I’m using Firefly Media Server on a Linksys NSLU2 running Debian Etch to stream my whole music collection to my Pinnacle SoundBridge HomeMusic. Many files in my collection are in Ogg Vorbis format and a few in Musepack too, which unfortunately aren’t natively supported by the SoundBridge. Luckily Firefly can transcode audio files on the fly e.g. using the ssc plug-in and any console application via shell scripts. But the problem with the Debian packages is that they don’t take into account the missing floating point unit (FPU) of the NSLU2 hardware, and that makes oggdec/ogg123 and mpc123 take ages – way below real-time – to transcode. Fixed point versions of the transcoders aren’t available in the Debian Etch package repositories even the sourcecode already exists, so I had to build them myself.
I first searched the Debian packages for fixed point versions.
I found the libvorbisidec package, which is the fixed point version of libvorbis also going by the name Tremor. The vorbis-tools is only available as normal floating-point version linked to libvorbisdec. For Musepack there are (floating-point) packages libmpcdec3 for the library and mpc123 for the application.
In the Firefly forums I found patches for vorbis-tools (providing the ogg123 and oggdec transcoders), so that I could build Tremor versions of the transcoder apps.
In the Musepack sources there’s already a define variable to build with fixed point math only. So I would just have to enable that and rebuild the library and transcoder.
To make a long story short, here are the Debian Etch ARM binary packages for fixed-point Ogg Vorbis and Musepack:
I will gladly provide the sources. Feel free to ask for them! You can download the Deb sources for libmpcdec and vorbis-tools further below.
Update
These are the integer Lenny ARM binaries. Libvorbisidec is available through the official repos.:
Update 2
Here are the Deb sources (.dsc, .diff.gz and .orig.tar.gz) to build your own binary Deb packages.
Performance now is very good on my 266 MHz NSLU2. From what I’ve seen in top, mpc123 and ogg123 stay below 50% CPU usage and decoding is done faster than real-time.
Only to show off how unbelievably cool I am ;), and in case somebody would like to reproduce these builds on another distribution, I’ll roughly describe the steps I’ve taken.
Build libvorbisidec
Pretty straight forward. As far as I remember I only had to rebuild the source package:
mkdir -p ~/debuild/libvorbisdec cd ~/debuild/libvorbisdec dget -x http://ftp.de.debian.org/debian/pool/main/libv/libvorbisidec/libvorbisidec_1.0.2+svn14261-1.dsc cd libvorbisidec-1.0.2 debuild -rfakeroot -uc -us cd .. sudo dpkg -i libvorbisidec1_1.0.2+svn14261-1_arm.deb libvorbisidec-dev_1.0.2+svn14261-1_arm.deb
Patch and build vorbis-tools
This one was trickier. The patches found on the forum aren’t complete. The older one is blindly changing the endianess of the resulting audio data, thereby producing only noise on the little endian Debian I use. The newer one misses linking mpcdec to libvorbisidec.
mkdir -p ~/debuild/vorbis-tools cd ~/debuild/vorbis-tools dget -x http://ftp.de.debian.org/debian/pool/main/v/vorbis-tools/vorbis-tools_1.1.1-6.dsc cp -pr vorbis-tools_1.1.1 vorbis-tools_1.1.1.wrk cd vorbis-tools_1.1.1.wrk [apply and manually fix the tremor patch] [create tremor patch file against vorbis-tools_1.1.1/] [copy patch file to vorbis-tools_1.1.1/debian/patches] [add patch file at bottom of vorbis-tools_1.1.1/debian/patches/series] [add libvorbisidec-dev dependency to vorbis-tools_1.1.1/debian/control and document Tremor versions in description] [increase version and add changes in changelog via dch -i] cd vorbis-tools_1.1.1 debuild -rfakeroot -uc -us cd .. dpkg -i vorbis-tools_1.1.1-7_arm.deb
Patch and build libmpcdec
Here I add a patch to enable the fixed-point define. Beware, the following steps are just written down from memory in a hurry. So expect flaws. :)
mkdir -p ~/debuild/libmpcdec cd ~/debuild/libmpcdec dget -x http://ftp.de.debian.org/debian/pool/main/libm/libmpcdec/libmpcdec_1.2.2-1.dsc cp -pr libmpcdec-1.2.2 libmpcdec-1.2.2.wrk vim libmpcdec-1.2.2.wrk/include/mpcdec/math.h [uncomment #define MPC_FIXED_POINT] mkdir libmpcdec-1.2.2.wrk/debian/patches diff -Naur libmpcdec-1.2.2 libmpcdec-1.2.2.wrk > libmpcdec-1.2.2.wrk/debian/patches/enable_fixed_point.diff cd libmpcdec-1.2.2.wrk dch -i [increases version in changelog. add some notes.] debuild -rfakeroot -uc -us cd .. dpkg -i libmpcdec3_1.2.2-2_arm.deb libmpcdec-dev_1.2.2-2_arm.deb
Build mpc123
This one has only to be rebuilt with the fixed-point libmpcdec version above installed.
mkdir -p ~/debuild/mpc123 cd ~/debuild/mpc123 dget -x http://ftp.de.debian.org/debian/pool/main/m/mpc123/mpc123_0.2.1-1.dsc cd mpc123-0.2.2 debuild -rfakeroot -uc -us cd .. dpkg -i mpc123_0.2.2-1_arm.deb
I haven’t found a fast enough way to transcode Monkey’s Audio (aka. APE) files yet, but that’s mainly because I don’t have any (which haven’t been transcoded to mp3 by myself already). For your information: Building the Monkey’s Audio Codec (MAC) for Linux did work.
I think when looking for more low resource or fixed-point codecs, a good place to look for is the Rockbox Wiki. That’s what I used too.
To make this Firefly Transcoding post more complete, here’s my current version of the ssc script:
#!/bin/sh
#
# script to facilitate server-side transcoding of ogg files
#
#
# Usage: mt-daapd-ssc.sh
#
# You may need to fix these paths:
#
WAVSTREAMER=/opt/mt-daapd-ssc/wavstreamer
OGGDEC=oggdec
OGG123=ogg123
FLAC=flac
MPC=mpc123
FFMPEG=/opt/mt-daapd-ssc/ffmpeg-quiet.sh
MAC=mac
ape_file() {
$MAC "$FILE" - -d | $WAVSTREAMER -o $OFFSET $FORGELEN
}
ffmpeg_file() {
$FFMPEG -i "$FILE" -acodec pcm_s16le -f wav - | $WAVSTREAMER -o $OFFSET $FORGELEN
}
mpc_file() {
$MPC --quiet --wav - "$FILE" | $WAVSTREAMER -o $OFFSET $FORGELEN
}
ogg_file() {
# $OGGDEC --quiet -o - "$FILE" | $WAVSTREAMER -o $OFFSET $FORGELEN
$OGG123 -q -d wav -f - "$FILE" | $WAVSTREAMER -o $OFFSET $FORGELEN
}
flac_file() {
$FLAC --silent --decode --stdout "$FILE" | $WAVSTREAMER -o $OFFSET $FORGELEN
}
FILE=$1
OFFSET=${2:-0}
# this is nonsense!
if [ "$3" != "" ]; then
FORGELEN="-l ${3%.*}"
fi
case "$1" in
*.[sS][hH][nN])
ape_file
;;
*.[sS][hH][nN])
ffmpeg_file
;;
*.[mM][pP][cC])
mpc_file
;;
*.[oO][gG][gG])
ogg_file
;;
*.[fF][lL][aA][cC])
flac_file
;;
*)
# here you could cat a generic "error" wav...
# cat /path/to/error.wav
;;
esac
Oh, FYI I’m using mt-daapd 0.2.4+r1376-1 from the Debian repo. I got the wavstreamer binary and the ssc script example by extracting them from a newer Debian package. The Firefly Wiki provides more information on transcoding implementation.
ChangeLog
[2008-04-11: Add Lenny Debs.]
[2008-06-06: Add Deb sources for libmpcdec and vorbis-tools.]
[2009-04-26: Fix box.net links.]
Bembel-B Blog 