Re: [linux-audio-dev] New subscriber

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Subject: Re: [linux-audio-dev] New subscriber
From: Kai Vehmanen (kaiv_AT_wakkanet.fi)
Date: su helmi  27 2000 - 13:59:13 EST


On Sun, 27 Feb 2000, Bruce Forsberg wrote:

> support 3-4 years ago it was lousy. Sox, and a few other programs was
> all there was. I must admit I am not in the "inner circle" of Linux

Btw; have you looked at Dave's Sound&MIDI pages? You probably
have, but just to make sure. ;) ... http://www.bright.net/~dlphilp/

> The one thing that upsets me is the number of people who are writing
> just applications (ie think how useful sox whould be if they wrote it
> as a library) and not creating libraries or writing stuff for
> window environments like KDE or GNOME. I wanted to write audio
> applications for Linux so I could pursue my hobby but did not find

Well, actually many project do put all the code into libraries
(at least that's what I do with ecasound), but writing generic
interfaces seems to be a difficult tasks. Putting the code
into a library isn't enough, the interface has to be reusable.

> interest. I am interested in developing a library that application
> writers who are writing non-audio apps can use to add audio capability to
> their apps with little effort. An example would be Star Office. I don't
> believe their presentation manager supports audio like MS Office. A
> library would make it easy for them if they decided to do so. The

Aah, you got a point there. So a kind of "audio toolkit"...?
I don't know of any this kind of (Linux) library projects.

> and writing audio files. That will be a small portion. There are some
> unique features in my library. One is the sample rate converter. It
> provides filtering and thus eliminates any anti-aliasing
> problems. It will also convert any sample rate to another. No M/N
> stuff. Another is the timer record class. It is used in the player test

Well, I maintain two audio libraries myself, libecasound and
libqtecasound. The first one is a generic audio library that
offers support for various file formats, effects (including
resampling), multichannel routing, etc... The latter one
offers audio related GUI objects. I haven't advertised these
much (as libraries), because there isn't enough good
documentation available just yet. But they are both used
by real working apps. I use them for ecasound, qtecasound and
ecawave, and some brave souls have already started to use ecasound
libs in their own projects. I've just registered the eca.cx domain
for all ecasound-related projects. But as long as I'm working on
this alone, it will develop slowly. Btw; it's written in C++
(started in 1997, now about ~1MB of source code). But I guess we are
aiming at different target users, and thus won't have that much
overlapping code.

As for others, at least Paul-Barton Davis has lots of his
code in libraries, but AFAIK he hasn't released them
officially as libraries. Some of the audio file libraries
support resampling and format conversion (?, or at least they
mean to support it in the future). I don't use KDE myself
(anymore), but I've heard good things about aRts. If and
when it become the KDE audio engine, it will probably
offer a good selection of audio services for all KDE apps.

One of the problems in coding generic audio modules is that
there aren't many standard practises. Different projects
represent audio data in different ways; some use variable
size fragments, others rely on static fragments; we have
various different drivers APIs (OSS, ALSA, ESD + all the
card specific packages); various file formats ... Shortly
put, quite a mess.

--
 Kai Vehmanen (kaiv_AT_wakkanet.fi)
 Webmaster, Wakkanet Oy


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