4 ms·

There’s no way they have a legitimate secret sauce though… right? This doesn’t seem like a hard problem to do. Maybe some of this https://en.m.wikipedia.org/wi

There’s no way they have a legitimate secret sauce though… right? This doesn’t seem like a hard problem to do. Maybe some of this https://en.m.wikipedia.org/wiki/Independent_component_analysis https://en.m.wikipedia.org/wiki/Independent_component_analys... Plus basic triangulation logic synced across a bunch of microphones?

kencausey 4y ago
There is also the matter of correctly identifying gunshots.
- anigbrowl 4y ago
  They get lots of false positives, from band practice to backfiring vehicle engines and (of course) fireworks.
HWR_14 4y ago
It's phenomenally hard. Echos, indirect routing (bouncing off buildings), sound waves changing speed as they go through various materials (like a lens). It's a very hard problem. Heck, a truly calibrated surround sound system requires using a microphone to measure the volume in place.
- matt_heimer 4y ago
  So can't you just do that? Install the system and then drive a calibration car that emits sounds and logs gps coordinates?
  - beckingz 4y ago
    Map every city in the US and world? Now that's a lot of work.
    - sbierwagen 4y ago
      Google was collecting point cloud data of US cities 15 years ago, I assume some GIS vendor somewhere is selling a copycat dataset to self driving car startups.
      - HWR_14 4y ago
        I doubt you could do it just based on point cloud data.
    - tracerbulletx 4y ago
      Could just do it for the areas that sign up for the system if it worked.
  - HWR_14 4y ago
    I would definitely object to any system that required a car to creep along every block and regularly make a simulated gunshot sound. It sounds prohibitively annoying. And how often would it have to be repeated?
- scottlamb 4y ago
  > It's phenomenally hard. Echos, indirect routing (bouncing off buildings), sound waves changing speed as they go through various materials (like a lens). It's a very hard problem. I doubt they've solved (or even have non trivial mitigations for) any of those subproblems, based on stories of how often they apply human "corrections". The portion they've implemented may be very easy to replicate.
- oneoff786 4y ago
  Sorry I meant to the level of accuracy they seem to have achieved. Which seems to be loosely flagging the location of bangs.

kencausey 4y ago

There is also the matter of correctly identifying gunshots.

anigbrowl 4y ago
They get lots of false positives, from band practice to backfiring vehicle engines and (of course) fireworks.

HWR_14 4y ago

It's phenomenally hard. Echos, indirect routing (bouncing off buildings), sound waves changing speed as they go through various materials (like a lens). It's a very hard problem. Heck, a truly calibrated surround sound system requires using a microphone to measure the volume in place.

matt_heimer 4y ago
So can't you just do that? Install the system and then drive a calibration car that emits sounds and logs gps coordinates?
- beckingz 4y ago
  Map every city in the US and world? Now that's a lot of work.
  - sbierwagen 4y ago
    Google was collecting point cloud data of US cities 15 years ago, I assume some GIS vendor somewhere is selling a copycat dataset to self driving car startups.
    - HWR_14 4y ago
      I doubt you could do it just based on point cloud data.
  - tracerbulletx 4y ago
    Could just do it for the areas that sign up for the system if it worked.
- HWR_14 4y ago
  I would definitely object to any system that required a car to creep along every block and regularly make a simulated gunshot sound. It sounds prohibitively annoying. And how often would it have to be repeated?
scottlamb 4y ago
> It's phenomenally hard. Echos, indirect routing (bouncing off buildings), sound waves changing speed as they go through various materials (like a lens). It's a very hard problem. I doubt they've solved (or even have non trivial mitigations for) any of those subproblems, based on stories of how often they apply human "corrections". The portion they've implemented may be very easy to replicate.
oneoff786 4y ago
Sorry I meant to the level of accuracy they seem to have achieved. Which seems to be loosely flagging the location of bangs.