3 ms·

Why does audio sound so bad over the phone? Why can we have 1Mbps broadband over these lines but not pristine audio?

mindcrime 5y ago
Are you talking about a landline phone or a cell phone? There are pretty big differences between the two, traditionally. More concretely, cell phones generally have shitty sounding audio largely due to the compression and other manipulation of the signal that happens in during the overall process.
- vel0city 5y ago
  Landline phones have largely been compressed data since the 70s, and we're still using the same compression algorithms on most phone networks to this day. ~~Most cell phones will use the exact same audio codecs as most landlines and this has been true for decades.~~ EDIT: Actually this isn't exactly true. Most "landlines" will use G.711 while most GSM cell phones will use AMR. Either way, both are pretty highly compressed audio sources but AMR lets you drag the quality even lower. https://en.wikipedia.org/wiki/G.711 https://en.wikipedia.org/wiki/G.711 https://en.wikipedia.org/wiki/Adaptive_Multi-Rate_audio_codec https://en.wikipedia.org/wiki/Adaptive_Multi-Rate_audio_code... Its been a long time since most landline phones were actually complete circuits from point A to B. Those old mechanical switches were crazy expensive to operate.
  - mindcrime 5y ago
    Either way, both are pretty highly compressed audio sources but AMR lets you drag the quality even lower. That may be what I'm thinking of. And IIRC, regarding land-line phones, the issue of compression varied depending on whether you were placing a local call or a long-distance call, and varied depending on the long-distance carrier. But, to be fair, I haven't thought about most of this stuff, or studied these issues, in about 20 years, since I last worked for a company that did telephony work. So quite possibly my memory is wrong, or my knowledge is just outdated now.
    - vel0city 5y ago
      It could be those long-distance carriers were transcoding the call at either end and using a more lossy codec internally. G.711 isn't exactly the most efficient compression algorithm but it was relatively cheap to work with when it came out which is why it was so popular. In the 2000's doing the transcoding on both ends of the distance carrier would probably be cheaper than adding more capacity on whatever long-haul lines were there, cheaper to buy some new hardware at each end instead of laying yet another cable or swap out all the RF equipment in between.

Are you talking about a landline phone or a cell phone? There are pretty big differences between the two, traditionally. More concretely, cell phones generally have shitty sounding audio largely due to the compression and other manipulation of the signal that happens in during the overall process.

vel0city 5y ago
Landline phones have largely been compressed data since the 70s, and we're still using the same compression algorithms on most phone networks to this day. ~~Most cell phones will use the exact same audio codecs as most landlines and this has been true for decades.~~ EDIT: Actually this isn't exactly true. Most "landlines" will use G.711 while most GSM cell phones will use AMR. Either way, both are pretty highly compressed audio sources but AMR lets you drag the quality even lower. https://en.wikipedia.org/wiki/G.711 https://en.wikipedia.org/wiki/G.711 https://en.wikipedia.org/wiki/Adaptive_Multi-Rate_audio_codec https://en.wikipedia.org/wiki/Adaptive_Multi-Rate_audio_code... Its been a long time since most landline phones were actually complete circuits from point A to B. Those old mechanical switches were crazy expensive to operate.
- mindcrime 5y ago
  Either way, both are pretty highly compressed audio sources but AMR lets you drag the quality even lower. That may be what I'm thinking of. And IIRC, regarding land-line phones, the issue of compression varied depending on whether you were placing a local call or a long-distance call, and varied depending on the long-distance carrier. But, to be fair, I haven't thought about most of this stuff, or studied these issues, in about 20 years, since I last worked for a company that did telephony work. So quite possibly my memory is wrong, or my knowledge is just outdated now.
  - vel0city 5y ago
    It could be those long-distance carriers were transcoding the call at either end and using a more lossy codec internally. G.711 isn't exactly the most efficient compression algorithm but it was relatively cheap to work with when it came out which is why it was so popular. In the 2000's doing the transcoding on both ends of the distance carrier would probably be cheaper than adding more capacity on whatever long-haul lines were there, cheaper to buy some new hardware at each end instead of laying yet another cable or swap out all the RF equipment in between.