Adaptive video slew rate for video delivery

Patent metadata

Field	Value
Publication number	US-11533526-B2
Application number	US-202217590365-A
Country	US
Kind code	B2
Filing date	Feb 1, 2022
Priority date	Feb 1, 2021
Publication date	Dec 20, 2022
Grant date	Dec 20, 2022

Abstract

Systems and methods for adaptively adjusting a slew rate of a dejitter buffer in a remote device in a distributed access architecture. The slew rate may be adjusted based on measurements of a fullness state of a buffer made over time. The measurements may be used to calculate a frequency offset value between the rate at which data leaves the buffer relative to the rate at which data enters the buffer and/or used to calculate a current working depth of the buffer. The adaptive slew rate adjustments may be based on the frequency offset value and/or the current working depth.

First claim

The invention claimed is:

1. A remote device that receives packetized video data from a video core through a packet-switched network, the device comprising:
a clock configured to operate in asynchronous mode;
a dejitter buffer that receives the video data from the packet-switched network and outputs the video data to at least one module that adjusts the video data before sending the video data in a downstream direction;
a processing device that applies a slew rate adjustment to the clock and the dejitter buffer, the slew rate adjustment varying over time based on a measured state of the dejitter buffer;
where the at least one module applies an offset value to a PCR value in the video data received from the packet switched network;
where the offset values are accumulated to produce an accumulated offset value, the accumulated offset value used to selectively add and/or selectively drop packets.

2. The remote device of claim 1 comprising an RPD.

3. The remote device of claim 1 comprising an RMD.

4. The remote device of claim 1 where the slew rate adjustment is based on a frequency offset determined by measuring a fullness state of the dejitter buffer over time.

5. The remote device of claim 4 where the slew rate adjustment is based on a measured current fullness state of the dejitter buffer.

6. The remote device of claim 1 where the magnitude of the accumulated offset value is reduced whenever a packet is selectively dropped and/or added.

7. The remote device of claim 1 where the slew rate adjustment eliminates a frequency offset by measuring a fullness state of the dejitter buffer repeatedly over time.

8. The remote device of claim 7 where the dejitter buffer is recentered after the frequency offset is eliminated.

9. A method for determining timing values to apply to packetized video data received asynchronously from a video core through a packet-switched network, the method comprising:
receiving the video data from the packet-switched network in a dejitter buffer according to a first time base and outputting the video data from the dejitter buffer according to a second time base and to at least one module that adds timing information to the video data before sending the video data in a downstream direction;
applying a slew rate adjustment to decrease a difference between the first time base and the second time base over an interval, the slew rate adjustment varying over time based on a measured state of the dejitter buffer;
where the at least one module applies an offset value to a PCR value in the video data received from the packet switched network;
where the offset values are accumulated to produce an accumulated offset value, the accumulated offset value used to selectively add and/or selectively drop packets.

10. The method of claim 9 implemented in an RPD.

11. The method of claim 9 implemented in an RMD.

12. The method of claim 9 where the slew rate adjustment is based on a frequency offset determined by measuring a fullness state of the dejitter buffer over time.

13. The method of claim 12 where the slew rate adjustment is based on a measured current fullness state of the dejitter buffer.

14. The method of claim 9 where the magnitude of the accumulated offset value is reduced whenever a packet is selectively dropped and/or added.

15. The method of claim 9 where the slew rate adjustment eliminates a frequency offset by measuring a fullness state of the dejitter buffer repeatedly over time.

16. The method of claim 15 including the step of reentering the dejitter buffer after the frequency offset is eliminated.

Assignees

• Arris Entpr Llc

Inventors

• Garvey Kevin
• Neugeboren Yair
• Looney Humphrey
• Dunning Stephen Graham
• Harrison Christopher T
• Tuffy Damien

Classifications

• H04N21/238 Primary

  Interfacing the downstream path of the transmission network, e.g. adapting the transmission rate of a video stream to network bandwidth; Processing of multiplex streams {(hybrid fiber coaxial [HFC] networks for downstream channel allocation for video distribution H04L12/2801; flow control in packet networks H04L47/10; real-time communication protocols in data switching networks H04L65/00; scheduling or organising the servicing of application requests H04L67/60)} · CPC title

• H04N21/23406

  involving management of server-side video buffer · CPC title

• H04N21/4302

  Content synchronisation processes, e.g. decoder synchronisation · CPC title

• H04N21/44004

  involving video buffer management, e.g. video decoder buffer or video display buffer · CPC title

• H04N21/4305

  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) · CPC title