# US 11,122,310 B2 · Video switching system

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 11,122,310 B2
- Document ID: US11122310B2
- Status: Granted
- Kind: B2
- Application number: 16/645,890
- Filed: 2017-09-14
- Published: 2020-09-03
- Granted: 2021-09-14
- Earliest claimed: 2017-09-14
- Assignees: Media Links Co., Ltd.
- Applicants: Media Links Co., Ltd.
- Inventors: Kazunori Nakamura; Kazuki Narita
- Web page: https://patentgrep.com/patent/US11122310B2

## CPC

- 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 1/08: by repeating transmission, e.g. Verdan system {(H04L1/1858 and H04L1/189 take precedence)}
- H04L 1/22: using redundant apparatus to increase reliability
- H04L 43/106: using time related information in packets, e.g. by adding timestamps
- H04L 65/611: for multicast or broadcast (systems for broadcast or conference H04L12/18; arrangements for broadcast or distribution combined with broadcast H04H20/00; arrangements for broadcast applications with a direct linkage to broadcast information or to broadcast space-time H04H60/00; selective distribution of broadcast services, e.g. multimedia broadcast multicast service [MBMS], H04W4/06)
- H04L 65/65: Network streaming protocols, e.g. real-time transport protocol [RTP] or real-time control protocol [RTCP]
- H04L 65/80: Responding to QoS
- H04L 69/40: for recovering from a failure of a protocol instance or entity, e.g. service redundancy protocols, protocol state redundancy or protocol service redirection (management of faults, events, alarms or notifications in data switching networks H04L41/06)
- H04N 5/268: Signal distribution or switching
- H04N 21/4305: {Synchronising client clock from received content stream, e.g. locking decoder clock with encoder clock, extraction of the PCR packets (arrangements for synchronising receiver with transmitter by comparing receiver clock with transmitter clock H04L7/0012; arrangements for synchronising receiver with transmitter wherein the receiver takes measures against momentary loss of synchronisation H04L7/0083)}
- H04N 21/6437: Real-time Transport Protocol [RTP]
- 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: PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)
- 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)

## Abstract

The video switching system includes a PTP grand master, a first and second transmitters configured to synchronize a time with the PTP grand master according to PTP, and a receiver connected to the first transmitter and the second transmitter over an IP-network. The first and second transmitter respectively receive video signals distributed from one video signal, divide the video signals into a plurality of IP-packets and set timestamps to the plurality of IP-packets, the timestamps based on the synchronized time according to PTP. The first transmitter sends the plurality of IP-packets set the timestamps as a first IP-packet stream via a first transmission path according to RTP. The second transmitter sends the plurality of IP-packets set the timestamps as a second IP-packet stream via a second transmission path according to RTP.

## Claims

### Claim 1

A video switching system comprising:
a first transmitter configured to synchronize a time with a Precision Time Protocol (PTP) grand master according to PTP;
a second transmitter configured to, independently from the synchronization by the first transmitter, synchronize a time with the PTP grand master according to PTP; and
a receiver connected to the first transmitter and the second transmitter over an IP-network,
wherein the first transmitter and the second transmitter respectively:
receive video signals distributed from one video signal;
divide the video signals into a plurality of IP-packets; and
set timestamps to the plurality of IP-packets, the timestamps based on the synchronized time according to PTP,
the first transmitter sends the plurality of IP-packets set with the timestamps as a first IP-packet stream via a first transmission path according to Real-time Transport Protocol (RTP), the second transmitter sends the plurality of IP-packets set with the timestamps as a second IP-packet stream via a second transmission path according to RTP,
the receiver is further configured to:
compare the timestamps set in the IP-packets between the first IP-packet stream and the second IP-packet stream to calculate a difference between the timestamps;
identify a pair of IP-packets including same payloads in the first IP-packet stream and the second IP-packet stream in response to determining that the difference is within a predetermined range;
if receiving the pair of IP-packets, select one of the pair of IP-packets to reconstruct video signals; and
if receiving one IP-packet of the pair of IP-packets only, use the one IP-packet to reconstruct the video signals.

### Claim 2 (depends on 1)

The video switching system according to claim 1, wherein the receiver is further configured to:
determine whether both the pair of IP-packets indicate a video from boundary by comparing fields indicating the video frame boundary in the respective IP-packets of the pair of IP-packets; and
identify the pair of IP-packets further in response to determining that both the pair of IP-packets indicate a video frame boundary.

### Claim 3 (depends on 1)

The video switching system according to claim 1, the synchronized time according to PTP is a RTP timestamp, and
the first transmitter and the second transmitter convert time information according to PTP into the RTP timestamp.

### Claim 4 (depends on 1)

The video switching system according to claim 1,
wherein the receiver is further configured to:
if receiving the pair of IP-packets, select one of the pair of IP-packets to construct a third IP-packet stream; and
if receiving one IP-packet of the pair of IP-packets only, use the one IP-packet to construct the third IP-packet stream.

### Claim 5 (depends on 4)

The video switching system according to claim 4, wherein the receiver configured to change at least one of MAC headers, IP headers and UDP headers and sets new numbered RTP sequence number in the third IP-packet stream.

### Claim 6

A video switching system comprising:
a first transmitter configured to:
receive video signals distributed from one video signal;
divide the video signals into a plurality of IP-packets;
set the Real-time Transport Protocol (RTP) sequence numbers to the plurality of IP-packets; and
send the plurality of IP-packets as a first IP-packet stream via a first transmission path;
a second transmitter configured to:
receive the distributed video signals;
divide the video signals into a plurality of IP-packets;
set the RTP sequence numbers to the plurality of IP-packets independently from the RTP sequence numbers set by the first transmitter; and
send the plurality of IP-packets as a second IP-packet stream via a second transmission path according to RTP;
a receiver connected to the first transmitter and the second transmitter over an IP network, the receiver configured to:
determine a first IP-packet indicating a video frame boundary in the first IP-packet stream;
determine a second IP-packet indicating a video frame boundary in the second IP-packet stream;
calculate a first delta value by subtracting a sequence number in the first IP-packet from a sequence number in any IP-packet in the first IP-packet stream;
calculate a second delta value by subtracting a sequence number in the second IP-packet from a sequence number in any IP-packet in the second IP-packet stream;
identify a pair of IP-packets including same payloads in the first IP-packet stream and the second IP-packet stream in response to that the first delta value and the second delta value match;
if receiving the pair of IP-packets, select one of the pair of IP-packets to reconstruct video signals; and
if receiving one IP-packet of the pair of IP-packets only, use the one IP-packet to reconstruct the video signals.

### Claim 7 (depends on 6)

The video switching system according to claim 6,
wherein the receiver is further configured to:
if receiving the pair of IP-packets, select one of the pair of IP-packets to construct a third IP-packet stream; and
if receiving one IP-packet of the pair of IP-packets only, use the one IP-packet to construct the third IP-packet stream.