Ask the subclass to allocate a buffer. The subclass decides which size this buffer should be. The default implementation will create a new buffer from the negotiated allocator.
Ask the subclass to create a buffer. The subclass decides which size this buffer should be. Other then that, refer to #GstBaseSrc<!-- -->.create() for more details. If this method is not implemented, @alloc followed by @fill will be called.
Ask the subclass to fill the buffer with data.
Element parent class
Subclasses can override any of the available virtual methods or not, as needed. At the minimum, the @fill method should be overridden to produce buffers.