input data to be parsed for frames.
a combination of input and output #GstBaseParseFrameFlags that convey additional context to subclass or allow subclass to tune subsequent #GstBaseParse actions.
media specific offset of input frame Note that a converter may have a different one on the frame's buffer.
output data.
subclass can set this to indicates the metadata overhead for the given frame, which is then used to enable more accurate bitrate computations. If this is -1, it is assumed that this frame should be skipped in bitrate calculation.