I'm unable to measure this, but I could swear that under Wayland (Weston, KWin) my touchpad mouse cursor movement is delayed by about 1 frame compared to X11 (KWin). It feels like when you enable the software cursor in a game. Does anyone feel the same? 🖱️
Causes of #DuoLingo#Bluetooth / #BluetoothAudio#latency
Not very timely, as DuoLingo starts laying off translators, but it might have implications for other apps and bluetooth audio.
Duolingo has noticeable latency issues on some bluetooth headphone setups, with threads on reddit and stack exchange like "Duolingo app Bluetooth delay", but no real solutions. On general bluetooth latency there is a Soundguys article (https://www.soundguys.com/android-bluetooth-latency-22732/) which suggests it should not be this bad in 2023, and a Pocketnow article suggesting Bluetooth 5.0 should improve things. I got my hands on a variety of bluetooth headsets and tried testing.
Testing on Samsung S23 Galaxy, supports Bluetooth 5.3. All tests with default connection settings (not adjusted via developer options, although for most of these devices bluetooth developer options don’t seem to offer many choices other than default).
Using phone audio or wired headphones via USB-C adapter (Anker USB C to 3.5mm Audio Adapter, A8195)
There is no noticeable latency. For each question where there is speech it plays without delay when the question comes up (if it is a spoken question) or when a word in the course language is pressed (for multiple selection word banks). Similarly the correct and incorrect answer sounds and lesson complete sounds play on tapping the corresponding "next" button without appreciable delay.
Anker Soundcore Spirit, A3403 (original spirit, ~2018). Bluetooth 5.0 (connects SBC). Sport style earbuds (with connecting wire and control bar). Very noticeable latency. In questions where speech plays it is slow to start, and the fade up is slow, so the start of the phrase might not be heard. For word-banks the word plays noticeably after the word has been tapped, similarly for correct/incorrect answer sounds and lesson complete.
Sony WH-1000XM3 (2018). Bluetooth 4.2. Over ear noise cancelling. Snappy response, very hard to differentiate from device audio or wired connection.
Kitsound/KS Harlem (~2017). Bluetooth 4.1. Over ear budget. Response similar to Sony, maybe a little more latency.
Belkin Soundform Bolt (2023). Bluetooth 5.2 (connects AAC, offers SBC). Completely wireless earbuds (Samsung Galaxy Bud style). A slight noticeable lag compared to the wired and over ear headphones, but less than soundcore spirit. Usable, possible to forget the lag is there.
Overall, bluetooth version seems less important than format. The over-ear Bluetooth models are more responsive and the Sony WH-1000XM3 is hard to differentiate from a wired connection, despite being Bluetooth 4.2. More aggressive power saving in earbuds compared to over-ear models may lead to more latency. The longer volume fade up of the Soundcore Spirit may also contribute to perceived latency and difficulty hearing the start of sentences, but the time to start playing still seems noticeably longer than for the Soundform bolt (based on word bank sound where the fade up doesn’t occur if words are already playing).
(As an aside, I got the Soundform Bolts recently to see if they'd address this issue, they do, but I wouldn't wholeheartedly recommend them: reluctant to switch pairing between devices, no volume control via the buds, can only turn off by replacing in the case.)
For part 2 of the Understanding Latency Series, we are doing a bit of mixing and matching.
Perhaps you have heard of "Tail At Scale", the CACM article that periodically made the rounds in the last decade. In this post, we provided interactive charts so you can play with that kind of setup and see for yourself the profound effect of simply issuing multiple requests at once.
If a better understanding of service runtime and learning to improve software performance is part your 2024 resolution (or not), may I suggest you start with a series of articles I am writing under the theme, Understanding Latency Series?
The first post, Latency Is A Curve, answers an existential question—how do you approach latency, after all?
I'm writing a new big book on software performance and scalability
If you'd like to see early chapter drafts from it, and potentially give me a little feedback (or answer a few simple questions I ask of you, about your impressions), in private? please let me know
OK seriously. The #latency is unbearable. This is going to be the insurmountable issue with the #Machiavelli bot. Over 3 minutes for the reply to federate back. I guess playing will be very … relaxed.
BlueRetro: Open source and low latency multiplayer Bluetooth controllers adapter for retro video game consoles (github.com)
Saw these on MyLifeInGaming last night and it looks like a cool open hardware project so I thought I'd post it here....