[openbeosmediakit] Summary (reposted to mailing list)

From: "Marcus Overhagen" <dos4gw@xxxxxx>
To: openbeosmediakit@xxxxxxxxxxxxx
Date: Wed, 21 Nov 2001 15:51:52 +0000


Aleksander Lodwich mailed that he was going to do a small 
documentation of media_server and libmedia.so interaction, which
will be quite useful during development.

Jens Winkler will convert the multiaudio API description from Gobe 
Productive format into some more common like PDF or HTML.

Anthony Quinn is willing to help, but currently busy, he will join in next
year.

To get something useful done fast, we will first recreate 
BSoundPlayer, BMediaFile & BMediaTrack
(these classes are most commonly used by applications)

to enable basic sound playback.

For this to work, we need to write a basic mixer,
contained in the media_server, which will be accessed
by the BSoundPlayer objects.
The mixer then outputs sound to the sound card
device driver. Some basic volume control would also
be nice. But we can't recreate the Media Preferences
application yet.

We should be able to do this first step in a few weeks. Than we have sound 
support
for OpenBeOS, using the original BeOS drivers.

Once we have done this, we can start spending month on recreating
the *real* MediaKit.

To replace BMediaTrack & BMediaFile, we can use

http://www.zip.com.au/~erikd/libsndfile/

it is LGPL, (as BeOS libroot.so), and supports
reading of multiple sound formats.

I'm in contact with the author, and already wrote an example 
player app that uses libsndfile to read files, and BSoundPlayer
to play them. Don't dowload the current version from his website, 
it's broken and will be replaced really soon.

for mp3 support, we can use AMP 0.7.6 or mpg123,
both are free software (no GPL)

Talking to device drivers is also simple,
a small API overview is here:
http://beos.overhagen.de/sounddriver_API.txt

example source code & test programs are here:
http://beos.overhagen.de/drivertest_R3.zip
http://beos.overhagen.de/drivertest_R4.zip

you need to kill the media servers before you
can use them.
kill -9 media_server
kill -9 media_addon_server

I already did a binary compatible libmedia.so, and also
did some initial experiements for talking from libmedia.so to a server
app using BMessages. 
(see files media_server.cpp & MediaRoster.cpp)

you can find it here
http://beos.overhagen.de/source.zip
and you may require these headers
http://beos.overhagen.de/OldMediaKit.zip

Please make yourself familiar with the source and
read the documentaion.

The first thing we will need to do is implement BSoundPlayer.
Who want's to do it?
Who want's to start BMediaFile / BMediaTrack ?

remember, the first implementation does not need
to support all the add-on interfaces for
Extractor / Decoder / Encoder / Writer.
Some simple wrapper for libsndfile & mp3 playback
will do.

I will set up a mailing list for us tomorrow.

regards
Marcus

[openbeosmediakit] Summary (reposted to mailing list)

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