EP1839440A2

EP1839440A2 - Visual radio broadcasting method, encoder and decoder for the method, and receiver using the decoder

Info

Publication number: EP1839440A2
Application number: EP06703615A
Authority: EP
Inventors: Jonghwa Won; Keonsik Oh; Jeongseop Lee; Sangjin Kim; Myungkook Yang; Jaehoon Cha; Jaeseob Shin; Yeonbae Kim; Sunghee Park; Sehoon Son; Kwangwoo Park
Original assignee: SBS; Pixtree Technologies Inc
Current assignee: SBS; Pixtree Technologies Inc
Priority date: 2005-01-20
Filing date: 2006-01-19
Publication date: 2007-10-03
Also published as: KR100753540B1; WO2006078130A2; EP1839440A4; WO2006078130A3; KR20060084610A

Abstract

A visual radio broadcasting method, an encoder and decoder for the method, and a receiver using the decoder are disclosed. The present invention is to provide a broadcasting method of transmitting a digital stream or packets multiplexed with still images extracted using video compression specifications having a rate less than one frame per second and digitally compressed audio signals. A case in which audio signals form main signals and related still images accompany the audio signals is an example. Additionally, the present invention provides an encoder for visual radio broadcasting, the encoder being used to transmit a radio broadcast of terrestrial DMB, wherein MPEG-4 ER-BSAC is used as an audio compression technology and MPEG-4 AVC (H.264) is used as a video compression technology. Additionally, the present invention provides a decoder for visual radio broadcasting, the decoder being used to receive a radio broadcast of terrestrial DMB broadcasting, wherein MPEG-4 ER-BSAC is used as an audio compression decoding technology and MPEG-4 AVC (H.264) is used as a video compression decoding technology. Additionally, the present invention provides a receiver using the decoder.

Description

VISUAL RADIO BROADCASTING METHOD, ENCODER AND DECODER FOR THE METHOD, AND RECEIVER USING THE

DECODER

Technical Field

[1] The present invention is to provide a broadcasting method of transmitting a digital stream or packets multiplexed with still images extracted using video compression specifications having a rate less than one frame per second and digitally compressed audio signals, an encoder and decoder for the broadcasting method, and a receiver using the decoder. Background Art

[2] The term "Visual radio" refers to a service in which audio signals form main signals and related images accompany the audio signals.

[3] This scheme may be applied to various digital broadcasting media such as DVB-H,

MediaFLO, ISDB-T and so on.

[4] For terrestrial broadcasting, visual radio using a terrestrial Digital Television

(DTV) method and visual radio using the moving image method of terrestrial Digital Multimedia Broadcasting (DMB) are applied.

[5] For satellite broadcasting, visual radio using a satellite digital television method and visual radio using the moving image method of satellite DMB are applied.

[6] The visual radio in terrestrial DMB is described below as an example of such an application.

[7] In order to implement visual radio using a method defined in "Standard for very- high frequency digital broadcasting transmission/reception matching (TTA.KO-07-0024)", that is, the standard for existing terrestrial DMB (DAB (Digital Audio Broadcasting)), MUSICAM (Masking pattern adapted Universal Sub-band Integrated Coding And Multiplexing), that is, the audio standard for DAB, may be employed, and images, that is, related Program Associated Data (PAD), may be transmitted in the form of an additional service.

[8] A bit rate used in this case is generally 192 kbps. Of 192 kbps, 160 kbps is assigned to MUSICAM signals for audio data, and about 32kbps is assigned to image data. In this case, the format of image data is generally Joint Photographic Experts Group (JPEG), and may be transmitted at various intervals according to a service provider.

Disclosure of Invention Technical Problem

[9] Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a highly value-added broadcasting method by extending the number of images that can be transmitted in conventional DAB audio broadcasting, an encoder and decoder for the broadcasting method, and a receiver using the decoder.

[10] However, the prior art can support basic visual radio broadcasting, but cannot support advanced radio broadcasting.

[11] That is, the number of images that can be transmitted is limited. In other words, about one-cut image can be transmitted for 7 to 8 seconds. Technical Solution

[12] In order to accomplish the above object in a broadcasting method related to application of digital broadcasting, the present invention provides a broadcasting method of transmitting a digital stream or packets multiplexed with still images extracted using video compression specifications and digitally compressed audio signals for respective broadcasting media.

[13] In this case, the moving image compression standards for respective digital media refer to respective compression standards used in a variety of digital broadcasting. For example, an image compression standard for DTV is Moving Picture Experts Group (MPEG)-2, and an image compression standard for DMB is MPEG-4. Accordingly, using the terrestrial DTV standard, visual radio can be implemented in a terrestrial DTV receiver, and using satellite broadcasting's own image compression standards, visual radio can be implemented in the satellite broadcasting (for example, Skylife).

[14] That is, the above-described concepts can be applied to all types of digital moving image broadcasting. In detail, they can be applied to satellite broadcasting, satellite DMB and terrestrial DTV, as well as terrestrial DMB.

[15] A case in which audio signals form main signals and related still images accompany the voice signals is an example.

[16] In more detail, the present invention provides a visual radio broadcasting method for radio broadcasting of terrestrial DMB, wherein MPEG-4 ER-BSAC is used as an audio compression and encoding technology, and MPEG-4 AVC (H.264) is used as a video compression and encoding technology.

[17] Additionally, the present invention provides an encoder for visual radio broadcasting, the encoder being used to transmit a radio broadcasting of terrestrial DMB, wherein MPEG-4 ER-BSAC is used as an audio compression and encoding technology, and MPEG-4 AVC (H.264) is used as a video compression and encoding technology.

[18] Additionally, the present invention provides a decoder for visual radio broadcasting, the decoder being used to receive a radio broadcasting of terrestrial DMB, wherein MPEG-4 ER-BSAC is used as an audio decompression and decoding technology, and MPEG-4 AVC (H.264) is used as a video decompression and decoding technology.

[19] Additionally, the present invention provides a receiver using the decoder.

Advantageous Effects

[20] As described above, the present invention applies compression technology differently while satisfying terrestrial DMB standards, so that it enables image transmission efficiency 4 to 5 times compare to the conventional technology while maintaining audio quality similar to that of conventional DMB, thereby enabling an effective slide show. That is, the present invention uses MPEG-4 ER-BSAC, more effective than the conventional MUSICAM by 20-30%, as audio compression technology, and MPEG-4 AVC (H.264) as video compression technology, so that superior effects that cannot be expected from the conventional terrestrial DMB can be achieved.

[21] Accordingly, the present invention is very effective in transmitting multimedia information. For example, in music broadcasting, the photographs of a master of ceremonies or materials for music can be transmitted through a larger number of image cuts. Moreover, in a program such as radio news, image informations corresponding to the headlines of a newspaper can be transmitted.

[22] Furthermore, the content of audio can be transmitted to hearing-impaired persons through images, and can be displayed via a Binary Format for Scenes (BIFS) channel that is defined in MPEG-4.

[23] According to the present invention, a radio broadcasting method capable of transmitting information efficiently, an encoder and a decoder for the broadcasting method, and a receiver using the decoder can be provided. Brief Description of the Drawings

[24] FIG. 1 is a block diagram illustrating an encoding system for a broadcasting method according to the present invention;

[25] FIG. 2 is a diagram illustrating examples of TS packets;

[26] FIG. 3 is a diagram illustrating mapping relationships between audio frames and

TS packets; and

[27] FIG. 4 is an example table illustrating detailed specifications according to the present invention. Mode for the Invention

[28] Reference should now be made to the drawings, in which the same reference numerals are used throughout the different drawings to designate the same or similar components.

[29] FlG. 1 is a block diagram illustrating an encoding system for a broadcasting method according to the present invention.

[30] In the present invention, MPEG-4 AVC (H.264), using only I frames, is used for the encoding of video signals, and MPEG-4 ER-BSAC is used for the encoding of audio signals. In this case, compressed audio and video signals are passed through SL packetization, that is, part of the MPEG-4 system, and are then converted into an MPEG-2 Transport Stream (TS).

[31] In order to provide the visual radio broadcasting of the present invention, various bit rates can be used. For example, a case where a bit rate of 160 kbps is used is described below.

[32] In the case of image data, according to the specifications, an Instantaneous Decoding Refresh (IDR) period is maximally 2 seconds, so that a method of transmitting one image for two seconds is employed. FlG. 2 is a diagram illustrating examples of TS packets.

[33] Terrestrial DMB uses MPEG-2 TS for transmission. That is, for any information, data is carried on a TS packet. A single TS packet has a 188-bits size, and comes to have a 204-bytes size after passing through Forward Error Correction (FEC). Accordingly, a 160 kbps data stream is composed of 98 TS packets as follows:

[34] 160,000 / (204*8) = 98 TS packets

[35] That is, the number of packets usable each second is 98.

[36] According to the DMB standard, at least four data are transmitted for the control of a stream. These data include a Program Association Table (PAT), a Program Map Table (PMT), a Binary Format for Scene (BIFS) and an Object Descriptor (OD).

[37] Each data is transmitted in the form of a single TS packet, and the period of the transmission must be within 0.5 seconds. Accordingly, control information is transmitted twice each second, so that a total of eight TS packets are used.

[38] In the case of audio data, in a BSAC method, a single frame includes 1024 samples. Accordingly, when a sampling frequency is 44.1 kHz,

[39] 44100/1024 = 43

[40] That is, 43 frames are generated.

[41] A TS packet is composed of a 4-bytes header and a 184-bytes payload. accordingly, the size of data that can be inserted into a single TS packet is maximally 184 bytes.

[42] The size of data occupied by a single audio frame is calculated by the following

Equation: [43] (1024 sample/44100(sampling frequency)) *bit rate

[44] An audio encoding bit rate that is required by a single audio frame to enter a single

TS is generally 56 kbps. However, if a higher bit rate, for example, 96 kbps, is employed to improve sound quality, a single audio frame must use two TSs. The number of TS packets is 86 (43 framesx2). Accordingly, the construction of a TS packet used when audio is used at 96 kbps in a 160 kbps environment is as follows:

[45] 98 = 8 pieces of control information (4x2) + 86 pieces of audio data + four pieces of video data

[46] In this case, a bit rate required to express video data using four TS packets is about

5 kbps. When video information is expressed using 5 kbps, serious degradation of image quality occurs. Accordingly, in order to improve video quality while maintaining audio quality, the number of TS packets assigned to audio must be reduced.

[47] For this purpose, in the present invention, the concept of the subframe of BSAC is used. The concept "Subframe" refers to a scheme of continuously processing a plurality of audio frames and transmitting the audio frames as if they are a single frame.

[48] This concept is introduced to efficiently transmit information having a small size just like audio signals.

[49] In the present invention, the size of a subframe is, for example, three. The three frames are transmitted through five TS packets. An audio encoding bit rate used in this case is 96 kbps. FIG. 3 illustrates mapping relationships between audio frames and TS packets.

[50] TS packets required when subframes are used are as follows:

[51] 98 = 8 pieces of control information (4x2) + 72 pieces of audio data ((43/3)x5) + 18 pieces of video data

[52] Since, in this case, the bit rate that can be assigned to video is about 25 kbps

(184x18x8), 50 kbps can be assigned to a case where one image is expressed for two seconds, so that high-quality images can be obtained.

[53] For reference, detailed specifications of an example according to the present invention are illustrated in FIG. 4.

[54] In the present invention, the concept "receiver" refers to a device for receiving radio or television signals and indicating them. The term "receiver" collectively refers to visual equipment, audio equipment, and audio and video equipment.

[55] Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims

[1] A broadcasting method, related to application of digital broadcasting, of transmitting a digital stream or packets multiplexed with still images extracted using video compression specifications and digitally compressed audio signals for respective broadcasting media.

[2] The broadcasting method as set forth in claim 1, wherein audio signals form main signals and related still images accompany the audio signals.

[3] A visual radio broadcasting method for radio broadcasting of terrestrial DMB, wherein MPEG-4 ER-BSAC is used as an audio compression and encoding technology , and MPEG-4 AVC (H.264) is used as a video compression and encoding technology.

[4] An encoder for visual radio broadcasting, the encoder being used to transmit a radio broadcasting of terrestrial DMB, wherein MPEG-4 ER-BSAC is used as an audio compression and encoding technology , and MPEG-4 AVC (H.264) is used as a video compression and encoding technology.

[5] A decoder for visual radio broadcasting, the decoder being used to receive a radio broadcasting of terrestrial DMB, wherein MPEG-4 ER-BSAC is used as an audio decompression and decoding technology , and MPEG-4 AVC (H.264) is used as a video decompression and decoding technology.

[6] A receiver using the decoder set forth in claim 5.