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Comment by dotancohen | Hacker News Reader

Any idea how much latency there is between the beginning of audio being played in an app, and it then coming out the headset?

I use wired headphones to study with Anki (AnkiDroid) because I've found most (inexpensive) Bluetooth headphones require a second or two to begin playing. As I'm dealing with short audio clips, this use case necessitates restarting the "audio playing" situation every few seconds.

Maybe the app developers could "play" quiet audio between these short clips. But barring such a development, I'd like to know if higher quality headphones might suffer from less latency in this regard.

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> I use wired headphones to study with Anki (AnkiDroid) because I've found most (inexpensive) Bluetooth headphones require a second or two to begin playing.

1-2 seconds is an eon for audio latency so I guess something else is going on than anything BT related in the headphones. Unless you have particularly bad luck in what headphones you use.

FWIW, I use a variety of cheap and not so cheap BT headphones across multiple devices and apps including AnkiDroid and have not perceived any latency.

If switching to wired removes the latency then it does seem to indicate something in the BT stack of your device. I wonder if you experience the lag when using AnkiDroid + BT on another device.

Thank you. I actually have since switched devices, but have not yet tested on the new device. The old device was a flagship phone, the Note 10 Lite. That phone served me well for four years, I'll test on the S24 Ultra that just replaced it. Thank you.

This is your host idling the connection due to the silence. Just keep something playing (like a stream of almost-silence) on loop and you won't have this problem.

Yes, but I was asking if high quality or newer Bluetooth audio devices have a lower latency.

I will suggest to the app developers to add optional silence. Thank you.

Yes, there are newer Bluetooth headphones with significantly lower latencies, either through LE Bluetooth audio or through codecs like AptX LL.

Most reviewers are already utterly unable to measure "normal" latency. In the very ridiculous chance you'll find a reviewer measuring wake up latency (which has little to do with the codec used), I wouldn't even trust it.

Yes, wake up latency is going to be a crapshoot, but you can eliminate it by playing a silent file at the expense of battery life. Actual latency though there's nothing you can do about it, so it's more important imo.

That's probably some sort of gate on your headphones that silences audio (by killing power to the amplifier circuitry) if it's below a threshold loudness level, to prevent users from hearing a hissing sound the cheap circuitry produces that is otherwise masked by other louder sounds. When gate opens again, it takes 1-2 seconds for the amplifier to power up completely.

Thank you. I've noticed this with multiple headphones, but they have all been inexpensive models.

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