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Understanding the PTP Media Profiles

The PTP media profiles comprise three profiles: SMPTE ST-2059-2, AES67, and AES67+SMPTE ST-2059-2. These profiles support video and audio applications for capture (for example, cameras) to be used in professional broadcast environments. These profiles supports PTP over IPv4 multicast and ordinary and boundary clocks.

Benefits of the PTP Media Profiles

  • The PTP media profiles enable multiple video and audio sources to stay in synchronization across multiple devices.

Functionality Common to the SMPTE ST-2059-2, AES67, and the AES67+SMPTE ST-2059-2 Profiles

These profiles include the following functionality:

Note:

These profiles do not use an alternate primary clock, path trace, unicast message negotiation, alternate time scales, or acceptable primary table.

  • Support for both ordinary clocks and boundary clocks as part of the IEEE 1588 PTP specification.

  • Support for encapsulating PTP over IPv4/UDP.

    Multicast is required for both PTP over IPv4 and PTP over UDP.

  • Support for IEEE 1588 delay request and response method for the path delay measurement.

  • Support for the default IEEE 1588 BMCA algorithm.

  • Support for standard management packets.

  • Support for IGMPv2.

    IGMPv3 is optional.

Understanding the SMPTE Profile

The SMPTE profile is based on the SMPTE ST-2059-2 standard and was created specifically to synchronize video equipment in a professional broadcast environment. The standard allows multiple video sources to stay in synchronization across various equipment by providing time and frequency synchronization to all devices. This standard is used with other SMPTE standards such as SMPTE ST 2059-1, which defines a point in time (the SMPTE Epoch) used for aligning real-time signals, and formula for ongoing signal alignment. Alignment is considered met when two clocks are within 1 microsecond of each other. This implies that each client should be accurate with +/- .5 microseconds of the central clock.

Understanding the AES67 Profile

The AES67 profile is based on the AES67 standard and supports professional quality audio applications for high performance streaming over IPv4 multicast transport in media networks with low latencies. This profile enables audio streams to be combined at a receiver and maintain stream synchronization. The standard uses IPv4 multicast and IGMP, plus the DiffServ and DSCP fields, to select packet quality of service. Audio devices transmit their content using RTP (Real Time Protocol).

Understanding the AES67+SMPTE ST-2059-2 Profile

The AES67+SMPTE ST-2059-2 profile is based on both the AES67 and SMPTE ST-2059-2 standards and is used in professional audio and video media applications. This profile enables the two standards to operate together over the same network.