KR20030065002A - Method of Transmitting Multimedia Streaming Data via Wireless Network and Receiver Using the Same - Google Patents

Abstract

PURPOSE: A method for transmitting and receiving multimedia streaming data through a wireless network and a receiving system are provided to transmit and receive multimedia streaming data using MPEG-4 on a radio communication network. CONSTITUTION: A video signal is coded using MPEG-4 simple profile to generate video streaming data, and an audio signal is coded to generate audio streaming data(10). IOD streaming data corresponding to the video streaming data and audio streaming data is generated, and the video streaming data, audio streaming data and IOD streaming data are multiplexed to generate the second multimedia streaming data(20). The second multimedia streaming data is packetized to create the first multimedia streaming data(30). The first multimedia streaming data is modulated to generate a multimedia signal and the multimedia signal is transmitted through a radio channel(40). The multimedia signal is received through the radio channel and demodulated into the first multimedia streaming data(50). The first multimedia streaming data is depacketized to generate the second multimedia streaming data(60). The second multimedia streaming data is demultiplexed to be divided into the video streaming data, audio streaming data and IOD streaming data(70). The video streaming data and audio streaming data are respectively decoded into the video signal and audio signal(80). The video signal and audio signal are output to a user(90).

Description

Method of transmitting and receiving multimedia streaming data via wireless network {Method of Transmitting Multimedia Streaming Data via Wireless Network and Receiver Using the Same}

The present invention relates to a data transmission and reception method and a reception apparatus suitable for the method, and more particularly, to transmission and reception of multimedia streaming data encoded in MPEG-4.

MPEG-4 is a data transmission protocol for efficiently compressing multimedia information including moving pictures. Therefore, when compressing video using MPEG-4, the amount of data is greatly reduced compared to other methods, and thus it has become a widely used video data compression standard. In addition, it has the advantage of excellent synchronization between video information and audio information.

However, in MPEG-4, unlike MPEG-1 and MPEG-2, which are conventional video compression methods, various types of information can be obtained in response to user input when playing a video. In particular, by defining scene descriptors and object descriptors that specify the display method and characteristics of objects to enable interaction with the user through scene synthesis according to scene description, various multimedia contents in object units To be included. In other words, each object of a scene is processed as separate data, and data for complex temporal and spatial correlation between objects is separately included for composition. .

Assuming that the video signal and the audio signal are transmitted together, in addition to the video streaming data and the audio streaming data, the scene descriptor streaming data and the object descriptor streaming data are further included. In the demuxing and decoding process of the receiving side receiving the streaming data, the initial object descriptor (hereinafter referred to as IOD) data first designates scene descriptor streaming data of a corresponding scene as an element streaming identifier of the scene descriptor. Then, by analyzing the information on the plurality of objects constituting the scene from the scene descriptor streaming data, to find the element streaming identifier of the object descriptor corresponding to each object in the object descriptor streaming data, through the element streaming identifier Again, the data corresponding to each object is found among the video streaming data and the audio streaming data. The video data and audio data of each object found in this way are recombined and output to the user as a scene.

However, since the rental width is limited in wireless communication, it is not suitable for transmitting / receiving MPEG-4 compressed multimedia streaming data that accommodates complex information as described above. In addition, the microprocessor mounted on the mobile terminal that emphasizes portability and low power consumption has a problem that it is difficult to process the complex demuxing and decoding process.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a method capable of transmitting and receiving multimedia streaming data using MPEG-4 in a wireless communication network and a receiving apparatus suitable for use in the method.

1 is a flowchart illustrating a method for transmitting and receiving multimedia streaming data according to an embodiment of the present invention.

2 is a block diagram illustrating an apparatus for receiving multimedia streaming data according to an embodiment of the present invention.

3 is a diagram showing the structure of multimedia streaming data used in the transmission and reception method according to the present invention.

4 illustrates the structure of an RTP packet.

<Description of the symbols for the main parts of the drawings>

100: control unit 110: receiving unit

120: demodulation unit 130: first buffer

140: depekitization part 150: demux part

160: decoding unit 170: second buffer

180: display unit 190: speaker

In order to achieve the above object, the multimedia streaming data transmission / reception method according to the present invention encodes a video signal to be transmitted using MPEG-4 simple profile to generate video streaming data and transmits an audio signal to be transmitted to G.723.1. A first step of generating audio streaming data by coding using any one of a codec, an MPEG-1 audio layer 3 codec, and an advanced audio codec (AAC); Generate IOD streaming data corresponding to the video streaming data and the audio streaming data, and mux the video streaming data, the audio streaming data, and the IOD streaming data using SL mux and flex mux, with an object descriptor track and scene descriptor Generating a second multimedia streaming data by muxing without generating a track and without including the element streaming identifier of the object descriptor and the element streaming identifier of the scene descriptor in the IOD streaming data; Generating a first multimedia streaming data by packetizing the second multimedia streaming data; Generating a multimedia signal by modulating the first multimedia streaming data and transmitting the multimedia signal through a wireless channel; Receiving a multimedia signal through a wireless channel and demodulating the multimedia signal into the first multimedia streaming data; Depacketizing the first multimedia streaming data to generate the second multimedia streaming data; A seventh step of demuxing the second multimedia streaming data using the flex demux and the SL demux to separate video streaming data, audio streaming data, and IDO streaming data; An eighth step of decoding the video streaming data and the audio streaming data into a video signal and an audio signal, respectively; And a ninth step of outputting the video signal and the audio signal to a user.

In addition, a receiver suitable for use in the method for transmitting and receiving multimedia streaming data according to the present invention does not include an object descriptor track and a scene descriptor track, and the IOD streaming data includes an element streaming identifier of an object descriptor and an element streaming identifier of a scene descriptor. Receiving unit for receiving a multimedia signal not included; A demodulator for demodulating the multimedia signal transmitted from the receiver and converting the multimedia signal into first multimedia streaming data; A de-packetization unit configured to de-packetize the first multimedia streaming data transmitted from the demodulator into second multimedia streaming data; A demux unit for separating the second multimedia streaming data transmitted from the depacketization unit into video streaming data, audio streaming data, and IOD streaming data; The video streaming data transmitted from the demux unit is decoded using an MPEG-4 simple profile to be converted into a video signal, and the audio streaming data transmitted from the demux unit is a G.723.1 codec and an MPEG-1 audio layer. A decoding unit which decodes using any one of 3 codecs and AAC and converts them into audio signals; A control unit controlling the de-pekitization unit, the demux unit, and the decoding unit; A display unit which outputs the video signal transmitted from the decoding unit to a screen; And a speaker for outputting the audio signal transmitted from the decoding unit through a speaker.

The above and other objects and features and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 is a diagram illustrating MPEG-4 data used in a multimedia streaming data transmission and reception method and a reception device according to the present invention. Unlike multimedia streaming data by general MPEG-4, the scene descriptor track and the object descriptor track are not included. In other words, unlike the ISO / IEC 14496-1, which defines the MPEG-4 system, multimedia streaming data consists of only IOD streaming data, video streaming data, and audio streaming data. Since the scene descriptor track and the object descriptor track are excluded, the scene descriptor element streaming identifier specifying the scene descriptor data and the object descriptor element streaming identifier specifying the object descriptor data are excluded from the IOD data.

The data decoding process at the receiving side is an element streaming identifier (ES_ID) of video streaming data 220 corresponding to esDescrptor [1]: Video 250 information among information corresponding to IOD streaming data 240 among the received packets 210. Extracts and specifies video streaming data 220. In the same manner, esDescrptor [2]: Audio streaming data 230 corresponding to Audio 260 is designated. The structure of the IOD streaming data 240 follows the standard of ISO / IEC 14496-1, which is as follows.

IOD {

bit (8) TAG; 0x02

bit (8) length; 0x38

bit (10) ObjectDecriptorID

bit (1) URL-FLAG; 0

bit (1) IncludeInlineProfileLevelFlag; 0

bit (4) reserved; 0b1111

bit (8) ODProfileLevelIndication; 0x80

bit (8) SceneProfileLevelIndication; 0xFF

bit (8) AudioProfileLevelIndication; main = 0x01

bit (8) VisualProfileLevelIndication; 0x03

bit (8) GraphicsProfileLevelIndication; 0xFF

esDescrptor [1]; Video

esDescrptor [2]; Audio

However, since the scene descriptor is not used in the transmission / reception method according to the present invention, the SceneProfileLevelIndication corresponding to the scene descriptor is not used.

3 is a diagram illustrating a case where only audio streaming data is transmitted and received. That is, the video streaming data and the audio streaming data are not necessarily transmitted at the same time, but may be transmitted as shown.

4 is a diagram illustrating a data structure of a Real Time Protocol (RTP) packet. According to a preferred embodiment of the present invention, RTP can be used as a transport protocol for transmitting multimedia streaming data. The RTP packet contains information for synchronization. Since the MPEG-4 layer already contains information for synchronization, the information on synchronization supported by the RTP packet is redundant, thus reducing the amount of data transmitted and received. For this reason, it is desirable to remove such duplicate information.

The specification of the RTP packet is defined in "Request for Comment: 1889-RTP." Referring to FIG. Set to 0 because X (Extension), which determines whether to use the extension header as a 1-bit field, is not used. In addition, the CC (CSRC Count) indicating the number of CSRC identifiers listed after the fixed header as a 4-bit field is set to 0 because the CSRC identifier is not used.

1 is a flowchart illustrating a method of transmitting and receiving multimedia streaming data according to an embodiment of the present invention. First, the transmission method (1) will be described. The video signal to be transmitted is encoded using MPEG-4 simple profile to generate video streaming data, and the audio signal to be transmitted is G.723.1 codec or MPEG-1 audio. A first step 10 of coding using one of the layer 3 codecs to generate audio streaming data is performed.

The video signal takes into account the MPEG-4 simple profile defined in ISO / IEC 14496-2, preferably the frame rate is about 2-15 frames / sec, and the image size is SQCIF (128x96) or QCIF (176x144). can do. This restriction is not essential, but merely a consideration to consider the rental width of the currently used wireless network.

The audio signal may be coded using any one of the G.723.1 codec, the MPEG-1 audio layer 3 codec, and the AAC according to the bit rate and the intended use.

Next, generate IOD streaming data corresponding to the video streaming data and the audio streaming data, and mux the video streaming data, the audio streaming data, and the IOD streaming data using the SL mux and the flex mux, but the object descriptor track and scene descriptor. The second step 20 is performed without generating the track and muxing the IOD streaming data without including the element streaming identifier of the object descriptor and the element streaming identifier of the scene descriptor. Since the SL mux and the flex mux follow the standard of ISO / IEC 14496-1, detailed description thereof will be omitted.

Not only does it use object descriptor tracks and scene descriptor tracks, but it does not use element streaming identifiers of object descriptors and scene descriptors of scene descriptors within IOD streaming data. Point directly. This approach can reduce the overhead of data packets rather than pointing video and audio streaming data across scene descriptors and object descriptors in the IOD. In addition, since the data processing of the demuxing and decoding stages is simple, the requirements of the processor of the portable terminal are not high.

Next, a third step 30 of packetizing the second multimedia streaming data to generate the first multimedia streaming data is performed. In this case, preferably, an RTP packet may be used. In addition, when using an RTP packet, preferably, it does not include a timestamp, a CCRC identifier, and an SSRC identifier because information on synchronization is already supported in MPEG-4.

Next, a fourth step 40 of generating a multimedia signal by modulating the first multimedia streaming data and transmitting the multimedia signal through a wireless channel is performed.

Referring to the reception method 2, first, a fifth step 50 of receiving the multimedia signal through a wireless channel and demodulating the first multimedia streaming data is performed. In this case, the method may further include buffering the first multimedia streaming data between the fifth step 5 and the sixth step 6 described later. This is to improve data dropping at the time of reception by sending the buffered data to a subsequent step when the data is delayed.

Next, a sixth step 60 of depacketizing the first multimedia streaming data to generate the second multimedia streaming data is performed.

Next, a seventh step (7) is performed to demux the second multimedia streaming data using the flex demux and the SL demux to separate the video streaming data, the audio streaming data, and the IDO streaming data. Since the operation of the flex demux and the SL demux is the same as that defined in ISO / IEC 14496-1, a detailed description thereof will be omitted.

Next, an eighth step 80 of decoding the video streaming data and the audio streaming data into the video signal and the audio signal is performed. In decoding, video streaming data and audio streaming data are directly pointed to by IDO streaming data. In this case, the method may further include buffering the video signal and the audio signal between the eighth step 80 and the ninth step 90 described later. More preferably, since a video signal having a large amount of data is often delayed, in this case, priority is given to the audio signal so that the delayed video signal is skipped, thereby preventing the multimedia streaming data output to the user from being interrupted. have.

Next, a ninth step 90 of outputting the video signal and the audio signal to a user is performed. In this case, the video signal is output to the terminal screen 180 of the user, and the audio signal is output through the terminal speaker 190 of the user.

In the multimedia streaming data transmission and reception method, preferably, any one of video streaming data and audio streaming data can be selectively transmitted and received.

2 is a block diagram of a multimedia streaming data receiving apparatus suitable for use in the method for transmitting and receiving multimedia streaming data of the present invention. The reception device includes a control unit 100, a reception unit 110, a demodulation unit 120, a depeetization unit 130, a demux unit 140, a decoding unit 160, a display unit 180, and a speaker 190. It consists of.

The receiver 110 does not include the object descriptor track and the scene descriptor track, and receives the multimedia signal that does not include the element streaming identifier of the object descriptor and the element streaming identifier of the scene descriptor in the IOD streaming data. The multimedia signal is the same signal as the multimedia signal described in the aforementioned multimedia streaming data transmission / reception method.

The demodulator 120 demodulates the multimedia signal transmitted from the receiver 110 and converts the multimedia signal into first multimedia streaming data. Preferably, the first buffer 130 may be further configured between the demodulator 120 and the de-packetization unit 140 to be described later, thereby buffering the first multimedia streaming data, thereby reducing the disconnection of the data. .

The depacketization unit 140 depackets the first multimedia streaming data transmitted from the demodulator 120 into the second multimedia streaming data. In this case, preferably, the first multimedia streaming data is packetized data using RTP, and the de-packetization unit 140 may de-packetize using RTP. More preferably, since MPEG-4 also includes data on synchronization, the first multimedia streaming data may not include a timestamp, CSRC identifier, and SSRC identifier because the data on synchronization in the RTP packet is duplicated. .

The demux unit 150 separates the second multimedia streaming data transmitted from the depacketization unit 140 into video streaming data, audio streaming data, and IOD streaming data. The demux unit 150 is composed of a flex demux 152 and an SL demux 154 according to ISO / IEC 14496-1.

The decoding unit 160 decodes the video streaming data transmitted from the demux unit 150 using an MPEG-4 simple profile to convert the video signal into a video signal, and the audio stream transmitted from the demux unit 150. The data is decoded using any one of the G.723.1 codec, the MPEG-1 audio layer 3 codec, and the AAC to be converted into an audio signal.

Preferably, the second buffer 170 is further included in the next stage of the decoding unit 160 to buffer the video signal and the audio signal output from the decoding unit 160 to display the display unit 180 and the speaker. And output to 190. More preferably, when the video signal is delayed, the audio signal may be prioritized to be skipped.

The control unit 100 controls the de-packetization unit 140, the demux unit 150, and the decoding unit 160. Since the control operation of the control unit 100 is the same as that of the general MPEG-4 data receiving apparatus, a detailed description thereof will be omitted.

The display unit 180 outputs the video signal transmitted from the decoder 160 to the user through the screen, and the speaker 190 outputs the audio signal transmitted from the decoder 160 to the user.

As described above, according to the method for receiving multimedia streaming data according to the present invention and a receiver suitable for the method, since the transmitted and received streaming data conforms to the MPEG-4 standard as a whole, video can be transmitted and received at a high compression rate. Easy transmission of multimedia data between communication networks. In addition, by eliminating the data related to the object orientation of MPEG-4, the amount of streaming data is greatly reduced and suitable for use in a wireless channel such as a mobile communication network in which the bandwidth is limited, and the demuxing and decoding algorithm is simple. Therefore, there is a remarkable effect suitable for implementing in a mobile terminal in which the system specification is relatively low and power consumption is a problem.

In addition, according to a preferred embodiment of the present invention, since the audio signal and the video signal are synchronized using the excellent signal synchronization function of MPEG-4, since the data used for synchronization can be omitted from the RTP packet, the transmission is performed. There is a remarkable effect that can reduce the amount of streaming data.

In addition, preferred embodiments of the present invention are disclosed for the purpose of illustration, those skilled in the art will be able to make various modifications, changes, additions, etc. within the spirit and scope of the present invention, such modifications and modifications belong to the scope of the claims You will have to look.

Claims (18)

The video signal to be transmitted is coded using MPEG-4 simple profile to generate video streaming data, and the audio signal to be transmitted is coded using any one of G.723.1 codec, MPEG-1 audio layer 3 codec and AAC. A first step of generating audio streaming data; Generate IOD streaming data corresponding to the video streaming data and the audio streaming data, and mux the video streaming data, the audio streaming data, and the IOD streaming data using SL mux and flex mux, with an object descriptor track and scene descriptor Generating a second multimedia streaming data by muxing without generating a track and without including the element streaming identifier of the object descriptor and the element streaming identifier of the scene descriptor in the IOD streaming data; Generating a first multimedia streaming data by packetizing the second multimedia streaming data; Generating a multimedia signal by modulating the first multimedia streaming data and transmitting the multimedia signal through a wireless channel; Receiving a multimedia signal through a wireless channel and demodulating the multimedia signal into the first multimedia streaming data; Depacketizing the first multimedia streaming data to generate the second multimedia streaming data; A seventh step of demuxing the second multimedia streaming data using the flex demux and the SL demux to separate video streaming data, audio streaming data, and IDO streaming data; An eighth step of decoding the video streaming data and the audio streaming data into a video signal and an audio signal, respectively; And a ninth step of outputting the video signal and the audio signal to a user. According to claim 1, The data packet communication is a multimedia streaming data transmission and reception method, characterized in that using the RTP. The method of claim 2, The packet using the RTP does not include a timestamp, CSRC identifier, and SSRC identifier. The method according to any one of claims 1 to 3, The transmitting and receiving method is a multimedia streaming data transmission and reception method, characterized in that only one of the video streaming data and audio streaming data can be selectively transmitted and received. The method according to any one of claims 1 to 3, And buffering the first multimedia streaming data between the fifth step and the sixth step. The method according to any one of claims 1 to 3, And buffering the video signal and the audio signal between the eighth step and the ninth step. The method of claim 6, And if the video signal is delayed, give priority to the audio signal and skip the video signal. The method of claim 4, wherein And buffering the streaming data between the fifth step and the sixth step. The method of claim 4, wherein And buffering the video signal and the audio signal between the eighth step and the ninth step. A receiver which does not include an object descriptor track and a scene descriptor track, and which receives the multimedia signal including the element streaming identifier of the object descriptor and the element streaming identifier of the scene descriptor in the IOD streaming data; A demodulator for demodulating the multimedia signal transmitted from the receiver and converting the multimedia signal into first multimedia streaming data; A de-packetization unit configured to de-packetize the first multimedia streaming data transmitted from the demodulator into second multimedia streaming data; A demux unit for separating the second multimedia streaming data transmitted from the depacketization unit into video streaming data, audio streaming data, and IOD streaming data; The video streaming data transmitted from the demux unit is decoded using an MPEG-4 simple profile to be converted into a video signal, and the audio streaming data transmitted from the demux unit is a G.723.1 codec and an MPEG-1 audio layer. A decoding unit which decodes using any one of 3 codecs and AAC and converts them into audio signals; A control unit controlling the de-pekitization unit, the demux unit, and the decoding unit; A display unit which outputs the video signal transmitted from the decoding unit to a screen; And And a speaker for outputting the audio signal transmitted from the decoding unit through a speaker. The method of claim 10, The first multimedia streaming data is data packetized using RTP; The de-packetization unit de-packetizing the multimedia streaming data receiving apparatus, characterized in that using the RTP. The method of claim 11, wherein the first multimedia streaming data, Multimedia streaming data receiving apparatus, characterized in that it does not include a time stamp, CSRC identifier, and SSRC identifier. The method according to any one of claims 10 to 12, The apparatus for receiving multimedia streaming data may selectively receive only one of video streaming data and audio streaming data. The method according to any one of claims 10 to 12, And a first buffer for buffering the first multimedia streaming data output from the demodulator and outputting the first multimedia streaming data to the de-packetization unit. The method according to any one of claims 10 to 12, And a second buffer configured to buffer the video signal and the audio signal output from the decoding unit and output the buffered output to the display unit and the speaker. The method of claim 15, wherein the second buffer is And if the video signal is delayed, give priority to the audio signal and skip the video signal. The method of claim 13, And a first buffer for buffering the first multimedia streaming data output from the demodulator and outputting the first multimedia streaming data to the de-packetization unit. The method of claim 13, And a second buffer configured to buffer the video signal and the audio signal output from the decoding unit and output the buffered output to the display unit and the speaker.