3 ms·

> POTS calls had noticably lower latency... which made conversations feel more natural. I wonder if there is a market for two data-lines into a home, one that

> POTS calls had noticably lower latency... which made conversations feel more natural. I wonder if there is a market for two data-lines into a home, one that emphasizes low latency and another that emphasizes large volume. The lag in current video/audio communications is pretty bad.

a-dub 5y ago
yeah. i was thinking about this a bunch at the start of the pandemic. what about building a video/audio conferencing system that focused on the psychophysical aspects of calls... things like reducing latency or mixing/synchronizing multiple channels over distances. problem is that there's a fair bit of fixed delay. a/d and d/a have fixed minimum latencies, as do codecs (although i think there's been focus and improvement there over the years), and then there is, of course, the public internet with its various hiccups that are often smoothed over with additional buffering/latency. i do wonder how much energy has been put into reducing perceived latency and the psychophysical aspects though. (also a very interesting domain) hard to beat the latency of a local analog signal though!
- thomasjudge 5y ago
  There are a number of projects aimed at delivering low-latency audio over the internet, I think some were started or used by musicians trying to be able to play together remotely
  - a-dub 5y ago
    ahh yeah, like this one: https://ccrma.stanford.edu/docs/common/JackTrip.html https://ccrma.stanford.edu/docs/common/JackTrip.html i wonder how well it works... also, since we're going down memory lane, who remembers the album isdn by the future sound of london? the name comes from the fact that they used hardware that was designed for musicians to jam over isdn digital calls (or more likely high latency high quality calls for audio distribution, given the state of audio codecs at the time), to produce the album across a large geographical area, if i remember right..
  - closeparen 5y ago
    The music thing is just tracking. You record a track, then someone else downloads it and records themselves on top of that track, then someone else downloads that… repeat for a whole choir if so desired. These sessions could be separated by hours or weeks. In the studio world they often are. The innovation here was to accelerate this process and make it happen with delays of hundreds of milliseconds to several seconds, instead. There’s no cheating the physics or the underlying network. You can’t interact with the “inner” musicians as the data only flows one way.
closeparen 5y ago
The key would be a circuit-switched network for real time communication. ISDN once promised low latency circuit switched video calling. Shame it never took off.
- a-dub 5y ago
  BRI was two bonded 64kbit channels. i think even with today's compression you'd be hard pressed to have a decent video call experience. PRI was 1.5mbit, but i'm not sure you could dial out all the constituent channels. (i think it was designed to either behave like a standard leased line or as an endpoint for BRIs to dial into) edit: looks like you can dial those out... but in practice it's either 2 channels at 128k or 6 at 384k. still not a lot of bandwidth for video (but probably great fixed latency) fun fact: i looked at starting up an isdn based isp in the 90s. isdn calls were charged by the minute back then, which wasn't great for that purpose... but if you set up a centrex (the phone company's managed cloud pbx as a service), then you could make intercom calls for free between stations... so, the isp would have been a business with each customer site as a branch office. :)

a-dub 5y ago

yeah. i was thinking about this a bunch at the start of the pandemic. what about building a video/audio conferencing system that focused on the psychophysical aspects of calls... things like reducing latency or mixing/synchronizing multiple channels over distances. problem is that there's a fair bit of fixed delay. a/d and d/a have fixed minimum latencies, as do codecs (although i think there's been focus and improvement there over the years), and then there is, of course, the public internet with its various hiccups that are often smoothed over with additional buffering/latency. i do wonder how much energy has been put into reducing perceived latency and the psychophysical aspects though. (also a very interesting domain) hard to beat the latency of a local analog signal though!

thomasjudge 5y ago
There are a number of projects aimed at delivering low-latency audio over the internet, I think some were started or used by musicians trying to be able to play together remotely
- a-dub 5y ago
  ahh yeah, like this one: https://ccrma.stanford.edu/docs/common/JackTrip.html https://ccrma.stanford.edu/docs/common/JackTrip.html i wonder how well it works... also, since we're going down memory lane, who remembers the album isdn by the future sound of london? the name comes from the fact that they used hardware that was designed for musicians to jam over isdn digital calls (or more likely high latency high quality calls for audio distribution, given the state of audio codecs at the time), to produce the album across a large geographical area, if i remember right..
- closeparen 5y ago
  The music thing is just tracking. You record a track, then someone else downloads it and records themselves on top of that track, then someone else downloads that… repeat for a whole choir if so desired. These sessions could be separated by hours or weeks. In the studio world they often are. The innovation here was to accelerate this process and make it happen with delays of hundreds of milliseconds to several seconds, instead. There’s no cheating the physics or the underlying network. You can’t interact with the “inner” musicians as the data only flows one way.

closeparen 5y ago

The key would be a circuit-switched network for real time communication. ISDN once promised low latency circuit switched video calling. Shame it never took off.

a-dub 5y ago
BRI was two bonded 64kbit channels. i think even with today's compression you'd be hard pressed to have a decent video call experience. PRI was 1.5mbit, but i'm not sure you could dial out all the constituent channels. (i think it was designed to either behave like a standard leased line or as an endpoint for BRIs to dial into) edit: looks like you can dial those out... but in practice it's either 2 channels at 128k or 6 at 384k. still not a lot of bandwidth for video (but probably great fixed latency) fun fact: i looked at starting up an isdn based isp in the 90s. isdn calls were charged by the minute back then, which wasn't great for that purpose... but if you set up a centrex (the phone company's managed cloud pbx as a service), then you could make intercom calls for free between stations... so, the isp would have been a business with each customer site as a branch office. :)