ændrük

This blog has moved.

ændrük — Fri, 16 Dec 2011 18:28:52 +0000

The new web address: 634942.com

The new XML feed: http://feeds.feedburner.com/634942

Wrapping up the long tail

ændrük — Thu, 22 Sep 2011 18:14:26 +0000

I don’t listen to a wide range of music. I tend to stick to just a handful of artists, listening to the albums I love over and over.

This gives the distribution of what artists I listen to a well-defined long tail, and I think Last.fm’s histogram doesn’t quite do it justice. With the assistance of the Last.fm API, the R wordclould package, a code sample, and some inspiration, I’ve generated a new visualization:

I think this more clearly illustrates the sheer difference in scale between the few dozen artists that I listen to regularly and the thousand others I’ve had opportunity to evaluate.

Custom keyboard symbols for Unity

ændrük — Sun, 04 Sep 2011 01:12:37 +0000

Dot stickers make an excellent tool for customizing the Apple aluminum keyboard.

Adrenaline triphosphate

ændrük — Wed, 13 Jul 2011 03:38:36 +0000

ATP.

That’s what it stands for, right?

Automatic submission of Rockbox scrobbler logs

ændrük — Thu, 07 Jul 2011 21:44:32 +0000

Rockbox has the ability to generate Audioscrobbler logs for later submission to Last.fm. A custom udev rule can be combined with a command-line Last.fm scrobbler to automate the process of submitting tracks every time the digital audio player is connected to the computer.

The udev rule is designed to call a script whenever a Rockbox device is connected:

# /etc/udev/rules.d/80-custom.rules

ACTION=="add", SUBSYSTEM=="block", ATTR{partition}=="1", ATTRS{vendor}=="Rockbox ", ATTRS{model}=="Internal Storage", RUN+="/opt/rockbox/upload-scrobbler-log"

Last.fm credentials can be stored in GNOME Keyring and accessed using gkeyring:

gkeyring.py --set --name 'http://www.last.fm/' --password 'YOUR_PASSWORD_HERE' -p username_value=YOUR_USERNAME_HERE,origin_url=http://www.last.fm/

The script will wait for the device to be mounted, retrieve the Last.fm credentials from GNOME Keyring, display a graphical notification using notify-send, call Laspyt to submit the scrobbler log, and then display a report:

#!/bin/bash
# /opt/rockbox/upload-scrobbler-log
# WARNING: This script must finish quickly because udev is effectively paused while it is running

# Run all this in the background and detach from the parent process
{

	ubuntuuser="ak"
	logfile="/tmp/upload-scrobbler-log.log"
	backupscrobblerlog="/tmp/scrobbler.log.backup"
	gkeyring="/opt/rockbox/gkeyring.py"
	laspyt="/opt/rockbox/laspyt.py"

	echo "Script starting at $(date)" >> "$logfile"

	dapdescription="$(echo -e "$ID_FS_LABEL_ENC")"
	echo "Detected $dapdescription at $DEVNAME" >> "$logfile"

	# Wait for filesystem to be automounted
	echo "Waiting up to 20 seconds for automount..." >> "$logfile"
	counter=0
	while [ $counter -lt 20 ]; do
		grep -q "$DEVNAME" /proc/mounts && break
		sleep 1
		let counter++
	done

	# Abort if timed out
	if [ $counter -ge 20 ]; then
		echo "Unable to locate mountpoint; aborting" >> "$logfile"
		exit 1
	fi

	# Determine mountpoint
	mountpoint="$(echo -e "$(grep $DEVNAME /proc/mounts | awk '{print $2}')")"
	echo "Detected mountpoint at $mountpoint" >> "$logfile"

	# Identify log file
	scrobblerlog="$mountpoint/.scrobbler.log"
	echo "Using scrobbler log file $scrobblerlog" >> "$logfile"

	# Get credentials from keyring
	echo "Getting credentials from keyring..." >> "$logfile"
	credentials="$(sudo -H -u $ubuntuuser \
		env $(grep -v "^#" /home/$ubuntuuser/.dbus/session-bus/$(cat /var/lib/dbus/machine-id)-0) \
		$gkeyring -p origin_url=http://www.last.fm/ --output username_value,secret)"
	username="$(echo "$credentials" | awk '{print $1}')"
	password="$(echo "$credentials" | awk '{print $2}')"
	if [ -z "$username" -o -z "$password" ]; then
		echo "Failed to get credentials; aborting" >> "$logfile"
		exit 1
	else
		echo "Got credentials for $username" >> "$logfile"
	fi

	# Back up scrobbler log
	echo "Backing up scrobbler log to $backupscrobblerlog" >> "$logfile"
	cp "$scrobblerlog" "$backupscrobblerlog"

	# Upload scrobbler log
	timezone="$(date +%:::z)"
	echo "Uploading scrobbler log file with timezone offset $timezone..." >> "$logfile"
	sudo -H -u $ubuntuuser \
		env DISPLAY=$(w -s $ubuntuuser | grep -m 1 " :" | awk "{print \$3}") \
		notify-send --icon "/usr/share/icons/Humanity/devices/48/multimedia-player.svg" \
			"Uploading scrobbler log" \
			"Submitting $(grep -v "^#" "$scrobblerlog" | wc -l) tracks from $dapdescription to Last.fm as $username"
	sudo -H -u $ubuntuuser \
		$laspyt --file "$scrobblerlog" --timezone "$timezone" --clear \
			--user "$username" --password "$password" \
			2>&1 | sed 's/\x1B\[[0-9;]*[mK]//g' >> "$logfile"

	# Report
	echo "Done" >> "$logfile"
	sudo -H -u $ubuntuuser \
		env DISPLAY=$(w -s $ubuntuuser | grep -m 1 " :" | awk "{print \$3}") \
		zenity --text-info --title "Scrobbler log upload" --filename "$logfile" &

} & disown

exit 0

Details from a run:

and confirmation on Last.fm:

Learning to use R

ændrük — Fri, 03 Jun 2011 23:29:10 +0000

To begin familiarizing myself with R, I’ve been experimenting with binned kernel density estimates using data from Ask Ubuntu.

The resulting plots aren’t very meaningful, but they’re quite pretty.

Implementing a hybrid SSD/HDD home folder

ændrük — Tue, 17 May 2011 16:55:40 +0000

I’m currently experimenting with a low-effort technique for mimicking the benefits of a hybrid solid state/hard disk drive.

My approach is to use a union mount with multiple writable branches to combine folders from both an SSD and HDD into a single home folder in the root filesystem. The result is a unified home folder that contains a mixture of files from each drive in a way that is transparent to the operating system:

Newly created files are stored on the same device as their parent folder. Files created at the root of the home folder are typically configuration files and so default to the SSD.

As the screenshot reveals, I have also drafted a Nautilus extension that detects which storage back end each file uses and labels those which use the SSD.

Implementation

The branches of the union mount exist externally as folders within the root filesystem. I chose to place them within /home/.ssd and /home/.hdd. On my system / already uses the SSD so /home/.ssd can simply exist as a regular folder, while /home/.hdd is mounted separately. /etc/fstab contains:

# / containing /home/.ssd (Physical SSD)
UUID=... / ext4 noatime,discard,errors=remount-ro 0 1
# /home/.hdd (Physical HDD)
UUID=... /home/.hdd ext4 errors=remount-ro 0 2

The default file creation policy in aufs is to store new files within the same branch as their parent folder, with files created in the root directory of the union filesystem defaulting to the first listed branch. As long as the SSD branch is listed first, no other policy needs to be explicitly defined:

# /home/ak from SSD and HDD mounts
none /home/ak aufs noauto,br:/home/.ssd/ak=rw:/home/.hdd/ak=rw 0 0

It is critical that this entry in /etc/fstab be mounted only after the previous two lines so that the incorporated branches contain mounted filesystems and not empty mount points. Until I learn how to specify a particular mount order in /etc/fstab, I have disabled automatic mounting of the union mount (noauto above) and instead mount it during /etc/rc.local:

# Workaround to mount aufs only *after* its branches exist
mount /home/ak

Back end detection is accomplished with a custom emblem in ~/.local/share/icons/hicolor/24x24/emblems and a Nautilus-Python extension saved as ~/.nautilus/python-extensions/ssd-emblem.py that checks for parallel files in /home/.ssd:

import os.path
import nautilus

class SsdEmblem(nautilus.InfoProvider):
    def __init__(self):
        pass

    def update_file_info(self, file):
        filepath = os.path.realpath(file.get_location().get_path())
        if filepath.find('/home/ak/') == 0 and os.path.exists(filepath.replace('/home/ak/', '/home/.ssd/ak/',1)) == True:
            file.add_emblem("ssd")

Thoughts

After using this for a week I’m pleased with the results. There is a noticeable improvement in login times compared with my previous configuration that stored the entire home folder on a HDD.

I would like there to be an easy way to switch the storage back end of individual files and folders, ideally via a Nautilus context menu item. This looks possible via UDBA, but there are several potential quirks involved that I haven’t spent the time to thoroughly investigate.

Obviously, more work would need to be done for this to be scalable to multi-user environments or to be compatible with encrypted home folders. I have no plans to develop these areas.

How to use only Faenza’s application icons

ændrük — Mon, 25 Apr 2011 17:22:04 +0000

The Faenza application icons fit nicely with Ubuntu 11.04′s Unity launcher, but the rest of the Faenza icon theme deviates too far from the default Ubuntu look-and-feel for my tastes. To use only the application icons from Faenza, create a “meta-theme” that symbolic links to Faenza’s application icons and inherits everything else from the default icon theme:

Create the folder ~/.icons/faenza-apps.
Symbolic link ~/.icons/faenza-apps/apps to /usr/share/icons/Faenza/apps.
Copy /usr/share/icons/Faenza/index.theme to ~/.icons/faenza-apps/index.theme.
In ~/.icons/faenza-apps/index.theme, change the name:
Name=Faenza for Applications
append ubuntu-mono-dark’s inheritances:
Inherits=ubuntu-mono-dark,Humanity-Dark,gnome,hicolor
delete unwanted directories:
Directories=apps/16.apps/22.apps/24.apps/32.apps/48.apps/scalable
and delete all directory stanzas except for the [apps] stanzas.
Choose the new theme in Applications ▸ Appearance ▸ Customize ▸ Icons.

Alternatively, just download the following file and drag-and-drop it into the Applications ▸ Appearance window:

faenza-apps.tar.gz (0.4 MB)

The end result:

A perspective on the role of advanced tools in Ubuntu

ændrük — Tue, 08 Mar 2011 23:21:03 +0000

A few weeks ago a new user on Ask Ubuntu asked how to close command-line applications in Linux. My snarky answer prompted another user to mention me in his, but I felt I had been misrepresented. I’d like to share my response here since I think it well illustrates a view I hold regarding the role of advanced software tools in Ubuntu:

djeikyb, I appreciate that you make the distinction between basic desktop usage and advanced command-line text editing. Ubuntu’s strength over other Linux distributions is in its ability to make the Linux desktop accessible by everyday computer users, whom to its credit are now increasingly permitted the unique luxury of never needing to know what editors like Vim even are.

It is with this special freedom in mind that I make the decision to work as high above traditional Linux command-line methods as I have the patience for during everyday computer use. I make the effort to utilize only simple and accessible tools largely because I can afford to. It would be inaccurate to say that I simply don’t like command-line text editors. To the contrary, I happen to be fond of Vim with its VimOutliner plugin, and I am indebted to it for its influence on the Vimperator/Pentadactyl project.

However, I view my personal use of these tools as a deviation from typical computer use. I am of the opinion that it would be a healthy development for the Ubuntu community to less readily suggest to newcomers that casual use of advanced tools with steep learning curves is the norm among everyday users.

Letseatlunch, if your goal is to become proficient in Vim, then by all means I encourage you to continue your pursuit of it. I only mean to communicate that, while, importantly, Ubuntu offers many such advanced tools that other operating systems lack altogether, learning to use them should never be a requirement for using Ubuntu.

Visualization of an audio codec driver

ændrük — Fri, 25 Feb 2011 19:50:31 +0000

A recent question on Ask Ubuntu has prompted me to try to better understand how my sound card works. I don’t really know where to begin, but a little poking around the ALSA Intel HDA driver in use on my ThinkPad X60 has revealed a fascinating presentation of how the laptop’s audio codec is represented by the driver (click to expand):

$ cat /proc/asound/Intel/codec#0
Codec: Analog Devices AD1981
Address: 0
Function Id: 0x1
Vendor Id: 0x11d41981
Subsystem Id: 0x17aa2025
Revision Id: 0x100200
No Modem Function Group found
Default PCM:
    rates [0x7f]: 8000 11025 16000 22050 32000 44100 48000
    bits [0xe]: 16 20 24
    formats [0x1]: PCM
Default Amp-In caps: ofs=0x00, nsteps=0x03, stepsize=0x27, mute=0
Default Amp-Out caps: ofs=0x3d, nsteps=0x3f, stepsize=0x05, mute=1
GPIO: io=4, o=0, i=0, unsolicited=1, wake=0
  IO[0]: enable=0, dir=0, wake=0, sticky=0, data=1, unsol=0
  IO[1]: enable=0, dir=0, wake=0, sticky=0, data=0, unsol=0
  IO[2]: enable=0, dir=0, wake=0, sticky=0, data=0, unsol=0
  IO[3]: enable=0, dir=0, wake=0, sticky=0, data=1, unsol=0
Node 0x02 [Audio Output] wcaps 0x30311: Stereo Digital
  Control: name="IEC958 Playback Con Mask", index=0, device=0
  Control: name="IEC958 Playback Pro Mask", index=0, device=0
  Control: name="IEC958 Playback Default", index=0, device=0
  Control: name="IEC958 Playback Switch", index=0, device=0
  Control: name="IEC958 Default PCM Playback Switch", index=0, device=0
  Control: name="IEC958 Playback Source", index=0, device=0
  Device: name="AD198x Digital", type="SPDIF", device=1
  Converter: stream=0, channel=0
  Digital: Enabled
  Digital category: 0x0
  PCM:
    rates [0x60]: 44100 48000
    bits [0x2]: 16
    formats [0x5]: PCM AC3
  Delay: 3 samples
  Connection: 2
     0x01* 0x04
Node 0x03 [Audio Output] wcaps 0x441: Stereo
  Device: name="AD198x Analog", type="Audio", device=0
  Converter: stream=0, channel=0
  Power states:  D0 D3
  Power: setting=D0, actual=D0
  Processing caps: benign=1, ncoeff=70
Node 0x04 [Audio Input] wcaps 0x100511: Stereo
  Device: name="AD198x Analog", type="Audio", device=0
  Converter: stream=0, channel=0
  SDI-Select: 0
  PCM:
    rates [0x7f]: 8000 11025 16000 22050 32000 44100 48000
    bits [0x6]: 16 20
    formats [0x1]: PCM
  Power states:  D0 D3
  Power: setting=D0, actual=D0
  Connection: 1
     0x15
Node 0x05 [Pin Complex] wcaps 0x400187: Stereo Amp-In Amp-Out
  Control: name="Master Playback Volume", index=0, device=0
    ControlAmp: chs=3, dir=Out, idx=0, ofs=0
  Control: name="Master Playback Switch", index=0, device=0
    ControlAmp: chs=3, dir=Out, idx=0, ofs=0
  Amp-In caps: ofs=0x00, nsteps=0x03, stepsize=0x27, mute=0
  Amp-In vals:  [0x00 0x00]
  Amp-Out caps: ofs=0x3d, nsteps=0x3f, stepsize=0x05, mute=1
  Amp-Out vals:  [0xb4 0xb4]
  Pincap 0x0001173f: IN OUT HP EAPD Detect Trigger ImpSense
    Vref caps: HIZ 50 GRD 80
  EAPD 0x0:
  Pin Default 0xc4014110: [Both] Line Out at Ext Right
    Conn = 1/8, Color = Green
    DefAssociation = 0x1, Sequence = 0x0
    Misc = NO_PRESENCE
  Pin-ctls: 0x40: OUT VREF_HIZ
  Unsolicited: tag=00, enabled=0
  Connection: 2
     0x03 0x0e*
Node 0x06 [Pin Complex] wcaps 0x400185: Stereo Amp-Out
  Amp-Out caps: ofs=0x3d, nsteps=0x3f, stepsize=0x05, mute=1
  Amp-Out vals:  [0x80 0x80]
  Pincap 0x0000001f: OUT HP Detect Trigger ImpSense
  Pin Default 0x422140f0: [N/A] HP Out at Ext Front
    Conn = 1/8, Color = Green
    DefAssociation = 0xf, Sequence = 0x0
  Pin-ctls: 0xc0: OUT HP
  Unsolicited: tag=00, enabled=0
  Connection: 2
     0x03 0x0e*
Node 0x07 [Pin Complex] wcaps 0x400104: Mono Amp-Out
  Amp-Out caps: ofs=0x3d, nsteps=0x3f, stepsize=0x05, mute=1
  Amp-Out vals:  [0x80]
  Pincap 0x00000010: OUT
  Pin Default 0x591311f0: [N/A] Speaker at Int ATAPI
    Conn = ATAPI, Color = Black
    DefAssociation = 0xf, Sequence = 0x0
    Misc = NO_PRESENCE
  Pin-ctls: 0x40: OUT
  Connection: 1
     0x0f
Node 0x08 [Pin Complex] wcaps 0x400083: Stereo Amp-In
  Control: name="Mic Boost", index=0, device=0
    ControlAmp: chs=3, dir=In, idx=0, ofs=0
  Amp-In caps: ofs=0x00, nsteps=0x03, stepsize=0x27, mute=0
  Amp-In vals:  [0x00 0x00]
  Pincap 0x00001727: IN Detect Trigger ImpSense
    Vref caps: HIZ 50 GRD 80
  Pin Default 0xc4a1502e: [Both] Mic at Ext Right
    Conn = 1/8, Color = Red
    DefAssociation = 0x2, Sequence = 0xe
  Pin-ctls: 0x24: IN VREF_80
  Unsolicited: tag=00, enabled=0
Node 0x09 [Pin Complex] wcaps 0x400187: Stereo Amp-In Amp-Out
  Amp-In caps: ofs=0x00, nsteps=0x03, stepsize=0x27, mute=0
  Amp-In vals:  [0x00 0x00]
  Amp-Out caps: ofs=0x3d, nsteps=0x3f, stepsize=0x05, mute=1
  Amp-Out vals:  [0xbf 0xbf]
  Pincap 0x00001737: IN OUT Detect Trigger ImpSense
    Vref caps: HIZ 50 GRD 80
  Pin Default 0x418130f0: [N/A] Line In at Ext Rear
    Conn = 1/8, Color = Blue
    DefAssociation = 0xf, Sequence = 0x0
  Pin-ctls: 0x20: IN VREF_HIZ
  Unsolicited: tag=00, enabled=0
  Connection: 2
     0x03* 0x0e
Node 0x0a [Pin Complex] wcaps 0x400301: Stereo Digital
  Pincap 0x00000010: OUT
  Pin Default 0x414411f0: [N/A] SPDIF Out at Ext Rear
    Conn = RCA, Color = Black
    DefAssociation = 0xf, Sequence = 0x0
    Misc = NO_PRESENCE
  Pin-ctls: 0x40: OUT
  Connection: 1
     0x02
Node 0x0b [Audio Selector] wcaps 0x300101: Stereo
  Connection: 6
     0x03 0x0c 0x09 0x0e* 0x05 0x18
Node 0x0c [Audio Mixer] wcaps 0x200101: Stereo
  Connection: 2
     0x1e 0x1f
Node 0x0d [Audio Selector] wcaps 0x30010c: Mono Amp-Out
  Control: name="Beep Playback Volume", index=0, device=0
    ControlAmp: chs=1, dir=Out, idx=0, ofs=0
  Control: name="Beep Playback Switch", index=0, device=0
    ControlAmp: chs=1, dir=Out, idx=0, ofs=0
  Amp-Out caps: ofs=0x0f, nsteps=0x0f, stepsize=0x0b, mute=1
  Amp-Out vals:  [0x80]
  Connection: 2
     0x10* 0x16
Node 0x0e [Audio Mixer] wcaps 0x200101: Stereo
  Connection: 8
     0x0d 0x11 0x12 0x13 0x1a 0x1b 0x1c 0x1d
Node 0x0f [Audio Mixer] wcaps 0x200100: Mono
  Connection: 1
     0x0b
Node 0x10 [Beep Generator Widget] wcaps 0x700000: Mono
Node 0x11 [Audio Selector] wcaps 0x30010d: Stereo Amp-Out
  Control: name="PCM Playback Volume", index=0, device=0
    ControlAmp: chs=3, dir=Out, idx=0, ofs=0
  Control: name="PCM Playback Switch", index=0, device=0
    ControlAmp: chs=3, dir=Out, idx=0, ofs=0
  Amp-Out caps: ofs=0x17, nsteps=0x1f, stepsize=0x05, mute=1
  Amp-Out vals:  [0x97 0x97]
  Connection: 1
     0x03
Node 0x12 [Audio Selector] wcaps 0x30010d: Stereo Amp-Out
  Control: name="Mic Playback Volume", index=0, device=0
    ControlAmp: chs=3, dir=Out, idx=0, ofs=0
  Control: name="Mic Playback Switch", index=0, device=0
    ControlAmp: chs=3, dir=Out, idx=0, ofs=0
  Amp-Out caps: ofs=0x17, nsteps=0x1f, stepsize=0x05, mute=1
  Amp-Out vals:  [0x80 0x80]
  Connection: 1
     0x08
Node 0x13 [Audio Selector] wcaps 0x30010d: Stereo Amp-Out
  Amp-Out caps: ofs=0x17, nsteps=0x1f, stepsize=0x05, mute=1
  Amp-Out vals:  [0x80 0x80]
  Connection: 1
     0x09
Node 0x14 [Power Widget] wcaps 0x500500: Mono
  Power states:  D0 D3
  Power: setting=D0, actual=D0
  Connection: 13
     0x0d 0x0e 0x0f 0x10 0x13 0x14 0x15 0x16 0x17 0x18 0x19 0x1a 0x1d
Node 0x15 [Audio Selector] wcaps 0x30010d: Stereo Amp-Out
  Control: name="Capture Volume", index=0, device=0
    ControlAmp: chs=3, dir=Out, idx=0, ofs=0
  Control: name="Capture Switch", index=0, device=0
    ControlAmp: chs=3, dir=Out, idx=0, ofs=0
  Control: name="Capture Source", index=0, device=0
  Amp-Out caps: ofs=0x00, nsteps=0x0f, stepsize=0x05, mute=1
  Amp-Out vals:  [0x80 0x80]
  Connection: 8
     0x0c* 0x09 0x0e 0x0f 0x19 0x05 0x18 0x17
Node 0x16 [Pin Complex] wcaps 0x400000: Mono
  Pincap 0x00000020: IN
  Pin Default 0x59f311f0: [N/A] Other at Int ATAPI
    Conn = ATAPI, Color = Black
    DefAssociation = 0xf, Sequence = 0x0
    Misc = NO_PRESENCE
  Pin-ctls: 0x20: IN
Node 0x17 [Pin Complex] wcaps 0x400081: Stereo
  Pincap 0x00000027: IN Detect Trigger ImpSense
  Pin Default 0x599311f0: [N/A] Aux at Int ATAPI
    Conn = ATAPI, Color = Black
    DefAssociation = 0xf, Sequence = 0x0
    Misc = NO_PRESENCE
  Pin-ctls: 0x20: IN
  Unsolicited: tag=00, enabled=0
Node 0x18 [Pin Complex] wcaps 0x400187: Stereo Amp-In Amp-Out
  Amp-In caps: ofs=0x00, nsteps=0x03, stepsize=0x27, mute=0
  Amp-In vals:  [0x00 0x00]
  Amp-Out caps: ofs=0x3d, nsteps=0x3f, stepsize=0x05, mute=1
  Amp-Out vals:  [0xbf 0xbf]
  Pincap 0x00001737: IN OUT Detect Trigger ImpSense
    Vref caps: HIZ 50 GRD 80
  Pin Default 0x41a190f0: [N/A] Mic at Ext Rear
    Conn = 1/8, Color = Pink
    DefAssociation = 0xf, Sequence = 0x0
  Pin-ctls: 0x24: IN VREF_80
  Unsolicited: tag=00, enabled=0
  Connection: 2
     0x03* 0x0e
Node 0x19 [Pin Complex] wcaps 0x400001: Stereo
  Pincap 0x00000020: IN
  Pin Default 0x9933e120: [Fixed] CD at Int ATAPI
    Conn = ATAPI, Color = White
    DefAssociation = 0x2, Sequence = 0x0
    Misc = NO_PRESENCE
  Pin-ctls: 0x20: IN
Node 0x1a [Audio Selector] wcaps 0x30010d: Stereo Amp-Out
  Amp-Out caps: ofs=0x17, nsteps=0x1f, stepsize=0x05, mute=1
  Amp-Out vals:  [0x80 0x80]
  Connection: 1
     0x05
Node 0x1b [Audio Selector] wcaps 0x30010d: Stereo Amp-Out
  Amp-Out caps: ofs=0x17, nsteps=0x1f, stepsize=0x05, mute=1
  Amp-Out vals:  [0x80 0x80]
  Connection: 1
     0x17
Node 0x1c [Audio Selector] wcaps 0x30010d: Stereo Amp-Out
  Amp-Out caps: ofs=0x17, nsteps=0x1f, stepsize=0x05, mute=1
  Amp-Out vals:  [0x80 0x80]
  Connection: 1
     0x18
Node 0x1d [Audio Selector] wcaps 0x30010d: Stereo Amp-Out
  Control: name="CD Playback Volume", index=0, device=0
    ControlAmp: chs=3, dir=Out, idx=0, ofs=0
  Control: name="CD Playback Switch", index=0, device=0
    ControlAmp: chs=3, dir=Out, idx=0, ofs=0
  Amp-Out caps: ofs=0x17, nsteps=0x1f, stepsize=0x05, mute=1
  Amp-Out vals:  [0x19 0x19]
  Connection: 1
     0x19
Node 0x1e [Audio Selector] wcaps 0x30010d: Stereo Amp-Out
  Amp-Out caps: ofs=0x00, nsteps=0x00, stepsize=0x00, mute=1
  Amp-Out vals:  [0x00 0x00]
  Connection: 1
     0x08
Node 0x1f [Audio Selector] wcaps 0x30010d: Stereo Amp-Out
  Amp-Out caps: ofs=0x00, nsteps=0x00, stepsize=0x00, mute=1
  Amp-Out vals:  [0x80 0x80]
  Connection: 1
     0x18

As their names suggest, these “nodes” are all connected on a directed graph. It’s difficult to follow the graph as written above, but Cytoscape can be used to produce a more manageable visualization:

This should be a valuable reference.