tag: add GstMeta for KLV metadata
Can be used to attach arbitrary metadata to buffers, such as timestamps, GPS data, etc.
See ITU Recommendation BT.1563-1 or SMPTE 336M for the KLV standard, and MISB EG 0902 (MISB Minimum Metadata Set) and other MISB standards and recommended practices for examples of KLV metadata local data sets for a variety of use cases. Also SMPTE ST380.
(I've also got patches to write this into and read this from Matroska files in the original bugzilla ticket, but those need more work and need a spec addition).