Android’s Bluetooth latency needs a serious overhaul | Hacker News Reader

Android’s Bluetooth latency needs a serious overhaul

soundguys.com

49 pointstomohawk17 comments

Latency is criminally neglected in nearly every piece of tech that I get to use.

Over the years, the number of transistors on the chip has grown - as has the lag.

Everything is laggy. Touchscreens are laggy (especially in embedded devices, like coffee machines). Webpages are laggy. USB keyboards are laggy, way more laggy than ones on Apple II [1].

And of course, wireless audio is obnoxiously laggy.

So much for removing the headphones jack.

[1]https://danluu.com/input-lag/

I just reinstalled Win10 (21H1 build) after SSD crash, previous build 1511 was from 2015 with disabled Windows Update (no patches for 6 years).

In build 1511 Win key opens Start menu instantly every time. In 21H1 SearchApp.exe process (120MB btw) is suspended and takes ~1 second (4GHz Intel) to resume before Start menu is allowed to show up :o You cant just disable SearchApp because it turns out Win10 performs actual search _every time_ you open start menu and will show empty Tiles otherwise. SearchApp suspends ~5 seconds after closing Start menu.

Win10 Taskbar has a hover time set to 400ms by default. You used to be able to edit MouseHoverTime and ExtendedUIHoverTime, afaik this no longer has effect and you are left with an arbitrary delay for thumbnail preview (couple hundred milliseconds).

and those are the most obvious every day delays in up to date freshly installed Windows 10 :o

Check if this has anything to do with memory compression. I think at some point windows 10 decided to compress memory (even if it has lots on hand) and it can lead to such delays. It shouldn't happen all the time though, just first time you access something in a awhile.

I've tried to set my kids up to watch movies in the car during long road trips, but the 10+ second bluetooth delay is brutal. Thankfully, we still have the headphone jack for wired audio.

Android, and not using VLC to adjust audio delay?

No, it's an iPad. Have not used VLC for iOS, but I might try. Luckily, the wired aux input has been working well enough.

Apple won't let VLXC ship certain codecs (something like that) so VLC on iPad is unfortunately not as super as elsewhere.

I don't disagree with you in general and I find the lack of focus on latency very frustrating (though the proliferation of 120hz screens seems to indicate that there's hope)

But with regard to the Dan Luu post I've tried to recreate his findings and maybe things have gotten better because with 170hz monitor and a run of the mill gaming keyboard I'm getting keypress to photon latencies in windows gVim of about 35ms as measured with a high speed camera.

This is made irrelevant for 90% of users who then use their keyboard & monitor in Discord, VS Code, and dozens of other JS-powered programs and sites.

sigh JS is imperfect but it doesn't just make everything it touches slow. I would be very surprised if in Discord for example any JS was blocking between you pressing a key and the key appearing in your text box.

In fact I took the time just now to run a few samples in Discord and it's looking like I'm getting the same 35-40ms keypress to photon latency as gVim with one 80ms outlier out of the 5 runs I did.

The difference is very noticeable on a less-than-new CPU (my x240 with an i7 4600U for example) when the text input triggers other UI changes. Even on my Ryzen 3600, switching channels in Discord has visible lag, regardless of network activity.

Compare this to any operation in Sublime Text/Merge and the difference is obvious.

The implication is also that more battery power is used for every action (not to mention vastly more memory), which matters for machines of any capability; but these are not latency-related concerns.

Android Web Audio latency is over 200-300ms on many devices and is deliberately introduced to kill WebGL browser games that could otherwise bypass the Play Store and its 30% tax. Google has plenty of engineers smart of enough to fix such a glaring latency issue that so many of us have been complaining about for so long but Play Store game profits are in the billions and Google isn't going to let a frictionless browser game experience kill that.

The Superpowered Latency Database[1] has many measurements showing just how bad Android latency is. (A select few devices do OK.) Note that Apple latency measurements look pretty good, because Apple uses different strategies to kill WebGL browser games: (1) Make WebGL slow and lacking features; (2) Prevent browser apps from going fullscreen; (3) Don't even let browser games ask if they can use gyro/tilt control, just block this outright because "Privacy". After all, if Epic Games could just put Fortnite inside mobile Safari their case against Apple wouldn't be so desperate. There's a demo version of Minecraft for the browser that I've never seen work on mobile browsers[2].

[1] https://superpowered.com/latency

[2] https://classic.minecraft.net/

No mention of the Gabeldorsche stack in the article, I wonder if the author is aware of it. Also my understanding of Oboe was that it's not specifically related to BT latency, but more related to the entire Audio stack latency (one reason why live music production is almost never done on Android but can be done relatively well on an iPad).

Anecdotally, I have tried to use the Gabeldorsche stack and noticed it was a lot more unstable (I would have to completely restart my phone every couple of days in order for devices to pair).

What a bunch of blather.

The article quotes: "As time went on, Bluetooth latency in the Android world improved significantly by 2021." Erm, no. You've presented no evidence along those lines.

If you go back to the original source, that is NOT what the graph claims. The original graphs are only about wired audio latency.

In addition, iPhone Bluetooth latency is not good either.

The problem, though, is mostly the Bluetooth specification and the fact that we codec the hell out of stuff to preserve power and wireless bandwidth.

Yes, the Android audio stack still is inferior to iPhone. But that has very little to due with Bluetooth.

And, to be fair, mostly no one cares as long as latency is consistent. When watching a video, for example, iPhones simply delay the video to match the added audio latency.

> iPhones simply delay the video to match the added audio latency

My android device does the same for youtube, but no other app. I can manually set it for VLC, but every game or other video app just have noticeably latency all the time.

Are these numbers correct?

In the chart at the bottom of the article it lists the Jan 2021 Android phones as having about 30-50ms latency.

Apple's only claiming around 150ms for their airpod pros.

I've been seeing this yearly for the last decade.

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