JP4823232B2 - Network management channel change in digital networks - Google Patents

Description

(Cross-reference of related applications)
This application claims the benefit of US Provisional Application No. 60 / 633,475, filed Dec. 6, 2004.

  The present invention relates generally to digital networks, and more particularly to a method and apparatus that enables channel changes in digital networks.

  In digital subscriber line (DSL) multicast / broadcast video systems, Internet Protocol (IP) multicast can be used to transmit compressed video to a set top box (STB). Internet Group Management Protocol (IGMP) is a mechanism for selecting which channel to view by sending a join request for the desired channel to a Digital Subscriber Line Access Multiplexer (DSLAM). When the channel is no longer needed, a leave request may be sent to the DSLAM.

  In commercial video with DSL broadcast systems, it is desirable to allow end users to quickly change channels. MPEG-2 and JVT / H. In general video compression standards such as H.264 / MPEG AVC, intra coding and inter coding are used. To properly decode, the decoder starts decoding from an intra-coded (I) picture or an instantaneous decoder refresh (IDR) picture or I slice, followed by subsequent inter-coding (P And B) The compressed video sequence must be decoded in the form of picture decoding. A group of pictures (GOP) may include at least one I picture and at least one P and / or B picture. Usually, if the image quality is the same, an I picture needs to encode more bits than a P or B picture, and the amount is often 3 to 10 times higher.

  When a receiver first starts to receive a program on a particular channel after a channel change or after the receiver is first turned on, the receiver receives an I picture to begin proper decoding. This has to be delayed.

  In order to minimize channel change delays in digital video broadcast systems, I pictures are typically transmitted frequently, eg, every N pictures. For example, to allow a 1/2 second delay (of the system's video compressor), generally N = 15 for 30 fps content. Since a compressed I picture is much larger than a compressed P or B picture, this greatly exceeds the bit rate required if I pictures are not inserted so often and the bit rate is greatly increased.

  In the first prior art system, the channel change stream is encoded and transmitted along with the normal video stream. The channel change stream includes low quality I pictures that are transmitted at a higher frequency than I pictures in the normal video bitstream. When the user tunes to a new channel, playback can begin when the first I picture is received, whether it is in a normal video stream or a channel change stream.

  In the second prior art system, for each program, in addition to the normal encoded stream, a channel change stream having a relatively low bit rate and a low resolution is encoded. When the channel change request is received by the subscriber premises equipment (CPE), a participation request is made to both the channel change stream and the normal stream of the newly selected program, and both streams are transmitted via the DSL link. Thereafter, the CPE appropriately switches from the channel change stream to the normal stream.

  In the second prior art system solution described above, the CPE needs to send both the normal stream and the channel change stream over the DSL link when a channel change request is made, so the CPE The bandwidth will increase until a “leave” request is initiated above. For example, if a user zapping between HD channels, the bandwidth utilization of a low resolution (in some cases SD resolution) channel may increase.

  Accordingly, it would be desirable and highly advantageous to have a method and apparatus that allows channel changes in digital networks that overcome the above-mentioned drawbacks of the prior art.

  The present invention addresses these and other shortcomings and disadvantages of the prior art, and it is an object of the present invention to provide a method and apparatus that allows channel changes in digital networks.

  According to one aspect of the present invention, a circuit is provided that allows channel changes in a digital network. The circuit has an input for receiving a channel change stream and a normal stream. The circuit further includes a multiplexer, a memory device, and a picture element detector. The multiplexer is for transmitting a channel change stream to the CPE device in response to a channel change request from a subscriber premises equipment (CPE) device. The memory device is for storing a flag set in response to a channel change request from the CPE device. This flag is set to request detection of picture elements in the normal stream. The picture element detector is for detecting a picture element in the normal stream after transmitting the channel change stream. The multiplexer transmits the normal stream to the CPE device instead of the channel change stream when a picture element is detected in the normal stream.

  In accordance with another aspect of the invention, a method is provided for enabling channel change in a digital network in a circuit connected to the digital network and having an input for receiving a channel change stream and a normal stream. The method includes transmitting a channel change stream to a CPE device in response to a channel change request from a subscriber premises equipment (CPE) device. The method further includes setting a flag requesting detection of a picture element in the normal stream in response to a channel change request from the CPE device. The method further includes detecting a picture element in the normal stream after transmitting the channel change stream. The method further includes transmitting the normal stream to the CPE device instead of the channel change stream when a picture element is detected in the normal stream.

  These and other aspects, features, and advantages of the present invention will become apparent from the following detailed description of exemplary embodiments, taken in conjunction with the accompanying drawings.

  The invention can be better understood with reference to the exemplary drawings.

  The present invention relates to a method and apparatus for enabling channel changes in a digital network.

  The present invention is advantageous because it improves on the first and second prior art systems described hereinabove and overcomes the aforementioned drawbacks associated therewith. For example, the present invention reduces the bandwidth consumption of a subscriber premises equipment (CPE) initiated low delay channel change mechanism in a digital subscriber line (DSL) system. In accordance with the principles of the present invention, the request for channel change is made by the CPE. In response to this request, the digital subscriber line access multiplexer (DSLAM) (or some other device upstream) switches to the low resolution channel change stream and then switches to the full resolution stream at the appropriate time. .

  It should be understood that the terms “customer premises equipment (CPE)” and “set top box (STB)” are used herein as interchangeable terms. The term “memoryless picture element” refers to a current picture element that is determined by a previous picture element or a subsequent picture element. Further, the terms “I picture” and “memoryless picture element” may be interchanged herein, referring to either an I slice, an instantaneous decoder refresh (IDR) picture, or an I picture. It should be understood that this is used as a simple term.

  Further, although the present invention is described herein primarily in the context of a specific example of a digital network, namely a digital subscriber line (DSL) network, given the teachings of the present invention disclosed herein, Those skilled in the art will appreciate that the present invention can be readily applied to any digital switching network without departing from the scope of the present invention.

  This specification illustrates the principles of the present invention. Accordingly, those skilled in the art will recognize that although not explicitly described or illustrated herein, various configurations can be devised that fall within the spirit and scope of the invention to implement the principles of the invention. I will.

  The teachings of all examples and conditions described herein are intended to assist the reader in understanding the principles of the invention and the concepts that the inventor provides to help advance the art. It should be construed that the invention has been set forth for purpose and the invention is not limited to these specifically described examples and conditions.

  Moreover, all statements regarding principles, aspects and embodiments of the invention, and specific examples thereof, are intended to include both structural and functional equivalents thereof. In addition, these equivalents include not only presently known equivalents, but also equivalents that will be developed in the future, that is, any elements that will be developed in the future that perform the same function regardless of structure. Shall.

  Thus, for example, those skilled in the art will appreciate that the block diagrams presented herein represent conceptual diagrams of exemplary circuits that implement the principles of the invention. Similarly, any flowcharts, flowcharts, state transition diagrams, pseudocode, etc. may be substantially represented in computer-readable media and executed by a computer or processor (which may or may not be explicit). It should also be understood to represent various processes.

  The functions of the various elements shown in the figures can be realized using dedicated hardware and hardware capable of executing software in conjunction with appropriate software. When implemented by a processor, these functions can be implemented by a single dedicated processor, by a single shared processor, or by multiple individual processors that can share part of them. You can also. Furthermore, the explicit use of the terms “processor” or “controller” should not be construed to refer only to hardware capable of executing software, but digital signal processor (DSP) hardware. , Implicitly including, but not limited to, read only memory (ROM), random access memory (RAM) and non-volatile storage for storing software.

  Conventional and / or custom hardware may also be included. Similarly, any switches shown in the drawings are conceptual only. The function of the switch can be implemented by the operation of program logic, by dedicated logic, by interaction between program control and dedicated logic, or by manual operation. Judgment can be made to select a specific technology.

  In the claims of this specification, any element expressed as a means for executing a specific function includes, for example, (a) a combination of circuit elements that execute the function, (b) firmware, microcode, and the like. And any form of software, including any combination of a suitable circuit for executing the function and executing the function. The invention as defined in the claims is to combine the functions performed by the various means recited in the manner required by the claims. It is thus regarded that any means that can carry out these functions are equivalent to those shown herein.

  As noted above, the present invention is advantageous because it provides a method and apparatus that allows channel changes in digital networks, including but not limited to digital subscriber line (DSL) networks. The present invention improves prior art systems, such as the second prior art system described above, by minimizing bandwidth consumption in the local loop of a DSL network, for example, as compared to the prior art.

  In prior art systems, such as the second prior art system described above, both a normal stream and a channel change stream are sent over the DSL link (local loop) when a channel change request is made, This raises the problem of increased bandwidth until the CPE initiates a “leave” request on the channel change stream. The present invention is advantageous because it solves this problem.

  Referring to FIG. 1, an exemplary end-to-end architecture to which the present invention can be applied is indicated generally by the reference numeral 100. Architecture 100 includes a content provider 110, a regional broadband network 120, a digital subscriber line access multiplexer (DSLAM) 130, a local loop 140, and a set top box (STB) 150. Content provider 110 includes a video encoder 112 having first and second outputs in signal communication with first and second inputs of multiplexer 114, respectively. The output of the multiplexer 114 is the output of the content provider 110 and is connected to the regional broadband network 120 by signal communication. The regional broadband network 120 is further connected to the input of the DSLAM 130 by signal communication.

  The DSLAM 130 includes a demultiplexer 132 having a first output in signal communication with the input of the I picture detector 133 and a second output in signal communication with the input of the I picture detector 134. The output of I picture detector 133 is connected in signal communication to a first input of channel change selection logic 135 and to a first input of delay unit 136. The output of the I picture detector 134 is connected in signal communication to the second input of the channel change selection logic 135 and the input of the storage device 137. A first output of the channel change selection logic 135 is connected in signal communication to a second input of the delay device 136. A second output of the channel change selection logic 135 is connected in signal communication with a first input of the selector 138. The output of the delay device is connected in signal communication to the second input of the selector 138. The output of the storage device 137 is connected to the third input of the selector 138 by signal communication.

The first input of the DSLAM 130 is connected in signal communication to the input of the demultiplexer 132, the second input of the DSLAM 130 is connected in signal communication to the third input of the channel change selection logic 135 , and the output of the DSLAM 130 is The output of the selector 138 is connected by signal communication. The second input and output of the DSLAM 130 is connected in signal communication to the local loop 140. It should be understood that DSLAM 130 may also be referred to herein as a “channel change processing unit”.

  The STB 150 includes a user interface 152 and a video decoder 154. The output of the STB 150 is connected in signal communication with the local loop 140 and the user interface 152, and the input of the STB 150 is connected in signal communication with the local loop 140 and the video decoder 154.

  The I picture detectors 133 and 134 are for detecting an I picture in the normal stream. The delay device 136 is for providing a variable delay.

  Video encoder 112 generates both a normal stream and a channel change stream of coded pictures. The normal stream and the channel change stream are multiplexed by the multiplexer 114 and transmitted to the DSLAM 130 via the regional broadband network 120. In FIG. 1, only one program encoder is shown for easy understanding. In an actual system, multiple programs are supported, so a block in the figure is provided for each supported program. The user makes a channel change request through the user interface 152 in the STB 150 and instructs switching to a new program to be viewed. This request is forwarded to the DSLAM 130.

  In a preferred embodiment of the present invention, the channel change stream is stored in a local storage device of DSLAM 130 (eg, local storage device 137) (or a remote storage device that DSLAM 130 can quickly access). During normal viewing, a normal stream is transmitted to the video decoder 154 of the STB 150 via the local loop 140. When a channel change request is initiated by the user interface of the STB 150, the channel change request is sent to the DSLAM 130 via the local loop 140. When receiving the channel change request, the DSLAM 130 starts to transmit the channel change stream stored in the new program from the I picture therein to the STB 150. Thereafter, at some point, the DSLAM 130 switches to normal stream transmission to the STB 150.

  By transmitting the channel change stream in addition to the normal stream, the bandwidth requirements of the regional broadband network 120 are increased. This increase in bandwidth continues until STB 150 initiates a “leave” request on the channel change stream.

  In the present invention, DSLAM (or an upstream processing element that processes a channel change request, hereinafter referred to as “DSLAM” 130) recognizes a normal stream and channel change stream pair available at its input. Further, the DSLAM 130 detects when an I picture appears on an arbitrary input stream using, for example, the I picture detectors 133 and 134. When the STB 150 initiates a channel change request, the DSLAM 130 first automatically switches the channel change stream to the STB 150 in the next available I picture. The DSLAM 130 then flags the arrival of the next I picture on the normal stream. As described above in connection with the first and second prior art systems, to save bandwidth, the frequency of I pictures is high in the channel change stream and the frequency of I pictures is low in the normal stream. When the next I picture arrives in the normal stream, it switches to correspond to the contractor who made the first request.

  The present invention is more bandwidth efficient in the DSL link (local loop 140), but the DSLAM 130 (or upstream channel change processing element) keeps track of switching between the channel change function and the normal stream function. Please understand that there is a need.

  FIG. 2 is a diagram illustrating an overall method (reference number 200) for enabling channel change in a digital subscriber line access multiplexer (DSLAM) of a DSL system. At start block 210, control passes to decision block 220. In decision block 220, it is determined whether a channel change request for playing the current program has been received. If no channel change request has been received, control returns to decision block 220. Otherwise, if a channel change request is received, control passes to function block 222. In function block 222, the coded I picture of the channel change stream is transmitted and control passes to function block 224. In function block 224, a flag for checking the arrival of the subsequent I picture on the normal stream is set, and control is passed to decision block 226. At decision block 226, it is determined whether a subsequent I picture on the normal stream has arrived. If a subsequent I picture on the normal stream has not arrived, control returns to decision block 226. Otherwise, if a subsequent I picture on the normal stream arrives, control passes to function block 240.

  In function block 240, the normal stream (including the subsequent I picture) is sent to the individual / device that requested the channel change, and control passes to function block 245. In function block 245, the flag is reset and control passes to decision block 250. At decision block 250, it is determined whether a channel change request to exit the current program has been received. If no channel change request has been received, control returns to function block 240. Otherwise, if a channel change request is received, control passes to end block 260.

  These and other features and advantages of the present invention can be readily ascertained by one skilled in the art based on the teachings herein. It should be understood that the teachings of the present invention can be implemented in various forms such as hardware, software, firmware, special purpose processors, or combinations thereof.

  It is taught that the present invention is most preferably implemented as a combination of hardware and software. Further, the software is preferably implemented as an application program implemented in a program storage device. The application program can be uploaded and executed on a machine having any suitable architecture. The machine is implemented on a computer platform having hardware such as one or more central processing units (“CPU”), random access memory (“RAM”) and input / output (“I / O”) interfaces. It is preferred that The computer platform may also include an operating system and microinstruction code. The various processes and functions described herein may be part of the microinstruction code or part of the application program or any combination thereof that can be executed by the CPU. In addition, various other peripheral devices may be connected to the computer platform such as an additional data storage device and a printing device.

  Further, since some of the system components and methods shown in the accompanying drawings are preferably implemented in software, the actual connection between system components or between process functional blocks will vary depending on the method of implementing the present invention. Please understand that there is. Given the teachings herein, one of ordinary skill in the related art will be able to contemplate these and similar embodiments or configurations of the present invention.

  Although exemplary embodiments have been described herein with reference to the accompanying drawings, the present invention is not limited to these specific embodiments, and those skilled in the art will understand the spirit or scope of the present invention. It should be understood that various changes and modifications can be made without departing. All such changes and modifications are intended to be included within the scope of the present invention as set forth in the appended claims.

1 is a block diagram illustrating an end-to-end structure according to the principles of the present invention. 6 is a flow diagram illustrating a method for enabling channel changes in a digital subscriber line (DSL) system according to the principles of the present invention.

Claims (9)

A circuit in the digital network, having an input for receiving a channel change stream and a normal stream, enabling the channel change in the digital network,
A multiplexer for transmitting a channel change stream of the requested channel to the CPE device in response to a channel change request from a subscriber premises equipment (CPE) device;
Wherein a memory device for storing a flag erected in response to the channel change request from the CPE device, the flag, requests the detection of memoryless picture element in the normal stream of the requested channel The memory device set and stored in the memory device is reset when a memoryless picture element is detected in the normal stream ; and
In response to the flag stored in the memory device, and the picture element detector for detecting a memoryless picture element in said normal stream after transmitting the channel change stream,
Including
The multiplexer transmits when memoryless picture element is detected in the normal stream, the CPE device the normal stream in place of the channel change stream,
The channel change stream contains more memoryless picture elements than the normal stream,
circuit.   The circuit of claim 1, wherein the circuit is implemented in a digital subscriber line access modem (DSLAM).   The circuit of claim 1, wherein the digital network is a digital subscriber line (DSL) network. The circuit of claim 1, wherein the memoryless picture element includes any of an I slice, an I picture, and an instantaneous decoder refresh (IDR) picture. A method for enabling channel change in a digital network in a circuit connected to the digital network and having an input for receiving a channel change stream and a normal stream comprising:
Utilizing a channel change stream that includes more memoryless picture elements than a normal stream;
In response to a channel change request from a subscriber premises equipment (CPE) device, transmitting a channel change stream of the requested channel to the CPE device;
A step to make a response to said channel change request flag to request the detection of memoryless picture element in the normal stream of the requested channel from the CPE device,
Resetting the flag when a memoryless picture element is detected in the normal stream;
Detecting a memoryless picture element in said normal stream after transmitting the channel change stream,
Method comprising when memoryless picture element is detected in the normal stream, and transmitting to the CPE device the normal stream in place of the channel change stream, the. 6. The method of claim 5 , further comprising setting a flag requesting detection of a memoryless picture element in the normal stream in response to a channel change request from the CPE device. 6. The method of claim 5 , further comprising implementing the circuit in a digital subscriber line access modem (DSLAM). The method of claim 5 , further comprising connecting the circuit to a digital subscriber line (DSL) network. In response to the channel change request from the CPE device, a flag for requesting detection of the memoryless picture element including I slice, I-picture, and any instantaneous decoder refresh (IDR) picture, wherein Item 6. The method according to Item 5 .

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