The idea consists in comparing 2 streams captured simultaneously (usually from the the pcap) by detecting content mismatch or measuring the delay, depending the use case.
| A) Quantify the delay and the possible differences between 2 streams of same essence. | B) Compare 2 media streams derived from the same initial stream. |
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| B) Validate the network redundancy (ST 2022-7) | D) Measure the audio-video synchronicity for eventual re-alignment |
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The 2 streams reflects 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 compares 2 extracted payloads: the reference, which is most likely the earliest with 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 a media-content-based* analysis is preferred.
Audio-to-audio: cross-correlation
Ancillary is not supported yet.