URGENT: Units of rtp.timestamp and frame.time_relative

frame.time_relative is in units of seconds; it has a fractional part, so it can have a higher resolution than one second.

As for RTP, to quote RFC 3550, the specification for RTP, "The timestamp reflects the sampling instant of the first octet in the RTP data packet. The sampling instant MUST be derived from a clock that increments monotonically and linearly in time to allow synchronization and jitter calculations (see Section 6.4.1). The resolution of the clock MUST be sufficient for the desired synchronization accuracy and for measuring packet arrival jitter (one tick per video frame is typically not sufficient). The clock frequency is dependent on the format of data carried as payload and is specified statically in the profile or payload format specification that defines the format, or MAY be specified dynamically for payload formats defined through non-RTP means.", so the units of the rtp.timestamp field depends on the type of payload - and might not be the same for all payloads of a given type and not be determinable just by looking at the RTP traffic.