KR101118265B1 - Method and Apparatus for providing the variable bit-rate service - Google Patents

Abstract

A device that provides a variable bit rate service in an AT-DMB (Advanced Terrestrial Digital Multimedia Broadcasting) transmission frame consisting of a base layer transport frame and an enhancement layer transport frame calculates an encoding bit rate according to the statistical multiplexing gain of a video service and simultaneously transmits an enhancement layer. A control unit for varying the size of the subchannels in the frame, and a video service is encoded based on the encoding bit rate to generate a base layer stream and an enhancement layer stream. The base layer stream is inserted into subchannels in the base layer transport frame, and the enhancement layer stream. Includes an encoder for inserting into a subchannel having a variable size in an enhancement layer transport frame.

DMB, SVC, Transport Frame, Layer Modulation

Description

Method and apparatus for providing variable bit rate service {Method and Apparatus for providing the variable bit-rate service}

The present invention relates to a method and apparatus for providing a variable bit rate service. In particular, the present invention relates to a method and apparatus for providing a variable bit rate service in Advanced Terrestrial Digital Multimedia Broadcasting (AT-DMB).

The present invention is derived from a study conducted as part of the Ministry of Knowledge Economy's information and communication standard development support project [Task Management Number: 2008-P1-07-07K70, Task name: DMB metadata standard development].

Terrestrial Digital Multimedia Broadcasting (hereinafter referred to as "T-DMB") is a mobile multimedia broadcasting system that adds video services to the European Eureka 147-based Digital Audio Broadcasting (DAB) system. T-DMB has a difficulty in varying the bit rate of an inserted AV (Audio Video) service due to a sub-channel fixedly allocated when setting a service configuration.

High-rate T-DMB transmission network, or AT-DMB (Advanced Terrestrial Digital Multimedia Broadcasting), is a broadcasting system that extends the capacity of transmission data up to twice by adding a new layer modulation method based on T-DMB. The AT-DMB uses the same frequency band as the existing T-DMB, and provides a larger number of available services than the T-DMB by increasing the transmission capacity up to twice.

In AT-DMB, a base layer transport frame and an enhancement layer transport frame are composed of one final transport frame through layer modulation. In addition, by utilizing scalable video compression technology, SD (Standard Definition) video service, which is four times higher than T-DMB quality, can be provided to existing T-DMB terminals in QVGA (Quarter Video Graphics Array) quality. In addition, new AT-DMB terminals may be provided with a video graphics array (VGA) quality.

When providing a plurality of channel video services through increased transmission capacity in AT-DMB, applying a variable bit rate will have a great advantage in terms of fixed bit rate, image quality distribution characteristics and bandwidth utilization. This is theoretically demonstrated in the statistical multiplexing technique.

Therefore, even in the case of AT-DMB which is capable of multiple channel services and employs scalable video compression technology, there is a need for an efficient method for applying a variable bit rate.

An object of the present invention is to provide a method and apparatus for providing a variable bit rate service which can improve video service quality distribution characteristics and bandwidth utilization rather than a fixed bit rate service.

Apparatus for providing a variable bit rate service to an AT-DMB (Advanced Terrestrial Digital Multimedia Broadcasting) transmission frame consisting of a base layer transport frame and an enhancement layer transport frame according to the characteristics of the present invention for achieving the above object

A base station stream and an enhancement layer stream are generated by calculating an encoding bit rate according to a statistical multiplexing gain of a video service, and simultaneously controlling a size of a subchannel in the enhancement layer transport frame, and encoding a video service based on the encoding bit rate. And inserting the base layer stream into a subchannel in the base layer transport frame, and inserting the enhancement layer stream into a subchannel having a variable size in the enhancement layer transport frame.

In addition, a method of providing a variable bit rate service to an AT-DMB transport frame consisting of a base layer transport frame and an enhancement layer transport frame according to another aspect of the present invention

Calculating an encoding bit rate according to the statistical multiplexing gain of the video service,

Varying a size of a subchannel corresponding to the enhancement layer transport frame, generating a base layer stream and an enhancement layer stream by encoding the video service based on the encoding bit rate, and converting the base layer stream into the base layer transport frame. And inserting the enhancement layer stream into a subchannel having a variable size in the enhancement layer transport frame.

According to an embodiment of the present invention, by providing a service of a variable bit rate to the additional transmission frame while being compatible with the existing T-DMB using AT-DMB, to provide a service of equal picture quality over all AV services can do.

In addition, according to an embodiment of the present invention, the method for providing a variable bit rate service is not only maintains the conventional service quality but also multiplexes at a variable bit rate when multiplexing the enhancement layer streams. We can get statistical multiplexing gain.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

Throughout the specification, when a part is said to "include" a certain component, it means that it can further include other components, without excluding other components unless specifically stated otherwise.

Hereinafter, a method and apparatus for providing a variable bit rate service according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a diagram schematically showing a T-DMB transmission frame in which an AV service is inserted in a general T-DMB.

Referring to FIG. 1, an AV encoder 10 encodes a video service, which is an AV video source, according to a T-DMB video transmission / reception matching standard (TTAS.KO-07.0026 / R1). Is generated, and the generated AV stream is inserted into the T-DMB transmission frame 100.

The T-DMB transport frame 100 includes a fast information channel (hereinafter referred to as "FIC") 110 and a main service channel (hereinafter referred to as "MSC") 120.

The FIC 110 is a channel for transmitting actual data on the MSC 120 through which channel in the MSC 120 is transmitted and information necessary for receiving a DMB signal.

The MSC 120 is a channel through which actual data such as video and audio are transmitted, and is composed of one or more sub-channels. Here, the one or more sub-channels include a DAB MSC (Digital Audio Broadcasting MSC) 121.

In detail, the plurality of AV encoders 10 encode AV sources (video service 1 and video service 2), respectively, to generate an AV stream, and the generated AV streams are subchannels (sub-ch1, sub) of the MSC 120. -ch2) respectively. At this time, the size (bit rate) of the MSC 120 is fixed in units of capacity (CU) capacity and is pre-assigned by the service provider, and the size information of the MSC 120 is transmitted to the user terminal through the FIC 110. (Not shown). That is, in the case of T-DMB, there is a problem in that the bit rate of the inserted AV service is variable due to the subchannel fixedly allocated when setting the service configuration.

Hereinafter, an apparatus for providing a variable bit rate service in AT-DMB according to an exemplary embodiment of the present invention will be described in detail with reference to FIG. 2.

2 is a diagram schematically illustrating an AT-DMB transport frame and an apparatus for providing a variable bit rate service applied to an AT-DMB transport frame according to an embodiment of the present invention.

Referring to FIG. 2, the AT-DMB transport frame 200 includes a base layer transport frame 210 and an enhancement layer transport frame 220 as a final transport frame through layer modulation. do. Here, the base layer transport frame 210 and the enhancement layer transport frame 220 is configured in the same manner as the T-DMB transport frame 100, respectively. On the other hand, subchannels of the base layer transport frame 210 are allocated at a fixed bit rate, and subchannels of the enhancement layer transport frame 220 are assigned at a variable bit rate.

The apparatus for providing a variable bit rate service includes a plurality of AV encoders 300 and a controller 400.

The plurality of AV encoders 300 receive a bit rate control signal from the control unit 400 and control bit rates according to encoding bit rates to encode the AV sources (video services 1, 2, 3, and 4), respectively, for the base layer stream and the enhancement layer. Create a stream. Also, the plurality of AV encoders 300 inserts the generated base layer stream and enhancement layer stream into subchannels of the base layer transport frame 210 and the enhancement layer transport frame 220, respectively. Here, the base layer stream is a transport stream compressed by multiplexing an AV source according to the T-DMB video transmission / reception matching standard (TTAS.KO-07.0026 / R1). The enhancement layer stream is a transport stream that is additionally compressed and multiplexed for high quality or high sound AV quality.

The plurality of AV encoders 300 according to the embodiment of the present invention are AV encoders to which a scalable encoding technique is applied. In this case, a scalable video coding (SVC) encoding technique uses a scalable method such as temporal, spatial and noise ratio (SNR) scalability.

A conventional T-DMB terminal or an AT-DMB terminal requiring basic service decodes only the base layer stream, and an AT-DMB terminal requiring high quality or high sound quality AV decodes the base layer stream and the enhancement layer stream simultaneously. .

In order to maintain backward compatibility, the base layer transport frame 210 according to an embodiment of the present invention is allocated at a fixed bit rate when configuring a subchannel. On the other hand, only the newly added enhancement layer transport frame 220 configures the subchannel size of the variable bit rate. In this way, the basic service provided through the base layer transport frame 210 maintains the conventional quality of service, while the enhancement layer transport frame 220 is multiplexed at a variable bit rate when multiplexed, thereby obtaining statistical multiplexing gains. . Here, the statistical multiplexing gain is a gain of the number of multiplexing services generated by varying and compressing the bit rate according to the statistical characteristics of the video reproduced for each of a plurality of AV sources, that is, the complexity of each scene.

The control unit 400 calculates the encoding bit rate according to the statistical multiplexing gain of the quality of all AV sources (video services 1, 2, 3, and 4) for a predetermined time, and controls the bit rate at the time of encoding according to the calculated encoding bit rate. To the plurality of AV encoders 300. At the same time, the control unit 400 transmits the subchannel size control signal to the subchannels sub-ch1, 2, 3 and 4 of the enhancement layer transmission frame 220, respectively, to vary the size of the subchannel.

The AV encoder 300 according to the embodiment of the present invention may maximize statistical multiplexing gain by using temporal scalability and SNR scalability characteristics. In the case of T-DMB, video compression is usually performed at 30 frames / sec for AV service. In this case, the effective data rate provided only by the base layer transport frame 210 is about 1.152 Mbps, and at the time of video compression at 30 frames / sec, two AV services are effective. On the other hand, when the temporal scalability method is used in the AV encoder 300, if the compressed stream of 15 frames / sec is transmitted for each service through the base layer stream and the remaining 15 frames / sec are transmitted through the enhancement layer stream at the same time, T The number of services can be up to twice that of DMB.

That is, an AT-DMB terminal that provides T-DMB or basic service will be able to provide a total of four services at a quality of 15 frame / sec, and an AT-DMB terminal that provides high quality service may have a quality of 30 frame / sec. Can provide. Here, the loss of the size (bit rate) of the MSC caused by the overhead of scalable coding and the overhead of the transport stream is compensated by the statistical multiplexing gain applied to the enhancement layer transport frame.

The apparatus for providing a variable bit rate service according to an exemplary embodiment of the present invention can provide up to twice as much service as the temporal picture quality is slightly reduced to 15 frames / sec for a T-DMB terminal user, and to an AT-DMB terminal user. It can provide up to twice the service with the same quality.

Next, a method of providing a variable bit rate service according to an exemplary embodiment of the present invention will be described in detail with reference to FIG. 3.

3 is a flowchart schematically illustrating a method of providing a variable bit rate service according to an exemplary embodiment of the present invention.

First, a method of providing a variable bit rate service according to an embodiment of the present invention is applied to an AT-DMB transmission frame 200. Here, the AT-DMB transport frame 200 is composed of a final transport frame through the layer modulation of the base layer transport frame 210 and the enhancement layer transport frame 220.

Referring to FIG. 3, the apparatus for providing a variable bit rate service varies and compresses the size (bit rate) of the MSC 120 according to a statistical characteristic of an image reproduced for each AV source for a predetermined time, that is, a complexity for each scene, and then multiplexes it. The encoding bit rate is calculated according to the gain of the number of multiplexing services generated by the operation (S301). In addition, a bit rate control signal for controlling a bit rate during encoding is generated according to the calculated encoding bit rate (S302).

The apparatus for providing a variable bit rate service while generating a bit rate control signal generates a subchannel size control signal capable of controlling the size of a subchannel of the enhancement layer transport frame 220 (S303) and uses the generated subchannel size control signal. The size of the subchannel of the enhancement layer transport frame 220 is varied (S304). In this case, the apparatus providing the variable bit rate service configures the subchannel size of the variable bit rate only in the enhancement layer transport frame 220. On the other hand, the apparatus for providing a variable bit rate service maintains backward compatibility by allocating a fixed bit rate when configuring a subchannel of the base layer transport frame 210.

The apparatus for providing a variable bit rate service encodes an AV source based on a bit rate control signal (S305) to generate a base layer stream and an enhancement layer stream (S306). Here, the base layer stream is a transport stream compressed by multiplexing an AV source according to the T-DMB video transmission / reception matching standard (TTAS.KO-07.0026 / R1). The enhancement layer stream is a transport stream that is additionally compressed and multiplexed for high quality or high sound AV quality.

The apparatus for providing a variable bit rate service inserts the generated base layer stream into a subchannel of the base layer transport frame 210, and inserts an enhancement layer stream into a subchannel of the enhancement layer transport frame 220 (S307).

The embodiments of the present invention described above are not implemented only through the apparatus and the method, but may be implemented through a program for realizing a function corresponding to the configuration of the embodiment of the present invention or a recording medium on which the program is recorded. Implementation may be easily implemented by those skilled in the art from the description of the above-described embodiments.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

1 is a diagram schematically showing a T-DMB transmission frame in which an AV service is inserted in a general T-DMB.

2 is a diagram schematically illustrating an AT-DMB transport frame and an apparatus for providing a variable bit rate service applied to an AT-DMB transport frame according to an embodiment of the present invention.

3 is a flowchart schematically illustrating a method of providing a variable bit rate service according to an exemplary embodiment of the present invention.

Claims (8)

An apparatus for providing a variable bit rate service in an advanced terrestrial digital multimedia broadcasting (AT-DMB) transmission frame including a base layer transport frame and an enhancement layer transport frame, A controller for calculating an encoding bit rate according to a statistical multiplexing gain determined by a complexity of an image corresponding to a video service, and varying a size of a subchannel in the enhancement layer transport frame based on the encoding bit rate; Encoding the video service based on a predetermined bit rate to generate a base layer stream, encoding the video service based on the encoding bit rate to generate an enhancement layer stream, and inserting the base layer stream into a subchannel in the base layer transport frame. And inserting the enhancement layer stream into a subchannel having a variable size in the enhancement layer transport frame. Variable bit rate service providing apparatus comprising a. The method of claim 1, And the statistical multiplexing gain is a gain of the number of multiplexing services generated by varying and compressing a bit rate according to a complexity of an image corresponding to the video service and multiplexing the compressed result. The method of claim 1, And the encoder uses a scalable encoding method comprising temporal, spatial and noise ratio scalability. The method of claim 3, And a bit rate loss caused by the overhead of the scalable encoding method is compensated by the statistical multiplexing gain applied to the enhancement layer transport frame. A method for providing a variable bit rate service in an AT-DMB transport frame composed of a base layer transport frame and an enhancement layer transport frame, Calculating an encoding bit rate according to a statistical multiplexing gain determined by a complexity of an image corresponding to a video service, Varying a size of a subchannel corresponding to the enhancement layer transport frame according to the encoding bit rate; Generating a base layer stream by encoding the video service based on a predetermined bit rate; Generating an enhancement layer stream by encoding the video service based on the encoding bit rate; Inserting the base layer stream into a subchannel corresponding to the base layer transport frame; and Inserting the enhancement layer stream into a subchannel having a variable size in the enhancement layer transport frame Variable bit rate service providing method comprising a. The method of claim 5, And calculating the encoding bit rate and varying the size of the subchannel are performed simultaneously. The method of claim 5, The calculating bit rate is Varying and compressing a bit rate according to a complexity of an image corresponding to the video service, and Calculating the encoding bit rate according to the statistical multiplexing gain, which is a gain of the number of multiplexing services generated by multiplexing each of the compressed results. Variable bit rate service providing method comprising a. The method of claim 5, And a subchannel corresponding to the base layer transport frame is a subchannel corresponding to the predetermined bit rate.

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