Difference between revisions of "Kinds of Reggae classes"
From MorphOS Library
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Every media format recognized by Reggae has its own demuxer. Demuxer class is responsible for format recognition, header decoding, metadata extraction and demultiplexing (hence the name) media streams to separate output ports. While there is no real demultiplexing in simple audio or image formats, splitting functionality between demuxer and decoder allows for code reusing, as multiple demuxers may use the same decoder class (for example all demuxers for audio formats using uncompressed PCM, use ''audiopcm.decoder''). | Every media format recognized by Reggae has its own demuxer. Demuxer class is responsible for format recognition, header decoding, metadata extraction and demultiplexing (hence the name) media streams to separate output ports. While there is no real demultiplexing in simple audio or image formats, splitting functionality between demuxer and decoder allows for code reusing, as multiple demuxers may use the same decoder class (for example all demuxers for audio formats using uncompressed PCM, use ''audiopcm.decoder''). | ||
| − | There are also a few "general" demuxers not associated with particular data format. They either handle some common metadata (like ''id3tag.demuxer''), or common compression schemes (''xpk.demuxer''). Such demuxers are usually the first stage of demuxer cascade. | + | There are also a few "general" demuxers not associated with particular data format. They either handle some common metadata (like ''id3tag.demuxer''), or common compression schemes at datastream level (''xpk.demuxer''). Such demuxers are usually the first stage of demuxer cascade. |
==Decoders== | ==Decoders== | ||
Revision as of 19:44, 16 August 2010
Grzegorz Kraszewski
Contents
Multimedia.class
This is the master class of Reggae. It estabilishes basic methods and attributes. It also performs Reggae initialization when opened the first time after boot. All other classes are subclasses of multimedia.class. This class is also responsible for data formats detection and automatic building of decoding tree. It also provides secondary functionality like event logging, metadata support, AltiVec friendly memory allocations and more. Because of all these features multimedia.class is the one and only Reggae class having shared library API except of BOOPSI (object) one.
Streams
Streams form input data abstraction layer of Reggae. A stream is always the first object in any Reggae processing structure. It has one output port. All streams have common set of attributes and methods for data fetching and control. Currently available streams are:
- memory.stream for accessing data in memory: buffered, generated or embedded in application code.
- file.stream for reading files via dos.library.
- http.stream is easy to use yet powerful implementation of HTTP/1.1 protocol client. It can fetch any network resource available via HTTP GET request.
While memory.stream and file.stream are relatively simple wrappers, http.stream is a component useful stadalone as well as a Reggae data source. Any application can just use it for easy data downloading via HTTP, without even touching sockets API and dealing with HTTP internals.
Demuxers
Every media format recognized by Reggae has its own demuxer. Demuxer class is responsible for format recognition, header decoding, metadata extraction and demultiplexing (hence the name) media streams to separate output ports. While there is no real demultiplexing in simple audio or image formats, splitting functionality between demuxer and decoder allows for code reusing, as multiple demuxers may use the same decoder class (for example all demuxers for audio formats using uncompressed PCM, use audiopcm.decoder).
There are also a few "general" demuxers not associated with particular data format. They either handle some common metadata (like id3tag.demuxer), or common compression schemes at datastream level (xpk.demuxer). Such demuxers are usually the first stage of demuxer cascade.