2 ms·

I wonder if there will ever be a chance to burn down this whole playback-oriented multimedia stack and build it back up for real time communication.

toast0 6y ago
It's possible, but it's not likely to come from established players. And it's going to have to sacrifice visual quality or use a ton of bandwidth (or both). I don't know if video calling tends to multiplex audio and video, or send separate streams; multiplexing audio onto the video could help reduce audio delay though. Standard voip uses a packet rate of 50 pps for audio, which means at least 20 ms between sampling and sending. Reducing that would be nice.
- com2kid 6y ago
  > It's possible, but it's not likely to come from established players. And it's going to have to sacrifice visual quality or use a ton of bandwidth (or both). Switching to Peer to Peer for 1:1 or small group chats would be nice. Low latency requirements being part of the BT spec would also be nice[1]. OS's fixing their drivers and entire end to end audio stack, that'd also be nice. Get that end to end latency locally to less than the e2e latency of the network packets! [1] Qualcomm has a low latency version of apt-x which is actually low latency, and Apple does fine with Airpods connected to Mac hardware.
  - closeparen 6y ago
    AirPods Pro connected to Mac hardware still run 144ms. That’s an eternity in live audio world, latency for a genuinely “pro” digital wireless microphone system is closer to 1.4ms.
    - com2kid 6y ago
      Holy cow, I misremembered. That is... so bad. How? Did they let the same people who designed Bluetooth LE's ANCS[1] go hog wild with the desktop stack? Edit: Also I wish that site tested latency for phone calls, since that is often a different protocol. [1] ANCS is, or at least last time I looked at it, a protocol designed by people who had obviously NEVER worked in the embedded or low power space. No limit on message size and no headers indicating the size of the incoming payload are two giant tells.

toast0 6y ago

It's possible, but it's not likely to come from established players. And it's going to have to sacrifice visual quality or use a ton of bandwidth (or both). I don't know if video calling tends to multiplex audio and video, or send separate streams; multiplexing audio onto the video could help reduce audio delay though. Standard voip uses a packet rate of 50 pps for audio, which means at least 20 ms between sampling and sending. Reducing that would be nice.

com2kid 6y ago
> It's possible, but it's not likely to come from established players. And it's going to have to sacrifice visual quality or use a ton of bandwidth (or both). Switching to Peer to Peer for 1:1 or small group chats would be nice. Low latency requirements being part of the BT spec would also be nice[1]. OS's fixing their drivers and entire end to end audio stack, that'd also be nice. Get that end to end latency locally to less than the e2e latency of the network packets! [1] Qualcomm has a low latency version of apt-x which is actually low latency, and Apple does fine with Airpods connected to Mac hardware.
- closeparen 6y ago
  AirPods Pro connected to Mac hardware still run 144ms. That’s an eternity in live audio world, latency for a genuinely “pro” digital wireless microphone system is closer to 1.4ms.
  - com2kid 6y ago
    Holy cow, I misremembered. That is... so bad. How? Did they let the same people who designed Bluetooth LE's ANCS[1] go hog wild with the desktop stack? Edit: Also I wish that site tested latency for phone calls, since that is often a different protocol. [1] ANCS is, or at least last time I looked at it, a protocol designed by people who had obviously NEVER worked in the embedded or low power space. No limit on message size and no headers indicating the size of the incoming payload are two giant tells.