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compensating encoder drift using prft box #33

Closed tlohmar closed 6 years ago

tlohmar commented 7 years ago

With MPEG2-TS, the frequent retransmission of the PCR timestamp is compensating encoder drift. The prft box provides a timestamp, when a segment was produced according to the encoder clock understanding. However, when reading 5th Edit or ISO-BMFF, the precise usage and the semantics of the parameters is not clear to me. I would like to understand, to what packager event the ntp_timestamp is referring to, so, how client will utilize the information.

In the semantics definition of the ntp_timestamp attribute, the decoding_time is references, which is incorrect.

Generally, it would be good to provide guidance to player vendors to use the prft box information for encoder drift compensation.