How does DirectShow manage default filters?

When I render a media file with DirectShow (allowing DirectShow to build the graph automatically) I see that DirectShow has a set of default filters it uses. I also observed that installing 3rd party filters may change some default filters (usually 3rd parties set their own filters as default). I was wonderi开发者_StackOverflow中文版ng how the default filters are managed (registry?) and how can I change them? How to cause a certain filter to be used by default?

Thanks, Aliza

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There is no such exactly thing as "default" filters in DirectShow. There is a merit system instead: each filter registration is provided with a merit for a filter. When fitler graph renders pins and streams, it starts with trying filters with higher merits.

See more at MSDN:

• Intelligent Connect
• Guidelines for Registering Filters