Pulseaudio loopback not working on BBB

Keith_Ruenheck · November 7, 2013, 6:52pm

I have a Beaglebone Black running Angstrom 3.8.13 connected (through USB) to a Burr-Brown PCM2900C CODEC. I can setup loopback with alsa, but not pulseaudio. The command is accepted, but the audio isn’t looped back. The commands I’m using are:

alsaloop -C hw:1,0 –P hw1:0 –t 50000 –T 1 (which works), and

pactl load-module module-loopback source=alsa_input.usb-BurrBrown_from_Texas_Instruments_USB_AUDIO_CODEC-00-CODEC.analog-stereo sink=alsa_output.usb-BurrBrown_from_Texas_Instruments_USB_AUDIO_CODEC-00-CODEC.analog-stereo latency_msec=50 (which doesn’t work)

When I run the same pactl command on my laptop, running Fedora 19, it works fine.

I have the following modules installed on the Beaglebone:

pulseaudio - 2.1-r9.16
pulseaudio-doc - 2.1-r9.16
pulseaudio-lib-alsa-util - 2.1-r9.16
pulseaudio-lib-protocol-native - 2.1-r9.16
pulseaudio-module-alsa-card - 2.1-r9.16
pulseaudio-module-alsa-sink - 2.1-r9.16
pulseaudio-module-alsa-source - 2.1-r9.16
pulseaudio-module-always-sink - 2.1-r9.16
pulseaudio-module-augment-properties - 2.1-r9.16
pulseaudio-module-card-restore - 2.1-r9.16
pulseaudio-module-console-kit - 2.1-r9.16
pulseaudio-module-default-device-restore - 2.1-r9.16
pulseaudio-module-detect - 2.1-r9.16
pulseaudio-module-device-restore - 2.1-r9.16
pulseaudio-module-filter-apply - 2.1-r9.16
pulseaudio-module-filter-heuristics - 2.1-r9.16
pulseaudio-module-intended-roles - 2.1-r9.16
pulseaudio-module-loopback - 2.1-r9.16
pulseaudio-module-native-protocol-unix - 2.1-r9.16
pulseaudio-module-null-sink - 2.1-r9.16
pulseaudio-module-position-event-sounds - 2.1-r9.16
pulseaudio-module-rescue-streams - 2.1-r9.16
pulseaudio-module-role-cork - 2.1-r9.16
pulseaudio-module-stream-restore - 2.1-r9.16
pulseaudio-module-suspend-on-idle - 2.1-r9.16
pulseaudio-module-switch-on-port-available - 2.1-r9.16
pulseaudio-module-udev-detect - 2.1-r9.16
pulseaudio-server - 2.1-r9.16

I’d like to use pulseaudio because of the added flexibility over alsa. Can anybody tell me what’s wrong?

Levi_Pearson · November 8, 2013, 9:51am

There’s not enough information to say for sure, but there are a couple of things to check. First, do a pactl list and see what state PulseAudio thinks its various components are in. It’s likely they’re stuck in a SUSPENDED state for some reason. I haven’t configured pulseaudio on my Bone yet, but on my Pandaboard I had to change the /etc/pulse/daemon.conf file so that it used resample-method=speex-fixed-3 instead of speex-float-3.

If those ideas don’t get you any further, try turning on more debugging information when you start up PulseAudio and give us a log dump.

Keith_Ruenheck · November 8, 2013, 8:05pm

Levi,
Thank you for responding.

Making resample-method=speex-fixed-3 in /etc/pulse/daemon.conf file didn’t help, still no loopback. I attached the file in case there are other questionable parameters.

The pactl list command showed that source #1 and sink #0 are ‘running’, the output is as follows:
Module #0

Name: module-device-restore
Argument:
Usage counter: n/a
Properties:
module.author = “Lennart Poettering”
module.description = “Automatically restore the volume/mute state of devices”
module.version = “2.1”

Module #1
Name: module-stream-restore
Argument:
Usage counter: n/a
Properties:
module.author = “Lennart Poettering”
module.description = “Automatically restore the volume/mute/device state of streams”
module.version = “2.1”

Module #2
Name: module-card-restore
Argument:
Usage counter: n/a
Properties:
module.author = “Lennart Poettering”
module.description = “Automatically restore profile of cards”
module.version = “2.1”

Module #3
Name: module-augment-properties
Argument:
Usage counter: n/a
Properties:
module.author = “Lennart Poettering”
module.description = “Augment the property sets of streams with additional static information”
module.version = “2.1”

Module #4
Name: module-alsa-card
Argument: device_id=“1” name=“usb-BurrBrown_from_Texas_Instruments_USB_AUDIO_CODEC-00-CODEC” card_name=“alsa_card.usb-BurrBrown_from_Texas_Instruments_USB_AUDIO_CODEC-00-CODEC” namereg_fail=false tsched=yes fixed_latency_range=no ignore_dB=no deferred_volume=yes card_properties=“module-udev-detect.discovered=1”
Usage counter: 2
Properties:
module.author = “Lennart Poettering”
module.description = “ALSA Card”
module.version = “2.1”

Module #5
Name: module-alsa-card
Argument: device_id=“0” name=“platform-sound.13” card_name=“alsa_card.platform-sound.13” namereg_fail=false tsched=yes fixed_latency_range=no ignore_dB=no deferred_volume=yes card_properties=“module-udev-detect.discovered=1”
Usage counter: 0
Properties:
module.author = “Lennart Poettering”
module.description = “ALSA Card”
module.version = “2.1”

Module #6
Name: module-udev-detect
Argument:
Usage counter: n/a
Properties:
module.author = “Lennart Poettering”
module.description = “Detect available audio hardware and load matching drivers”
module.version = “2.1”

Module #7
Name: module-native-protocol-unix
Argument:
Usage counter: n/a
Properties:
module.author = “Lennart Poettering”
module.description = “Native protocol (UNIX sockets)”
module.version = “2.1”

Module #8
Name: module-default-device-restore
Argument:
Usage counter: n/a
Properties:
module.author = “Lennart Poettering”
module.description = “Automatically restore the default sink and source”
module.version = “2.1”

Module #9
Name: module-rescue-streams
Argument:
Usage counter: n/a
Properties:
module.author = “Lennart Poettering”
module.description = “When a sink/source is removed, try to move their streams to the default sink/source”
module.version = “2.1”

Module #10
Name: module-always-sink
Argument:
Usage counter: n/a
Properties:
module.author = “Colin Guthrie”
module.description = “Always keeps at least one sink loaded even if it’s a null one”
module.version = “2.1”

Module #11
Name: module-intended-roles
Argument:
Usage counter: n/a
Properties:
module.author = “Lennart Poettering”
module.description = “Automatically set device of streams based of intended roles of devices”
module.version = “2.1”

Module #12
Name: module-suspend-on-idle
Argument:
Usage counter: n/a
Properties:
module.author = “Lennart Poettering”
module.description = “When a sink/source is idle for too long, suspend it”
module.version = “2.1”

Module #13
Name: module-console-kit
Argument:
Usage counter: n/a
Properties:
module.author = “Lennart Poettering”
module.description = “Create a client for each ConsoleKit session of this user”
module.version = “2.1”

Module #14
Name: module-position-event-sounds
Argument:
Usage counter: n/a
Properties:
module.author = “Lennart Poettering”
module.description = “Position event sounds between L and R depending on the position on screen of the widget triggering them.”
module.version = “2.1”

Module #15
Name: module-role-cork
Argument:
Usage counter: n/a
Properties:
module.author = “Lennart Poettering”
module.description = “Mute & cork streams with certain roles while others exist”
module.version = “2.1”

Module #16
Name: module-filter-heuristics
Argument:
Usage counter: n/a
Properties:
module.author = “Colin Guthrie”
module.description = “Detect when various filters are desirable”
module.version = “2.1”

Module #17
Name: module-filter-apply
Argument:
Usage counter: n/a
Properties:
module.author = “Colin Guthrie”
module.description = “Load filter sinks automatically when needed”
module.version = “2.1”

Module #18
Name: module-switch-on-port-available
Argument:
Usage counter: n/a
Properties:

Module #19
Name: module-loopback
Argument: source=alsa_input.usb-BurrBrown_from_Texas_Instruments_USB_AUDIO_CODEC-00-CODEC.analog-stereo sink=alsa_output.usb-BurrBrown_from_Texas_Instruments_USB_AUDIO_CODEC-00-CODEC.analog-stereo latency_msec=50
Usage counter: n/a
Properties:
module.author = “Pierre-Louis Bossart”
module.description = “Loopback from source to sink”
module.version = “2.1”

Sink #0
State: RUNNING
Name: alsa_output.usb-BurrBrown_from_Texas_Instruments_USB_AUDIO_CODEC-00-CODEC.analog-stereo
Description: USB AUDIO CODEC Analog Stereo
Driver: module-alsa-card.c
Sample Specification: s16le 2ch 44100Hz
Channel Map: front-left,front-right
Owner Module: 4
Mute: no
Volume: 0: 54% 1: 54%
0: -16.00 dB 1: -16.00 dB
balance 0.00
Base Volume: 100%
0.00 dB
Monitor Source: alsa_output.usb-BurrBrown_from_Texas_Instruments_USB_AUDIO_CODEC-00-CODEC.analog-stereo.monitor
Latency: 0 usec, configured 16666 usec
Flags: HARDWARE HW_MUTE_CTRL HW_VOLUME_CTRL DECIBEL_VOLUME LATENCY
Properties:
alsa.resolution_bits = “16”
device.api = “alsa”
device.class = “sound”
alsa.class = “generic”
alsa.subclass = “generic-mix”
alsa.name = “USB Audio”
alsa.id = “USB Audio”
alsa.subdevice = “0”
alsa.subdevice_name = “subdevice #0”
alsa.device = “0”
alsa.card = “1”
alsa.card_name = “USB AUDIO CODEC”
alsa.long_card_name = “BurrBrown from Texas Instruments USB AUDIO CODEC at usb-musb-hdrc.1.auto-1.6,”
alsa.driver_name = “snd_usb_audio”
device.bus_path = “platform-musb-hdrc.1.auto-usb-0:1.6:1.0”
sysfs.path = “/devices/ocp.2/47400000.usb/musb-hdrc.1.auto/usb1/1-1/1-1.6/1-1.6:1.0/sound/card1”
udev.id = “usb-BurrBrown_from_Texas_Instruments_USB_AUDIO_CODEC-00-CODEC”
device.bus = “usb”
device.vendor.id = “08bb”
device.vendor.name = “BurrBrown from Texas Instruments”
device.product.id = “29c0”
device.product.name = “USB AUDIO CODEC”
device.serial = “BurrBrown_from_Texas_Instruments_USB_AUDIO_CODEC”
device.string = “hw:1”
device.buffering.buffer_size = “352800”
device.buffering.fragment_size = “176400”
device.access_mode = “mmap+timer”
device.profile.name = “analog-stereo”
device.profile.description = “Analog Stereo”
device.description = “USB AUDIO CODEC Analog Stereo”
alsa.mixer_name = “USB Mixer”
alsa.components = “USB08bb:29c0”
module-udev-detect.discovered = “1”
device.icon_name = “audio-card-usb”
Ports:
analog-output: Analog Output (priority: 9900)
Active Port: analog-output
Formats:
pcm

Sink #1
State: SUSPENDED
Name: alsa_output.platform-sound.13.analog-stereo
Description: TI BeagleBone Black Analog Stereo
Driver: module-alsa-card.c
Sample Specification: s32le 2ch 48000Hz
Channel Map: front-left,front-right
Owner Module: 5
Mute: no
Volume: 0: 100% 1: 100%
0: 0.00 dB 1: 0.00 dB
balance 0.00
Base Volume: 100%
0.00 dB
Monitor Source: alsa_output.platform-sound.13.analog-stereo.monitor
Latency: 0 usec, configured 0 usec
Flags: HARDWARE DECIBEL_VOLUME LATENCY
Properties:
alsa.resolution_bits = “32”
device.api = “alsa”
device.class = “sound”
alsa.class = “generic”
alsa.subclass = “generic-mix”
alsa.name = “”
alsa.id = “HDMI nxp-hdmi-hifi-0”
alsa.subdevice = “0”
alsa.subdevice_name = “subdevice #0”
alsa.device = “0”
alsa.card = “0”
alsa.card_name = “TI BeagleBone Black”
alsa.long_card_name = “TI BeagleBone Black”
device.bus_path = “platform-sound.13”
sysfs.path = “/devices/ocp.2/sound.13/sound/card0”
device.string = “hw:0”
device.buffering.buffer_size = “131072”
device.buffering.fragment_size = “8192”
device.access_mode = “mmap+timer”
device.profile.name = “analog-stereo”
device.profile.description = “Analog Stereo”
device.description = “TI BeagleBone Black Analog Stereo”
module-udev-detect.discovered = “1”
device.icon_name = “audio-card”
Ports:
analog-output: Analog Output (priority: 9900)
Active Port: analog-output
Formats:
pcm

Source #0
State: IDLE
Name: alsa_output.usb-BurrBrown_from_Texas_Instruments_USB_AUDIO_CODEC-00-CODEC.analog-stereo.monitor
Description: Monitor of USB AUDIO CODEC Analog Stereo
Driver: module-alsa-card.c
Sample Specification: s16le 2ch 44100Hz
Channel Map: front-left,front-right
Owner Module: 4
Mute: no
Volume: 0: 100% 1: 100%
0: 0.00 dB 1: 0.00 dB
balance 0.00
Base Volume: 100%
0.00 dB
Monitor of Sink: alsa_output.usb-BurrBrown_from_Texas_Instruments_USB_AUDIO_CODEC-00-CODEC.analog-stereo
Latency: 0 usec, configured 2000000 usec
Flags: DECIBEL_VOLUME LATENCY
Properties:
device.description = “Monitor of USB AUDIO CODEC Analog Stereo”
device.class = “monitor”
alsa.card = “1”
alsa.card_name = “USB AUDIO CODEC”
alsa.long_card_name = “BurrBrown from Texas Instruments USB AUDIO CODEC at usb-musb-hdrc.1.auto-1.6,”
alsa.driver_name = “snd_usb_audio”
device.bus_path = “platform-musb-hdrc.1.auto-usb-0:1.6:1.0”
sysfs.path = “/devices/ocp.2/47400000.usb/musb-hdrc.1.auto/usb1/1-1/1-1.6/1-1.6:1.0/sound/card1”
udev.id = “usb-BurrBrown_from_Texas_Instruments_USB_AUDIO_CODEC-00-CODEC”
device.bus = “usb”
device.vendor.id = “08bb”
device.vendor.name = “BurrBrown from Texas Instruments”
device.product.id = “29c0”
device.product.name = “USB AUDIO CODEC”
device.serial = “BurrBrown_from_Texas_Instruments_USB_AUDIO_CODEC”
device.string = “1”
module-udev-detect.discovered = “1”
device.icon_name = “audio-card-usb”
Formats:
pcm

Source #1
State: RUNNING
Name: alsa_input.usb-BurrBrown_from_Texas_Instruments_USB_AUDIO_CODEC-00-CODEC.analog-stereo
Description: USB AUDIO CODEC Analog Stereo
Driver: module-alsa-card.c
Sample Specification: s16le 2ch 44100Hz
Channel Map: front-left,front-right
Owner Module: 4
Mute: no
Volume: 0: 100% 1: 100%
0: 0.00 dB 1: 0.00 dB
balance 0.00
Base Volume: 100%
0.00 dB
Monitor of Sink: n/a
Latency: 946634983247447 usec, configured 16666 usec
Flags: HARDWARE DECIBEL_VOLUME LATENCY
Properties:
alsa.resolution_bits = “16”
device.api = “alsa”
device.class = “sound”
alsa.class = “generic”
alsa.subclass = “generic-mix”
alsa.name = “USB Audio”
alsa.id = “USB Audio”
alsa.subdevice = “0”
alsa.subdevice_name = “subdevice #0”
alsa.device = “0”
alsa.card = “1”
alsa.card_name = “USB AUDIO CODEC”
alsa.long_card_name = “BurrBrown from Texas Instruments USB AUDIO CODEC at usb-musb-hdrc.1.auto-1.6,”
alsa.driver_name = “snd_usb_audio”
device.bus_path = “platform-musb-hdrc.1.auto-usb-0:1.6:1.0”
sysfs.path = “/devices/ocp.2/47400000.usb/musb-hdrc.1.auto/usb1/1-1/1-1.6/1-1.6:1.0/sound/card1”
udev.id = “usb-BurrBrown_from_Texas_Instruments_USB_AUDIO_CODEC-00-CODEC”
device.bus = “usb”
device.vendor.id = “08bb”
device.vendor.name = “BurrBrown from Texas Instruments”
device.product.id = “29c0”
device.product.name = “USB AUDIO CODEC”
device.serial = “BurrBrown_from_Texas_Instruments_USB_AUDIO_CODEC”
device.string = “hw:1”
device.buffering.buffer_size = “352800”
device.buffering.fragment_size = “176400”
device.access_mode = “mmap+timer”
device.profile.name = “analog-stereo”
device.profile.description = “Analog Stereo”
device.description = “USB AUDIO CODEC Analog Stereo”
alsa.mixer_name = “USB Mixer”
alsa.components = “USB08bb:29c0”
module-udev-detect.discovered = “1”
device.icon_name = “audio-card-usb”
Formats:
pcm

Source #2
State: SUSPENDED
Name: alsa_output.platform-sound.13.analog-stereo.monitor
Description: Monitor of TI BeagleBone Black Analog Stereo
Driver: module-alsa-card.c
Sample Specification: s32le 2ch 48000Hz
Channel Map: front-left,front-right
Owner Module: 5
Mute: no
Volume: 0: 100% 1: 100%
0: 0.00 dB 1: 0.00 dB
balance 0.00
Base Volume: 100%
0.00 dB
Monitor of Sink: alsa_output.platform-sound.13.analog-stereo
Latency: 0 usec, configured 0 usec
Flags: DECIBEL_VOLUME LATENCY
Properties:
device.description = “Monitor of TI BeagleBone Black Analog Stereo”
device.class = “monitor”
alsa.card = “0”
alsa.card_name = “TI BeagleBone Black”
alsa.long_card_name = “TI BeagleBone Black”
device.bus_path = “platform-sound.13”
sysfs.path = “/devices/ocp.2/sound.13/sound/card0”
device.string = “0”
module-udev-detect.discovered = “1”
device.icon_name = “audio-card”
Formats:
pcm

Sink Input #0
Driver: module-loopback.c
Owner Module: 19
Client: n/a
Sink: 0
Sample Specification: s16le 2ch 44143Hz
Channel Map: front-left,front-right
Format: pcm, format.sample_format = ““s16le”” format.rate = “44100” format.channels = “2” format.channel_map = ““front-left,front-right””
Mute: no
Volume: 0: 54% 1: 54%
0: -16.00 dB 1: -16.00 dB
balance 0.00
Buffer Latency: 1992569 usec
Sink Latency: 0 usec
Resample method: speex-float-3
Properties:
media.name = “Loopback from USB AUDIO CODEC Analog Stereo”
media.role = “abstract”
media.icon_name = “audio-card-usb”
module-stream-restore.id = “sink-input-by-media-role:abstract”

Source Output #0
Driver: module-loopback.c
Owner Module: 19
Client: n/a
Source: 1
Sample Specification: s16le 2ch 44100Hz
Channel Map: front-left,front-right
Format: pcm, format.sample_format = ““s16le”” format.rate = “44100” format.channels = “2” format.channel_map = ““front-left,front-right””
Mute: no
Volume: 0: 100% 1: 100%
0: 0.00 dB 1: 0.00 dB
balance 0.00
Buffer Latency: 0 usec
Source Latency: 0 usec
Resample method: n/a
Properties:
media.name = “Loopback to USB AUDIO CODEC Analog Stereo”
media.role = “abstract”
media.icon_name = “audio-card-usb”
module-stream-restore.id = “source-output-by-media-role:abstract”

Client #0
Driver: protocol-native.c
Owner Module: 7
Properties:
application.name = “GNOME Volume Control Media Keys”
native-protocol.peer = “UNIX socket client”
native-protocol.version = “26”
application.id = “org.gnome.VolumeControl”
application.icon_name = “multimedia-volume-control”
application.version = “2.32.0”
application.process.id = “508”
application.process.user = “root”
application.process.host = “beaglebone”
application.process.binary = “gnome-settings-daemon”
window.x11.display = “:0”
application.language = “C”
application.process.machine_id = “1a7682b7f5434568b514c002207bee65”
application.process.session_id = “1a7682b7f5434568b514c002207bee65-946766939.42508-1421050874”

Client #3
Driver: protocol-native.c
Owner Module: 7
Properties:
application.name = “pactl”
native-protocol.peer = “UNIX socket client”
native-protocol.version = “26”
application.process.id = “595”
application.process.user = “root”
application.process.host = “beaglebone”
application.process.binary = “pactl”
application.language = “C”
window.x11.display = “:0.0”
application.process.machine_id = “1a7682b7f5434568b514c002207bee65”
application.process.session_id = “1a7682b7f5434568b514c002207bee65-946766939.42508-1421050874”

Card #0
Name: alsa_card.usb-BurrBrown_from_Texas_Instruments_USB_AUDIO_CODEC-00-CODEC
Driver: module-alsa-card.c
Owner Module: 4
Properties:
alsa.card = “1”
alsa.card_name = “USB AUDIO CODEC”
alsa.long_card_name = “BurrBrown from Texas Instruments USB AUDIO CODEC at usb-musb-hdrc.1.auto-1.6,”
alsa.driver_name = “snd_usb_audio”
device.bus_path = “platform-musb-hdrc.1.auto-usb-0:1.6:1.0”
sysfs.path = “/devices/ocp.2/47400000.usb/musb-hdrc.1.auto/usb1/1-1/1-1.6/1-1.6:1.0/sound/card1”
udev.id = “usb-BurrBrown_from_Texas_Instruments_USB_AUDIO_CODEC-00-CODEC”
device.bus = “usb”
device.vendor.id = “08bb”
device.vendor.name = “BurrBrown from Texas Instruments”
device.product.id = “29c0”
device.product.name = “USB AUDIO CODEC”
device.serial = “BurrBrown_from_Texas_Instruments_USB_AUDIO_CODEC”
device.string = “1”
device.description = “USB AUDIO CODEC”
module-udev-detect.discovered = “1”
device.icon_name = “audio-card-usb”
Profiles:
output:analog-mono: Analog Mono Output (sinks: 1, sources: 0, priority. 100)
output:analog-mono+input:analog-mono: Analog Mono Duplex (sinks: 1, sources: 1, priority. 101)
output:analog-mono+input:analog-stereo: Analog Mono Output + Analog Stereo Input (sinks: 1, sources: 1, priority. 160)
output:analog-stereo: Analog Stereo Output (sinks: 1, sources: 0, priority. 6000)
output:analog-stereo+input:analog-mono: Analog Stereo Output + Analog Mono Input (sinks: 1, sources: 1, priority. 6001)
output:analog-stereo+input:analog-stereo: Analog Stereo Duplex (sinks: 1, sources: 1, priority. 6060)
input:analog-mono: Analog Mono Input (sinks: 0, sources: 1, priority. 1)
input:analog-stereo: Analog Stereo Input (sinks: 0, sources: 1, priority. 60)
off: Off (sinks: 0, sources: 0, priority. 0)
Active Profile: output:analog-stereo+input:analog-stereo
Ports:
analog-output: Analog Output (priority: 9900)
Part of profile(s): output:analog-mono, output:analog-mono+input:analog-mono, output:analog-mono+input:analog-stereo, output:analog-stereo, output:analog-stereo+input:analog-mono, output:analog-stereo+input:analog-stereo

Card #1
Name: alsa_card.platform-sound.13
Driver: module-alsa-card.c
Owner Module: 5
Properties:
alsa.card = “0”
alsa.card_name = “TI BeagleBone Black”
alsa.long_card_name = “TI BeagleBone Black”
device.bus_path = “platform-sound.13”
sysfs.path = “/devices/ocp.2/sound.13/sound/card0”
device.string = “0”
device.description = “TI BeagleBone Black”
module-udev-detect.discovered = “1”
device.icon_name = “audio-card”
Profiles:
output:analog-stereo: Analog Stereo Output (sinks: 1, sources: 0, priority. 6000)
off: Off (sinks: 0, sources: 0, priority. 0)
Active Profile: output:analog-stereo
Ports:
analog-output: Analog Output (priority: 9900)
Part of profile(s): output:analog-stereo

Thank you again for your help,
Keith

daemon.conf (2.28 KB)

Levi_Pearson · November 8, 2013, 10:04pm

Levi,
Thank you for responding.

Making resample-method=speex-fixed-3 in /etc/pulse/daemon.conf file didn’t help, still no loopback. I attached the file in case there are other questionable parameters.

The pactl list command showed that source #1 and sink #0 are ‘running’, the output is as follows:

OK, the following entry lets us know Sink #0 is running, and everything looks to be in good shape there.

Notice that it has a ‘Monitor Source’, which is essentially a way to get at all the samples that have been sent to this sink and thus to its audio port. If samples were playing, we’d expect to see the monitor source active.

Sink #0
State: RUNNING
Name: alsa_output.usb-BurrBrown_from_Texas_Instruments_USB_AUDIO_CODEC-00-CODEC.analog-stereo
Description: USB AUDIO CODEC Analog Stereo
Driver: module-alsa-card.c
Sample Specification: s16le 2ch 44100Hz
Channel Map: front-left,front-right
Owner Module: 4
Mute: no
Volume: 0: 54% 1: 54%
0: -16.00 dB 1: -16.00 dB
balance 0.00
Base Volume: 100%
0.00 dB
Monitor Source: alsa_output.usb-BurrBrown_from_Texas_Instruments_USB_AUDIO_CODEC-00-CODEC.analog-stereo.monitor
Latency: 0 usec, configured 16666 usec
Flags: HARDWARE HW_MUTE_CTRL HW_VOLUME_CTRL DECIBEL_VOLUME LATENCY
Properties:
alsa.resolution_bits = “16”
device.api = “alsa”
device.class = “sound”
alsa.class = “generic”
alsa.subclass = “generic-mix”
alsa.name = “USB Audio”
alsa.id = “USB Audio”
alsa.subdevice = “0”
alsa.subdevice_name = “subdevice #0”
alsa.device = “0”
alsa.card = “1”
alsa.card_name = “USB AUDIO CODEC”
alsa.long_card_name = “BurrBrown from Texas Instruments USB AUDIO CODEC at usb-musb-hdrc.1.auto-1.6,”
alsa.driver_name = “snd_usb_audio”
device.bus_path = “platform-musb-hdrc.1.auto-usb-0:1.6:1.0”
sysfs.path = “/devices/ocp.2/47400000.usb/musb-hdrc.1.auto/usb1/1-1/1-1.6/1-1.6:1.0/sound/card1”
udev.id = “usb-BurrBrown_from_Texas_Instruments_USB_AUDIO_CODEC-00-CODEC”
device.bus = “usb”
device.vendor.id = “08bb”
device.vendor.name = “BurrBrown from Texas Instruments”
device.product.id = “29c0”
device.product.name = “USB AUDIO CODEC”
device.serial = “BurrBrown_from_Texas_Instruments_USB_AUDIO_CODEC”
device.string = “hw:1”
device.buffering.buffer_size = “352800”
device.buffering.fragment_size = “176400”
device.access_mode = “mmap+timer”
device.profile.name = “analog-stereo”
device.profile.description = “Analog Stereo”
device.description = “USB AUDIO CODEC Analog Stereo”
alsa.mixer_name = “USB Mixer”
alsa.components = “USB08bb:29c0”
module-udev-detect.discovered = “1”
device.icon_name = “audio-card-usb”
Ports:
analog-output: Analog Output (priority: 9900)
Active Port: analog-output
Formats:
pcm

This entry shows us the monitor source for Sink 0, but as you can see it’s currently in the IDLE state, meaning that no samples are being played out.

Source #0
State: IDLE
Name: alsa_output.usb-BurrBrown_from_Texas_Instruments_USB_AUDIO_CODEC-00-CODEC.analog-stereo.monitor
Description: Monitor of USB AUDIO CODEC Analog Stereo
Driver: module-alsa-card.c
Sample Specification: s16le 2ch 44100Hz
Channel Map: front-left,front-right
Owner Module: 4
Mute: no
Volume: 0: 100% 1: 100%
0: 0.00 dB 1: 0.00 dB
balance 0.00
Base Volume: 100%
0.00 dB
Monitor of Sink: alsa_output.usb-BurrBrown_from_Texas_Instruments_USB_AUDIO_CODEC-00-CODEC.analog-stereo
Latency: 0 usec, configured 2000000 usec
Flags: DECIBEL_VOLUME LATENCY
Properties:
device.description = “Monitor of USB AUDIO CODEC Analog Stereo”
device.class = “monitor”
alsa.card = “1”
alsa.card_name = “USB AUDIO CODEC”
alsa.long_card_name = “BurrBrown from Texas Instruments USB AUDIO CODEC at usb-musb-hdrc.1.auto-1.6,”
alsa.driver_name = “snd_usb_audio”
device.bus_path = “platform-musb-hdrc.1.auto-usb-0:1.6:1.0”
sysfs.path = “/devices/ocp.2/47400000.usb/musb-hdrc.1.auto/usb1/1-1/1-1.6/1-1.6:1.0/sound/card1”
udev.id = “usb-BurrBrown_from_Texas_Instruments_USB_AUDIO_CODEC-00-CODEC”
device.bus = “usb”
device.vendor.id = “08bb”
device.vendor.name = “BurrBrown from Texas Instruments”
device.product.id = “29c0”
device.product.name = “USB AUDIO CODEC”
device.serial = “BurrBrown_from_Texas_Instruments_USB_AUDIO_CODEC”
device.string = “1”
module-udev-detect.discovered = “1”
device.icon_name = “audio-card-usb”
Formats:
pcm

Here we have the actual source attached to the audio input. It’s also running, but if you look down at the latency field, you can see the first signs of the problem. It’s configured for 16666 usec of latency, but the calculated latency is MUCH higher! Still, it’s not clear from this entry why it’s so high.

Source #1
State: RUNNING
Name: alsa_input.usb-BurrBrown_from_Texas_Instruments_USB_AUDIO_CODEC-00-CODEC.analog-stereo
Description: USB AUDIO CODEC Analog Stereo
Driver: module-alsa-card.c
Sample Specification: s16le 2ch 44100Hz
Channel Map: front-left,front-right
Owner Module: 4
Mute: no
Volume: 0: 100% 1: 100%
0: 0.00 dB 1: 0.00 dB
balance 0.00
Base Volume: 100%
0.00 dB
Monitor of Sink: n/a
Latency: 946634983247447 usec, configured 16666 usec
Flags: HARDWARE DECIBEL_VOLUME LATENCY
Properties:
alsa.resolution_bits = “16”
device.api = “alsa”
device.class = “sound”
alsa.class = “generic”
alsa.subclass = “generic-mix”
alsa.name = “USB Audio”
alsa.id = “USB Audio”
alsa.subdevice = “0”
alsa.subdevice_name = “subdevice #0”
alsa.device = “0”
alsa.card = “1”
alsa.card_name = “USB AUDIO CODEC”
alsa.long_card_name = “BurrBrown from Texas Instruments USB AUDIO CODEC at usb-musb-hdrc.1.auto-1.6,”
alsa.driver_name = “snd_usb_audio”
device.bus_path = “platform-musb-hdrc.1.auto-usb-0:1.6:1.0”
sysfs.path = “/devices/ocp.2/47400000.usb/musb-hdrc.1.auto/usb1/1-1/1-1.6/1-1.6:1.0/sound/card1”
udev.id = “usb-BurrBrown_from_Texas_Instruments_USB_AUDIO_CODEC-00-CODEC”
device.bus = “usb”
device.vendor.id = “08bb”
device.vendor.name = “BurrBrown from Texas Instruments”
device.product.id = “29c0”
device.product.name = “USB AUDIO CODEC”
device.serial = “BurrBrown_from_Texas_Instruments_USB_AUDIO_CODEC”
device.string = “hw:1”
device.buffering.buffer_size = “352800”
device.buffering.fragment_size = “176400”
device.access_mode = “mmap+timer”
device.profile.name = “analog-stereo”
device.profile.description = “Analog Stereo”
device.description = “USB AUDIO CODEC Analog Stereo”
alsa.mixer_name = “USB Mixer”
alsa.components = “USB08bb:29c0”
module-udev-detect.discovered = “1”
device.icon_name = “audio-card-usb”
Formats:
pcm

Here we’ve got the loopback module, which is what is connecting the source and sink. Everything looks fine until we get to the Buffer Latency, which is pretty high: 1992569 usec. That’s nearly 2 seconds for samples to get through the buffer! Clearly the problem is here. And two lines down, we see the reason: The resample method is still speex-float-3, and the implementation must be using soft floating point emulation somewhere.

Sink Input #0
Driver: module-loopback.c
Owner Module: 19
Client: n/a
Sink: 0
Sample Specification: s16le 2ch 44143Hz
Channel Map: front-left,front-right
Format: pcm, format.sample_format = ““s16le”” format.rate = “44100” format.channels = “2” format.channel_map = ““front-left,front-right””
Mute: no
Volume: 0: 54% 1: 54%
0: -16.00 dB 1: -16.00 dB
balance 0.00
Buffer Latency: 1992569 usec
Sink Latency: 0 usec
Resample method: speex-float-3
Properties:
media.name = “Loopback from USB AUDIO CODEC Analog Stereo”
media.role = “abstract”
media.icon_name = “audio-card-usb”
module-stream-restore.id = “sink-input-by-media-role:abstract”

This is the source end of the loopback; no issues here. Apparently all the work gets done in the sink end of the loopback.

Source Output #0
Driver: module-loopback.c
Owner Module: 19
Client: n/a
Source: 1
Sample Specification: s16le 2ch 44100Hz
Channel Map: front-left,front-right
Format: pcm, format.sample_format = ““s16le”” format.rate = “44100” format.channels = “2” format.channel_map = ““front-left,front-right””
Mute: no
Volume: 0: 100% 1: 100%
0: 0.00 dB 1: 0.00 dB
balance 0.00
Buffer Latency: 0 usec
Source Latency: 0 usec
Resample method: n/a
Properties:
media.name = “Loopback to USB AUDIO CODEC Analog Stereo”
media.role = “abstract”
media.icon_name = “audio-card-usb”
module-stream-restore.id = “source-output-by-media-role:abstract”

So, if you look at the config file you posted, you’ll see semicolons in front of all the config directives. I know it’s screwy, but that’s actually one of the comment characters for pulseaudio’s config syntax. You changed the right line, but it was a comment before and it’s still a comment! Delete the semicolon at the front of that line and you should be in much better shape.

Keith_Ruenheck · November 11, 2013, 11:00pm

Levi,
Thank you very much for your thorough response, and for finding the problem with my pulseaudio config file. It was silly of me to assume that the # characters at the top of the file were the only way to comment out lines. Now that my resample method is speex-fixed-3, pulseaudio works much better, but there is a two second lag between input and output. That’s understandable due to the two second buffer latency indicated in sink input #0 (see pactl list response below), but I don’t see how that number is derived. Do you have thoughts on this?

Module #0
Name: module-device-restore
Argument:
Usage counter: n/a
Properties:
module.author = “Lennart Poettering”
module.description = “Automatically restore the volume/mute state of devices”
module.version = “2.1”