Switching a client from unicasting to multicasting by increasing the unicast stream rate to the client

• US 7,788,393 B2
• Filed: 02/23/2006
• Issued: 08/31/2010
• Est. Priority Date: 02/23/2005
• Status: Active Grant

• Current Assignee: Synamedia Limited
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Sherer, W. Paul, Pickens, John, Palfreyman, Andrew, Connery, Glenn, Blattman, Kirk
• Primary Examiner(s): Chan; Wing F
• Assistant Examiner(s): WOO, ANDREW M
• Application Number:
  US11/360,080
• Publication Number:
  US 20060200574A1
• Time in Patent Office: 1,650 Days
• Field of Search: 709/230, 709/231
• US Class Current: 709/231
• CPC Class Codes: H04L 12/185 with management of multicast group membership
• CPC Class Codes: H04L 12/1863 comprising mechanisms for improved reliability, e.g. status reports arrangements for detecting or preventing errors by carrying supervisory signal the return channel H04L1/16
• CPC Class Codes: 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
• CPC Class Codes: H04L 65/612 for unicast
• CPC Class Codes: H04L 65/613 for the control of the source by the destination control signals issued by the client directed to the server or network components specially adapted for selective content distribution H04N21/637
• CPC Class Codes: H04L 65/752 adapting media to network capabilities
• CPC Class Codes: H04L 65/80 Responding to QoS
• CPC Class Codes: H04N 21/23406 involving management of server-side video buffer
• CPC Class Codes: H04N 21/238 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 Class Codes: H04N 21/23805 Controlling the feeding rate to the network, e.g. by controlling the video pump
• CPC Class Codes: H04N 21/26616 for merging a unicast channel into a multicast channel, e.g. in a VOD application, when a client served by unicast channel catches up a multicast channel to save bandwidth data multicast over packet-switching network H04L12/18
• CPC Class Codes: H04N 21/2668 Creating a channel for a dedicated end-user group, e.g. insertion of targeted commercials based on end-user profiles information retrieval from the Internet by querying with filtering and personalisation G06F16/9535; arrangements for replacing or switching information during the broadcast H04H20/10; push services over packet-switching network H04L12/1859; adaptation of message content in packet-switching networks H04L51/063
• CPC Class Codes: H04N 21/4384 involving operations to reduce the access time, e.g. fast-tuning for reducing channel switching latency
• CPC Class Codes: H04N 21/44004 involving video buffer management, e.g. video decoder buffer or video display buffer
• CPC Class Codes: H04N 21/44016 involving splicing one content stream with another content stream, e.g. for substituting a video clip
• CPC Class Codes: H04N 21/6405 Multicasting data broadcast and multicast in packet switching networks H04L12/18
• CPC Class Codes: H04N 21/6408 Unicasting

Abstract

Switching a client from unicasting back to multicasting involves accumulating enough digital video content at the client to bridge the time it takes to transition from receiving the digital video content via unicasting to receiving the digital video content via multicasting. Digital video content is accumulated at the client by temporarily increasing the stream rate of the unicast stream above the playout rate. While the digital video content is being streamed at the increased rate, the amount of digital video content stored in the client'"'"'s stream buffer grows. The stream rate is held at the increased rate until the client accumulates enough frames in its buffer to be able to bridge the time it takes to transition from receiving the digital video content via unicasting to receiving the digital video content via multicasting.

Claims

1. A method for switching a client from displaying digital video content provided via unicasting to displaying digital video content provided via multicasting, the method comprising:

providing digital video content to a client via unicasting at a first rate;

increasing the rate at which the digital video content is provided to the client via unicasting to a second rate; and

after the digital video content has been provided to the client via unicasting at the second rate for a first time interval, switching to providing the digital video content to the client via multicasting instead of unicasting;

wherein the digital video content provided via unicasting and multicasting is related to the same channel; and

wherein the first time interval is a time interval that allows the client to buffer enough digital video content to switch to multicasting without skipping a frame of the digital video content for the channel.

2. The method of claim 1 wherein the first rate is equal to the playout rate of the client and the second rate is greater than the playout rate of the client.

3. The method of claim 1 further comprising servicing channel change requests in a digital video network that is capable of distributing digital video content to clients via multicasting and unicasting, the method comprising:

providing digital video content to the client via multicasting, the digital video content being related to a first channel;

detecting a channel change request related to the client, the channel change request requesting a change to a second channel;

providing digital video content related to the second channel to the client via unicasting in response to the channel change request; and

continuing to provide digital video content related to the second channel to the client via unicasting until a pre-established condition is met, wherein continuing to provide digital video content related to the second channel to the client via unicasting until a pre-established condition is met involves unicasting multiple frames of the digital video content related to the second channel to the client.

4. The method of claim 3 further comprising switching to providing digital video content related to the second channel to the client via multicasting after the pre-established condition is met.

5. A system for switching a client from displaying digital video content provided via unicasting to displaying digital video content provided via multicasting, the system comprising:

a multicast return controller configured to;

provide digital video content to a client via unicasting at a first rate;

increase the rate at which the digital video content is provided to the client via unicasting to a second rate; and

after the digital video content has been provided to the client via unicasting at the second rate for a first time interval, switch to providing the digital video content to the client via multicasting instead of unicasting;

wherein the digital video content provided via unicasting and multicasting is related to the same channel; and

wherein the first time interval is a time interval that allows the client to buffer enough digital video content to switch to multicasting without skipping a frame of the digital video content.

6. The system of claim 5 wherein the first rate is equal to the playout rate of the client and the second rate is greater than the playout rate of the client.

7. The system of claim 5 further comprising means for servicing channel change requests in a digital video network that is capable of distributing digital video content to clients via multicasting and unicasting, the means for servicing channel change requests being configured to:

provide digital video content to a client via multicasting, the digital video content being related to a first channel;

detect a channel change request related to the client, the channel change request requesting a change to a second channel;

provide digital video content related to the second channel to the client via unicasting in response to the channel change request; and

continue to provide digital video content related to the second channel to the client via unicasting until a pre-established condition is met, wherein continuing to provide digital video content related to the second channel to the client via unicasting until a pre-established condition is met involves unicasting multiple frames of the digital video content related to the second channel to the client.

8. The system of claim 7 further comprising means for switching to providing digital video content related to the second channel to the client via multicasting after the pre-established condition is met.

9. A method for switching a client from displaying digital video content provided via unicasting to displaying digital video content provided via multicasting, the method comprising:

receiving digital video content received via unicasting;

playing out the buffered digital video content;

increasing the rate at which the digital video content is received via unicasting to increase the amount of buffered digital video content; and

switching to receiving the digital video content via multicasting instead of unicasting after a first time interval of the increased rate;

wherein the digital video content provided via unicasting and multicasting is related to the same channel; and

wherein the first time interval is a time interval that allows the client to buffer enough digital video content to switch to multicasting without skipping a frame of the digital video content.

10. The method of claim 9 wherein the rate at which the digital video content is received is increased to a rate that is greater than the playout rate of the client.

11. The method of claim 9 further comprising servicing channel change requests in a digital video network that is capable of distributing digital video content to clients via multicasting and unicasting, the method comprising:

providing digital video content to a client via multicasting, the digital video content being related to a first channel;

detecting a channel change request related to the client, the channel change request requesting a change to a second channel;

providing digital video content related to the second channel to the client via unicasting in response to the channel change request; and

continuing to provide digital video content related to the second channel to the client via unicasting until a pre-established condition is met, wherein continuing to provide digital video content related to the second channel to the client via unicasting until a pre-established condition is met involves unicasting multiple frames of the digital video content related to the second channel to the client.

12. The method of claim 11 further comprising switching to providing digital video content related to the second channel to the client via multicasting after the pre-established condition is met.