- A. get a sense the evolution of a media across a processing unit by comparing the input and the output
- B. compare the output of 2 pipelines taking the same stream as input
- C. validate the network redundancy (ST 2022-7)
- D. measure the audio-video synchronicity for eventual re-alignment (ancillary is a todo)
Those 2 usecases are actually similar, only the interpretation of the result differs.
The idea consists in probing and comparing 2 streams reflecting the same content but at 2 different logical points of the network, i.e. multicast groups.
This type of inter-stream analysis aims at measuring the propagation delay through the network path and determine the transparency of a processing chain.
Regarless of the media type, the algorithm takes as input 2 extracted paloads: the reference, which is most likely the earliest and the main (terminology inspired by ffmpeg).
Since RTP timestamp can be overwritten by any processing equipment, it doesn't provide a reliable measurement reference and media-content-based analysis is preferred.