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Original commit message from CVS: * docs/pwg/advanced-scheduling.xml: * docs/pwg/advanced-tagging.xml: * docs/pwg/advanced-types.xml: * docs/pwg/building-boiler.xml: * docs/pwg/building-chainfn.xml: * docs/pwg/building-signals.xml: * docs/pwg/building-state.xml: * docs/pwg/building-testapp.xml: * docs/pwg/intro-basics.xml: * docs/pwg/other-manager.xml: * docs/pwg/other-source.xml: Typo fixes. * docs/pwg/other-manager.xml: Add some first content. No example code yet. * gst/elements/gstfilesink.c: (gst_filesink_handle_event): Remove double newlines.
54 lines
2.1 KiB
XML
54 lines
2.1 KiB
XML
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<!-- ############ chapter ############# -->
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<chapter id="chapter-other-manager" xreflabel="Writing a Manager">
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<title>Writing a Manager</title>
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<para>
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Managers are elements that add a function or unify the function of
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another (series of) element(s). Managers are generally a
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<classname>GstBin</classname> with one or more ghostpads. Inside them
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is/are the actual element(s) that matters. There is several cases where
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this is useful. For example:
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</para>
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<itemizedlist>
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<listitem>
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<para>
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To add support for private events with custom event handling to
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another element.
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</para>
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</listitem>
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<listitem>
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<para>
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To add support for custom pad <function>_query ()</function>
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or <function>_convert ()</function> handling to another element.
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</para>
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</listitem>
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<listitem>
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<para>
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To add custom data handling before or after another element's data
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handler function (generally its <function>_chain ()</function>
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function).
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</para>
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</listitem>
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</itemizedlist>
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<para>
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This chapter will explain the setup of managers. As a specific example,
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we will try to add EOS event support to source elements. This can be
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used to finish capturing an audio stream to a file. Source elements
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normally don't do any EOS handling at all, so a manager is perfect to
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extend those element's functionalities.
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</para>
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<para>
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Specifically, this element will contain two child elements: the actual
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source element and a <quote>helper element</quote> that implement an
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event handler on its source pad. This event handler will respond to
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EOS events by storing them internally and returning the event (rather
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than data) on the next call to the <function>_get ()</function>
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function. After that, it will go into EOS and set the parent (and
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thereby the contained source element) to EOS as well. Other events will
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be forwarded to the source element, which will handle them as usual.
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</para>
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<programlisting>
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..
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</programlisting>
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</chapter>
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