[SOLVED] Choppy sound using Bluetooth (Zero 2 W)

[Crackerjb]

@citro

Very interesting, this. Following my tests for @Crackerjb in his thread I repeated with 64-bit moOde 8.1.1 on a Pi Zero 2 W (or W 2; it seems to get called both). The target was again my JBL Flip2 Bluetooth speaker.

Shazam! Where I was getting clear audio from the Pi3As, I get choppy audio from the Zero 2 W.

It isn't clear to me what's going on here. All my test boards are out in the open and have exhibited no problem with WiFi and BT communications up to now. I may try later to see if the same issue exists with the 32-bit build.

I'll have to think about this. In the meantime maybe someone else is already working it out.

Regards,
Kent

Kent

I did some research and found this - I think the antennae on the Pi is shared between the WiFi and the BT and if they are on the same xmit band ( ie 2.4Ghz ) there may be issues. Also it could be that the Pi Zero just does not have the horsepower to drive the Moode application and the wifi/BT all together so the result is choppy sound ?

https://forums.raspberrypi.com/viewtopic.php?t=286379

[citro]

Choppy audio over Bluetooth with WiFi on was also an issue with previous Raspberry Pi's (B 3+)
I don't think this bug is hardware related.

[TheOldPresbyope]

Choppy audio over Bluetooth with WiFi on was also an issue with previous Raspberry Pi's (B 3+)
I don't think this bug is hardware related.

Let's stay focused on the Zero 2 W, shall we?

At this point, I'm going to shelf this issue until 8.1.2 is released since Tim's identified a bug in the 8.1.1 BlueZ configuration code which makes this experimenting more of a chore than it need be.

Regards,
Kent

[citro]

Thank you.
I did not indend to digress - just noticing the issue is not rare, and shows up in different hardware / projects.

[Sniglar]

Spookily similar issue reported by @Lukesan when Zero 2 W was new...

https://moodeaudio.org/forum/showthread.php?tid=4418 

...and into moode 8

https://moodeaudio.org/forum/showthread....77&page=10

My Zero 2 W on moode 8.0.2 and 8.1.1 (64 bit) still has these constant regular interrupts when connected to a speaker using bluetooth.

[citro]

Just tested with 8.1.2 - legacy. Same issue.

[Tim Curtis]

Works fine for me using a 3B+ to an Anker Soundcore speaker. Playing a radio station for past 30 mins and no glitches whatsoever.

I don't have a Zero 2 W and so not able to try and repro. I would check the Raspberry Pi Forums to see if there are recent posts regarding RaspiOS Bullseye, 5.15.32 kernel, Zero 2 W and Bluetooth.

[TheOldPresbyope]

[JBL Flip 2 Bluetooth speaker used in all "MPD audio output -> Bluetooth" testing. All Pi's under test are connected to LAN via onboard WiFi.]

I do have a Zero 2 W and an audio dropout roughly every 0.5 sec seems to occur only with it running moOde 8.0.2 (32-bit) or 8.1.2 (32-bit and 64-bit). It does not occur with the Zero 2 W running moOde 7.6.1 (32-bit). I'm not seeing any suggestive messages in the logs.

However, Bluetooth audio output seems fine running moOde 8.1.2 on any of an old Zero W (32-bit moOde), several Pi3A+ (32-bit and 64-bit moOde), a Pi3B+ (64-bit moOde). I believe it was ok on an RPi4B too but it's not available ATM to check.

Very curious. ISTR long ago getting a similar but not necessarily the same repetitive interruption to output when I was first using my Creative Tech USB-BT adapter. IIRC the problem then was due to mismatched bitrate sampling frequency but the problem disappeared at some point in the evolution of moOde and I haven't thought about it in years. 

I suppose a recent change to kernel/drivers could be implicated but it's not obvious why it would affect only the Zero 2 W.  A quick search didn't turn up an useful hits on the Raspberry Pi Forum.

Regards,
Kent

[TheOldPresbyope]

As a followup, adding an external USB-WiFi adapter (at the end of a 0.5 ft USB extension cable), disabling the onboard WiFi (dtoverlay=disable-wifi in /boot/config.txt), and rebooting was sufficient to start getting clear MPD audio output over Bluetooth from my Raspberry Pi 2 W.

FWIW, both internal and external WiFi adapters associated with my Access point on the 2.4 GHz band.

Regards,
Kent

[citro]

I tried moOde 7.6.1 and the results are mixed: it is much better than 8.1.2, but there are times when interruptions are often, and there are times when they are far apart.

I came across the "output rate" information: listening to radio stations on Bluetooth speaker, it shows 1.411Mbps. Is this related to digital transfer rate of data over Bluetooth ? If so, is there any way to lower it ?