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622a80da54
Original commit message from CVS: Moved "Filter Writer's Guide" to "Plugin Writer's Guide". Divided existing info from old guide into several files, one per chapter. The guide still needs much work ...
89 lines
3 KiB
XML
89 lines
3 KiB
XML
<!-- ############ chapter ############# -->
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<chapter id="cha-building-types">
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<title>Types and Properties</title>
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<para>
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There is a very large set of possible types that may be used to pass data
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between elements. Indeed, each new element that is defined may use a new
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data format (though unless at least one other element recognises that
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format, it will be most likely be useless since nothing will be able to
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link with it).
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</para>
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<para>
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In order for types to be useful, and for systems like autopluggers to
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work, it is neccessary that all elements agree on the type definitions,
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and which properties are required for each type. The &GStreamer; framework
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itself simply provides the ability to define types and parameters, but
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does not fix the meaning of types and parameters, and does not enforce
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standards on the creation of new types. This is a matter for a policy to
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decide, not technical systems to enforce.
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</para>
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<para>
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For now, the policy is simple:
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<itemizedlist>
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<listitem>
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<para>
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Do not create a new type if you could use one which already exists.
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</para>
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</listitem>
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<listitem>
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<para>
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If creating a new type, discuss it first with the other &GStreamer;
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developers, on at least one of: IRC, mailing lists, the &GStreamer;
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wiki.
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</para>
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</listitem>
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<listitem>
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<para>
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Try to ensure that the name for a new format is as unlikely to
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conflict with anything else created already, and is not a more
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generalised name than it should be. For example: "audio/compressed"
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would be too generalised a name to represent audio data compressed
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with an mp3 codec. Instead "audio/mp3" might be an appropriate name,
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or "audio/compressed" could exist and have a property indicating the
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type of compression used.
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</para>
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</listitem>
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<listitem>
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<para>
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Ensure that, when you do create a new type, you specify it clearly,
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and get it added to the list of known types so that other developers
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can use the type correctly when writing their elements.
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</para>
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</listitem>
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</itemizedlist>
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</para>
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<!-- ############ sect1 ############# -->
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<sect1 id="sect1-types-test" xreflabel="Building a Simple Format for Testing">
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<title>Building a Simple Format for Testing</title>
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<para>
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</para>
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</sect1>
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<!-- ############ sect1 ############# -->
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<sect1 id="sect1-types-mime" xreflabel="A Simple Mime Type">
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<title>A Simple Mime Type</title>
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<para>
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</para>
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</sect1>
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<!-- ############ sect1 ############# -->
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<sect1 id="sect1-types-properties" xreflabel="Type Properties">
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<title>Type Properties</title>
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<para>
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</para>
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</sect1>
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<!-- ############ sect1 ############# -->
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<sect1 id="sect1-types-typefind" xreflabel="Typefind Functions and Autoplugging">
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<title>Typefind Functions and Autoplugging</title>
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<para>
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</para>
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</sect1>
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</chapter>
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