distortion in Audio

[MP1993]

I use a LinkIt smart 7688 (OpenWrt) with shairport-sync 2.1.15-1. I connect the modul with my smartphone(app:AllConnect). If i adjust the volume at the smartphone to a higher Volume, the distortion become less, but it is still there.

install:
opkg install shairport-sync

[mikebrady]

Thanks for the report. Can you describe the distortion? Does it happen with every track?

[MP1993]

It is not easy to discripe. I have record the sound
http://vocaroo.com/i/s1IDyBlP5yhu .
I adjust the volume at the middle of the track.
The loud Plopp is not part of the audiosignal. It is the smartphone which beats against the earphone.

It happened with every track.
Madplay works perfect.

[mikebrady]

Hmm – I can't really hear anything, not the music, not the noise, almost nothing at all...

[MP1993]

Now i have record this Version with speaker and computer microphone, it should be louder.
http://vocaroo.com/i/s0JasCmzI7dt
I adjust the volume at 0:11.(Smartphone)
madplay works with no distortion. (100% clear)

List of all installed:

alsa-lib - 1.0.28-1
alsa-utils - 1.0.28-2
avahi-dbus-daemon - 0.6.31-12
avrdude - 6.1-1
base-files - 157-r47501
busybox - 1.23.2-1
ca-certificates - 20150426
cgi-io - 1
coreutils - 8.23-1
coreutils-stty - 8.23-1
curl - 7.40.0-3
dbus - 1.9.14-1
dnsmasq - 2.73-1
dropbear - 2015.67-1
firewall - 2015-07-27
fstools - 2015-09-15-cc63723d886fde2cd364a545b7cb05b70721b83f
gdbserver - 7.8-2
git - 2.3.5-1
git-http - 2.3.5-1
hidapi - 0.8.0-rc1-1
hostapd-common - 2015-03-25-1
ip6tables - 1.4.21-1
iptables - 1.4.21-1
iwinfo - 2015-06-01-ade8b1b299cbd5748db1acf80dd3e9f567938371
jshn - 2015-11-08-10429bccd0dc5d204635e110a7a8fae7b80d16cb
jsonfilter - 2014-06-19-cdc760c58077f44fc40adbbe41e1556a67c1b9a9
kernel - 3.18.21-1-21b1917b8e608140bb986afce29743a4
kmod-ac97 - 3.18.21-1
kmod-fs-autofs4 - 3.18.21-1
kmod-fs-exfat - 3.18.21+git-20150301-1
kmod-fs-vfat - 3.18.21-1
kmod-gpio-button-hotplug - 3.18.21-1
kmod-i2c-core - 3.18.21-1
kmod-i2c-ralink - 3.18.21-1
kmod-input-core - 3.18.21-1
kmod-ip6tables - 3.18.21-1
kmod-ipt-conntrack - 3.18.21-1
kmod-ipt-core - 3.18.21-1
kmod-ipt-nat - 3.18.21-1
kmod-ipv6 - 3.18.21-1
kmod-leds-gpio - 3.18.21-1
kmod-ledtrig-netdev - 3.18.21-1
kmod-ledtrig-usbdev - 3.18.21-1
kmod-lib-crc-ccitt - 3.18.21-1
kmod-lib-lzo - 3.18.21-1
kmod-mmc - 3.18.21-1
kmod-nf-conntrack - 3.18.21-1
kmod-nf-conntrack6 - 3.18.21-1
kmod-nf-ipt - 3.18.21-1
kmod-nf-ipt6 - 3.18.21-1
kmod-nf-nat - 3.18.21-1
kmod-nf-nathelper - 3.18.21-1
kmod-nls-base - 3.18.21-1
kmod-nls-cp437 - 3.18.21-1
kmod-nls-iso8859-1 - 3.18.21-1
kmod-nls-iso8859-15 - 3.18.21-1
kmod-nls-iso8859-2 - 3.18.21-1
kmod-nls-utf8 - 3.18.21-1
kmod-ppp - 3.18.21-1
kmod-pppoe - 3.18.21-1
kmod-pppox - 3.18.21-1
kmod-regmap - 3.18.21-1
kmod-scsi-core - 3.18.21-1
kmod-sdhci - 3.18.21-1
kmod-sdhci-mt7620 - 3.18.21-1
kmod-slhc - 3.18.21-1
kmod-sound-core - 3.18.21-1
kmod-sound-mtk - 3.18.21-1
kmod-sound-soc-core - 3.18.21-1
kmod-usb-core - 3.18.21-1
kmod-usb-ohci - 3.18.21-1
kmod-usb-storage - 3.18.21-1
kmod-usb2 - 3.18.21-1
kmod-video-core - 3.18.21-1
kmod-video-uvc - 3.18.21-1
kmod-video-videobuf2 - 3.18.21-1
libavahi-client - 0.6.31-12
libavahi-dbus-support - 0.6.31-12
libavahi-nodbus-support - 0.6.31-12
libblobmsg-json - 2015-11-08-10429bccd0dc5d204635e110a7a8fae7b80d16cb
libbz2 - 1.0.6-2
libc - 0.9.33.2-1
libcurl - 7.40.0-3
libdaemon - 0.14-5
libdb47 - 4.7.25.4.NC-4.1
libdbus - 1.9.14-1
libelf1 - 0.161-1
libexpat - 2.1.0-3
libffi - 3.0.13-1
libftdi1 - 1.2-3
libgcc - 4.8-linaro-1
libgdbm - 1.11-1
libiconv - 7
libid3tag - 0.15.1b-4
libip4tc - 1.4.21-1
libip6tc - 1.4.21-1
libiwinfo - 2015-06-01-ade8b1b299cbd5748db1acf80dd3e9f567938371
libiwinfo-lua - 2015-06-01-ade8b1b299cbd5748db1acf80dd3e9f567938371
libjpeg - 9a-1
libjson-c - 0.12-1
libjson-script - 2015-11-08-10429bccd0dc5d204635e110a7a8fae7b80d16cb
liblua - 5.1.5-1
libmad - 0.15.1b-3
libmraa - 0.8.0-70600dece4138b0c0dbaff42f57828f1559cd840
libncurses - 5.9-2
libnl-tiny - 0.1-4
libopenssl - 1.0.2d-1
libpolarssl - 1.3.14-1
libpopt - 1.16-1
libpthread - 0.9.33.2-1
libreadline - 6.3-1
librt - 0.9.33.2-1
libsoxr - 0.1.1-2
libsqlite3 - 3081101-1
libstdcpp - 4.8-linaro-1
libthread-db - 0.9.33.2-1
libubox - 2015-11-08-10429bccd0dc5d204635e110a7a8fae7b80d16cb
libubus - 2015-05-25-f361bfa5fcb2daadf3b160583ce665024f8d108e
libubus-lua - 2015-05-25-f361bfa5fcb2daadf3b160583ce665024f8d108e
libuci - 2015-08-27.1-1
libuci-lua - 2015-08-27.1-1
libupm - 0.4.0-04dc6df4297a7766d6f1a8fef9699d586e7e0d92
libusb-1.0 - 1.0.19-1
libusb-compat - 0.1.4-1
libuv - 1.4.2-1
libxml2 - 2.9.2-3
libxtables - 1.4.21-1
lua - 5.1.5-1
luci - git-15.310.29077-7200d69-1
luci-app-firewall - git-15.310.29077-7200d69-1
luci-app-mjpg-streamer - git-15.310.29077-7200d69-1
luci-app-samba - git-15.310.29077-7200d69-1
luci-base - git-15.310.29077-7200d69-1
luci-lib-ip - git-15.310.29077-7200d69-1
luci-lib-json - git-15.310.29077-7200d69-1
luci-lib-nixio - git-15.310.29077-7200d69-1
luci-mod-admin-full - git-15.310.29077-7200d69-1
luci-proto-ipv6 - git-15.310.29077-7200d69-1
luci-proto-ppp - git-15.310.29077-7200d69-1
luci-theme-bootstrap - git-15.310.29077-7200d69-1
luci-theme-openwrt - git-15.310.29077-7200d69-1
madplay-alsa - 0.15.2b-4
mjpg-streamer - r182-7
mountd - 2015-08-19-d5926d3848b1e9c6147f0bd908a35d20cdef50b5
mtd - 21
mtk-linkit - 1
mtk-linkit-webui - 2015-11-18-fc0e87bd38f626242e807ce865440bb013dece0b
mtk-sdk-wifi - 2015-06-01-ade8b1b299cbd5748db1acf80dd3e9f567938371
netifd - 2015-09-27-509ffb22475ebdd5291d510a098f996473951344
node - v0.12.7-1
node-arduino-firmata - 0.3.3-1
node-cylon - 0.22.0-1
node-cylon-firmata - 0.22.0-1
node-cylon-gpio - 0.22.0-1
node-cylon-i2c - 0.22.0-1
node-hid - 0.4.0-1
node-serialport - 1.4.6-1
odhcp6c - 2015-07-13-024525798c5f6aba3af9b2ef7b3af2f3c14f1db8
odhcpd - 2015-05-21-2ebf6c8216287983779c8ec6597d30893b914a7c
opkg - 9c97d5ecd795709c8584e972bfdf3aee3a5b846d-9
ppp - 2.4.7-6
ppp-mod-pppoe - 2.4.7-6
procd - 2015-10-26-d5fddd91b966424bb63e943e789704d52382cc18
python - 2.7.9-5
python-base - 2.7.9-5
python-codecs - 2.7.9-5
python-compiler - 2.7.9-5
python-ctypes - 2.7.9-5
python-db - 2.7.9-5
python-decimal - 2.7.9-5
python-distutils - 2.7.9-5
python-email - 2.7.9-5
python-gdbm - 2.7.9-5
python-light - 2.7.9-5
python-logging - 2.7.9-5
python-multiprocessing - 2.7.9-5
python-ncurses - 2.7.9-5
python-openssl - 2.7.9-5
python-pip - 1.5.6-1
python-pydoc - 2.7.9-5
python-pyserial - 2.7-1
python-setuptools - 7.0-1
python-sqlite3 - 2.7.9-5
python-unittest - 2.7.9-5
python-xml - 2.7.9-5
rpcd - 2015-01-10-f00890cd6eb47ad9bb5da0fb6c50aedc8406e7c5
rpcd-mod-iwinfo - 2015-01-10-f00890cd6eb47ad9bb5da0fb6c50aedc8406e7c5
rpcd-mod-rpcsys - 2015-01-10-f00890cd6eb47ad9bb5da0fb6c50aedc8406e7c5
samba36-server - 3.6.25-4
shairport-sync - 2.1.15-1
spi-tools - 1-cc6a41fdcec60610703ba6db488c621c64952898
strace - 4.8-1
swconfig - 10
terminfo - 5.9-2
uboot-envtools - 2014.10-2
ubox - 2015-07-14-907d046c8929fb74e5a3502a9498198695e62ad8
ubus - 2015-05-25-f361bfa5fcb2daadf3b160583ce665024f8d108e
ubusd - 2015-05-25-f361bfa5fcb2daadf3b160583ce665024f8d108e
uci - 2015-08-27.1-1
uhttpd - 2015-11-08-fe01ef3f52adae9da38ef47926cd50974af5d6b7
uhttpd-mod-ubus - 2015-11-08-fe01ef3f52adae9da38ef47926cd50974af5d6b7
usign - 2015-05-08-cf8dcdb8a4e874c77f3e9a8e9b643e8c17b19131
wireless-tools - 29-5
wpad-mini - 2015-03-25-1
yunbridge - 160-f2042052115e71ad2c91f77e78d21db8275fcdd6
zlib - 1.2.8-1

[othiman]

Sounds like a sample rate problem. What sound card are you using? Does it support 44.1 kHz?

[mikebrady]

I can hear it now, and it really does sound terrible. Can you try using an Apple device with it, to see where the problem might lie?

[MP1993]

I have no apple device, but i tried many differents android apps. It is with every app the same noise. I use the I2S output of the MT7688. The DAC chip is a WM8960.
Supporting sample rates of the WM8960: 8, 11.025, 12, 16, 22.05, 24, 32, 44.1, 48

[mikebrady]

Perhaps you could borrow an Apple device and use it as a reference. My experience of Android implementations of AirPlay is that they are generally pretty poor.

[mikebrady]

Thanks for this contribution. Closing the issue. Please open a new one if necessary.