KR101220175B1 - Method for generating and processing hierarchical pes packet for digital satellite broadcasting based on svc video - Google Patents

Abstract

The present invention relates to a method for generating and processing hierarchical split PES packets for digital satellite broadcasting based on SVC video. More specifically, when SVC video is applied to a digital satellite broadcasting system, the hierarchical structure of the SVC video is considered on the transmitting side. To generate a layered PES packet and efficiently process the received layered PES packet at a receiving side.

Digital Satellite Broadcast, SVC, DVB-S2, Layered Separation, PES Packet

Description

Method for Generating and Processing Layered PES Packet for SSC Video-based Digital Satellite Broadcasting {METHOD FOR GENERATING AND PROCESSING HIERARCHICAL PES PACKET FOR DIGITAL SATELLITE BROADCASTING BASED ON SVC VIDEO}

The present invention relates to a method for generating and processing a layered PES packet for SVC video-based digital satellite broadcasting. More specifically, when applying SVC video to a digital satellite broadcasting system, the transmitting side considers the hierarchical structure of the SVC video. To generate a layered PES packet and efficiently process the received layered PES packet at a receiving side.

The present invention is derived from the research conducted as part of the IT growth engine technology development project of the Ministry of Knowledge Economy and the Ministry of Information and Telecommunication Research and Development. [Task management number: 2007-S-008-02, Title: Development of satellite broadcasting transmission technology for 21 GHz band] ].

Scalable video coding (SVC), H.264's scalable encoding technology, has problems of low compression efficiency, inability to support complex scalability, and high implementation complexity. It is a scalable encoding technique developed at the end of 2007 to solve the problem.

SVC encodes several video layers into one bitstream. The SVC layer is composed of one base layer (BL) and a plurality of enhancement layers (EL) that can be stacked on the base layer successively. do. Each enhancement layer can represent the maximum bit rate, frame rate, and resolution given to each layer based on lower layer information.

In SVC, as more enhancement layers are accumulated, various bit rates, frame rates, and resolutions can be supported. Therefore, a variety of bandwidth diversity problems, receiver terminal performance and resolution problems, and content consumer preference issues are mixed. You can solve it. Therefore, it is an encoding technology suitable for multimedia content services in a UMA (Universal Multimedia Access) environment.

On the other hand, since digital satellite broadcasting is greatly affected by weather conditions caused by rainfall in terms of service environment, a method for solving this problem should be prepared. Accordingly, an attempt has been made to apply an SVC encoding technique capable of providing adaptive video services to various environments in a DVB-S2 based digital satellite broadcasting system.

To this end, a technique for efficiently generating and processing PES packets in consideration of the hierarchical structure of SVC video is required.

Accordingly, the present invention is to solve the above problems of the prior art, when applying the SVC video to the digital satellite broadcasting system, a method for generating a layered PES packet in consideration of the hierarchical structure of the SVC video on the transmitting side; The present invention provides a method of processing a layered PES packet received at a receiving side.

According to an aspect of the present invention, there is provided a method for generating a layer-separated PES packet, by grouping a plurality of base layer network abstraction layer (NAL) units included in one group of picture (GOP) to form a base layer PES. Generating a packet; And generating a plurality of enhancement layer PES packets by grouping enhancement layer NAL units associated with each of the plurality of base layer NAL units, wherein the plurality of base layer NAL units have index numbers according to the extracted order. The plurality of enhancement layer PES packets associated with each of the plurality of base layer NAL units are assigned the same index number as the associated base layer NAL unit.

At this time, the payload of the base layer PES packet, GOP ID field for storing identification information of the GOP; A layer ID field for storing layer information of the PES payload; A BL header length field for storing a length of a header to be added; A BL size field for storing the size of the base layer NAL unit; And a header including a BL index field for storing index information of the base layer NAL unit.

The payload of the enhancement layer PES packet may include: a GOP ID field for storing identification information of a GOP; A layer ID field for storing layer information of the PES payload; And a header including a BL index field for storing the same index information as the base layer NAL unit associated with the enhancement layer PES packet.

On the other hand, according to another aspect of the present invention, a method for processing a layered PES packet includes: separating base layer NAL units from the base layer PES packet when a base layer PES packet is received from a transmitter; Storing the separated base layer NAL units in a buffer according to the index number order; When the enhancement layer PES packet having the index N is received from the transmitting side, transferring a base layer NAL unit having the index N to the decoder in the buffer; And extracting enhancement layer NAL units from the enhancement layer PES packet having the index N and delivering the enhancement layer NAL units to the decoder.

In this case, the transmitting of the base layer NAL unit to the decoder and extracting the enhancement layer NAL units and delivering the enhancement layer NAL units to the decoder include one GOP starting with a base layer PES packet having an index 1 and an enhancement layer PES packet. It is repeated in index number order until the SVC video decoding for is completed.

According to the present invention, by considering the hierarchical structure of the SVC video, by separating the NAL units of the base layer and the enhancement layer into PES packets, the LDPC encoding rate can be differentiated for each layer, thereby enabling differential packet protection. It is possible to implement a digital satellite broadcasting system with improved availability.

In addition, the transmitting side of the digital satellite broadcasting system can minimize the overhead of generating the PES packet by separating the base layer and the enhancement layer, and there is no need to rearrange the NAL units in decoding order for the SVC decoding on the receiving side. Processing delay time can be reduced.

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. In the following detailed description of the preferred embodiments of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. In the drawings, like reference numerals are used throughout the drawings.

1 is a block diagram of a digital satellite broadcasting system based on SVC video.

Referring to FIG. 1, in a scalable video coding (SVC) video-based digital satellite broadcasting system, a network abstraction layer (NAL) unit belonging to a base layer and an enhancement layer from a compressed SVC bitstream is first. After extracting and extracting, a packetized elementary stream (PES) packet is generated for each layer from the extracted NAL units (10). At this time, the base layer can express the resolution of the CIF (Common Image Format) (352 pixels x 288 lines) standard to provide a low resolution broadcasting service, and the enhancement layer is the 4CIF (704 pixels x 576 lines) standard for the high resolution broadcasting service. The resolution can be expressed.

Subsequently, the PES packet is divided into MPEG-2 Transport Stream (TS) packets and then made into a base band (BB) frame (20), and the BB frame is transmitted through LDPC (Low Density Parity Check) encoding (30).

At this time, LDPC encoding is an error correction technique for coping with a problem of rainfall or cloud availability during satellite broadcasting service, and in the present invention, LDPC encoding provides differential packet protection for base layer and enhancement layer video (Unequal). In order to perform Error Protection (UEP), the SVC video is separated into a base layer and an enhancement layer at the transmitting side to be PES packetized.

Specifically, since the enhancement layer is a useless layer without the base layer, the information of the base layer may be regarded as more important in any case than the information of the enhancement layer. Therefore, by applying LDPC encoding differentially to the base layer and the enhancement layer, the availability of satellite broadcasting service can be effectively increased. To this end, SVC video should be PES packetized in a form in which the base layer and the enhancement layer are separated from each other.

Hereinafter, a method of generating and processing a layered PES packet according to the present invention will be described in more detail with reference to FIGS. 2 to 5. In this case, the method and the method for generating a layered PES packet according to the present invention are performed in 'PES encoding' and 'PES decoding' illustrated in FIG. 1, respectively.

FIG. 2 is a diagram illustrating an order of NAL units in one GOP (Group of Picture) after SVC extraction.

Each picture included in one GOP is composed of one NAL unit belonging to the base layer and a plurality of NAL units belonging to the enhancement layer. At this time, the NAL unit (BL NAL unit) belonging to the base layer has a NAL type of "1" or "5", and the NAL unit (EL NAL unit) belonging to an enhancement layer has a NAL type of "20". In addition, a NAL unit having a NAL type of "5" indicates a BL NAL unit belonging to an Instantaneous Decoding Refresh (IDR) picture, and a NAL unit having a NAL type of "1" indicates a BL NAL unit belonging to a picture that is not an IDR picture.

As shown in Fig. 2, after SVC extraction, a plurality of EL NAL units belonging to the same picture are placed after each BL NAL unit. However, when the BL NAL unit and the EL NAL units are separated from each other in this order and then PES packetized and transmitted, the receiving side performs the original order as shown in FIG. 2 before performing SVC video decoding. The process of relocating NAL units is needed, which incurs overhead and processing delays.

Accordingly, the present invention proposes a method for generating and processing a layered PES packet for minimizing overhead and processing delay caused by a NAL unit relocation at a receiving side.

3 is a diagram illustrating a method for generating a PES packet by separating a base layer and an enhancement layer NAL unit for each GOP unit according to the present invention according to the present invention.

According to the present invention, BL NAL units having a NAL type of "1" or "5" are separately grouped to generate a base layer PES packet, and EL NAL units associated with one BL NAL unit are generated. Grouping into one to generate an enhancement layer PES packet (EL PES packet). At this time, an index is used to identify an EL PES packet grouping EL NAL units associated with a specific base layer.

In other words, the EL NAL units associated with each BL NAL unit are assigned the same index number as the BL NAL unit to constitute an EL PES packet. In this case, header information as shown in FIG. 4 is added to the hatched portions of the PES payloads of the BL PES packet and the EL PES packet.

For example, in the BL PES packet, the BL NAL unit having the index 1 and the EL NAL units included in the EL PES packet having the index 1 are NAL units belonging to the same picture. Accordingly, the BL NAL unit and the EL NAL units may have a hierarchical relationship with each other based on the 'index 1' information during PES decoding.

4 is a diagram illustrating a configuration of a header added to a layered PES packet generated according to the present invention, and FIG. 4A illustrates a configuration of a header added to a BL PES packet, and FIG. ) Shows the configuration of a header added to the EL PES packet.

As shown in FIG. 4, the header added to the BL PES packet includes a GOP ID (4 bit), a layer ID (4 bit), a BL header length (16 bit), a BL size (16 bit), and a BL index (8 bit). Field, and the header added to the EL PES packet includes a GOP ID (4 bit), a layer ID (4 bit), and a BL index (8 bit). The information stored in each field is as follows. .

GOP ID: Identification information of GOP

Layer ID: Layer Information of PES Payload

BL header length: Length of header added (bytes)

BL size: Size of BL NAL unit (bytes)

BL index: Index information of BL NAL unit

The layered PES packets generated according to the above-described method are sequentially generated as MPEG-2 TS packets according to the index number order, starting with the BL PES packet. Base layer data and enhancement layer data divided into separate PES packets according to layers are applied with different coding rates according to their importance in the LDPC encoding step to enable differential packet protection.

Meanwhile, the receiving side reconstructs the layered PES packet according to the present invention from the received TS packets, extracts NAL units from the reconstructed layered PES packet, and delivers the NAL units to the SVC video decoding unit.

5 is a diagram illustrating a procedure of extracting a NAL unit from a layered separated PES packet reconstructed at a receiving side according to the present invention.

First, when the BL PES packet is reconstructed, each BL NAL unit is separated from the BL PES packet using the header information added to the payloader of the BL PES packet, and then the BL NAL unit is stored in the BL buffer in the order of the index number. do.

Next, when the EL PES packet having the index 1 is reconstructed, the BL NAL unit having the index 1 is transferred to the SVC video decoding unit in the BL buffer, and the EL NAL units are sequentially extracted from the EL PES packet having the index 1 and delivered to the SVC video decoding unit. do.

Thereafter, indexes 2, 3, ... are processed in the same manner as index 1. In other words, when the EL PES packet having the index 2 is reconstructed, the BL NAL unit having the index 2 is transferred to the SVC video decoding unit in the BL buffer, and the EL NAL units are sequentially extracted from the EL PES packet having the index 2 and delivered to the SVC video decoding unit. do.

The NAL unit extraction process is repeatedly performed in the order of index number until the SVC video decoding for one layered GOP is completed.

The present invention is not limited to the above-described embodiments and the accompanying drawings. It will be apparent to those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

1 is a block diagram of a digital satellite broadcasting system based on SVC video,

2 is a view showing a sequence of NAL units within 1 GOP after SVC extraction;

3 is a diagram illustrating a method for generating a PES packet by separating a base layer and an enhancement layer NAL unit for each GOP unit according to the present invention;

4 is a diagram showing the configuration of a header added to a layered PES packet generated according to the present invention; and

5 is a diagram illustrating a procedure of extracting a NAL unit from a layered separated PES packet reconstructed at a receiving side according to the present invention.

Claims (5)

Generating a base layer PES packet by grouping a plurality of base layer network abstraction layer (NAL) units included in one group of picture (GOP); And Grouping enhancement layer NAL units associated with each of the plurality of base layer NAL units to generate a plurality of enhancement layer PES packets; Index numbers are assigned to the plurality of base layer NAL units according to the extracted order, and a plurality of enhancement layer PES packets associated with each of the plurality of base layer NAL units are assigned the same index number as the associated base layer NAL unit. Method of generating a layer-separated PES packet, characterized in that. The method of claim 1, In the payload of the base layer PES packet, A GOP ID field for storing identification information of the GOP; A layer ID field for storing layer information of the PES payload; A BL header length field for storing a length of a header to be added; A BL size field for storing the size of the base layer NAL unit; And And a header including a BL index field for storing index information of the base layer NAL unit. The method of claim 1, In the payload of the enhancement layer PES packet, A GOP ID field for storing identification information of the GOP; A layer ID field for storing layer information of the PES payload; And And a header including a BL index field for storing the same index information as the base layer NAL unit associated with the enhancement layer PES packet. Separating base layer NAL units from the base layer PES packet when a base layer PES packet is received from a transmitting side; Storing the separated base layer NAL units in a buffer according to the index number order; When the enhancement layer PES packet having the index N is received from the transmitting side, transferring a base layer NAL unit having the index N to the decoder in the buffer; And And extracting enhancement layer NAL units from the enhancement layer PES packet having the index N and forwarding the enhancement layer NAL units to the decoder. 5. The method of claim 4, Delivering the base layer NAL unit to a decoder and extracting the enhancement layer NAL units and delivering to the decoder, A method of processing a layer-separated PES packet, characterized in that it is repeatedly performed in the order of an index number starting with a base layer PES packet having an index 1 and an enhancement layer PES packet until the SVC video decoding for one GOP is completed.

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