communication under such restrictions
- z0r 7y ago
  There's a demoscene magazine intermittently published in 'demo' form: http://www.hugi.scene.org/ http://www.hugi.scene.org/
  - kozak 7y ago
    Would be cool to make a demo that would fit on a magazine page in something like a QR code (scannable with a normal phone).

enneff 7y ago

I love the idea, because there's something to almost ideal to me about the 3.5" floppy disk format. I wish I had some reason to use them today, and so I really want this to work. However the audio quality is just terrible; it may be intelligible, but it is unlistenable IMO.

ajroach42 7y ago
Oh for sure. It's garbage. But opus still sounds pretty good until you get down to around 10kbps (this, iirc, is 6 or 7.)
- baroffoos 7y ago
  If you really wanted to crunch the size you could store the podcast as a text file and run it through text to speech when you want to listen to it.
  - mgoetzke 7y ago
    that might be the next AI level of compression of just about everything. Very lossy, but very small.
  - netsharc 7y ago
    It would be.. spooky. Just like the lady who voiced Siri just had to record sounds (letters and combinations of letters) that can be combined for text-to-speech, one could do that for podcasters... But then it means you can make your podcaster say anything you want.
    - Rhinobird 7y ago
      like an audio PDF or something.
  - fsiefken 7y ago
    Combined with a good text compressor you could get > 100 hours of speech on it. http://www.mattmahoney.net/dc/text.html http://www.mattmahoney.net/dc/text.html

Scaevolus 7y ago

For super low bitrate speech, (1.44MB/30 minutes is 6.4kbps), codec2 is better than Opus, and can go to even lower bitrates. When combined with WaveNet, the audio quality is incredible, though required compute power is ridiculous. https://auphonic.com/blog/2018/06/01/codec2-podcast-on-floppy-disk/#wavenet-examples https://auphonic.com/blog/2018/06/01/codec2-podcast-on-flopp...

microcolonel 7y ago
> For super low bitrate speech, (1.44MB/30 minutes is 6.4kbps), codec2 is better than Opus At the top end of that, I think that's not the case. Certainly starting at 3200bps, Opus just becomes a non-option (and codec2 becomes an option). I have a trove of librivox audiobooks in codec2 from some tests I did, and I've given some of them extensive listens to get a feel for it. Without an improved decoder that isn't a WaveNet, it's still not always fun trying to understand what is said.
est31 7y ago
> the audio quality is incredible, though required compute power is ridiculous. LPCnet gives similar quality with much less compuation needed: http://www.rowetel.com/wordpress/?p=6482 http://www.rowetel.com/wordpress/?p=6482 https://people.xiph.org/~jm/demo/lpcnet/ https://people.xiph.org/~jm/demo/lpcnet/ https://people.xiph.org/~jm/demo/lpcnet_codec/ https://people.xiph.org/~jm/demo/lpcnet_codec/
- fsiefken 7y ago
  Yes, amazing, but can it be played through Chrome, VLC, mpv or more importantly Android and iOS?
  - cbhl 7y ago
    Broad compatibility is important, but is there someone who has actually hooked up a USB floppy drive to an Android or iPhone or iPad and read files off of it?

_emacsomancer_ 7y ago

opus sounds amazingly good down to pretty low bitrates in general though, but this obviously pushes beyond those limits

climber604 7y ago

That feeling of nostalgia when reading about 486 DX and Sound Blaster Pro.

bArray 7y ago

I really like this idea, I was personally playing around with the idea of a bootable magazine that you could read in an emulator. Another idea was to release an entire album of music on a floppy disk. Both ideas I'm part way through, but have been incredibly busy. I prefer the sound of the MP3 in the examples, although both are really dull. I think using some modern codec like WaveNet or others, whilst sounding better, kind of defeats the point. I think MP3 is really as new a codec as I would want to go, especially as pretty much any device that can play audio that is actively used today can read an MP3 file. (I'm somebody who still uses an MP3 player.) That said, I think these floppycasts should simply be shorter, the easier they are to create, the more likely the idea won't die in the crib. I think 15 or 20 minutes is really not too bad for a start (especially a solo act), specials could come in multiple parts and still be in keeping of the theme.

Endy 7y ago

I'm looking forward to hearing the actual releases. I still use floppies when I can, and I still have a bunch of old PCs hanging around. It'll be good to have a valid reason to boot them up.

fsiefken 7y ago

Excellent, I did similar experiments in the past. RealAudio (ACELP) with Helix is also an efficient option, but Opus is the best. For more quality you can reformat your floppy with 2MF 3.0, it gives you 2 megabytes on a floppy instead of 1.44. I used it to get the bible on it and a stripped down bootable dos+win3.1.. unpack on a ramdrive and start the app. People next to me were still stuck in the University provided dos wp 5.1 wordprocessors while I could do WYSIWYG editing with true type fonts!

ChrisArchitect 7y ago

kinda was hoping for some fun pics of floppy disks..... ;) And also this all reminds of old demoscene/music tracker days when groups would release "music disks"

CharlesW 7y ago

Hey ajroach42, can you describe the AAC profile you used, and which encoder? I'm interested to see how small one could get an HE-AAC v2 encode. Would you mind linking to the uncompressed source as well?

Aser 7y ago

Note that you can only fit 1.38MB on a standard floppy.

deleted 7y ago

[deleted]

ekphrasis 7y ago

Reminds me of https://floppyswop.co.uk https://floppyswop.co.uk: "a place for sharing any files small enough to fit on a conventional floppy disc (1.44meg high density), art, media, sound, noise, its up to you, all files are hosted here for taking and swopping..".

atannen 7y ago

Regarding resampling to 8kHz, traditional telephony resampled to 300 Hz to 3400 Hz. AM (medium wave) radio was up to about 5000 Hz https://en.wikipedia.org/wiki/Voice_frequency https://en.wikipedia.org/wiki/Voice_frequency

Trixter 7y ago

LPC (think Speak'n'spell, PCjr speech adapter, etc.) and variants is really the only way to achieve this. A 1.44MB floppy has 1,457,664 bytes available after formatting. LPC at 2400 bits per second means you can store 80 minutes of speech on a 1.44MB floppy. A big flaw in the OP's testing is that he converted the audio to 8-bit PCM before feeding it to the encoders. That added 48dB of high-frequency noise and distortion for absolutely no reason. He might have found his sibilants ("s" sounds) sounding better had he not done that.

jokoon 7y ago

There is so many things you could do to make things go well on very small devices that would cost almost nothing today, if we decided to adopt interface and software standards to run on durable hardware. Meanwhile phones are always getting faster and faster and always becoming obsolete every year. Throwing software away means we are forced to throw hardware away. I wish that someday we could just decide to stick to a single system and not change things, so that system can last 10 years and work on the same durable phone. It would require making hard choices in OS and software design, but it would be really worth it. I hope a day will come where computers or smartphones will be able to last 10 or maybe 20 years and still be affordable. To be honest I don't think I want to be involved in learning how to develop apps on any phone for those reasons. At least microsoft and linux are able to maintain a minimal amount of backward compatibility. For developers that's really important. You don't have a good ecosystem or a good phone if you cannot attract developers to build apps.