# US 10,455,126 B2 · Precision timing for broadcast network

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- Number: US 10,455,126 B2
- Document ID: US10455126B2
- Status: Granted
- Kind: B2
- Application number: 15/796,461
- Filed: 2017-10-27
- Published: 2018-02-22
- Granted: 2019-10-22
- Earliest claimed: 2015-04-10
- Assignees: Gvbb Holdings S.A.R.L.
- Applicants: Gvbb Holdings S.A.R.L.
- Inventors: Charles S. Meyer
- Web page: https://patentgrep.com/patent/US10455126B2

## CPC

- H04N 5/04: Synchronising (for television systems using pulse code modulation H04N7/56)
- H04J 3/0667: {Bidirectional timestamps, e.g. NTP or PTP for compensation of clock drift and for compensation of propagation delays (arrangements for monitoring round trip delays in packet switching networks H04L43/0864)}
- H04N 21/242: Synchronisation processes, e.g. processing of PCR [Programme Clock References] {(arrangements for synchronising broadcast or distribution via plural systems in broadcast distribution systems H04H20/18)}
- H04L 7/033: using the transitions of the received signal to control the phase of the synchronising-signal-generating means, e.g. using a phase-locked loop
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04J: MULTIPLEX COMMUNICATION (transmission in general H04B; peculiar to transmission of digital information H04L5/00; systems for the simultaneous or sequential transmission of more than one television signal H04N7/08; in exchanges H04Q11/00; stereophonic systems H04S)
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)

## Abstract

The present aspects relate to techniques of timing synchronization of audio and video (AV) data in a network. In particular, the techniques for a AV master to distribute AV data encoded with one or more time markers to a plurality of processing nodes. The one or more time markers may be indexed to a precision time protocol (PTP) time stamp used as a time reference. In one technique, the nodes extract the time markers to determine an offset value that is applied to a PLL to synchronize AV data packets at a distribution node or a processing node. In another technique the distribution node or the processing node determines the worst case path, which corresponds to a system offset value. The distribution node then reports the system offset value to the AV master, which in turn adjusts the phase based on the report.

## Claims

### Claim 1

A system for synchronizing transmission of audio/video (AV) data in a media distribution network, the system comprising:
a memory; and
processor configured to implement instructions stored on the memory so as to provide:
a media transmission controller configured to control transmission of a plurality of data streams having packetized AV data across a plurality of network paths to a plurality of receiving nodes with the packetized AV data comprising one or more timestamps;
a network delay determiner configured to determine a network delay of each of the plurality of network paths based on a delay calculation generated by each of the plurality of receiving nodes based on the one or more timestamps and having received at least one of the plurality of data streams transmitted across the plurality of network paths;
a network delay calculator configured to calculate a system offset value for the media distribution network by comparing the determined network delay of each of the plurality of network paths to determine the system offset value based on a worst network path of the plurality of network paths that experiences a longest network delay for receiving the respective data stream; and
a media stream synchronizer configured to synchronize the plurality of data streams processed by one receiving node of the plurality of receiving nodes by generating a buffer allocation control based on the system offset value and transmitting the buffer allocation control to the one receiving node from the plurality of data streams, such that the one receiving node allocates a sufficient amount of memory space in at least one media buffer based on the buffer allocation control, with the allocated memory space being configured to accommodate delayed packetized AV data in the plurality of data streams to prevent overflow during synchronized media playout of the packetized AV data based on the one or more timestamps.

### Claim 2 (depends on 1)

The system according to claim 1, further comprising a data encoder configured to encode the packetized AV data of the plurality of data streams to each have the one or more timestamps.

### Claim 3 (depends on 2)

The system according to claim 2, wherein the one or more timestamps are indexed to a precision time protocol (PTP) used as a time reference for the media distribution network.

### Claim 4 (depends on 3)

The system according to claim 3, wherein the network delay determiner determines the network delay of each of the plurality of network paths based on the PTP indexed to the one or more timestamps in the packetized AV data of the plurality of data streams.

### Claim 5 (depends on 2)

The system according to claim 2, further comprising:
a phase lock loop at each of the plurality of receiving nodes configured to lock a phase of the packetized AV data of the data streams received at the respective receiving node to align the received data streams based on the respective one or more timestamps of the packetized AV data; and
a frequency determiner configured to determine one or more frequencies of the packetized AV data of the data streams received at the respective receiving node.

### Claim 6 (depends on 5)

The system according to claim 5, wherein the network delay determiner is further configured to calculate the delay calculation based on the locked phase and determined one or more frequencies of the packetized AV data.

### Claim 7

A system for synchronizing audio/video (AV) data in a media distribution network, the system comprising:
a memory; and
a processor configured to implement instructions stored on the memory so as to provide:
a media transmission controller configured to control transmission of a plurality of data streams having packetized AV data across a plurality of network paths to at least one receiving node with the packetized AV data comprising one or more timestamps;
a network delay determiner configured to determine a network delay of at least one of the plurality of network paths based on a delay calculation generated by the at least one receiving node based on the one or more timestamps for the respective data stream transmitted across the at least one network path; and
a media stream synchronizer configured to synchronize the plurality of data streams processed by the at least one receiving node by generating a buffer allocation control based on the determined network delay and transmitting the buffer allocation control to the at least one receiving node from the plurality of data streams, such that the at one receiving node reserves sufficient space in at least one media buffer based on the buffer allocation control to prevent overflow during synchronized media playout of the packetized AV data based on the one or more timestamps.

### Claim 8 (depends on 7)

The system according to claim 7, further comprising a network delay calculator configured to calculate the system offset value for the media distribution network by comparing the determined network delay of each of the plurality of network paths to determine the system offset value based on a worst network path of the plurality of network paths that experiences a longest network delay for receiving the respective data stream.

### Claim 9 (depends on 8)

The system according to claim 8, wherein the media stream synchronizer synchronizes the plurality of data streams processed by the at least one receiving node by reserving the space of the at least one media buffer at the at least one receiving node based on the calculated system offset value to accommodate delayed packetized AV data in the plurality of data streams.

### Claim 10 (depends on 7)

The system according to claim 7, further comprising a data encoder configured to encode the packetized AV data of the plurality of data streams to each have the one or more timestamps.

### Claim 11 (depends on 10)

The system according to claim 10,
wherein the one or more timestamps are indexed to a precision time protocol (PTP) used as a time reference for the media distribution network; and
wherein the network delay determiner determines the network delay of each of the plurality of network paths based on the PTP indexed to the one or more timestamps in the packetized AV data of the plurality of data streams.

### Claim 12 (depends on 10)

The system according to claim 10, further comprising:
a phase lock loop at each of the plurality of receiving nodes configured to lock a phase of the packetized AV data of the data streams received at the respective receiving node to align the data streams based on the respective one or more timestamps of the packetized AV data; and
a frequency determiner configured to determine one or more frequencies of the packetized AV data of the data streams received at the respective receiving node.

### Claim 13 (depends on 12)

The system according to claim 12, wherein the network delay determiner is further configured to calculate the delay calculation based on the locked phase and determined one or more frequencies of the packetized AV data.

### Claim 14

A media distribution system for synchronizing audio/video (AV) data for media playout, the system comprising:
a data encoder configured to encode AV data of a plurality of data streams to each have timestamps indexed to a precision time protocol (PTP) configured as a time reference for a media distribution network;
a memory; and
a processor configured to implement instructions stored on the memory so as to provide:
a media transmission controller configured to control transmission of the plurality of data streams having the AV data across a plurality of network paths in the media distribution network to at least one receiving node;
a network delay determiner configured to determine a network delay of the plurality of data streams with the AV data transmitted across the plurality of network paths in the media distribution network to the at least one receiving node;
a network delay calculator configured to calculate a system offset value for the media distribution network by comparing the determined network delay of each of the plurality of network paths to determine the system offset value based on a worst network path of the plurality of network paths that experiences a longest network delay for receiving the respective data stream;
a media stream synchronizer configured to prevent overflow during media playout of the AV data by generating a system offset value calculated from the determined network delay and transmitting the system offset value to the at least one receiving node from the plurality of data streams, such that the at least one receiving node sets sufficient space in at least one media buffer based on the generated and transmitted system offset value to delay synchronizing the plurality of data streams processed by the at least one receiving node; and
wherein the network delay determiner is configured to determine the network delay of each of the plurality of network paths based on the PTP indexed to the timestamps in the AV data of the plurality of data streams.

### Claim 15 (depends on 14)

The media distribution system according to claim 14, wherein the media stream synchronizer synchronizes the plurality of data streams processed by the at least one receiving node by reserving sufficient space in the at least one media buffer at the at least one receiving node based on the calculated system offset value to accommodate delayed AV data in the plurality of data streams to prevent overflow during media playout of the AV data.

### Claim 16 (depends on 14)

The media distribution system according to claim 14, further comprising:
a phase lock loop at each of the plurality of receiving nodes configured to lock a phase of the AV data of the data streams received at the respective receiving node to align the data streams based on the respective one or more timestamps of the AV data; and
a frequency determiner configured to determine one or more frequencies of the AV data of the data streams received at the respective receiving node.

### Claim 17 (depends on 16)

The media distribution system according to claim 16, wherein the network delay determiner is further configured to calculate the delay calculation based on the locked phase and determined one or more frequencies of the AV data.