It was concluded that it would be more useful if a function that provided a data segment from
the original clip just provided a new Clip, i.e. useful things like PTS and meta is still
available in the segment. So, BytesForPTSInterval was renamed to TrimToPTSRange and now
provides a Clip. The test for this function was updated accordingly.
writing Clip.Bytes required a change to the Clip type. The Clip type now possess a slice that
references the memory in which the Frames should reference for the media. Appropriate changes have
been made to Extract and TestExtract to accomidate this change.
payload.go has been added which will contain functionality for dealing with MTS
payloads. A function has been added called Extract, which will return a Clip. Clip
is a type representing a sequence of media frames ([]Frame). Type Frame has been
added which represents a media frame. It provides fields to hold the media as
byte slice, PTS to hold the PES timestamp, an ID for identification of codec type
and finally the relevant Meta from the most recent PMT.