A few brief notes on an audio player I built for my stereo. The main
requirements were support for Ogg Vorbis and FLAC, and usability at a distance
from my armchair. Also, I did not want to pay as much as these PC-based
players cost when you buy them as a box.
- Mainboard
-
VIA EPIA-LN 10000EAG. Fanless, ITX (17 x 17 cm) form factor, including C7 CPU
@ 1GHz, which is more than sufficient for audio decoding. It is comparably
inexpensive but still modern enough to have SATA disk interfaces.
I wasted some time debugging the drivers of the sound card before
noticing that the PCI slot connections were the problem. The springs in the
slot of this mainboard are so soft that the contact with the card is bad.
Removing and re-inserting the card muiltiple times solves the problem.
- Sound card
-
Echoaudio
MiaMIDI
. A solid but not extravagantly expensive
musician/audiophile sound card. Unlike other manufacturers, Echoaudio put
their specs on the web
openly, and their openness about drivers (they provide a reference
implementation to developers) results in good Linux support. They are
compatible with both home and professional audio equipment because the analog
output level and S/PDIF mode can be switched. The card is both 5V and 3.3V PCI
slot compatible, even though all pictures on the web show it as a 5V only card,
so don't worry.
Each of the analog I/Os transmits a single channel despite being
3-contact TRS jacks. The 3 contacts are for balanced (differential) cables in
professional audio. If you (like me) want to wire it up to your home stereo,
you need a pair of two-contact TRS-to-RCA cables. The drivers behind
the jacks automatically sense a 2-conductor cable has been connected and will
not try to drive the level between the two shorted contacts.
- Power supply
-
A fanless laptop-style 12V power brick and a 90W PicoPSU to generate the various voltages the mainboard needs. The
PicoPSU is a small board which plugs
into the mainboard power connector and has a reputation for high efficiency.
- Hard disk
-
A 320 GB Seagate Momentus 7200.3 (ST9320421AS). A 5400 RPM drive might have
been quieter, but that is mostly an issue for people who live far from any
church and road and other habitation, and in a room with no external walls or
water pipes or mechanical wall clocks... (But see below on how I mounted the
disk.)
Update: I have now replaced the hard disk by a 64GB solid-state disk
(Kingston SSDNow), which is still sufficient capacity for storing all my music
in FLAC format. This makes the player totally silent; it was mainly the
clicking of the drive stepping the read/write heads that was annoying.
- Display
-
Fujitsu/Siemens Scenicview E19-8 19. The cheapest and most low-quality monitor
in the world. Its hue changes with the angle of view, and its sharpness is
"limited", but it is sufficient when viewed at a distance, as in my
case. A more serious issue is that is makes a slight high-pitched noise; but
when it is mounted on the wall, fortunately not much of it is transmitted
perpendicularly.
- Input devices
-
Logitech Cordless Trackman Wheel. Unlike mice, trackballs can be used without
a flat surface, and a cordless one is a remote control for graphical programs.
Unfortunately they are not widely sold, and there are few models. A
presentation mouse/trackball may also be suitable, but the Trackman's scroll
wheel helps selecting songs from a HTML page (see below). Its reach is 2
metres or more provided you put the receiver on a horizontal surface as
intended; putting it in the vertical did not work.
As for a keyboard, I have an old one connected in case of trouble, but it is
not used for operating the player.
Total cost (spring 2009): 124 (MB) + 19 (RAM) + 129 (sound) + 88 (HD) + 87
(power) + 110 (display) + 56 (trackball) = 447 EUR (PC) + 166 EUR (peripherals)
= 613 EUR
Power consumption: 29 W (PC) + 27 W (display) = 58 W. Switched off: 6.9 W (PC)
+ 0 W (!) (display)
The solid-state disk I substituted for the hard disk was 30 EUR more at a much
smaller capacity. Power consumption has been reduced by about two Watts.
- Operating system
-
Gentoo Linux. Flexible enough to allow building a small system, but still
manages dependencies. Downside: you have to compile everything on your local
box, which takes a while.
- Audio player
-
gmplayer. The only choice because I wanted to enlarge control
elements so they could be
seen/used from a distance. Other players allow theming, but not resizing or
rearrangement of the control elements. My new, extra large gmplayer
skin can be found here (screenshot see below). It was drawn with xfig, and then exported as
a bitmap and divided up by a script using ImageMagick. The sources are
included, so you can modify it.
gmplayer does not support playing all audio files in a directory when
a directory is passed on the command line. Besides, selecting an album with a
web browser (see next item) does not allow you to pass multiple files to an
external application. This is solved by having the browser call a launch script, which calls
gmplayer with a playlist of all audio files in the directory.
This script also takes care of a major disadvantage of (g)mplayer,
namely that it does not support gapless playback. This is important when songs continue across track/file
boundaries, as is the
case for classical and some modern music. The launch script fixes this problem
by making mplayer output raw PCM data to a named pipe (which it
expects to be there; use mkfifo), from which the ALSA play program
aplay reads. The buffering the system provides for the named pipe is
sufficient to bridge the delays mplayer introduces when changing
files. (See here for a stand-alone example of how this works. If you find
you need more buffering, try my audio FIFO
program.)
- Album selection
-
I store all my music in the FLAC lossless compression format. It is organised in three
hierarchies of
directories for the genre, the band or composer and the album. To select what
to play, I click on an image of the album cover in a web browser (I use links). The covers are located in the directories containing
the audio files; I scanned them or found them on
the web and converted them to thumbnails using this script, which uses ImageMagick. This longish Perl script generates a HTML page
with cover images for each genre. It also automatically generates the files
containing their own absolute paths, so that the launch script knows where to
look for audio files. These files are linked to by the album covers, and the
browser's file associations are set so that this file type is passed to the
player launch script.
- Startup and shutdown
-
TuxOnIce for
hibernation and accordingly quick startup and shutdown. Total startup time is
22 seconds, which seems a
lot. But it takes 7 seconds after the power button is pressed for the BIOS
to display the first screen, and the grub menu appears at 12 seconds. At 20
seconds the display blacks out to readjust, and displays the X screen two
seconds later. So more than half the startup time is due to the BIOS. A newer
type of mainboard might help here. Shutting down takes some 15 seconds.
Because the MiaMIDI sound card has to have firmware loaded before it can
function, its driver has to be unloaded before hibernating and reloaded after
resuming. This is achieved by putting the following line into the TuxOnIce
configuration file, /etc/hibernate/common.conf:
UnloadModules snd_mia
TuxOnIce is conservative and will refuse to shut down if removing a module is
not successful, such as when some program is still using it. To allow shutting
down even when some player is still running, I put the following lines into the
common.conf:
OnSuspend 83 killall -q -KILL gmplayer || true
OnSuspend 83 killall -q -KILL mplayer || true
OnSuspend 84 killall -q -KILL aplay || true
OnSuspend 85 killall -q echomixer || true
OnResume 11 sudo -u dj -H -b /usr/bin/echomixer
This causes any player programs I use to be killed before trying to unload the
sound card driver, and the Echoaudio card mixer to be relaunched on resume.
The "|| true" lets the shutdown go ahead even if no process
could be killed (because no player was running). The sudo starts the
echomixer as a non-root user.
- Audio mixer
-
echomixer, part of the ALSA-tools package, is a mixer program specific to Echoaudio cards.
As well as setting mixer levels, it allows adjusting the card's special
functions such as consumer/professional I/O modes, and displaying a VU metre.
- Case
-
None, really. (You probably wouldn't want to follow my lead here.) It would
be hard to get a case which fits with the sound card sticking up out of the PCI
slot, and I didn't want to bother with PCI extenders. Besides, when putting a
fanless mainboard in a case, a case fan is recommended, which sort of defeats
the purpose of having a fanless mainboard. Also, I am not shocked by the sight
of bare electronics, so I just bought an aluminum plate with a grid of holes
which I bent to form a box open at two ends. The mainboard is on the top, and
the hard disk and power supply inside. The power brick is stowed away there
too, the reverse of the trick used by salesdroids to make a device smaller.
- Hard disk
-
After some disappointing experiment with (too hard) rubber mounts, I hit on a
simple, effective and cheap way of acoustically decoupling the hard disk from
anything that might resonate with it and amplify its noise. I used short
strips of 19mm climber's webbing to suspend it from the top of my home-made
case. The fastening at both ends of the strips consists of screws pushed
through it, which disqualifies them for climbing but is amply good enough for
the negligible weight they have to support.
- Display
-
The display is VESA
mount compatible, which in this case means four M4
screw threads in its back in a 100mm square. You can buy wall mounts for such
displays for 50 to
200 Euros, but unless you need pivoting, there is a simpler solution. I
fastened two of the metal plates carpenters use to nail beams of wood together
and which any DIY shop stocks to the back of the case (measure distances
between holes before you buy) and mounted the display on the wall by suspending
the plates from wall hooks on their bigger holes.
