KR102117508B1 - Method for receiving transport characteristics of multimedia data in broadcast system - Google Patents

Abstract

The present invention relates to a method for receiving media data in a multimedia system, including a process of receiving a transport packet including transmission characteristic information of the media data, wherein the media data includes at least one data unit, and the A transport packet is generated based on the data unit, and the transmission characteristic information includes bitstream information for transmission of the media data and quality of service (QoS) information of the media data, and the quality of service information is And a first field indicating a characteristic of packet loss and a second field classifying a service class of the media data, wherein the bitstream information includes a first field indicating a minimum bit rate of the data unit and the media of the media data. And a second field indicating the maximum buffer size for data transmission.

Description

How to receive multimedia data transmission feature information from broadcasting system {METHOD FOR RECEIVING TRANSPORT CHARACTERISTICS OF MULTIMEDIA DATA IN BROADCAST SYSTEM}

The present invention relates to a method and apparatus for transmitting a multimedia data packet in a broadcasting system, and more particularly, to one or more media processing units (MPUs) in a broadcasting system supporting multimedia services based on Internet protocols. It relates to a method for receiving the transmission feature information of the multimedia data in units of MPU for QoS (Quality Of Service) control, when the multimedia content to be serviced in a dynamically changing network environment over time.

Ability to reserve resources and guarantee reserved resources in IEEE802.16 (WIMAX), IEEE802.11e (WiFi TXOP), 3GPP 3rd Generation Partnership Project Universal Mobile Telecommunication System (UMTS), and 3GPP Long Term Evolution (LTE) There is this. In the real-time multimedia service, such a resource reservation protocol can be used to guarantee the quality of service. Typically, the Internet Engineering Task Force (IETF) defines parameters required for network resource reservation between the user's terminal and the content server in the resource reservation protocol (RSVP).

1 is a diagram illustrating a process of expressing variable bit rate data with a double leaky bucket parameter.

Variable Bit Rate (VBR) traffic is represented by a double leaky bucket using four parameters (Rg, Rp, Bp, B) included in the traffic specification (Tspec). Rg is an average given bit rate, and even if it exceeds this bit rate momentarily, overflow does not occur when stored in the buffer. The required buffer size is promised in B in advance. Similarly, peak bit rates are reserved. Assuming that the peak bit rate is maintained within a period in which one packet is transmitted, the buffer size Bp for the peak bit rate Rp may be determined as the maximum size of the service data unit (SDU). This value can usually be expressed in MTU (Maximum Transfer Unit).

Table 1 shows that the four parameters of the double leaky bucket are used in various protocols.

IETF RSVP,
IEEE802.11e
'tspec' IEEE802.16 (WIMAX) 3GPP UMTS ＆ LTE MPEG-4 OD ATM Rp p Min. reserved traffic rate Maximum bitrate (4B) avgBitrate PCR Bp M SDU size Maximum SDU size MAX_AU_SIZE CDVT Rg r Max. sustained traffic rate Guaranteed bitrate (4B) AverageBitRate SCR Bg b Maximum Latency k * Maximum SDU bufferSizeDB BT

Therefore, it is advantageous in terms of compatibility with other protocols to generate transport characteristics of multimedia using a double leaky bucket parameter. In general, such a resource reservation protocol is performed in the process of establishing a service session for providing a multimedia service, and while the service continues, that is, end-to-end on the network that transmits data for the entire multimedia content. It is assumed to be established in. However, reserving resources between end-to-end services is not possible in a general open Internet environment. In addition, in the case of a core network, stable and broadband transmission is possible, whereas as it approaches the end, a problem occurs due to resource sharing among multiple users. In particular, in the case of wireless and mobile communication networks, the network resource environment changes dynamically due to various reasons such as user movement and radio wave interference.

2 shows SINR results measured for 10 minutes in an IEEE 802.16 network environment.

In such a dynamic network environment in which SINR changes in real time, it is difficult to guarantee the reserved resources when a resource is reserved at the start of a session using a conventional RSVP. In addition, due to the nature of the mobile environment, when the user moves, the base station is different, so a new resource reservation process is required. In such a dynamic network environment, when the resource is reserved to guarantee the QoS of the multimedia service, resource reservation in a unit shorter than the overall resource reservation of the content is effective. Accordingly, a method for inserting MPU Delivery Characteristics information, which is auxiliary information for controlling QoS for the MPU, should be provided in units of a media processing unit (MPU), which is a detailed unit constituting media content.

The problem to be solved by the present invention is to provide a method and apparatus for effectively guaranteeing QoS of a multimedia service by providing feature information on media data that can be temporally distinguished in a dynamic network environment.

A method of receiving media data in a multimedia system according to an embodiment of the present invention includes a process of receiving a transmission packet generated based on a media data unit (MPU), wherein the transmission packet includes at least one MPU Contains transmission feature information for transmission of an asset, and the transmission feature information includes bitstream information for transmission of the asset and quality of service (QoS) information of the asset, and the quality of service information is the asset And a second field for classifying the asset's service class, and a first field indicating the minimum bit rate of the MPU and a maximum for transmission of the asset. A second field indicating a buffer size is included, and the transport packet further includes a flag indicating that the transport characteristic information of the asset is present.

According to the present invention, more effective QoS control is possible in a dynamically changing transmission environment, such as a mobile network, by utilizing feature information for transmission for each media data unit in a small time unit.

1 is a diagram illustrating a process of expressing variable bit rate data with a double leaky bucket parameter.
2 is a view showing SINR results measured for 10 minutes in an IEEE 802.16 network environment.
3 is a view showing the structure of an MMT encapsulator header according to an embodiment of the present invention
4 is a view showing an example of utilizing feature information for transmission of media data between an MMT server and a client according to an embodiment of the present invention

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The terms used are terms selected in consideration of functions in an embodiment, and the meaning of the terms may vary according to a user's or operator's intention or precedent. Therefore, the meaning of the term used in the embodiments described below, if specifically defined in this specification, will follow the definition, if there is no specific definition should be interpreted as meaning that those skilled in the art generally recognize.

Feature information on the media data of the MPU unit proposed by the present invention may be generated in a process of capturing (capture, grab) and encapsulation of pre-encoded media data. The method of using the generated feature information in the transmission process is as follows. In an embodiment of the present invention, for convenience of description, description is made based on MPEG Media Transport (MMT), which is currently being standardized by Moving Picture Experts Group (MPEG), but the present invention is not limited thereto. Since the MMT system is internally divided into an encapsulation layer, a delivery layer, and a control (signaling) layer according to its function, a method of utilizing feature information according to each layer is described below. Describe separately.

MMT encapsulation layer

The MMT encapsulation layer performs a function of generating feature information for media data of the MPU unit proposed by the present invention.

3 shows the header structure of the MMT encapsulation layer.

Since the MMT asset composed of one or more MPUs means individual components (eg, video components or audio components) constituting media content, media data characteristic information is present for each MMT asset. The feature information of each MMT asset unit may be utilized for overall QoS control and resource reservation of services in the session establishment process of the corresponding MMT asset using RSVP described above. The feature information of the MPU unit proposed in the present invention is added as information for transmission and QoS control by using flags for one or more MPUs constituting an MMT asset, that is, an MPU group.

MMT control layer

The MMT control layer is responsible for exchanging service discovery information, quality of experience (QoE) management information, and digital rights management (DRM) information between the server and the client. In the process of exchanging service discovery information, since a network resource reservation process can be performed to establish a session, QoS control such as resource reservation is performed using media feature information included in the MMT asset. As described above, QoS control in the asset unit is performed in the overall content unit, so in a dynamic environment, QoS control in the MPU group unit, which is a smaller unit, is required.

MMT delivery layer

The MMT delivery layer is responsible for the function of transmitting the encapsulated media data packet from the server to the client and for exchanging information between layers in the terminal (for example, a cross-layer interface). To this end, the MMT transport layer generates transport packets. In the MMT transport layer, QoS-related information to be included in each transport packet is obtained from feature information in order to guarantee QoS of the transport packet.

FIG. 4 illustrates an embodiment in which the characteristics of media data generated in the MMT encapsulation layer are used in the media transmission service process.

The MPU delivery characteristic of the MPU group unit proposed in the present invention is generated in the MMT server 601 side encapsulation layer (E layer 603) and inserted in the form of a flag. The media feature information of the MPU group unit proposed in the present invention includes information necessary for resource reservation (eg, double leaky bucket parameter; bitstream_descriptor) and information indicating relative priority for each packet by being included in each transport packet (QoS_descriptor) It is divided into. The bitstream_descriptor is transmitted 606 to the control layer (C layer, 605) and is transmitted to the C layer 609 of the client 602 through signaling protocols such as RTSP (Real-Time Stream Protocol) and SIP (Session Initiation Protocol). . In the case of QoS_descriptor, information parsed from C layer 605 is delivered 607 to a delivery layer (D layer, 604), inserted into every delivery packet, and then a data channel is established. It can be delivered to the client 602 and an intermediate network device (not shown). Alternatively, information may be obtained and transmitted by directly accessing the encapsulation header of data transmitted through the 608 path and parsing the corresponding field. Since this series of processes is performed in units of MPU, it can be performed in units of time shorter than units of assets.

Next, syntax and semantics for media feature information in units of MPU groups according to an embodiment of the present invention will be described in detail.

The syntax and semantics for each field of auxiliary information for transmission and QoS control of the MPU group unit (or media data unit in a time unit smaller than an asset such as GOP) proposed in the present invention are shown in Table 2. In Table 2, the name of each field, the size, and the type of the variable representing each field are selected in consideration of the functions in the embodiment as described above, and thus may vary according to the intention or precedent of the user or operator. However, the meaning of each field must follow the definition provided in this specification.

Syntax No. Of bits Mnemonic MPU_Header () {
mpu_length;
header_length;
mpu_sequence_number;
number_of_au;
for (int i = 0; i <number_of_au; i ++) {
au_length;
}
private_header_flag;
if (private_header_flag == 1) {
private_header_length
private_header
}
MPU_delivery_characteristic_header_flag;
if (MPU_delivery_characteristic_header_flag == 1) {
QoS_descriptor () {
loss_priority;
delay_priority;
class_of_service;
hybrid_sync_indicator;
}
Bitstream_descriptor () {
sustainable_rate;
buffer_size;
peak_rate;
max_MFU_size;
MFU_perid;
}
}
}
MPU_Payload ()

Element or Attribute Name Use Description mpu_sequence_number specifies sequence number of MPU in a single MMT Asset. It is incremented by 1 and will be unique within in an MMT Asset. number_of_au specifies the number of AUs in this MPU. au_length specifies length of each AU in this MPU private_header_flag indicates that there is private_header private_header_length specifies the length of private_header MPU_delivery_characteristic_header_flag Flag indicating the presence of MDC. If 1, MDC information follows. loss_priority It shows the characteristics of MPU transmission packet loss.
11: loss priority 0 (Lossless)
10: loss priority 1 (Lossy, High priority)
01: loss priority 2 (Lossy, Medium priority)
00: loss priority 3 (Lossy, Low priority) delay_priority Characterizes delay sensitivity of MPU.
11: high sensitivity: end-to-end delay << 1sec (e.g., VoIP, video-conference)
10: medium sensitivity: end-to-end delay approx. 1 sec (e.g., live-streaming)
01: low sensitivity: end-to-end delay <5 ~ 10 sec (e.g., VoD)
00: do n’t care (e.g., FTP, file download) class_of_service The characteristics of MPU data are divided into the characteristics of bitstreams.
111: The Constant Bit Rate (CBR) service class shall guarantee peak bitrate at any time to be dedicated for transmission of the MPU. This class is appropriate for realtime services which require fixed bitrate such as VoIP without silence suppression.
110: The Real-Time Variable Bit Rate (rt-VBR) service class shall guarantee sustainable bitrate and allow peak bitrate for the MPU with delay constraints over shared channel. This class is appropriate for most realtime services such as video telephony, videoconferencing, streaming service, etc.
101: The Non-Real-Time Variable Bit Rate (nrt-VBR) service class shall guarantee sustainable birate and allow peak bitrate for the MPU without delay constraint over shared channel such as file downloading.
100: The Available Bit Rate (ABR) class shall not guarantee any bitrate, but may report available bitrate for feedback control. This class is appropriate for applications which can be adaptive to time-varying bitrate such as video streaming with RTCP feedback.
011: The Unspecified Bit Rate (UBR) class shall not guarantee any bitrate and shall not indicate congestion. This class is appropriate for interactive applications such as Web browsing. UBR service is equivalent to the common term “best effort service”. hybrid_sync_indicator Flag for transmission synchronization. If 1, there is no need to consider transmission synchronization with other MPUs, and if 0, transmission synchronization must be considered.
1: no dependency.
0: dependent on other MPU for synchronization in hybrid delivery. sustainable_rate The sustainable_rate  defines the minimum bitrate that shall be guaranteed for continuous delivery of the MPU. The sustainable_rate  corresponds to drain rate in token bucket model. The sustainable_rate  is expressed in kilobits of MFU (or MPU) per second. buffer_size The buffer_size  defines the maximum buffer size for delivery of the MPU. The buffer absorbs excess instantaneous bitrate higher than the sustainable_rate  and the buffer_size  shall be large enough to avoid overflow. The buffer_size  corresponds to bucket depth in token bucket model. Buffer_size  of a CBR (constant bit rate) MPU shall be zero. The buffer_size  is expressed in kilobits peak_rate The peak_rate  defines peak bitrate during continuous delivery of the MPU. The peak_rate  is the highest average bit rate during every MFU period . The peak_rate  is expressed in kilobits of MFU (or MPU) per second. MFU_period The MFU period  defines minimum period of MFU during continuous delivery of the MPU. The MFU period  is expressed in millisecond. max_MFU_size The max_MFU_size is the maximum size of MFU, which is MFU_period * peak_rate. The max_MFU_size is expressed in kilobits.

That is, as shown in Table 3, sustainable_rate represents the minimum bit rate guaranteed for MPU data transmission, buffer_size represents the maximum buffer size for MPU data transmission, peak_rate represents the peak bit rate during MPU data transmission, and MFU_period is MFU (Media Fragment Unit) represents the minimum period, and max_MFU_size represents the maximum size of the MFU.

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 concept of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

Claims (5)

A method for receiving media data in a multimedia system,
And receiving a transport packet generated based on the media data unit (MPU),
The transport packet includes transmission characteristic information for transmission of an asset including at least one MPU,
The transmission characteristic information includes bitstream information for transmission of the asset and quality of service (QoS) information of the asset,
The quality of service information includes a first field indicating characteristics of packet loss of the asset and a second field classifying the service class of the asset,
The bitstream information includes a first field indicating a minimum bit rate of the MPU and a second field indicating a maximum buffer size for transmission of the asset,
The transport packet further includes a flag indicating that the transmission characteristic information of the asset is present. According to claim 1,
The bitstream information includes a third field indicating a peak bit rate for transmission of the asset, a fourth field indicating a period of the subunit of the MPU for transmission of the asset, and a fifth field indicating the maximum size of the subunit. A method further comprising at least one of the fields. According to claim 1,
The quality of service information further comprises a third field indicating a characteristic for the delay sensitivity of the asset. According to claim 1,
The service class is a method of classifying a type of a bitstream representing a fixed bit rate or a variable bit rate. delete

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