The Time Media framework provides the common architecture shared by the media-specific frameworks. The Audio, Video, and MIDI frameworks build directly on this base. The Telephony framework leverages the audio input and output capabilities provided by the Audio framework.
The Time Media User Interface framework integrates the time-media support and the Presentation framework, providing a consistent control interface for displaying time media in the Workspace.
After reading this chapter, you should understand the underlying architecture of the time-media system and:
Media components represent real-world objects such as audio mixers, speakers, and filters.
Media players are special types of media components that represent playing and recording devices such as tape recorders and VCRs. Players are used to play, record, and synchronize media data.
Media sequences are played by media players, much the way a video cassette is played by a VCR. These data files are streams of media data that contain clips of audio, video, or MIDI data.
Media ports represent the physical input and output ports for media players and other media components. Ports are used to connect media components and transfer data between the components.
These abstractions resemble the use of audio and video in the real world. Media sequences are loaded into players that support functions such as play, record, stop, and seek. Media components representing such things as speakers, mixers, and filters are connected through their ports, much the way you connect instruments, amps, and speakers with patch cords.
| Performance considerations for time media | ||
| The performance goals for time media depend on both the type of media and the audience to which it is presented. For example, professional media applications require a guaranteed minimum bandwidth for all media stream. Even partial reductions in the data rate or dynamic range are not acceptable. | For some casual users of audio and video, however, a partial reduction in data rate or dynamic range is acceptable as long as the information is not perceptibly changed. There are even some applications where a reduction in both the data rate and dynamic range is tolerable, even if it noticeably changes the information. |
Since performance requirements vary according to media and audience, the time-media system does not specify how media streams degrade-- it is specified in individual player classes.
Players track time with the timing services and must determine how to resolve timing problems.
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