Thanks to Nathan Dietsch, John P Speno, Rafael Najmanov,
Barry Branch and Ann Cantelow for quick and informative
answers!
Solution:
MP3-players:
1. xmms (www.xmms.org)
This player compiles and runs ok and can decode mp3:s to files to
other audio formats. It cannot play music on the workstation audio
hardware, because it doesn't have drivers for it (at least not for
ES1888 sound device). It may be possible to have this player work on
workstations with Digital AudioFile -driver supported hardware
(
http://ftp.digital.com/pub/digital/AF/). ES1888 is just not among the
supported hardware for the AF.
Otherwise, this program is well made, it can be easily expanded with
plug-ins as they become available (no need to recompile everything).
2. mpg123 (
http://www.sfs.nphil.uni-tuebingen.de/~hipp/mpg123.html)
This is a command line utility to decode MP3s. It can play them on the
audio device on Tru64 Unix without problems and it can also convert to
other formats.
3. xaudio/mxaudio (
http://www.xaudio.com/)
Xaudio is another command line utility, that can both save the data in
other formats and play it on audio device. mxaudio is a graphical
Motif interface to xaudio; looks quite nice. This program is shareware,
so it is appropriate to pay something for it for continued
use. Xaudio/mxaudio are available ready to run, in binary format.
MP3 encoders:
1. LAME (or not-LAME,
http://hive.me.gu.edu.au/not_lame/)
LAME is a command line driven utility to encode MP3:s from WAV and
other formats. Is is available at least in source format and compiles
with minor corrections with gcc and GNU make. It does _not_ work with
DEC CC, which produces code giving floating exception while the gcc
compiled binary runs happily.
LAME is quite good, on an XP1000 it can encode 128kbit, full stereo
44,1 kHz MP3 at 4x -speed - this is an amazing rate compared to
anything I've seen before!
Note, that the use of LAME may be restricted in some countries! It
contains patented algorithms (at least Germany and USA), which may or
may not be a problem. Fortunately, the algorithm is not patented in
this country, so we are able to use the technology free.
We decided to use xaudio and LAME, they are in fact much better than I
could imagine. Command line utilities are easy to incorporate into
automated scripts to compress/decompress audio datafiles.
For those, who are concerned of legal aspects regarding the use of MP3,
we are using the software for compressing data from some of our
scientific instruments. It was fastest, cheapest and easiest to set up
an old PC with a Soundblaster and hook up analog devices to that
through an VDO. Voila, you have a two-channel digitizing system with
all the necessary software coming with it!
When you record the data as WAV, convert to MP3 and back to raw data,
the MP3 converter has effectively removed most of the background
noise. This is much easier than trying to find suitable
parameters for a Matlab filter, when the data is read to Matlab for
analysis. As PC is slow like a snail doing the filtering, we wanted to
use an Alpha instead.
Besides, MP3:s are far more an efficient way to compress audio data
than anything else. As an added bonus, one can listen to music with
the same software, if needed.
--
ArNO
2
Received on Thu Aug 12 1999 - 13:43:17 NZST