Sets the given getcaps function for the pad. getcaps should return the
allowable caps for a pad in the context of the element's state, its link to
other elements, and the devices or files it has opened. These caps must be a
subset of the pad template caps. In the NULL state with no links, getcaps
should ideally return the same caps as the pad template. In rare
circumstances, an object property can affect the caps returned by getcaps,
but this is discouraged.
You do not need to call this function if pad's allowed caps are always the
same as the pad template caps. This can only be true if the padtemplate
has fixed simple caps.
For most filters, the caps returned by getcaps is directly affected by the
allowed caps on other pads. For demuxers and decoders, the caps returned by
the srcpad's getcaps function is directly related to the stream data. Again,
getcaps should return the most specific caps it reasonably can, since this
helps with autoplugging.
Note that the return value from getcaps is owned by the caller, so the
caller should unref the caps after usage.
Sets the given getcaps function for the pad. getcaps should return the allowable caps for a pad in the context of the element's state, its link to other elements, and the devices or files it has opened. These caps must be a subset of the pad template caps. In the NULL state with no links, getcaps should ideally return the same caps as the pad template. In rare circumstances, an object property can affect the caps returned by getcaps, but this is discouraged. You do not need to call this function if pad's allowed caps are always the same as the pad template caps. This can only be true if the padtemplate has fixed simple caps. For most filters, the caps returned by getcaps is directly affected by the allowed caps on other pads. For demuxers and decoders, the caps returned by the srcpad's getcaps function is directly related to the stream data. Again, getcaps should return the most specific caps it reasonably can, since this helps with autoplugging. Note that the return value from getcaps is owned by the caller, so the caller should unref the caps after usage.