You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
409 lines
10 KiB
409 lines
10 KiB
<chapter id="future-work">
|
|
<title>Future Work</title>
|
|
|
|
<para>
|
|
This section describes some of the &arts; work that is in progress.
|
|
Development progresses quickly, so this information may be out of date.
|
|
You should check the TODO list file and the <link
|
|
linkend="mailing-lists">mailing list</link> archives to see what new
|
|
functionality is planned. Feel free to get involved in new design and
|
|
implementation.
|
|
</para>
|
|
|
|
<para>
|
|
This is a draft document which tries to give you an overview how new
|
|
technologies will be integrated in &arts;. Namely, it does cover the
|
|
following:
|
|
</para>
|
|
|
|
<itemizedlist>
|
|
<listitem><para>How interfaces work.</para></listitem>
|
|
<listitem><para>Codecs - decoding of mp3 or wav streams in a form that
|
|
they can be used as data.</para></listitem>
|
|
<listitem><para>Video.</para></listitem>
|
|
<listitem><para>Threading.</para></listitem>
|
|
<listitem><para>Synchronization.</para></listitem>
|
|
<listitem><para>Dynamic expansion/masquerading.</para></listitem>
|
|
<listitem><para>Dynamic composition.</para></listitem>
|
|
<listitem><para>&GUI;</para></listitem>
|
|
<listitem><para>&MIDI;</para></listitem>
|
|
</itemizedlist>
|
|
|
|
<para>
|
|
This is work in progress. However, it should be the base if you want to
|
|
see new technology in &arts;. It should give you a general idea how
|
|
these problems will be addressed. However, feel free to correct anything
|
|
you see here.
|
|
</para>
|
|
|
|
<para>
|
|
Things that will be use &arts; technology (so please, coordinate your
|
|
efforts):
|
|
</para>
|
|
|
|
<itemizedlist>
|
|
<listitem>
|
|
<para>
|
|
<application>KPhone</application> (voice over <acronym>IP</acronym>)
|
|
</para>
|
|
</listitem>
|
|
|
|
<listitem>
|
|
<para>
|
|
&noatun; (video / audio player)
|
|
</para>
|
|
</listitem>
|
|
|
|
<listitem>
|
|
<para>
|
|
&artscontrol; (sound server control program, for scopes)
|
|
</para>
|
|
</listitem>
|
|
|
|
<listitem>
|
|
<para>
|
|
<application>Brahms</application> (music sequencer)
|
|
</para>
|
|
</listitem>
|
|
|
|
<listitem>
|
|
<para><application>Kaiman</application> (&kde;2 media player - kmedia2 compliant)
|
|
</para>
|
|
</listitem>
|
|
|
|
<listitem>
|
|
<para>
|
|
<application>mpglib</application>/<application>kmpg</application>
|
|
(<acronym>mpg</acronym> audio and video playing technology)
|
|
</para>
|
|
</listitem>
|
|
|
|
<listitem>
|
|
<para>
|
|
<application>SDL</application> (direct media layer for games not
|
|
yet started but maybe nice)
|
|
</para>
|
|
</listitem>
|
|
|
|
<listitem>
|
|
<para>
|
|
<application>electric ears</application> (author contacted me - status
|
|
unknown)
|
|
</para>
|
|
</listitem>
|
|
</itemizedlist>
|
|
|
|
<sect1 id="interfaces-how">
|
|
<title>How Interfaces Work</title>
|
|
|
|
<!-- I think this is now obsolete and documented elsewhere ? -->
|
|
|
|
<para>
|
|
&MCOP; interfaces are the base of the &arts; concept. They are the
|
|
network transparent equivalent to C++ classes. Whenever possible you
|
|
should orient your design towards interfaces. Interfaces consist of four
|
|
parts:
|
|
</para>
|
|
|
|
<itemizedlist>
|
|
<listitem><para>Synchronous streams</para></listitem>
|
|
<listitem><para>Asynchronous streams</para></listitem>
|
|
<listitem><para>Methods</para></listitem>
|
|
<listitem><para>Attributes</para></listitem>
|
|
</itemizedlist>
|
|
|
|
<para>
|
|
These can be mixed in any way you like. New technologies should be
|
|
defined in terms of interfaces. Read the sections about asynchronous
|
|
streams and synchronous streams, as well as the KMedia2 interfaces,
|
|
which are a good example how such things work
|
|
</para>
|
|
|
|
<para>
|
|
Interfaces are specified in <literal role="extension">.idl</literal>
|
|
code and run through the <command>mcopidl</command> compiler. You
|
|
derive the
|
|
<classname><replaceable>Interfacename</replaceable>_impl</classname>
|
|
class to implement them, and use
|
|
<function>REGISTER_IMPLEMENTATION(Interfacename_impl)</function> to
|
|
insert your object implementations into the &MCOP; object system.
|
|
</para>
|
|
|
|
</sect1>
|
|
|
|
<sect1 id="codecs">
|
|
<title>Codecs - Data Decoding</title>
|
|
|
|
<para>
|
|
The kmedia2 interfaces allow you to ignore that wav files, mp3s and
|
|
whatever consist of data streams. Instead, you only implement methods to
|
|
play them.
|
|
</para>
|
|
|
|
<para>
|
|
Thus, you can write a wave loading routine in a way that you can play
|
|
wave files (as PlayObject), but nobody else can use your code.
|
|
</para>
|
|
|
|
<para>
|
|
Asynchronous streams would be the alternative. You define an interface
|
|
which allows you to pass data blocks in, and get data blocks out. This
|
|
looks like that in &MCOP;:
|
|
</para>
|
|
|
|
<programlisting>
|
|
interface Codec {
|
|
in async byte stream indata;
|
|
out async byte stream outdata;
|
|
};
|
|
</programlisting>
|
|
|
|
|
|
<para>
|
|
Of course codecs could also provide attributes to emit additional data,
|
|
such as format information.
|
|
</para>
|
|
|
|
<programlisting>
|
|
interface ByteAudioCodec {
|
|
in async byte stream indata;
|
|
out async byte stream outdata;
|
|
readonly attribute samplingRate, bits, channels;
|
|
};
|
|
</programlisting>
|
|
|
|
<para>
|
|
This <interfacename>ByteAudioCodec</interfacename> for instance could be
|
|
connected to a <interfacename>ByteStreamToAudio</interfacename> object,
|
|
to make real float audio.
|
|
</para>
|
|
|
|
<para>
|
|
Of course, other Codec types could involve directly emitting video data,
|
|
such as
|
|
</para>
|
|
|
|
<programlisting>
|
|
interface VideoCodec {
|
|
in async byte stream indata;
|
|
out video stream outdata; /* note: video streams do not exist yet */
|
|
};
|
|
</programlisting>
|
|
|
|
<para>
|
|
Most likely, a codec concept should be employed rather than the
|
|
<quote>you know how to play and I don't</quote> way for instance
|
|
<interfacename>WavPlayObject</interfacename> currently uses. However,
|
|
somebody needs to sit down and do some experiments before an
|
|
<acronym>API</acronym> can be finalized.
|
|
</para>
|
|
|
|
</sect1>
|
|
|
|
<sect1 id="video">
|
|
<title>Video</title>
|
|
|
|
<para>
|
|
My idea is to provide video as asynchronous streams of some native
|
|
&MCOP; data type which contains images. This data type is to be created
|
|
yet. Doing so, plugins which deal with video images could be connected
|
|
the same way audio plugins can be connected.
|
|
</para>
|
|
|
|
<para>
|
|
There are a few things that are important not to leave out, namely:
|
|
</para>
|
|
|
|
<itemizedlist>
|
|
<listitem>
|
|
<para>
|
|
There are <acronym>RGB</acronym> and <acronym>YUV</acronym> colorspaces.
|
|
</para>
|
|
</listitem>
|
|
<listitem>
|
|
<para>
|
|
The format should be somehow tagged to the stream.
|
|
</para>
|
|
</listitem>
|
|
<listitem>
|
|
<para>
|
|
Synchronization is important.
|
|
</para>
|
|
</listitem>
|
|
</itemizedlist>
|
|
|
|
<para>
|
|
My idea is to leave it possible to reimplement the
|
|
<classname>VideoFrame</classname> class so that it can store stuff in a
|
|
shared memory segment. Doing so, even video streaming between different
|
|
processes would be possible without too much pain.
|
|
</para>
|
|
|
|
<para>
|
|
However, the standard situation for video is that things are in the same
|
|
process, from the decoding to the rendering.
|
|
</para>
|
|
|
|
<para>
|
|
I have done a prototypic video streaming implementation, which you can
|
|
download <ulink
|
|
url="http://space.twc.de/~stefan/kde/download/video-quickdraw.tar.gz">here
|
|
</ulink>. This would need to be integrated into &MCOP; after some
|
|
experiments.
|
|
</para>
|
|
|
|
<para>
|
|
A rendering component should be provided that supports XMITSHM (with
|
|
<acronym>RGB</acronym> and <acronym>YUV</acronym>), Martin Vogt told me
|
|
he is working on such a thing.
|
|
</para>
|
|
|
|
</sect1>
|
|
|
|
<sect1 id="threading">
|
|
<title>Threading</title>
|
|
|
|
<para>
|
|
Currently, &MCOP; is all single threaded. Maybe for video we will no
|
|
longer be able to get around threading. Ok. There are a few things that
|
|
should be treated carefully:
|
|
</para>
|
|
|
|
|
|
<itemizedlist>
|
|
<listitem><para>
|
|
SmartWrappers - they are not threadsafe due to non-safe reference
|
|
counting and similar.
|
|
</para>
|
|
</listitem>
|
|
<listitem>
|
|
<para>
|
|
Dispatcher / I/O - also not threadsafe.
|
|
</para>
|
|
</listitem>
|
|
</itemizedlist>
|
|
|
|
<para>
|
|
However, what I could imagine is to make selected modules threadsafe,
|
|
for both, synchronous and asynchronous streaming. That way - with a
|
|
thread aware flow system, you could schedule the signal flow over two or
|
|
more processors. This would also help audio a lot on multiprocessor
|
|
things.
|
|
</para>
|
|
|
|
<para>
|
|
How it would work:
|
|
</para>
|
|
|
|
|
|
<itemizedlist>
|
|
<listitem>
|
|
<para>The Flow System decides which modules should calculate what - that
|
|
is:
|
|
</para>
|
|
<itemizedlist>
|
|
<listitem><para>video frames (with process_indata method)</para></listitem>
|
|
<listitem><para>synchronous audio streams
|
|
(calculateBlock)</para></listitem>
|
|
<listitem><para>other asynchronous streams, mainly byte
|
|
streams</para></listitem>
|
|
</itemizedlist>
|
|
</listitem>
|
|
<listitem>
|
|
<para>
|
|
Modules can calculate these things in own threads. For audio, it makes
|
|
sense to reuse threads (⪚ render on four threads for four processors,
|
|
no matter if 100 modules are running). For video and byte decompression,
|
|
it may be more confortable to have a blocking implementation in an own
|
|
thread, which is synchronized against the rest of &MCOP; by the flow
|
|
system.
|
|
</para>
|
|
</listitem>
|
|
|
|
<listitem>
|
|
<para>
|
|
Modules may not use &MCOP; functionality (such as remote invocations)
|
|
during threaded operation.
|
|
</para>
|
|
</listitem>
|
|
</itemizedlist>
|
|
|
|
</sect1>
|
|
|
|
<sect1 id="synchronization">
|
|
<title>Synchronization</title>
|
|
|
|
<para>
|
|
Video and &MIDI; (and audio) may require synchronization. Basically, that
|
|
is timestamping. The idea I have is to attach timestamps to asynchronous
|
|
streams, by adding one timestamp to each packet. If you send two video
|
|
frames, simply make it two packets (they are large anyway), so that you
|
|
can have two different time stamps.
|
|
</para>
|
|
|
|
<para>
|
|
Audio should implicitely have time stamps, as it is synchronous.
|
|
</para>
|
|
|
|
</sect1>
|
|
|
|
<sect1 id="dynamic-composition">
|
|
<title>Dynamic Composition</title>
|
|
|
|
<para>
|
|
It should be possible to say: An effect FX is composed out of these
|
|
simpler modules. FX should look like a normal &MCOP; module (see
|
|
masquerading), but in fact consist of other modules.
|
|
</para>
|
|
|
|
<para>
|
|
This is required for &arts-builder;.
|
|
</para>
|
|
|
|
</sect1>
|
|
|
|
<sect1 id="gui">
|
|
<title>&GUI;</title>
|
|
|
|
<para>
|
|
All &GUI; components will be &MCOP; modules. They should have attributes
|
|
like size, label, color, ... . A <acronym>RAD</acronym> builder
|
|
(&arts-builder;) should be able to compose them visually.
|
|
</para>
|
|
|
|
<para>
|
|
The &GUI; should be saveable by saving the attributes.
|
|
</para>
|
|
|
|
</sect1>
|
|
|
|
<sect1 id="midi-stuff">
|
|
<title>&MIDI;</title>
|
|
|
|
<para>
|
|
The &MIDI; stuff will be implemented as asynchronous streams. There are
|
|
two options, one is using normal &MCOP; structures to define the types
|
|
and the other is to introduce yet another custom types.
|
|
</para>
|
|
|
|
<para>
|
|
I think normal structures may be enough, that is something like:
|
|
</para>
|
|
|
|
<programlisting>
|
|
struct MidiEvent {
|
|
byte b1,b2,b3;
|
|
sequence<byte> sysex;
|
|
}
|
|
</programlisting>
|
|
|
|
<para>
|
|
Asynchronous streams should support custom stream types.
|
|
</para>
|
|
|
|
</sect1>
|
|
|
|
</chapter>
|
|
|
|
|