There is an existing PMT mapping between PCR_%s and an mpegtsmux sink
pad name, where %s equals the program number that the PCR corresponds
to. We re-purpose this functionality to also support a mapping between
PCR_%s and an arbitrary PID. If this mapping is set, then the header PCR
PID is set to this value, and PCR is attached to the stream with this
PID.
Note: the current implementation also attaches PCR to the video stream,
so this may be inefficient.
Co-authored-by: Jordan Yelloz <jordan.yelloz@collabora.com>
Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/5726>