Stuttering audio and buffer underruns when WiFi is enabled about bt-speaker

[lukasjapan]

Thanks for sharing.

Looks like a common problem with the Pi and people fix it by investing in an additional WiFi or Bluetooth dongle.

More info:

• https://www.raspberrypi.org/forums/viewtopic.php?f=28&t=154576
• https://www.raspberrypi.org/forums/viewtopic.php?f=28&t=140471
• raspberrypi/linux#1402

[photon-schiesser]

@lnorton89 I can confirm that behavior regarding wlan0.

I am using a Raspberry Pi Zero W. I was also seeing overruns in the journal. I saw your comment and brought down wlan0 while playing music. The dropouts immediately stopped. Now it is playing quite smoothly.

Are the WiFi and Bluetooth chips on these boards (RPi 3 & Zero W) sharing a bus or channel? Perhaps that is the cause.

Could we attempt to get around this by using a lower sampling rate on the ALSA side?

A temporary workaround that would work for my use-case is to have a hook when a bluetooth client connects/disconnects that brings up/down the WiFi.

[lnorton89]

I am having what appears to be the same issue; from my Galaxy S4 I can pair and play audio but with severe drop outs / noise / crazy things happening with audio playback speed (double speed!). With a Galaxy S5 I can pair and play audio as well with zero drop outs but with a fair amount of static in the background.

I have an idle load of 25% with bt_speaker.py being the source. I have uninstalled PulseAudio but have not updated bluez (due to inability to / no straightforward instructions to do so).

What can I do to troubleshoot this further / correct the issue? I have Wi-Fi disabled via the taskbar tool to do so.

[ritiek]

I am tinkering more into this and I found something weird.

I ran the command $ aplay - and KeyboardInterrupt (Control-C) it after a few seconds and then restarted the service $ sudo systemctl restart bt_speaker. I was able to connect back to my Pi and stream music without any issues! I am able to reproduce this behavior consistently and it works for me every time. Also, I am using an Android device (OnePlus Two) to stream music so this might also help with #12 (comment).

I have no idea what's happening at the moment. I'll see more into this if I can find anything useful.

Can you guys test this out?

[ElShapovalov]

I have same problem with sound (very fast with pauses) (Samsung A5 2017).
I am a noob in python programming, but i change line 182 in file codecs.py (https://github.com/lukasjapan/bt-speaker/blob/master/bt_manager/codecs.py#L182), i set max_len=10240 and the problem is gone, even with working wi-fi.

[lukasjapan]

It looks like the daemon is not sending the audio data fast enough so alsa complains.
If it works with your phone it sounds like some compatibility issue with bluez (the linux bluetooth system).

In general you could try to do the following things in case of underruns:

1. Check the CPU load
   Maybe the decoding process does not have enough resources.

2. Check for PulseAudio
   If PulseAudio is installed I would recomnend to uninstall it.
   aplay should send the data straight to the soundcard.

3. Update bluez
   Try another version or wait for an update of bluez. For this repository, at least bluez5 is needed.

In your case, the best bet would be option 3, I suppose.

[lukasjapan]

Playback with double speed and such may indicate that format negotiation (sampling rate, channels, etc) failed. But I am not sure about that since the arriving stream is encoded anyway.

If I can get hand on a device that reproduces the error, maybe I will look into this in the future.

[lnorton89]

After some digging and messing around I was able to test with my S3 and have no issues with that device. After attempting to setup a hotspot via wlan0 when I brought the adapter up the dropouts occurred again. Taking down wlan0 reverses that action and also allows my S4 to perform without issues. I'm guessing when I disabled the wlan0 via the GUI it really wasn't disabled because I'm doing all of this via SSH. Using another Wi-Fi adapter via USB works and does not cause drop outs with either handset.

[pathammer]

I can confirm that using an external wifi adapter resolves the original issue I reported. I'll let @lukasjapan decide if he wants to close the issue.

[lukasjapan]

I'll leave it open for people to know. Using WiFi and Bluetooth at the same time is a very likely use case.

[matisflores]

Hi @lukasjapan, great project.
You consider add 'ifconfig wlan0 (up|down)' on connect/disconnect events?
I add 'subprocess.Popen('ifconfig wlan0 down', shell=True)' but nothing happen.

[pathammer]

The bt-speaker user probably doesn't have permission to bring down a network interface. You could give it permission by adding it to the correct system group.

On Sat, May 20, 2017, 4:33 PM tebo02ar ***@***.***> wrote: Hi @lukasjapan <https://github.com/lukasjapan>, great project. You consider add 'ifconfig wlan0 (up|down)' on connect/disconnect events? I add 'subprocess.Popen('ifconfig wlan0 down', shell=True)' but nothing happen. — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#4 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAeq3nlCZHOZvayZl5yo_iZiKPAG69Muks5r73hPgaJpZM4M3zOn> .

-- Patrick Hammer

[jdubbandroid]

I'm experiencing the same problem, only with an Anker Bluetooth keyboard, not a speaker. The keyboard works fine until I enable Bluetooth on my brand new Pi 3 model B. Then it stops working.

[ritiek]

I am facing a similar problem on my Pi 2. I use an external wifi adapter but disabling it doesn't fix the problem.

[ritiek]

Another thing I noticed that if I remove bt-speaker service and run the python file directly without root, the sound works fine as well. It causes problems only when running as root. Although, stuff like volume control, etc. is not available without root. Going to take a better look.

[ritiek]

As an update, I tried to follow this gist and now everything works perfect for me, including volume control.

[photon-schiesser]

@ElShapovalov Thank you! I tried your suggestion, but I found that changing it to 32768 (2^15, seemed like a good number?) did the trick. I was still getting underruns with 10240. WiFi still on as well! Thank you!

Edit: Of course, as I send this message, I started getting underruns again... :( Strangely, after about 2 minutes of perfect playback. I was streaming, but now I am playing a downloaded song via YouTube Music app on Android 5.1.1. Will report back.

[insoPL]

I had same problems (Stuttering audio and buffer underruns) when connecting from sm-t530. I checked 2 different android phones and everything worked smoothly. I can confirm that changing max_len to 10240 did the trick. I'm still getting 1/2 second lag but i guess with raspberry pi zero running bt and wifi it will just be like that.

[roflmaostc]

For me I had to adapt /etc/bt_speaker/config.ini:
play_command = aplay -Dplug:default -f cd -

Now it works flawlessly with a external USB card.

[pktmterenceg]

Confirming that @ScheissSchiesser 's suggestion above to increase the buffer to 32768 works with the wifi interface off (ifconfig lwan0 down).

I found that playing music from iTunes (12.8) from a Mac (Mac OS 10.13) produced the stuttering effect/underrun situation described by others here.

[Josonosimiti]

Hello, how exactly can i edit codecs.py? I have the same issue with audio playing too fast and stopping every 2 seconds.