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>Chapter 20. More on factories</H1
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>
The small application we created in the previous chapter used the
concept of a factory to create the elements. In this chapter we will
show you how to use the factory concepts to create elements based
on what they do instead of what they are called.
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We will first explain the concepts involved before we move on
to the reworked helloworld example using autoplugging.
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If we take a look at how the elements were created in the previous
example we used a rather crude mechanism:
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> ...
/* now it's time to get the parser */
decoder = gst_element_factory_make ("mad", "decoder");
...
</PRE
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> While this mechanism is quite effective it also has some big problems:
The elements are created based on their name. Indeed, we create an
element, mad, by explicitly stating the mad element's name. Our little
program therefore always uses the mad decoder element to decode
the MP3 audio stream, even if there are three other MP3 decoders in the
system. We will see how we can use a more general way to create an
MP3 decoder element.
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> We have to introduce the concept of MIME types and capabilities
added to the source and sink pads.
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