Introduction to the Media Kit

Matt Wronkiewicz

Be Users Group at UIUC

Introduction This presentation gives an

overview of the structure and use of the new Media Kit, part of BeOS R4.

What is the BeOS?

Multimedia OS Can run with Windows or MacOS

on the same computer Designed for video and audio

professionals Newer and more efficient than

other operating systems Easy to program

Topics of Discussion

Uses Structure Classes Communicating with the Media Kit A simple application

Uses Allows you to write video and audio

players and editors. Reads audio from files and sound

cards Reads video from files (QuickTime,

MPEG, AVI) Simplifies development of applications. Example: The Media Kit can be used to

write a DVD disk player.

Structure Media Kit provides translators and

the foundation for writing players and editors

Translator add-ons read media files such as MPEG movies from disk

Allows you to create your own translators and filters

Applications can use translators and filters to play video and sound

Architecture

Kernel Level Drivers

ApplicationMedia Server Media Kit

Library

Add-OnsMedia

Add-Ons

Classes Media Nodes: (Can mix these)

Media Producer (BBufferProducer) Media Consumer

(BBufferConsumer) Time Source (BTimeSource) Media File (BFileInterface)

Media Roster (BMediaRoster)

Media Producer

Sends audio or video data to other objects

Represents a file or piece of hardware like a sound card

Connects to Media Consumers Example: Sound generator

Media Consumer

Receives A/V data from Media Producers

Can be paired with a Media Consumer to create a filter

Example: Audio mixer Example: Video player

Time Source

Can be used to synchronize audio and video

Default time source is the computer’s clock

Example: Satellite transmission

Media File

Accesses data files to provide media

Writes sound and movie files

Media Roster

Keeps track of media translators and filters

Supplies media nodes for requested format

Supplies default audio and video sources and the audio mixer

Communicating with the Media Kit Subclass media node classes to

create new nodes Link Producers with Consumers

(BBufferProducer::Connect) Ask the Media Roster to provide

system and third-party nodes Put a media node in a user-

installable add-on (BMediaAddOn)

Using the Nodes Together

Sound File

(BBufferProducer, BFileInterface)

High Frequency Filter

(BBufferConsumer, BBufferProducer)

Audio Mixer

(BBufferConsumer)

Sample Audio Player

void playsound(entry_ref* file) {BSound sound(&file);BSoundPlayer player;player.Start();player.SetVolume(1.0);BSoundPlayer::play_id id;id = player.StartPlaying(sound);player.WaitForSound(id);

}

Summary Media Kit makes it easier to write

multimedia applications Pluggable architecture allows

programs to work together Pre-made add-ons reduce

development time