Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Show HN: Beatsync – perfect audio sync across multiple devices

github.com

Post reply on HN
Print view View original

51–60 of 135 posts

Re: Show HN: Beatsync – perfect audio sync across multiple devices

#51

Post by raisedbyninjas »

freemanjiang wrote: post #20
whimsy wrote: post #9

This is very, very cool; it's a thing I've been looking for on my backburner for several years. It's a very interesting problem. There are a ton of directions I can think about you taking it in. The household application: this one is already pretty directly applicable. Have a bunch of wireless speakers and you should be able to make it sound really good from anywhere, yes? You would probably want support for static c…

Thank you for the kind words! Yeah, I think it gets a lot more complicated once you start dealing with speaker hardware. It pretty much only works for the device's native speaker at the moment. The instant you start having wireless speakers (eg. bluetooth) or any sort of significant delay between commanding playback and the actual sound coming out, the latency becomes audible.

For devices with mics, can you have them play a test chirp to measure the latency of Bluetooth or other laggy sound stack?

Re: Show HN: Beatsync – perfect audio sync across multiple devices

#54

Post by LordGrignard »

hello! the app looks very polished and I'm sure there's a lot of usecases of this for everyone else, but for me I wanted to ask whether this can be used to sync playlist progress of your offline library (its flac ofc) across devices? its something I have not found a solution for at all, other than some Plex thingy which is paid, and if you're synchronizing for millisecond accuracy it should work for simply keeping track of the shuffle order of the playlist and last played song (I. e. the position in the ordered playlist)?

Re: Show HN: Beatsync – perfect audio sync across multiple devices

#56

Post by freemanjiang »

RicoElectrico wrote: post #47

Does this resync periodically? (I mean not only when a new track starts)

It doesn't at the moment, but I think it probably should. There's a non-trivial amount of clock drift that can happen over long periods of time.

Re: Show HN: Beatsync – perfect audio sync across multiple devices

#57

Post by Michael9876 »

freemanjiang wrote: post #40
lacoolj wrote: post #34

Very very cool idea, but this is a bummer: "Optimized for Chrome on macOS. Unstable for other platforms..." Once that changes (at the very least, the macOS part), I can't wait to play with it!

It works on other platforms! Just not as smooth as Chrome.

[dead]

Re: Show HN: Beatsync – perfect audio sync across multiple devices

#59

Post by moomin »

recursive wrote: post #50
moomin wrote: post #22

Earlier quoted context omitted.

More, the speed of light puts a hard cap on how simultaneous you can be. Wolfram Alpha reckons New York to London is 19ms in a vacuum, more using fibre. Going off on a tangent: Back in the days of Live Aid, they tried doing a transatlantic duet. Turns out it’s literally physically impossible because if A songs when they hear B, then B hears A at least 38ms too late, which is too much for the human body to handle and…

It's a less hard problem than the duet. If the round-trip is 38ms, you can estimate that the one-way latency is 19ms. You tell the the other client to play the audio now , and you schedule it for 19ms in the future. That's assuming standard OS and hardware and drivers can manage latency with that degree of precision, which I have serious doubts about. In a duet, your partner needs to hear you now and you need to hear…

You’re right that it’s an easier problem, but it’s still trickier than it looks. Remember the point of this is to be listening together. To do that, you need to be able to communicate your reactions. And then you’re back to the 38ms (in practice it’s probably twice that). Either way, at 120bpm that’s over a bar!

If you _don’t_ have real time communication, then you don’t really need to solve this problem. But the problem is fundamentally unsolvable because the speed of light (in a vacuum) is the speed of causality and, as I say, puts a hard cap on simultaneity. This tends to be regarded as obvious at interstellar distances but it affects us at transatlantic distances too.

Post reply on HN