RPi0W (Raspberry Pi Zero W) Audio Randomly Cutting Out

[Xenograph]

I have a snapcast-server (0.29.0) streaming to two snapclients (0.29.0) on Raspberry Pi Zero W boards, each which have the same USB DAC soundcard. I'm streaming music via Spotify/librespot using Spotify Connect.

The issue I'm having is that audio cuts out randomly, for random periods of time. Sometimes everything works fine for awhile, other times it cuts out frequently. Both clients cut out, but not simultaneously, they cut out independently. The cut out can be anything from sub-second in duration to several seconds long (or even longer I think).

What I have checked/tried:

1. I checked resource usage on the Pi. No issues with CPU/RAM usage.
2. I checked WiFi via iwlist wlan0 scanning (see log attached below). Looks good to me.
3. SSH'd into the Pi, I ran a ping to my router and watched the latency numbers while audio was dropping out. I found no correlation, although latency in general is a bit unstable, fluctuating between 2ms and over 100ms occasionally. But it doesn't seem that bad.
4. I tried switching the ALSA device using -s flag to hw/plughw
5. I tried adding --player alsa:buffer_time=10,fragments=8
6. I checked the server logs, nothing out of the ordinary.
7. I checked the client logs, there were occasional errors about pMiniBuffer and pShortBuffer getting full, but they don't correlate in time with when the drop outs occur.

Linux chai-room-speaker 6.6.31+rpt-rpi-v6 #1 Raspbian 1:6.6.31-1+rpt1 (2024-05-29) armv6l GNU/Linux

wlan0     Scan completed :
          Cell 01 - Address: A6:05:D6:CB:68:1D
                    Channel:11
                    Frequency:2.462 GHz (Channel 11)
                    Quality=70/70  Signal level=-38 dBm  
                    Encryption key:on
                    ESSID:"hb-ha"
                    Bit Rates:1 Mb/s; 2 Mb/s; 5.5 Mb/s; 11 Mb/s; 6 Mb/s
                              9 Mb/s; 12 Mb/s; 18 Mb/s
                    Bit Rates:24 Mb/s; 36 Mb/s; 48 Mb/s; 54 Mb/s
                    Mode:Master
                    Extra:tsf=0000000000000000
                    Extra: Last beacon: 2605585350ms ago
                    IE: Unknown: 000568622D6861
                    IE: Unknown: 010882848B960C121824
                    IE: Unknown: 03010B
                    IE: Unknown: 050400020000
                    IE: Unknown: 0706555304010B1E
                    IE: Unknown: 23021700
                    IE: Unknown: 2A0100
                    IE: Unknown: 32043048606C
                    IE: IEEE 802.11i/WPA2 Version 1
                        Group Cipher : CCMP
                        Pairwise Ciphers (1) : CCMP
                        Authentication Suites (2) : PSK unknown (8)
                    IE: Unknown: 0B050B00B15625
                    IE: Unknown: 460573DA00000C
                    IE: Unknown: 2D1AAD0903FFFF000000000000000000000100000000000000000000
                    IE: Unknown: 3D160B000500000000000000000000000000000000000000
                    IE: Unknown: 7F0A04000F02000000400040
                    IE: Unknown: BF0C92798933FAFF0000FAFF0000
                    IE: Unknown: C005000B00FCFF
                    IE: Unknown: C911040D8645649E05D6CB6810CB914B5946FE
                    IE: Unknown: FF1A230D01081A4010006040880F41811C110800FAFFFAFF191CC771
                    IE: Unknown: FF0724F43F0029FCFF
                    IE: Unknown: FF022763
                    IE: Unknown: FF0E260D03A4FF27A4FF4243FF6232FF
                    IE: Unknown: FF0F6C8700E00101001876081200222220
                    IE: Unknown: FF066A0411000000
                    IE: Unknown: DD1300156D00010100010282A681069C05D6CB681C
                    IE: Unknown: DD138CFDF001010201000201010303010100040101
                    IE: Unknown: DD180050F20201010D0003A4000027A4000042435E0062322F00
                    IE: Unknown: C911040D8645FF9E05D6CB6810CB914B5946FE
                    IE: Unknown: FF022703
                    IE: Unknown: DD3900156D00010100010282A681069C05D6CB681C892437353531636466342D333830302D343033332D383062632D346162306430383565623361
                    IE: Unknown: DD0700037F05010001
                    IE: Unknown: DD168CFDF0040000494C51030209720100000000F9FF0000
                    IE: Unknown: DD078CFDF004010100

Nov 25 14:49:26 chai-room-speaker snapclient[22330]: diff to server [ms]: 8.07698e+07
Nov 25 14:49:26 chai-room-speaker snapclient[22330]: Failed to get chunk
Nov 25 14:49:26 chai-room-speaker snapclient[22330]: No chunks available
Nov 25 14:49:26 chai-room-speaker snapclient[22330]: PCM name: hw:CARD=Device,DEV=0, sample rate: 44100 Hz, channels: 2, buffer time: 80>
Nov 25 14:49:26 chai-room-speaker snapclient[22330]: Using default buffer_time: 80 ms, default fragments: 4
Nov 25 14:49:26 chai-room-speaker snapclient[22330]: Sampleformat: 44100:16:2, stream: 44100:16:2
Nov 25 14:49:26 chai-room-speaker snapclient[22330]: Mixer mode: software, parameters: <none>
Nov 25 14:49:26 chai-room-speaker snapclient[22330]: Direct hardware device without any conversions, idx: 3, sharing mode: unspecified, >
Nov 25 14:49:26 chai-room-speaker snapclient[22330]: Player name: alsa, device: hw:CARD=Device,DEV=0, description: USB Audio Device, USB>
Nov 25 14:49:26 chai-room-speaker snapclient[22330]: Codec: flac, sampleformat: 44100:16:2
Nov 25 14:49:26 chai-room-speaker snapclient[22330]: ServerSettings - buffer: 1000, latency: 0, volume: 20, muted: 0
Nov 25 14:49:26 chai-room-speaker snapclient[22330]: My MAC: "b8:27:eb:d0:16:e1", socket: 9
Nov 25 14:49:26 chai-room-speaker snapclient[22330]: Connected to 192.168.3.2
Nov 25 14:49:26 chai-room-speaker snapclient[22330]: Connecting to 192.168.3.2:1704
Nov 25 14:49:26 chai-room-speaker snapclient[22330]: Resolving host IP for: 192.168.3.2
Nov 25 14:49:26 chai-room-speaker snapclient[22330]: Version 0.29.0, revision 208066e5
Nov 25 14:49:25 chai-room-speaker systemd[1]: Started snapclient.service - Snapcast client.
Nov 25 14:49:25 chai-room-speaker systemd[1]: snapclient.service: Consumed 24min 56.813s CPU time.
Nov 25 14:49:25 chai-room-speaker systemd[1]: Stopped snapclient.service - Snapcast client.
Nov 25 14:49:25 chai-room-speaker systemd[1]: snapclient.service: Deactivated successfully.
Nov 25 14:49:25 chai-room-speaker snapclient[22148]: Snapclient terminated.
Nov 25 14:49:25 chai-room-speaker systemd[1]: Stopping snapclient.service - Snapcast client...
Nov 25 14:49:25 chai-room-speaker snapclient[22148]: Received signal 15: Terminated
Nov 25 14:49:03 chai-room-speaker snapclient[22148]: pMiniBuffer->full() && (abs(pMiniBuffer->mean()) > 50): 62894
Nov 25 14:00:39 chai-room-speaker snapclient[22148]: pShortBuffer->full() && (abs(shortMedian_) > 5): 15991
Nov 25 14:00:39 chai-room-speaker snapclient[22148]: pShortBuffer->full() && (abs(shortMedian_) > 5): 15991
Nov 25 13:35:55 chai-room-speaker snapclient[22148]: pShortBuffer->full() && (abs(shortMedian_) > 5): 6962
Nov 25 13:35:55 chai-room-speaker snapclient[22148]: pBuffer->full() && (abs(median_) > 2): 6951
Nov 25 13:07:41 chai-room-speaker snapclient[22148]: pShortBuffer->full() && (abs(shortMedian_) > 5): 33037
Nov 25 13:07:41 chai-room-speaker snapclient[22148]: pShortBuffer->full() && (abs(shortMedian_) > 5): 33037
Nov 25 13:07:41 chai-room-speaker snapclient[22148]: pShortBuffer->full() && (abs(shortMedian_) > 5): 33037
Nov 25 12:37:04 chai-room-speaker snapclient[22148]: pShortBuffer->full() && (abs(shortMedian_) > 5): 32838
Nov 25 12:37:04 chai-room-speaker snapclient[22148]: pShortBuffer->full() && (abs(shortMedian_) > 5): 3283

$ ping 192.168.3.1
PING 192.168.3.1 (192.168.3.1) 56(84) bytes of data.
64 bytes from 192.168.3.1: icmp_seq=1 ttl=64 time=6.97 ms
64 bytes from 192.168.3.1: icmp_seq=2 ttl=64 time=14.7 ms
64 bytes from 192.168.3.1: icmp_seq=3 ttl=64 time=2.60 ms
64 bytes from 192.168.3.1: icmp_seq=4 ttl=64 time=3.74 ms
64 bytes from 192.168.3.1: icmp_seq=5 ttl=64 time=4.41 ms
64 bytes from 192.168.3.1: icmp_seq=6 ttl=64 time=5.82 ms
64 bytes from 192.168.3.1: icmp_seq=7 ttl=64 time=5.81 ms
64 bytes from 192.168.3.1: icmp_seq=8 ttl=64 time=4.03 ms
64 bytes from 192.168.3.1: icmp_seq=9 ttl=64 time=7.45 ms
64 bytes from 192.168.3.1: icmp_seq=10 ttl=64 time=16.4 ms
64 bytes from 192.168.3.1: icmp_seq=11 ttl=64 time=5.21 ms
64 bytes from 192.168.3.1: icmp_seq=12 ttl=64 time=4.49 ms
64 bytes from 192.168.3.1: icmp_seq=13 ttl=64 time=4.28 ms
64 bytes from 192.168.3.1: icmp_seq=14 ttl=64 time=4.85 ms
64 bytes from 192.168.3.1: icmp_seq=15 ttl=64 time=71.5 ms
64 bytes from 192.168.3.1: icmp_seq=16 ttl=64 time=3.50 ms
64 bytes from 192.168.3.1: icmp_seq=17 ttl=64 time=88.9 ms
64 bytes from 192.168.3.1: icmp_seq=18 ttl=64 time=6.57 ms
64 bytes from 192.168.3.1: icmp_seq=19 ttl=64 time=2.50 ms
64 bytes from 192.168.3.1: icmp_seq=20 ttl=64 time=9.67 ms
64 bytes from 192.168.3.1: icmp_seq=21 ttl=64 time=5.30 ms
64 bytes from 192.168.3.1: icmp_seq=22 ttl=64 time=2.57 ms
64 bytes from 192.168.3.1: icmp_seq=23 ttl=64 time=19.9 ms
64 bytes from 192.168.3.1: icmp_seq=24 ttl=64 time=9.84 ms
64 bytes from 192.168.3.1: icmp_seq=25 ttl=64 time=5.19 ms
64 bytes from 192.168.3.1: icmp_seq=26 ttl=64 time=20.6 ms
64 bytes from 192.168.3.1: icmp_seq=27 ttl=64 time=14.5 ms
64 bytes from 192.168.3.1: icmp_seq=28 ttl=64 time=2.68 ms
64 bytes from 192.168.3.1: icmp_seq=29 ttl=64 time=3.11 ms
64 bytes from 192.168.3.1: icmp_seq=30 ttl=64 time=2.58 ms
64 bytes from 192.168.3.1: icmp_seq=31 ttl=64 time=2.86 ms
64 bytes from 192.168.3.1: icmp_seq=32 ttl=64 time=9.67 ms
64 bytes from 192.168.3.1: icmp_seq=33 ttl=64 time=5.96 ms
64 bytes from 192.168.3.1: icmp_seq=34 ttl=64 time=102 ms
64 bytes from 192.168.3.1: icmp_seq=35 ttl=64 time=5.78 ms
64 bytes from 192.168.3.1: icmp_seq=36 ttl=64 time=6.71 ms

[DrMikeyS]

I have had a similar issue. From what I can gather, snapclient is fine and the issue is with the pi zero sound device. When mine fails the device works fine if I reboot the whole system. However, just rebooting snapclient has no effect. As in your case, the logs seem to show snapclient working fine. Network also fine as I am SSHing into it over wifi.

I am using this sound card.

Next time it happens I'll try and debug the soundcard element, but I suspect that's where the issue is.

[DrMikeyS]

I think I figured it out - for me at least. I'd enabled dwc2 for another project. Disabling that seems to have improved stability on the pi zero

[badaix]

Converted into a discussion