JP2017126941A - Content distribution system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a content distribution system.SOLUTION: A content distribution system includes a send and receive interface for receiving at least three video streams of different contents from a content distribution server via a communication network. At least one of three video streams is received at high bit rate. A video stream received at high bit rate is reproduced, as a main program channel, in a main program channel region, and the reminders of the three video streams are reproduced, as adjacent program channels, in at least two adjacent program channel regions adjacent, respectively, to a pair of opposite ends of the main program chain region of a display. The main program chain region can move in any direction of the at least two adjacent program channel regions, in response to user operation, for switching the program channel.SELECTED DRAWING: Figure 20

Description

  The present invention relates to a content distribution system.

  In recent years, with the rapid spread of user terminals such as smartphones, performance has been improved, and a user who owns a user terminal can connect to the Internet from any place and receive various services. Many services are performed via a base station near the user.

  On the Internet, a moving image service is provided using various applications such as YouTube (trademark) and Nico Nico Douga (trademark). Such streaming video distribution services have become widespread with the widening of the Internet and the popularization of CDN (Content Delivery Network). Using HTTP, a cache can be used, and firewalls and NATs can be easily overcome, and servers Since there is an advantage such as being able to prepare easily, distribution using HTTP / TCP is becoming mainstream.

  In addition, due to advances in information and communication technology, the application of wireless LAN devices has spread not only to office computers and networks, but also to general households, due to the decline in the price of devices with wireless functions. Utilizing the portability of a wireless terminal such as a smartphone, a public wireless LAN service for connecting a wireless LAN to a public network has been started, and the use of a wireless LAN in a city or in a store has become commonplace. This makes it possible to connect to the Internet via a wireless LAN in various places, and the opportunities for use are increasing. Since a wireless LAN normally does not require connection of a LAN cable, if there is an access point (AP), the Internet can be used regardless of the location.

  Here, for example, when a TV channel is transmitted through an IP network using an IP multicast stream or a unicast stream, such as IPTV, a time required for a media stream of a new channel to start being played on TV, The time required to generate the first image frame of a new channel contributes to the channel switching time, called channel zapping time. To save network bandwidth, TV channels are assigned to users only when required and are digitally encoded. This lengthens the channel switching time.

  In particular, the channel switching time in an IPTV network can be several seconds, which results in a lack of user satisfaction. Therefore, the main problem with IPTV channel switching is that the user satisfaction is due to long switching delay, i.e. the time from the start of switching until the video from the selected channel starts playing on the TV screen. Is lack of.

  Therefore, a content distribution system and a user terminal that can realize seamless channel switching without causing the user to feel the channel switching time are desired.

For example, Patent Literature 1 is a node in an IPTV network that distributes media via a channel from a media content distributor to a connectable set-top box of a user who receives the distributed media.
Means for retrieving information regarding the channel zapping behavior of the user;
A prediction device configured to predict at least one channel that would be selected by the user based on the retrieved information;
An initiator configured to subscribe to the predicted channel;
And a buffer configured to buffer the subscribed predicted channel to enable fast channel switching.

JP 2010-514334 A

  The node of the above-mentioned patent document 1 is configured to predict at least one channel that will be selected by the user based on information on the channel zapping behavior of the past user and subscribe to the predicted channel. However, the user does not always switch the channel to a channel predicted in advance by zapping.

  Even if the channel is subscribed to the channel predicted in advance, the interruption always occurs during the switching, and the seamless channel switching cannot be realized.

Thus, according to a first aspect of the present invention, the present invention is a user terminal comprising a memory and a processor connected to a content distribution server via a communication network,
A transmission / reception interface for receiving at least three video streams of different content from the content distribution server via the communication network, wherein at least one of the three video streams is received at a high bit rate; The rest of the video stream is received at a low bit rate,
The at least one of the three video streams received at the high bit rate is played as a main program channel in the main program channel region, and the at least one of the three video streams received at the low bit rate A display that plays back the remaining ones as adjacent program channels in at least two adjacent program channel regions each adjacent to a pair of opposing ends of the main program channel region;
The main program channel region is a user terminal that can move in either direction of the at least two adjacent program channel regions in response to a user operation for switching program channels.

According to the second aspect of the present invention, the present invention plays back at least three video streams of different contents in a user terminal including a memory and a processor connected to a content distribution server via a communication network. A way to
Receiving at least one of the three video streams of the different content at the transmit / receive interface from the content distribution server via the communication network, wherein at least one of the three video streams is received at a high bit rate. The remaining of the three video streams are received at a low bit rate,
The at least one of the three video streams received at the high bit rate is played as a main program channel in the main program channel region of the display, and the at least one of the three video streams received at the low bit rate Replaying the rest of the as adjacent program channels in at least two adjacent program channel regions, each adjacent to a pair of opposing ends of the main program channel region of the display,
The main program channel region is a video stream playback method that can move in either direction of the at least two adjacent program channel regions in response to a user operation for switching program channels.

Furthermore, according to a third aspect of the present invention, the present invention plays back at least three video streams of different content on a user terminal including a memory and a processor connected to a content distribution server via a communication network. A program for executing a method for performing
Receiving at least one of the three video streams of the different content at the transmit / receive interface from the content distribution server via the communication network, wherein at least one of the three video streams is received at a high bit rate. The remaining of the three video streams are received at a low bit rate,
The at least one of the three video streams received at the high bit rate is played as a main program channel in the main program channel region of the display, and the at least one of the three video streams received at the low bit rate Replaying the rest of the as adjacent program channels in at least two adjacent program channel regions, each adjacent to a pair of opposing ends of the main program channel region of the display,
The main program channel area is a video stream playback program that can move in either direction of the at least two adjacent program channel areas in response to a user operation for switching program channels.

  According to the present invention, seamless channel switching can be realized without causing the user to feel the channel switching time during viewing of the real-time video stream, and user satisfaction can be improved.

It is a figure which shows the whole structure of the radio | wireless communication network for implementing the content delivery system according to this invention. 1 is a diagram illustrating a configuration of a mobile communication network 104. FIG. It is a functional block diagram of user terminal 118-i. It is a figure which shows the hardware constitutions of the content delivery server. 2 is a diagram illustrating a hardware configuration of a database server 124. FIG. It is a figure which shows the hardware constitutions of the SNS server. 2 is a diagram illustrating a hardware configuration of a database server 130. FIG. 2 is a diagram illustrating a hardware configuration of Web servers 120 and 126. FIG. It is a functional block diagram of an OFDM modulation / demodulation unit. It is a figure which shows the mode of the storage of the real-time video stream in the content database 510 of the database server 124. FIG. It is a figure which shows delivery of the real-time video stream according to a RTP (Real Time Transport) protocol. It is a figure which shows the data structure of a RTP packet. FIG. 2 is a diagram illustrating HTTP Live Streaming (HLS) protocol streaming. It is a sequence diagram which shows establishment of the session between the user terminal 118-i and the content delivery server 122. It is a flowchart of the adaptive bit allocation process performed between NodeB110 or eNodeB112 and the user terminal 118-i. It is a figure which shows the display part 210 of the user terminal 118-i which displayed the real-time program guide. It is a figure which shows the structure of the hierarchical QoS (Quality of Service) control function according to a RTP protocol. It is a figure which shows the structure of the QoS control function according to a HTTP Live Streaming (HLS) protocol. It is a sequence diagram of the symbol rate (bandwidth) negotiation performed between the content distribution server 122 and the user terminal 118-i. It is a flowchart of the zapping operation while viewing a program on the user terminal 118-i. It is a figure which shows the mode of the zapping of the horizontal direction (longitudinal direction) on the display part 210 of the user terminal 118-i. It is a figure which shows the mode of the zapping of the horizontal direction (longitudinal direction) on the display part 210 of the user terminal 118-i. It is a figure which shows the mode of the zapping of the vertical direction on the display part 210 of the user terminal 118-i. It is a sequence diagram which shows 1st Embodiment of the spreading | diffusion to SNS of a video stream fragment. It is a sequence diagram which shows 2nd Embodiment of the spreading | diffusion of the video stream fragment to SNS. It is a sequence diagram which shows 3rd Embodiment of the spreading | diffusion to SNS of a video stream fragment | piece. It is a figure which shows operation at the time of posting the video stream fragment corresponding to the designated reproduction | regeneration time to a SNS site. It is a figure which shows operation at the time of posting the video stream fragment corresponding to the designated reproduction | regeneration time to a SNS site. It is a figure which shows operation at the time of posting the video stream fragment corresponding to the designated reproduction | regeneration time to a SNS site.

  While the invention is susceptible to various modifications and alternative forms, exemplary embodiments of the invention are shown by way of example in the drawings and are herein described in detail. However, the description herein of exemplary embodiments is not intended to limit the invention to the particular forms disclosed, but is intended to be construed as limiting the invention as defined by the claims. Includes all modifications, equivalents, and alternatives falling within the spirit and scope.

(1) Overall Configuration of Network FIG. 1 is a diagram showing an overall configuration of a wireless communication network for implementing a content distribution system according to the present embodiment.

  The wireless communication network 100 includes an upper network 102 that functions as a core network and a plurality of mobile communication networks 104. The core network 102 includes a plurality of content service routers 106, and the plurality of mobile communication networks 104 can include a radio network controller (RNC) 108, a plurality of NodeBs 110, and a plurality of eNodeBs 112, respectively. A content provider 114 that distributes content such as a real-time video stream, and an SNS service provider 116 that provides a social network service (SNS) such as Twitter and Line are connected to the upper network 102, and a plurality of user terminals 118-i (i = ,..., N) are connected to a plurality of mobile communication networks 104. Here, the index i of the user terminal corresponds to the user id.

  The content provider 114 includes a web server 120, a content distribution server 122, and a database server 124, and the SNS service provider 116 includes a web server 126, an SNS server 128, and a database server 130.

  User terminals 118-i are smartphones, tablet terminals, cellular phones, personal digital assistants, text messaging devices, pagers, network interface cards, notebook computers, desktop computers, and personal digital assistants (PDAs). May be. User terminals 118-i can communicate by exchanging information over an air interface (or wireless communication link) that includes several communication channels, such as a traffic channel, a signaling channel, a paging channel, etc. .

  The core network 102 may be a circuit switched network such as a public switched telephone network (PSTN) or a packet based network such as the Internet. The core network 102 includes at least a portion of any mobile communication network 104 that provides data communication via wireless signals. The mobile communication network 104 includes, for example, a wireless local area network (WLAN) that uses WiFi / WiMax communication. An exemplary implementation of the mobile communication network 104 may be implemented as a corporate or campus corporate network, or as a “hot spot” in a public place such as an airport, coffee shop, etc. The mobile communication network 104 further includes one or more access points that provide wireless connections to a plurality of user terminals 118-i. Access points include base stations, base station routers, and access networks.

  The air interface communication channel is defined according to one or more wireless communication protocols used by the core network 102 or the mobile communication network 104. The core network 102 and the mobile communication network 104 are typically used for data communication, but may be networks that can transfer voice communication such as VoIP calls. For example, the core network 102 and the mobile communication network 104 may be widely deployed to provide various communication services such as voice, video, packet data, messaging, broadcast, and so on. These communication networks may be multiple access networks that can support multiple user terminals by sharing available network resources. Such multiple access networks include, for example, code division multiple access (CDMA) networks, time division multiple access (TDMA) networks, frequency division multiple access (FDMA) networks, orthogonal frequency division multiple access (OFDMA) networks, and single carriers. Includes frequency division multiple access (SC-FDMA) networks. For example, an air interface communication channel operating according to code division multiple access (CDMA) is defined by an orthogonal code that modulates a radio signal used to transmit information over the air interface. The air interface communication channel may also be determined by the frequency of the carrier used to transmit information over the air interface. For example, in orthogonal frequency division multiple access (OFDMA), one or more user terminals 118-i may share multiple orthogonal frequencies or tones.

  Here, the terms “network” and “system” are often used interchangeably. A CDMA network may implement a radio technology such as Universal Terrestrial Radio Access (UTRA), CDMA2000, etc. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. CDMA2000 covers IS-2000, IS-95 and IS-856 standards. A TDMA network may implement a radio technology such as Global System for Mobile Communications (GSM). The OFDMA network implements wireless technologies such as Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash OFDMA, etc. Can do. UTRA and E-UTRA are part of Universal Mobile Telecommunication System (UMTS). 3GPP Long Term Evolution (LTE) and LTE Advanced (LTE-A) are newly released UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A, and GSM are described in the “3rd Generation Partnership Project” (3GPP). CDMA2000 and UMB are described in “3rd Generation Partnership Project 2” (3GPP2).

  FIG. 2 is a diagram showing the configuration of the mobile communication network 104.

  The mobile communication network 104 may include multiple NodeBs 110, multiple eNodeBs 112, a radio network controller (RNC) 108, and other network entities. NodeB 110 and eNodeB 112 are stations that communicate with user terminal 118-i and may also be referred to as base stations, access points, or other terms. Each NodeB-1 to NodeB-3 can provide radio coverage to a macro cell that is a specific geographical area.

  Macrocells can cover a relatively large geographical area (a few kilometers in radius) and allow unrestricted access by user terminals 118-i that have subscribed to the service. Each eNodeB 112 can provide radio coverage to femtocells, picocells, etc., which are relatively small geographic areas, and allows unrestricted access by user terminals 118-i subscribed to the service. A femtocell is limited by a user terminal 118-i, such as a user terminal 118-i in a limited subscriber group (CSG) that has an association with the femtocell, a user terminal 118-i for a user at home, etc. Enable access. A Serving eNodeB 112 may be referred to as a femto eNodeB or a home eNodeB (HNB), and an eNodeB handling a pico cell may be referred to as a pico eNodeB. In the example of FIG. 2, NodeB-1, NodeB-2, and NodeB-3 may be macro NodeBs handling macro cells 132, 134, and 136, respectively. Four of the eNodeBs 112 are femto eNodeBs that handle femtocells, and the other one of the eNodeBs 112 is a pico eNodeB that handles picocells.

  The mobile communication network 104 may be a heterogeneous network including various types of eNodeBs, relays, and the like. These different types of eNodeBs may have different transmission power levels, different coverage areas, and different impacts on mobile communication network 104 interference. For example, a macro NodeB may have a high transmit power level (20 watts), while a pico eNodeB, a femto eNodeB, and a relay may have a lower transmit power level (1 watt). In FIG. 2, a solid line with a double-pointed arrow indicates communication between the Node B 110 or the eNodeB 112 that handles the user terminal 118-i and the user terminal 118-i via the downlink and uplink. A double arrowed signal is shown.

  The mobile communication network 104 can support synchronous or asynchronous operation. For synchronous operation, the NodeB and eNodeB can have similar frame timing, and transmissions from different eNodeBs can be aligned approximately in time. For asynchronous operation, the eNodeB can have different frame timings, and transmissions from different eNodeBs may not be aligned in time.

  The RNC 108 is connected to the NodeB 110 and the eNodeB 112 via a radio link, and controls the NodeB 110 and the eNodeB 112. The RNC 108 can communicate with the NodeB 110 and the eNodeB 112 via the core network 102 (backhaul network). The NodeB 110 and the eNodeB 112 can communicate with each other directly or indirectly via a wireless backhaul or a wired backhaul.

  LTE typically uses orthogonal frequency division multiplexing (OFDM) on the downlink and single carrier frequency division multiplexing (SC-FDM) on the uplink. OFDM and SC-FDM divide the system bandwidth into multiple orthogonal subcarriers, commonly referred to as tones. Each subcarrier may be modulated with data. Modulation symbols are generally transmitted in the frequency domain with OFDM and in the time domain with SC-FDM. The spacing between adjacent subcarriers may be fixed, and the total number of subcarriers depends on the system bandwidth. The number of subcarriers per system bandwidth is 128, 256, 512, 1024, or 2048 for a system bandwidth of 1.25, 2.5, 5, 10, or 20 [MHz], respectively. May be. The system bandwidth can be composed of multiple subbands. The subbands can cover, for example, 1.08 [MHz], and for system bandwidths of 1.25, 2.5, 5, 10, or 20 [MHz], one, two, There are 4, 8, or 16 subbands.

(2) User Terminal FIG. 3 is a functional block diagram of the user terminal 118-i.

  The user terminal 200 includes a digital processing unit 202, a baseband unit 204, and an RF unit 206. The digital processing unit 202 includes an input unit 208, a display unit 210, a storage device 212, a memory 214, and a CPU 216. The CPU 216 implements various functions by reading the program stored in the storage device 212 into the memory 214 and executing it. The memory 214 includes, for example, a random access memory (RAM) and / or a read only memory (ROM). The storage device 212 includes a tape drive, a floppy drive, a hard disk drive, or a compact disk drive. The input unit 208 receives data input, and includes, for example, a keyboard, a mouse, a trackball, a touch panel, a microphone, and the like. The display unit 210 includes, for example, a display and a speaker that output data.

  The baseband unit 204 can include a demodulator 218, a modem unit 220, an OFDM demodulator 222, and a modem unit 224 according to the purpose. Similarly, the RF unit may include a receiving unit 226, a transmitting / receiving unit 228, a tuner 230, and a transmitting / receiving unit 232 according to the purpose.

  For example, the transmission / reception unit 232 and the modulation / demodulation unit 224 can be used to perform voice communication via a wideband CDMA (WCDMA) network or a mobile communication global system (GSM) network. The modem 224 can use a scheme such as BPSK, QPSK, 8-level PSK, 16-level QAM, 32-level QAM, etc. as the primary modulation scheme. The modulation / demodulation unit 224 spreads the spectrum by multiplying the signal subjected to the primary modulation by a PN code or Gold code assigned to each user terminal 118-i and having a small cross-correlation, or a Walsh-Hadamard code orthogonal to each other. The signal that has been transmitted to the transmitter / receiver 232 The transmission / reception unit 232 performs analog / digital (A / D) conversion on the received spread spectrum signal, amplifies it with an amplifier, and transmits it from the antenna. In the reception operation, the transmission / reception unit 232 performs analog-digital (A / D) conversion on the received signal, and the modem unit 224 performs multiplication on the synchronized code sequence again, and performs despreading to restore the original signal. The modem unit 224 performs filtering processing on the despread wideband signal using a low-pass filter (LPF) in order to remove the interference signal in the narrow band.

  Further, the tuner 230 and the OFDM demodulator 222 can be used to receive a video stream from the content provider 114. The tuner 230 is configured to be able to change the reception band. The tuner 230 can receive the instruction of the center frequency from the CPU 216 and move the reception band by moving the center frequency based on the instruction of the center frequency. The tuner 230 can be configured using an all-digital phase-locked loop (ADPLL). The ADPLL may be configured using an adder circuit and a time-to-digital converter (TDC) circuit for converting the delay difference into a digital value for phase comparison. The ADPLL may include a digitally controlled oscillator (DCO) that controls the oscillation frequency with a digital value, which enables process portability, scalability, low voltage operation, and affects output signal phase noise. Noise sources can also be limited. The ADPLL may shorten the convergence time by digitally switching the loop gain of the system at the time of tuning, and may use a fractional system having a MASH Δ-Σ configuration at the time of fine adjustment of the output frequency and convergence. The tuner 230 sends the frequency-selected received signal to the OFDM demodulator 222.

For example, the OFDM demodulator 222 may be configured as shown in the lower part of FIG. The OFDM modulation method is a modulation method in which a plurality of subcarriers are used for one subband, and parallel transmission is performed by digitally modulating each subcarrier with different data. The OFDM demodulator 222 filters a signal received by the antenna 1020 using a band pass filter (BPF) 1022. The OFDM demodulator 222 performs conversion from the carrier band signal to the baseband signal. Specifically, the OFDM demodulator 222 multiplies the received signal by cos (2πf _c t) to obtain an in-phase component, and performs filtering using a low-pass filter (LPF) 1024. Similarly, the OFDM demodulator 222 multiplies the received signal by −sin (2πf _c t) to obtain a quadrature component, and performs filtering using the LPF 1024. The OFDM demodulator 222 samples (A / D conversion) each of the in-phase component and the quadrature component (1026), and converts the A / D converted signal into a serial-to-parallel converter (S / P). )) Divide into a plurality of data series by 1028. The transmission rate of the data series after S / P output is lower than the transmission rate of the received signal.

  The OFDM demodulator 222 removes the guard interval during S / P conversion (1030). The guard interval (cyclic prefix) is usually used by connecting the latter half of the baseband OFDM symbol at the head. The addition of the guard interval makes it possible to effectively eliminate the influence of intersymbol interference under the condition that the delay spread of the multipath is less than the guard interval length.

  The OFDM demodulator 222 performs discrete Fourier transform (DFT) processing on the signal from which the guard interval has been removed (1032). A symbol obtained by performing Fast Fourier Transform (FFT) on a received symbol sequence includes only transmission path characteristics and noise components corresponding to the carrier frequency at which the symbol is transmitted, and does not include any influence from other symbols. The OFDM demodulator 222 performs an equivalent process (1034) for correcting the influence of the transmission path characteristic in order to correctly determine the symbol, and a parallel-to-serial converter (parallel-to-serial converter) for the equivalent process. (P / S)) 1036 performs P / S conversion to obtain the transmitted original digital data series. As the equivalent process, a minimum mean square error (MMSE) equivalent may be used.

  The OFDM demodulator 222 performs primary demodulation on the P / S converted symbol sequence (1038) and extracts a baseband signal. The OFDM demodulator 222 performs trellis decoding processing on the extracted baseband signal (1040). When the OFDM modulation scheme is applied to video stream distribution, the modulation scheme of each OFDM carrier needs to be multi-level modulation such as 16QAM in order to obtain a sufficient bit rate within a certain transmission bandwidth. There are often. In this case, if the bit rate is increased while the bandwidth is constant, the bit error rate characteristics deteriorate. However, as a means for minimizing the deterioration, each carrier wave of OFDM is trellis coded modulation (TCM). May be. Trellis decoding can be performed by a soft decision Viterbi algorithm. The OFDM demodulator 222 performs bit determination using the trellis-decoded one and obtains a bit error rate (1042).

(3) Content Distribution Server FIG. 4 is a diagram illustrating a hardware configuration of the content distribution server 122.

  The content distribution server 400 includes a CPU 402, a memory 404, a storage device 406, an input unit 408, an output unit 410, a transmission / reception interface (I / F) 412, a content search unit 414, and a search information generation unit 416. , A search log generation unit 418, a browsing log generation unit 420, a stream segmenter 422, and a media encoder 424. The storage device 406 may be a hard disk drive, a solid state drive, a flash memory, or the like that stores various data and programs. The CPU 402 implements various functions by reading the program stored in the storage device 406 into the memory 404 and executing it. The transmission / reception interface 412 is an interface for connecting to the core network 102, and is an adapter for connecting to Ethernet (registered trademark), a modem for connecting to a public telephone line network, or the like. The input unit 408 may be a keyboard, a mouse, a trackball, a touch panel, a microphone, or the like that receives data input. The output unit 410 may be a display, a printer, a speaker, or the like that outputs data.

  The transmission / reception I / F 412 may be configured using, for example, an OFDM modulation / demodulation unit shown in FIG. The reception operation of the transmission / reception I / F 412 is the same as the operation of the OFDM demodulator 222 of the user terminal 118-i.

The transmission / reception I / F 412 receives video stream data from the database server 124 (1002), and performs trellis coding processing on the symbol sequence of the received video stream data (1004). The transmission / reception I / F 412 performs primary modulation on the symbol series that has been subjected to trellis encoding processing, and digitally modulates the data represented by the symbol series. The transmission / reception I / F 412 divides the digitally modulated symbol sequence into a plurality of data sequences by the S / P converter 1008. The transmission rate of the data sequence after S / P output is lower than the transmission rate of the original video stream. The transmission / reception I / F 412 performs inverse discrete Fourier transform (IDFT) processing on the data series after the S / P output (1010). The transmission / reception I / F 412 performs P / S conversion on a symbol sequence subjected to inverse fast Fourier transform (IFFT) by a P / S converter 1012 to obtain a transmission digital data sequence. The transmission / reception I / F 412 performs continuation (D / A conversion) on the transmission digital data sequence (1016). The transmission / reception I / F 412 multiplies the transmission digital data sequence by cos (2πf _c t) to obtain an in-phase component, and multiplies the transmission digital data sequence by −sin (2πf _c t) to obtain a quadrature phase component. The transmission / reception I / F 412 amplifies the obtained in-phase component and quadrature component by the amplifier 1018 and transmits the amplified signal through the antenna 1020.

  The content search unit 414 searches the database server 124 for the content specified by the selection signal from the user terminal 118-i. The search information generation unit 416 generates content sequence information searched in response to the selection signal from the user terminal 118-i in a form associated with the “user id” i, and The sequence information is sent to the search log generation unit 418. The search log generation unit 418 generates a search log by assigning a search date and time to information related to the searched content sequence. The search log generation unit 418 sends a search log obtained by adding the search date and time to the information related to the searched content sequence to the browsing log generation unit 420. The browsing log generation unit 420 determines whether the search based on the selection signal from the user terminal 118-i corresponds to browsing or simply searches based on the time when the user i actually viewed the content. To do. In some cases, the user i sends a selection signal from the user terminal 118-i in the process of zapping a program (channel), and the content is recorded in the search log. This is because there are cases where viewing is performed for the purpose of browsing. The browsing log generation unit 420 outputs, as a browsing log, a search log sent from the search log generation unit 418 that corresponds to browsing by a selection signal from the user terminal 118-i.

  Media encoder 424 receives the real-time video stream signal from database server 124 and encodes and encapsulates the received real-time video stream signal for distribution. The encoding is H.264. It is performed in a format receivable by the user terminal 118-i, such as H.264 video and HE-AAC audio. A receivable distribution format is an MPEG-2 transport stream. The media encoder 424 transmits the real-time video stream packet encoded with the MPEG-2 transport stream to the stream segmenter 422 via the LAN. Based on the input from the media encoder 424, the stream segmenter 422 A plurality of video stream segment files including a plurality of transport stream (ts) files including a plurality of segments of an MPEG-2 transport stream carrying an H.264 video stream are generated.

(4) Database Server FIG. 5 is a diagram illustrating a hardware configuration of the database server 124.

  The database server 500 includes a content search information database 502, a user browsing log database 504, a user search log database 506, a user personal information database 508, a content database 510, a fragment-pointer correspondence table 512, and an SNS service provider address. A database 514 and a user posting history database 516 are included. Content search information database 502, user browsing log database 504, user search log database 506, and user personal information database 508 form a user information area indexed by “user id” i, content database 510, The fragment-pointer correspondence table 512 forms a content area indexed by “content id” l, and the SNS service provider address database 514 and the user posting history database 516 form an SNS service provider information area.

  The content search information database 502 stores information related to the content sequence searched in response to the selection signal from the user terminal 118-i generated by the search information generation unit 416. Information regarding the retrieved content sequence is stored in association with "user id" i. The user search log database 506 stores a search log generated by adding a search date and time to information related to a content sequence searched by the search log generation unit 418. The search log is stored in a form associated with “user id” i. The user browsing log database 504 stores the browsing log generated by the browsing log generation unit 420 extracting and searching the search log corresponding to the browsing by the selection signal from the user terminal 118-i. For each “user id” i, the user personal information database 508 stores the personal information of the user i, that is, the gender, age, address, occupation, terminal used, presence of credit, point balance, e-mail transmission of the user i. Stores presence and absence.

  The content database 510 stores content in units of video stream fragments obtained by dividing a real-time video stream into arbitrary lengths for each “content id” l. Each video stream fragment consists of encoded data for each fragment and a header attached to each encoded data. Distribution of the real-time video stream may be performed in units of video stream fragments. The fragment-pointer correspondence table 512 stores the correspondence between each video stream fragment and a pointer that specifies the storage location of the fragment in the content database 510.

  The SNS service provider address database 514 stores address information for each SNS service provider 116. The user posting history database 516 stores a series of video stream fragments posted by the user i in association with the “user id” i.

(5) SNS Server, Database Server, and Web Server FIG. 6 is a diagram illustrating a hardware configuration of the SNS server 128.

  The SNS server 600 includes a CPU 602, a memory 604, a storage device 606, an input unit 608, an output unit 610, a transmission / reception interface (I / F) 612, a video stream fragment reception unit 614, and a message reception unit 616. , A message posting unit 618 and a video stream fragment posting unit 620. The CPU 602, the memory 604, the storage device 606, the input unit 608, the output unit 610, and the transmission / reception interface (I / F) 612 are the same as those of the content distribution server 122.

  The video stream fragment receiving unit 614 receives a video stream fragment posted to an SNS site such as Twitter (trademark) from the content provider 114 or the user terminal 118-i. The video stream fragment receiving unit 614 can cooperate with the content provider 114. When the user terminal 118-i transmits a video stream fragment posting request to the SNS service provider 116 via the content provider 114, the content provider 114 A video stream fragment posted from 114 may be received. The video stream fragment receiving unit 614 receives the video stream fragment posted from the user terminal 118-i when the user terminal 118-i downloads the video stream fragment from the content provider 114 and then uploads it. May be. The message receiving unit 616 receives a posted message from the user terminal 118-i. The message posting unit 618 posts the received message on the SNS site. The video stream fragment posting unit 620 posts the posted video stream fragment on the SNS site.

  FIG. 7 is a diagram illustrating a hardware configuration of the database server 130.

  The database server 700 includes a message posting history database 702, a video stream fragment posting history database 704, a user personal information database 706, a message database 708, a video stream fragment database 710, a content provider address database 712, and a user posting history. Database 714. The message posting history database 702, the video stream fragment posting history database 704, and the user personal information database 706 form a user information area indexed by “user id” i, and the message database 708 and the video stream fragment database 710 are The SNS area is formed, and the content provider address database 712 and the user posting history database 714 form a content provider information area.

  The message posting history database 702 stores, for each “user id” i, a sequence of messages posted by the user i to the SNS service provider 116 with the date and time of posting. The video stream fragment posting history database 704 stores, for each “user id” i, a sequence of video stream fragments posted by the user i to the SNS service provider 116 with the date and time of posting. The user personal information database 706 stores, for each “user id” i, gender, age, address, occupation, terminal used, presence / absence of credit, point balance, presence / absence of e-mail transmission, and the like.

  The message database 708 stores messages that are posted and posted on the SNS site, and the video stream fragment database 710 stores video stream fragments that are posted and posted on the SNS site. The content provider address database 712 stores address information for each content provider 114. The user posting history database 714 includes, for each content identified by “content id” l and for each posted message, a sequence of “user id” that posted the content, and “user id” that posted the message. The sequence is stored.

  FIG. 8 is a diagram illustrating a hardware configuration of the Web servers 120 and 126.

  The Web server 400 includes a CPU 402, a memory 404, a storage device 406, an input unit 408, a transmission / reception interface 410, and an output unit 412. The CPU 602, the memory 604, the storage device 606, the input unit 608, the output unit 610, and the transmission / reception interface (I / F) 612 are the same as those of the content distribution server 122.

(6) Distribution of Real-Time Video Stream FIG. 10 is a diagram showing how the real-time video stream is stored in the content database 510 of the database server 124.

  The content database 510 stores content in units of video stream fragments obtained by dividing a real-time video stream into arbitrary lengths for each “content id” l. In this storage method, while a real-time video stream is viewed on the user terminal 118-i, posting of the video stream fragment at an arbitrary position of the real-time video stream to the SNS site can be easily performed using only the user terminal 118-i. Make possible by way. Each video stream fragment includes encoded data for each fragment, a header attached to each encoded data, and a prefix portion indicating a unique type of file.

  For example, a unique type consisting of four alphabetic characters may be assigned to the prefix portion 902 according to the type of data to be stored. The header portion 904 stores the frame size of the encoded data, the length of the reproduction time, address information indicating the storage position of the encoded data, and header information such as decoding and display time. Here, for example, if only one header part is provided in one real-time video stream segment, the header information is stored in the one header part, so the header is proportional to the playback time length of the real-time video stream. The size of the part increases. As a result, even when playing back while downloading, as in progressive download, it is necessary to obtain the header portion before starting playback, and there is a problem that the waiting time until the playback time is increased. Therefore, in this embodiment, the header portion 904 is provided for each video stream fragment.

  The encoded data is stored in the order of decoding alternately between audio frames and video frames in units of frames. At the time of reproduction, the encoded data is obtained as frame data based on the address by specifying the storage address of the frame corresponding to the desired reproduction time with reference to the header portion.

  FIG. 11 is a diagram showing delivery of a real-time video stream according to the RTP (Real Time Transport) protocol.

The RTP protocol is a protocol for packetizing real-time data such as video and audio and transmitting it on an IP network. In streaming according to the RTP protocol, the user terminal 118-i receives content stored in the content distribution server 122 in the following procedure. That is,
Procedure 1. Address information of the content distribution server 122 for acquiring encoded data of video and audio is acquired.

  Procedure 2. A session is established between the user terminal 118-i and the content distribution server 122.

  Procedure 3. An RTP packet storing video and audio encoded data is received.

For example, RTSP (Real Time Streaming Protocol) can be used as a protocol for controlling communication between the content distribution server and the user terminal 118-i, and playback control such as playback start, end, and pause is performed. Can be executed as a command according to RTSP. For transmission / reception of RTSP data, a communication channel different from RTP can be used, and a reliable transfer control protocol (Transmission Control Protocol (TCP)) can be used for a lower layer.

  FIG. 12 is a diagram illustrating a data structure of an RTP packet.

  The RTP header portion 1202 is a counter of an RTP packet, a payload type that is a value indicating the identification information and playback time of video encoded data and audio encoded data stored in the RTP payload 1204, and the type of real-time video stream to be transmitted. It includes a sequence number and a time stamp that is the sampling time of the first byte of payload data. The RTP payload portion 1204 includes a payload header 1206 and payload data 1208. The payload header 1206 includes header information specific to the encoding method, and the payload data 1208 stores encoded data. The payload format that is a data storage method in the payload portion 1208 is H.264. A format for each encoding method such as H.264 or AAC (Advanced Audio Coding) can be employed.

  FIG. 13 is a diagram illustrating HTTP Live Streaming (HLS) protocol streaming.

  The HTTP Live Streaming protocol streaming requires that the content distribution server 122 encodes a moving image file to be distributed, divides it, and creates a playlist file indicating in what order the files should be reproduced at the same time. The media encoder 424 of the content distribution server 122 transmits the video to be distributed to H.264. The stream segmenter 422 divides the file every specified number of seconds and generates an index file including a playlist at the same time. The user terminal 118-i can reproduce a moving image by downloading the divided files in order according to the index file including the playlist.

  Media encoder 424 receives the real-time video stream signal from database server 124 and encodes and encapsulates the received real-time video stream signal for distribution. The encoding is H.264. It is performed in a format receivable by the user terminal 118-i, such as H.264 video and HE-AAC audio. A receivable distribution format is an MPEG-2 transport stream. The media encoder 424 does not change the setting of the real-time video stream such as the size of the video data or the codec type during the encoding of the real-time video stream, and it is unavoidable to change the setting of the real-time video stream. The media encoder 424 changes the setting of the real-time video stream at the segment boundary and sets a predetermined tag for the subsequent segment. The media encoder 424 transmits the real-time video stream packet encoded with the MPEG-2 transport stream to the stream segmenter 422 via the LAN. Based on the input from the media encoder 424, the stream segmenter 422 A plurality of video stream segment files including a plurality of transport stream (ts) files including a plurality of segments of an MPEG-2 transport stream carrying an H.264 video stream are generated. The stream segmenter 422 generates an index file (M3U8) including a playlist of a plurality of media files. The index file is used to obtain information and location regarding the availability of these multiple media files.

  In HTTP Live Streaming, videos with different bandwidths (symbol rates) such as “Low Quality”, “Middle Quality”, and “High Quality” shown in FIG. 13 are prepared, and the information is described in the index file. be able to. This enables the user terminal 118-i that reproduces the moving image to switch to the moving image having a different bandwidth according to its own environment.

  FIG. 14 is a sequence diagram showing establishment of a session between the user terminal 118-i and the content distribution server 122.

  The NodeB 110 and the eNodeB 112 transmit a synchronization signal used for a cell search by the user terminal 118-i via an SCH (Synchronization Channel). The user terminal 118-i searches for and acquires an SCH for synchronization (step S1402). When the user terminal 118-i supplements the SCH, the user terminal 118-i establishes synchronization and acquires the cell id. The NodeB 110 and the eNodeB 112 include minimum information such as a system bandwidth, a system frame number, and the number of transmission antennas that the user terminal 118-i should read first after a cell search via a PBCH (Physical Broadcast Channel). A signal is being transmitted. The user terminal 118-i acquires information specific to the NodeB 110 or the eNodeB 112 such as the system bandwidth, the system frame number, and the number of transmission antennas by supplementing the P-BCH (Primary Broadcast Channel) (step S1404). . The user terminal 118-i acquires information on the PRACH (Physical Random Access Channel) by supplementing the Dynamic Broadcast Channel (D-BCH), and specifies the frequency position of the PRACH (step S1406). The user terminal 118-i transmits the RACH preamble to the NodeB 110 or the eNodeB 112 based on the uplink frequency band and the PRACH frequency position obtained in Step S1406 (Step S1408).

The NodeB 110 or the eNodeB 112 receives the RACH preamble from the user terminal 118-i and performs adaptive bit allocation processing (step S1410). Based on the communication channel conditions estimated from the RACH preamble symbols, the NodeB 110 or eNodeB 112 initiates an adaptive assignment procedure to assign appropriate frequency slots and bits to all user terminals 118-i, and sets the system channel capacity. maximize. j (j = 1,..., N _c ) is a subcarrier number, m (m = 1,..., N _m ) is a number indicating the type of modulation scheme, and H (i, j) is based on a preamble symbol. Given the communication channel frequency response estimated using uplink RACH preamble symbols structured with pilot tones, the carrier to noise power ratio (for user terminal 118-i on subcarrier j under multipath fading environment ( CNR) is
Can be estimated. Here, the variable m is, for example, m = 1 when the modulation scheme is BPSK, m = 2 when QPSK, and m = 3, 16-value QAM when 8-value PSK. When m = 4 and 32-value QAM, m = 5 and when 128-value QAM, m = 7, indicating the number of bits that can be transmitted in one symbol.

If Q () is an error complement function, user terminal 118 on subcarrier j when using the m-bit modulation scheme using estimated carrier-to-noise power ratio R ^(CNR) (i, j, m). The predicted value E ^(BER) (i, j, m) of the bit error rate (BER) characteristic for -i is
It becomes. here,
It is.

By taking the sum of the number of bits that can be allocated across all frequency slots, the overall communication channel condition V _i for each user terminal 118- _i is
It is obtained. V _i is a N _u × 1 matrix. For each component of the matrix M _{i, s,} a matrix in which the corresponding component is 0 when the component is 0 and the corresponding component is 1 when the component is an integer other than 0 is defined as A _{i, s.} To do. For example, if the number of bits that can be allocated to the user terminal 118-i in the frequency slot s is 0, that is, the target PER commonly required in the system regardless of the modulation scheme that the user terminal 118-i uses. If the user terminal 118-i cannot use the frequency slot s by not satisfying the characteristic E ^(PER) _{0 ,} the i and s components of the matrix A _{i, s} are 0. On the other hand, when the number of bits that can be allocated to the user terminal 118-i in the slot s is m bits, the i and s components of the matrix A _{i, s} are 1. Depending on the number of user terminals 118-i available for frequency slot s, the overall communication channel condition W _s for slot _s is
It is obtained.

Appropriate frequency slots and bits are adaptively assigned to each user terminal 118-i according to the following criteria, using matrices V _i and W _s . That is,
Standard 1. User terminals 118-i with smaller values of V _i have higher priority in allocation.

Standard 2. For a user terminal 118-i, more frequency slot having smaller values of W _s have a higher priority in the assignment.

By using the above criteria, user terminals 118-i with larger values of V _i and W _s have lower priority, but even so, more flexible frequency slot allocation can be achieved. . The reason is that user terminals 118-i having larger values of V _i and W _s have more opportunities in frequency slot allocation, even if the allocation order is later. Therefore, it is possible to reduce the interruption of communication with the user terminal 118-i due to the frequency slot not being assigned.

  FIG. 15 is a flowchart of adaptive bit allocation processing performed between the NodeB 110 or the eNodeB 112 and the user terminal 118-i.

In step S1504, the NodeB 110 or the eNodeB 112 sets “user id” to i = 1. In step S1506, the NodeB 110 or the eNodeB 112 sets “frequency slot number” to s = 1. The NodeB 110 or the eNodeB 112 sets the initial value E ^(PER) ₀ (i, s) of the packet error rate characteristic to E ^(PER) ₀ (i, s) = 0 (step S1508). In step S1510, the NodeB 110 or the eNodeB 112 sets “Modulation scheme type” to m = 1. The NodeB 110 or the eNodeB 112 sets the initial value E ^(BER) ₀ of the bit error rate to E ^(BER) ₀ = 0. In step S1504, NodeB 110 or eNodeB 112 sets “subcarrier number” to j = 1.

NodeB110 or eNodeB112, based on the uplink RACH preamble symbols received from the user terminal 118-i, in the case of types m of the modulation scheme, the user terminal 118-i at sub-carrier j, the carrier-to-noise power ratio ^{R ( CNR)} (i, j, m) is estimated (step S1516). The NodeB 110 or the eNodeB 112 predicts the bit error rate characteristic E ^(BER) (i, j, m) using the carrier-to-noise power ratio R ^(CNR) (i, j, m) (step S1518). When the bit error rate characteristic satisfies E ^(BER) (i, j, m)> E ^(BER) ₀ , the Node B 110 or the eNode B 112 has E ^(BER) ₀ ← E ^(BER) (i, j, m). (This means the process of substituting the value of E ^(BER) (i, j, m) into the variable E ^(BER) _{0. The} same applies hereinafter) and the process of j _max ← j is performed (step S1520).

The NodeB 110 or the eNodeB 112 determines whether the “subcarrier number” j is smaller than s (N _c +1) / N _s (step S1522). When the “subcarrier number” j is smaller than s (N _c +1) / N _s , the NodeB 110 or the eNodeB 112 performs the process of j ← j + 1 (Step S1524), and the process returns to Step S1516.

If the “subcarrier number” j is greater than or equal to s (N _c +1) / N _s , the NodeB 110 or eNodeB 112 uses the value of j _max and uses the worst BER characteristic B ^(BER) for the frequency slot s. (I, s, m) is obtained, and the packet error rate characteristic E ^(PER) (i, s, m) is predicted (step S1526). When the packet error rate characteristic satisfies E ^(PER) ₀ (i, s) <E ^(PER) (i, s, m) ≦ E ^(PER) ₀ , the NodeB 110 or the eNodeB 112 has E ^(PER) _0. (I, s) ← E ^(PER) (i, s, m) and m _max (i, s) ← m are processed (step S1528). Here, E ^(PER) ₀ is a target PER characteristic commonly required in the system, and m _max (i, s) is a condition E ^(PER) (for user terminal 118-i in slot s. i, s, m) ≦ E ^{(PER) The} maximum m satisfying ₀ .

The NodeB 110 or the eNodeB 112 determines whether the “modulation scheme type” m is smaller than N _m (step S1530). When the “modulation scheme type” m is smaller than N _m , the NodeB 110 or the eNodeB 112 performs the process m ← m + 1 (step S1532), and the process returns to the step S1512. When the modulation scheme type “m” is N _m or more, the NodeB 110 or the eNodeB 112 stores m _max (i, s) of each user terminal 118-i in the slot s (step S1534). The NodeB 110 or the eNodeB 112 Then, it is determined whether or not “frequency slot number” s is smaller than N _s (step S1536) If “frequency slot number” s is smaller than N _s , NodeB 110 or eNodeB 112 determines s ← s + 1. or performs the processing (step S1538), the processing returns. frequency slot number "when s is greater than or equal to _{N s} is Node B 110 or eNodeB112 is" in step S1508 the user id "i is smaller than _{N u} It is determined whether or not (step S1540). When "user id" i is smaller than _{N u} is the NodeB110 or eNodeB112, i ← i + 1 of the processing carried out (step S1542), the process returns to step S1506. When "user id" i is greater than or equal to _{N u} is Node B 110 or eNodeB112 the priority slot for each user terminal 118-i, and according to the priority of the bit allocation for each user terminal 118-i, the frequency slot And adaptively assign bits m of the modulation scheme.

  Returning to FIG. 14 again, the NodeB 110 or the eNodeB 112 transmits frequency slot, modulation bit, and time slot allocation information to the user terminal 118-i (step S1412). The user terminal 118-i transmits a response to the notification of the frequency slot, the number of modulation symbol bits, and the time slot allocation information to the NodeB 110 or the eNodeB 112 (step S1414). The user terminal 118-i transmits a video stream distribution request to the NodeB 110 or the eNodeB 112 (step S1416), and the NodeB 110 or eNodeB 112 transmits the video stream distribution request to the content distribution server 122 (step S1418). At this stage, the user terminal 118-i and the content distribution server 122 are ready for data communication (step S1420). The content distribution server 122 transmits the program guide to the NodeB 110 or the eNodeB 112 (step S1422), and the NodeB 110 or eNodeB 112 transmits the program guide to the user terminal 118-i (step S1424).

  For example, the program guide may be configured as shown in FIG. In the illustrated example, the horizontal direction (longitudinal direction) of the display unit 210 corresponds to each program channel, and the vertical direction corresponds to each time slot. As shown in the figure, the program guide shown in FIG. 16 can be freely scrolled in the longitudinal direction, the longitudinal direction, and the oblique direction, and can also be rotated to draw a circle. For example, the program channels include “Abema News”, “Live Sports”, “Sport 1”, and “Sport 2”. Among these, “Abema News” and “Live Sports” are live, that is, live broadcast. “Sport 1” and “Sport 2” may be live broadcast or video recording.

  As described above, the decisive difference between the video stream distribution of the present embodiment and the conventional Video On-Demand stream distribution is that (1) each program (program) is distributed according to the schedule determined by the program table, (2) Live, that is, it is possible to view live broadcasts. According to the video stream distribution according to the present embodiment, the reserved viewing of the program and the reserved recording of the program can be viewed by designating the program channel and the time zone by the above program table, and the program missed in the past It is also possible to view by specifying in the program guide.

  Returning again to FIG. 14, in response to receiving the program guide, the user terminal 118-i transmits a selection signal indicating the program channel in which the program selected by the user i is distributed to the NodeB 110 or the eNodeB 112 (step S1426), NodeB 110 or eNodeB 112 transmits the selection signal to content distribution server 122 (step S1428). The selection signal is used when viewing a program such as a live broadcast or a recorded broadcast distributed by the content distribution server 122 according to the program guide, and when viewing a program already distributed by the content distribution server 122 (time-shifted viewing). In both cases, the content is sent from the user terminal 118-i to the content distribution server 122 via the NodeB 110 or the eNodeB 112. The selection signal is used to specify a program channel to be selected when viewing a currently distributed program or a program to be distributed in the future. In the case of so-called time-shifted viewing, a content is specified. Used to do. The content distribution server 122 that has received the selection signal performs a symbol rate (bandwidth) negotiation with the user terminal 118-i (step S1430).

  The bandwidth negotiation performed between the content distribution server 122 and the user terminal 118-i is performed by, for example, a hierarchical QoS (Quality of Service) control function in the case of distribution of a real-time video stream according to the RTP protocol. Is called.

  FIG. 17 is a diagram showing a configuration of a hierarchical QoS control function according to the RTP protocol.

The content database 510 of the database server 124 stores, for example, content encoded at a plurality of encoding rates of F ₁ [Gbps], F ₁ [Gbps], F ₃ [Gbps],. When the transfer rate is adjusted by bandwidth control between the server 122 and the user terminal 118-i, the data amount is adjusted by selecting the content. The content distribution server 122 stores content information and an MVX file describing server information, and selects an optimal content by a bandwidth negotiation function when a session is established between the user terminal 118-i and the content distribution server 122. . In the MVX file describing the content information and server information, the number of media data held by the content and information on the bandwidth are described. The congestion prediction and detection function, transfer rate control function, and limited retransmission function are the same as those in the frame thinning-out type video distribution system, but if the bandwidth is increased or decreased in the congestion prediction and detection function, the hierarchical content The content is switched by the selection function.

  The bandwidth negotiation function is a system bandwidth that can be received from the state of the mobile communication network 104 to which the user terminal 118-i is connected when the user terminal 118-i establishes an initial session with the content distribution server 122. This function recognizes the width and notifies the content distribution server 122 of the width. The bandwidth negotiation function according to the RTP protocol performs session management by RTSP and RTCP, and performs bandwidth negotiation when an initial session is established using RTSP and RTCP. The content distribution server 122 selects and distributes the optimum content for the notified band from among the plurality of hierarchical contents held as the content.

  The transfer rate control function of frame decimation-type QoS control uses a frame rate control function to thin out moving image frames. Therefore, there is a tendency for the frame rate to decrease extremely during congestion, and it seems like a continuous still screen. In some cases, the playback quality deteriorates due to the playback of the video. On the other hand, the hierarchical QoS control adds a hierarchical content selection function as one function of the transfer rate control function, and can estimate the available bandwidth dynamically by the congestion prediction and detection function. The content selection function controls the transfer rate by dynamically switching to the optimum content based on this bandwidth. In such a hierarchical QoS control method, the transfer rate control does not control the bandwidth by adjusting only the frame rate unlike the frame thinning-out QoS control, so that a freeze time occurs on the playback side even at the time of congestion. It is difficult to achieve smooth playback.

  FIG. 18 is a diagram illustrating a configuration of a QoS control function according to the HTTP Live Streaming (HLS) protocol.

  In the reproduction of HTTP Live Streaming, the user terminal 118-i reads the playlist of the index file (M3U8), accesses the divided media files in the order shown in the playlist, and performs the reproduction. First, read the top index file, then access and play the media file URL described in the index file, and then access and play the media file URL listed next. Are played sequentially. Finally, the index file is read again and the playback ends. For this reason, in normal streaming playback, once a connection is established, the connection is not disconnected until the end of playback. However, in HTTP Live Streaming playback, connection establishment and disconnection are repeated each time a different file is accessed.

  In the reproduction of HTTP Live Streaming, videos with different bandwidths (symbol rates) such as “Low Quality”, “Middle Quality”, and “High Quality” shown in FIG. 13 are prepared, and the information is stored in the index file. Can be described. This enables the user terminal 118-i that reproduces the moving image to switch to the moving image having a different bandwidth according to its own environment. For example, when the environment of the mobile communication network 104 that handles the user terminal 118-i is deteriorated, it is possible to switch to a moving image with a lower bandwidth than now. In addition, when there are a plurality of content distribution servers 122 that distribute moving images as well as information of different bandwidths, the information can be described in an indexable file. This means that even when a failure occurs in any of the content distribution servers 122, even if the video stream cannot be reproduced, the user terminal 118-i does not have another content described in the index file. By accessing the distribution server 122, it is possible to reproduce a moving image.

In addition to the RTP protocol and the HLS protocol, QoS control according to MPEG-DASH (Dynamic Adaptive Streaming over HTTP) may be performed. In the delivery of real-time video stream in accordance with MPEG-DASH, variations in watch videos in a variety of user terminals 118-i, considering the user's environment bandwidth such, the symbol rate so that reproduction is not interrupted By doing so, it is possible to view the moving image with the optimum quality for the system band. For example, when the mobile communication network 104 is congested and the bandwidth is narrow, if the video is distributed at a high bit rate, playback may be interrupted, so the bit rate is changed to an optimal one, Ensure that playback is not interrupted.

  In order to switch the bit rate, media files corresponding to a plurality of bit rates are prepared in advance in the database server 124 of the content provider 114, and information about these is described in an MPD (Media Presentation Description) file. . The user terminal 118-i first acquires the MPD file and executes analysis. Information necessary for streaming delivery such as program timing, media file acquisition destination, maximum bit rate, and minimum bit rate is acquired by analysis, a video stream segment is acquired using an HTTP GET request, and streaming is started. After a certain amount of buffering, the system bandwidth is also monitored, the bit rate is determined by this measurement, and a sufficient buffer amount is maintained and secured.

  FIG. 19 is a sequence diagram of a symbol rate (bandwidth) negotiation performed between the content distribution server 122 and the user terminal 118-i.

The user terminal 118-i that has received the program guide from the content distribution server 122 transmits a selection signal to the content distribution server 122 via the NodeB 110 or the eNodeB 112 (steps S1912 and S1914). Content delivery server 122 which has received the selection signal transmits a lowest real-time video stream symbol rate _{F 1} of the program (program) to the Node B 110 or ENodeB112 (step S1916), Node B 110 or ENodeB112 causes the user terminal 118-i The real-time video stream is transmitted (step S1918). The user terminal 118-i demodulates and decodes the real-time video stream of the lowest symbol rate _{F 1} received, estimates the bit error rate (step S1920). The user terminal 118-i is, it is determined whether increasing the received symbol rate _{F 1} based on the estimated bit error rate (step S1922). At this time, when the estimated bit error rate is extremely low and it is difficult to estimate the signal power to noise power ratio (SNR), the user terminal 118-i increases the transmission symbol rate and decreases the modulation index. The content distribution server 122 is requested to transmit. The user terminal 118-i transmits a symbol rate increase request signal to the NodeB 110 or the eNodeB 112 (step S1924), and the NodeB 110 or eNodeB 112 transmits the symbol rate increase request signal to the content distribution server 122 (step S1926). Content delivery server 122 having received the symbol rate increase request signal, and transmitting real-time video stream next lower symbol rate _{F 2} of the program in the Node B 110 or ENodeB112 (step S1928), Node B 110 or ENodeB112 the user terminal 118-i The real-time video stream is transmitted to (step S1930). By repeating this procedure, the highest symbol rate that can be received in the current environment of the mobile communication network in which the user terminal 118-i is handled is determined.

  Referring back to FIG. 14, once the highest symbol rate that can be received in the current environment of the mobile communication network in which the user terminal 118-i is handled is determined, the content distribution server 122 determines the determination. Distribution of the real-time video stream of the program selected at the selected symbol rate is started (step S1432).

(7) Zapping Operation During Program Viewing FIG. 20 is a flowchart of the zapping operation during program viewing on the user terminal 118-i. FIG. 21 and FIG. 22 are diagrams illustrating a state of zapping in the horizontal direction (longitudinal direction) on the display unit 210 of the user terminal 118-i. FIG. 23 is a diagram illustrating a state of zapping in the vertical direction on the display unit 210 of the user terminal 118-i.

  As shown in the upper diagram of FIG. 21, in the lateral zapping operation, a session between the user terminal 118-i and the content distribution server 122 is established, and the real-time video stream of the selected program channel is recorded. After the start of reception, the selected main program channel is displayed in the center portion, and two adjacent program channels of the main program channel are displayed in the left and right portions of the main program channel. In this state, the selected main program channel is received and reproduced at a high symbol rate, and two adjacent program channels are received and reproduced at a symbol rate lower than the symbol rate of the main program channel. Two adjacent program channels are displayed smaller than the main program channel. Similarly, in the left diagram of FIG. 23, the selected main program channel is displayed in the center portion, and two adjacent program channels of the main program channel are displayed in the upper and lower portions of the main program channel. Similarly, the selected main program channel is received and reproduced at a high symbol rate, and two adjacent program channels are received and reproduced at a symbol rate lower than the symbol rate of the main program channel. Two adjacent program channels are displayed smaller than the main program channel.

When the user i tries to move the display position of the main program channel in one direction with his / her finger as shown in the figure, the user terminal 118-i moves the display position of the main program channel to the input unit 208. Detected as input by user i (step S2004). The CPU 216 of the user terminal 118-i monitors the movement amount of the display position of the main program channel (step S2006). CPU216 of the user terminal 118-i, the amount of movement of the display position of the main program channel determines whether or not a first threshold value _{x 1} or more (step S2008). If the movement amount of the display position of the main program channel is not the first threshold value x ₁ or more, the process returns to step S2006, CPU 216 of user terminal 118-i, the movement of the display position of the main program channel Continue monitoring volume. If the movement amount of the display position of the main program channel is a first threshold value x ₁ above, the user terminal 118-i CPU 216 is the one direction is a moving direction of the reception and reproduction of the adjacent program channels The process ends (step S2010). This state is shown in the lower diagram of FIG. 21 and the middle diagram of FIG.

After completing the reception and reproduction of the adjacent program channel in one direction, the CPU 216 of the user terminal 118-i monitors the movement amount of the display position of the main program channel (step S2012). CPU216 of the user terminal 118-i, the amount of movement of the display position of the main program channel determines whether or not a second threshold value _{x 2} or more (step S2014). If the movement amount of the display position of the main program channel is not the second threshold value x ₂ or more, CPU 216 of user terminal 118-i is, again, the amount of movement of the display position of the main program channel first threshold value determines whether or not x ₁ or more (step S2016). If the amount of movement of the display position of the main program channel is the first threshold value x ₁ or more (x ₁ ≦ (the amount of movement of the display position of the main program channel) <x _2), the process returns to step S2012, The CPU 216 of the user terminal 118-i continues to monitor the movement amount of the display position of the main program channel after the reception and reproduction of the adjacent program channel in one direction which is the first movement direction is finished. If the amount of movement of the display position of the main program channel has become smaller than the first threshold value x ₁ ((the amount of movement of the display position of the main program channel) <x ₁₎ is, CPU 216 of user terminal 118-i is Then, reception and reproduction of the adjacent program channel in one direction which is the first movement direction is started again (step S2018), the processing returns to step S2006, and the CPU 216 of the user terminal 118-i displays the display position of the main program channel Continue monitoring the amount of movement. This condition, the user i is once but the display position of the main program channel is moved beyond the first threshold value x _1, then the threshold x ₁ movement amount of the first display position of the main program channel It means that it has returned to become smaller.

In step S2014, the movement amount of the display position of the main program channel if the second threshold x ₂ or more, the one direction is the first direction of movement yet other direction of the adjacent program channels in the opposite direction Reception and playback of the adjacent adjacent program channel is started (step S2020). The state at this point is shown in the lower diagram of FIG. 22 and the right diagram of FIG. After starting the reception and playback of the adjacent program channel adjacent to the adjacent program channel in the other direction opposite to the one direction, the CPU 216 of the user terminal 118-i monitors the movement amount of the display position of the main program channel. (Step S2022). The CPU 216 of the user terminal 118-i determines whether or not the adjacent program channel in the other direction opposite to the one direction which is the first movement direction has reached the initial position (center portion) of the main program channel. (Step S2024). When the adjacent program channel in the other direction opposite to the one direction has reached the initial position (middle portion) of the main program channel, the CPU 216 of the user terminal 118-i is in the first moving direction. Receiving and playing back the adjacent program channel in the other direction opposite to one direction at a high symbol rate to produce a precise movie, and receiving and playing back the original main program channel at a low symbol rate to produce a coarse movie It is displayed (step S2028). In this state, the adjacent program channel in the other direction opposite to the first moving direction is the main program channel, and the CPU 216 of the user terminal 118-i A selection signal designating the program channel is generated and transmitted to the content distribution server 122. The search log generation unit 418 of the content distribution server 122 generates a search log, transmits the search log to the database server 124, and the database server 124 stores the search log in the user search log database 506.

If it is determined in step S2024 that the adjacent program channel in the other direction opposite to the first moving direction has not reached the initial position (center portion) of the main program channel, the user terminal 118-i the CPU216, the movement amount of the display position of the main program channel is equal to or second threshold value _{x 2} or more (step S2026). If the amount of movement of the display position of the main program channel is a second threshold value x ₂ or more, the process returns to step S2022, the user terminal 118-i CPU 216 is the movement amount of the display position of the main program channel Continue monitoring. In step S2026, when the movement amount of the display position of the main program channel is smaller than the second threshold value _{x 2,} the process returns to step S2016, CPU 216 of user terminal 118-i is again the main program movement amount of the display position of the channel is equal to or the first threshold value x ₁ or more.

If the amount of movement of the display position of the main program channel is the first threshold value x ₁ or more (x ₁ ≦ (the amount of movement of the display position of the main program channel) <x _2), the process returns to step S2012, The CPU 216 of the user terminal 118-i continues to monitor the movement amount of the display position of the main program channel after completing the reception and reproduction of the adjacent program channel in one direction. This condition, the user i is once but the display position of the main program channel is moved beyond the second threshold value x _2, then the threshold x ₂ movement amount of the second display position of the main program channel It means that it has returned to become smaller.

If the amount of movement of the display position of the main program channel has become smaller than the first threshold value x ₁ ((the amount of movement of the display position of the main program channel) <x ₁₎ is, CPU 216 of user terminal 118-i is Then, reception and reproduction of the adjacent program channel in one direction which is the first movement direction is started again (step S2018), the process returns to step S2006, and the CPU 216 of the user terminal 118-i displays the display position of the main program channel. Continue monitoring the amount of movement. This condition, the user i is once but moves the display position of the main program channel exceeds the second threshold value x _2, then the threshold x ₁ movement amount of the first display position of the main program channel It means that it has returned to become smaller.

(8) Spreading of video stream fragment to SNS The user terminal 118-i according to the present embodiment specifies an arbitrary playback time of the real-time video stream while viewing the real-time video stream, and the SNS service provider 116 Via, a video stream fragment corresponding to the designated playback time can be posted to the SNS site. FIG. 27 to FIG. 29 are diagrams showing operations when posting a video stream fragment corresponding to the designated playback time to the SNS site.

  As shown in FIG. 27, when the user i touches a paper airplane mark in the lower right portion of the screen of the display unit 210 of the user terminal 118-i, a diffusion screen on which a comment can be input is displayed. As shown in FIG. 28, after user i inputs a comment and touches the display “tweet” in the lower right part of the screen, the video stream fragment and the comment corresponding to the playback time specified in the SNS site are posted. Is done.

  FIG. 24 is a sequence diagram illustrating a first embodiment of spreading of video stream fragments into the SNS.

The content distribution server 122 of the content provider 114 distributes the real-time video stream to the _first user terminal 118-i ₁ (step S2402). At this time, after receiving the real-time video stream, the first user terminal 118-i ₁ temporarily buffers the received real-time video stream and performs buffering after a predetermined time (about 2 seconds) from the time of reception. Play the real-time video stream. When the user i designates a video stream fragment corresponding to the playback time during viewing of the real-time video stream, the first user terminal 118-i ₁ transmits a video stream fragment selection signal to the content provider 114 (step S2404). Here, the RTP header portion 1202 received by the _first user terminal 118-i1 includes a sequence number that is a counter of the RTP packet, a time stamp that is a sampling time of the first byte of payload data, and the like. the first user terminal 118-i ₁ is, as information for specifying the specified video stream fragment, transmits including sequence number and time stamp to the video stream fragment selection signal. In the case of distribution according to the HLS protocol, the index file received by the _first user terminal 118-i ₁ includes information on the positions of a plurality of media files to be reproduced. The terminal 118-i ₁ includes information on the position of the media file as information for designating the designated video stream fragment, and transmits it by including it in the video stream fragment selection signal. Furthermore, in the case of distribution in accordance with the MPEG-DASH (Dynamic Adaptive Streaming HTTP) protocol, the MPD file received by the _first user terminal 118-i ₁ contains information on the program timing and media file acquisition destination. Therefore, information about program timing and media file acquisition destination is included in the video stream fragment selection signal and transmitted.

The content provider 114 that has received the video stream fragment selection signal identifies the selected video stream fragment and stores the identified video stream fragment (step S2406). Here, the header portion 904 of each video stream fragment stored in the content database 510 of the database server 124 stores address information indicating the storage position of the encoded data, and header information such as decoding and display time. Therefore, the content provider 114 can specify the selected video stream fragment based on the information. The first user terminal _{118-i 1} transmits the post request message posting and the selected video streams fragment SNS service provider 116 (step S2408). The SNS service provider 116 stores and displays the posted message (step S2410).

The second user terminal 118-i ₂ transmits a message posted to the SNS service provider 116 and a viewing request for the selected video stream fragment (step S2412). The SNS service provider 116 notifies that there is a request for browsing the message posted to the content provider 114 and the selected video stream fragment (step S2414). The SNS service provider 116 transmits the content of the posted message to the _second user terminal 118-i ₂ (step S2416), and the content provider 114 is selected by the _second user terminal 118-i _2. The transmitted video stream fragment is transmitted (step S2418).

  In this embodiment, the selected video stream fragment is not stored in the database server 130 of the SNS service provider 116.

  Further, according to the present embodiment, by using only the user terminal 118-i, the SNS of the video stream fragment at an arbitrary position of the real-time video stream is viewed while the real-time video stream is viewed on the user terminal 118-i. Posting to the site is possible in a simple way. This can be achieved by using the database server 124 together with the real-time video stream storage method shown in FIG. 10 and the real-time video stream delivery methods shown in FIGS. 11 to 13 and FIGS. It is.

  FIG. 25 is a sequence diagram illustrating a second embodiment of spreading the video stream fragment to the SNS.

The content distribution server 122 of the content provider 114 distributes the real-time video stream to the _first user terminal 118-i ₁ (step S2502). When the user i designates a video stream fragment corresponding to the playback time while viewing the real-time video stream, the first user terminal 118-i ₁ transmits a video stream fragment selection signal to the content provider 114 (step S2504). Here, the RTP header portion 1202 received by the _first user terminal 118-i1 includes a sequence number that is a counter of the RTP packet, a time stamp that is a sampling time of the first byte of payload data, and the like. the first user terminal 118-i ₁ is, as information for specifying the specified video stream fragment, transmits including sequence number and time stamp to the video stream fragment selection signal. In the case of distribution according to the HLS protocol, the index file received by the _first user terminal 118-i ₁ includes information on the positions of a plurality of media files to be reproduced. The terminal 118-i ₁ includes information on the position of the media file as information for designating the designated video stream fragment, and transmits it by including it in the video stream fragment selection signal. Further, in the case of distribution according to the MPEG-DASH protocol, the MPD file received by the _first user terminal 118-i ₁ includes information on the program timing and the acquisition destination of the media file. And information on the acquisition destination of the media file are included in the video stream fragment selection signal and transmitted.

The first user terminal _{118-i 1} downloads the video stream fragments selected from the content provider 114 (step S2506). At this time, the header portion 904 of each video stream fragment stored in the content database 510 of the database server 124 stores address information indicating the storage position of the encoded data and header information such as decoding and display time. Therefore, the content provider 114 can obtain the selected video stream fragment based on the information. The first user terminal _{118-i 1} stores the downloaded selected video stream fragments (step S2508). The first user terminal 118-i ₁ sends a message posting and a posting request for the selected video stream fragment to the SNS service provider 116 (step S2510), and uploads the selected video stream fragment to the SNS service provider 116. (Step S2512). The SNS service provider 116 stores the uploaded selected video stream fragment in the video stream fragment database 710 of the database server 130 (step S2514).

The second user terminal 118-i ₂ transmits a message posted to the SNS service provider 116 and a viewing request for the selected video stream fragment (step S2516). The SNS service provider 116 transmits the content of the posted message to the _second user terminal 118-i ₂ (step S2518), and sends the selected video stream fragment to the second user terminal 118-i _2. Transmit (step S2520).

  According to the present embodiment, by using only the user terminal 118-i, while viewing the real-time video stream at the user terminal 118-i, to the SNS site of the video stream fragment at an arbitrary position of the real-time video stream. Can be posted in a simple way. This can be achieved by using the database server 124 together with the real-time video stream storage method shown in FIG. 10 and the real-time video stream delivery methods shown in FIGS. 11 to 13 and FIGS. It is.

  FIG. 26 is a sequence diagram illustrating a third embodiment of spreading the video stream fragment to the SNS.

The content distribution server 122 of the content provider 114 distributes the real-time video stream to the _first user terminal 118-i ₁ (step S2602). When the user i designates a video stream fragment corresponding to the playback time during viewing of the real-time video stream, the first user terminal 118-i ₁ transmits a video stream fragment selection signal to the content provider 114 (step S2604). Here, the RTP header portion 1202 received by the _first user terminal 118-i1 includes a sequence number that is a counter of the RTP packet, a time stamp that is a sampling time of the first byte of payload data, and the like. the first user terminal 118-i ₁ is, as information for specifying the specified video stream fragment, transmits including sequence number and time stamp to the video stream fragment selection signal. In the case of distribution according to the HLS protocol, the index file received by the _first user terminal 118-i ₁ includes information on the positions of a plurality of media files to be reproduced. The terminal 118-i ₁ includes information on the position of the media file as information for designating the designated video stream fragment, and transmits it by including it in the video stream fragment selection signal. Further, in the case of distribution according to the MPEG-DASH protocol, the MPD file received by the _first user terminal 118-i ₁ includes information on the program timing and the acquisition destination of the media file. And information on the acquisition destination of the media file are included in the video stream fragment selection signal and transmitted.

The content provider 114 that has received the video stream fragment selection signal identifies the selected video stream fragment and stores the identified video stream fragment (step S2606). Here, the header portion 904 of each video stream fragment stored in the content database 510 of the database server 124 stores address information indicating the storage position of the encoded data, and header information such as decoding and display time. Therefore, the content provider 114 can specify the selected video stream fragment based on the information. The first user terminal 118-i ₁ sends a message posting and a posting request for the selected video stream fragment to the content provider 114 (step S2608), and the content provider 114 sends the message posting and the SNS service provider 116 with the message posting and A posting request for the selected video stream fragment is transmitted (step S2616). The SNS service provider 116 stores and displays the posted message (step S2612).

The second user terminal 118-i ₂ transmits a posted message and a request for viewing the selected video stream fragment to the content provider 114 (step S2614), and the content provider 114 transmits the request to the SNS service provider 116. A viewing request for the posted message and the selected video stream fragment is transmitted (step S2616). Content provider 114, the SNS service provider 116 transmits the video stream fragments that have been selected (step S2618), SNS service provider 116, the second user terminal _{118-i 2,} sends a video stream fragments that have been selected (Step S2620). The SNS service provider 116 transmits the content of the posted message to the _second user terminal 118-i ₂ (step S2622).

  According to the present embodiment, by using only the user terminal 118-i, while viewing the real-time video stream at the user terminal 118-i, to the SNS site of the video stream fragment at an arbitrary position of the real-time video stream. Can be posted in a simple way. This can be achieved by using the database server 124 together with the real-time video stream storage method shown in FIG. 10 and the real-time video stream delivery methods shown in FIGS. 11 to 13 and FIGS. It is.

As shown in FIG. 29, when the second user terminal 118-i ₂ browses the selected video stream fragment, “content” stored in the user posting history database 714 of the database server 130 of the SNS service provider 116 is stored. For each content identified by id “l” and for each posted message, the sequence of “user id” that posted the content and the sequence of “user id” that posted the message are displayed in the form of a list. Is done.

  Each step of the above method according to the present invention may be performed by an operator terminal (not shown) having a CPU and a memory. In an embodiment of the present invention, the software program used to execute the above method may be stored in a program storage device such as a digital data storage medium, and these program storage devices Are machine-readable or computer-readable, and these computers or machines encode program instructions as machine-executable programs or computer-executable programs, and the encoded program instructions are the method of the present invention. Some or all of these steps are executed. The program storage device can be, for example, a digital storage, a magnetic storage medium such as a magnetic disk and magnetic tape, a hard drive, or an optically readable digital data storage medium.

  The present invention may be software and / or a combination of software and hardware, for example, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), It may be implemented using a general purpose computer, or any other hardware equivalent.

  The above description merely provides a disclosure of specific embodiments of the invention and is not intended to limit the invention to only the above embodiments. Accordingly, it is recognized that the present invention is not limited to the embodiments described above, but rather, those skilled in the art can devise alternative embodiments that fall within the scope of the present invention.

100: wireless communication network 102: upper network 104: mobile communication network 106: content service router 108: radio network controller (RNC)
110: NodeB
112: eNodeB

Claims (15)

A user terminal including a memory and a processor connected to a content distribution server via a communication network,
A transmission / reception interface for receiving at least three video streams of different content from the content distribution server via the communication network, wherein at least one of the three video streams is received at a high bit rate; The rest of the video stream is received at a low bit rate,
The at least one of the three video streams received at the high bit rate is played as a main program channel in the main program channel region, and the at least one of the three video streams received at the low bit rate A display that plays back the remaining ones as adjacent program channels in at least two adjacent program channel regions each adjacent to a pair of opposing ends of the main program channel region;
The main program channel region is movable in either direction of the at least two adjacent program channel regions in response to a user operation for program channel switching. The user terminal according to claim 1,
When the main program channel area moves in the direction of one of the at least two adjacent program channel areas in response to a user operation, the processor moves the main program channel area. Monitoring
When the movement amount of the main program channel area reaches a predetermined first threshold, the processor reproduces data in the one adjacent program channel area adjacent to the end of the movement direction of the main program channel area. Controlling the transmission / reception interface and the display to end reception and playback of adjacent program channels,
When the amount of movement of the main program channel region reaches a predetermined second threshold, the processor, the other adjacent program channel region adjacent to the end of the main program channel region opposite to the moving direction Controlling the transmission / reception interface and the display to start reception and playback of an adjacent program channel next to the other adjacent program channel being played in
The processor, when the other adjacent program channel area adjacent to the end of the main program channel area in the direction opposite to the moving direction reaches the initial position of the main program channel area, A channel is received and played back at the high bit rate, and the main program channel played back in the main program channel region moved to the initial position of the one adjacent program channel region is received and played back at the low bit rate. A user terminal for controlling the transmission / reception interface and the first display. The user terminal according to claim 1,
The user terminal, wherein the at least three video streams of the different contents are distributed from the content distribution server by designating the main program channel according to a program guide. In the user terminal according to claim 3,
The program guide lists contents distributed in the past by the content distribution server, and by specifying the content distributed in the past according to the program guide, the content distributed in the past is sent from the content distribution server. User terminal to be delivered. The user terminal according to claim 1,
The at least three video streams of the different content are delivered from the content delivery server according to a protocol selected from the group consisting of a real time transport protocol (RTP), an HTTP live streaming (HLS) protocol, and an MPEG-DASH protocol. , User terminal. A method for playing back at least three video streams of different contents in a user terminal including a memory and a processor connected to a content distribution server via a communication network,
Receiving at least one of the three video streams of the different content at the transmit / receive interface from the content distribution server via the communication network, wherein at least one of the three video streams is received at a high bit rate. The remaining of the three video streams are received at a low bit rate,
The at least one of the three video streams received at the high bit rate is played as a main program channel in the main program channel region of the display, and the at least one of the three video streams received at the low bit rate Replaying the rest of the as adjacent program channels in at least two adjacent program channel regions, each adjacent to a pair of opposing ends of the main program channel region of the display,
The video stream playback method, wherein the main program channel region is movable in either direction of the at least two adjacent program channel regions in response to a user operation for switching program channels. The video stream reproduction method according to claim 6, wherein
The amount of movement of the main program channel area when the main program channel area moves in the direction of one of the at least two adjacent program channel areas in response to a user operation. Monitoring steps,
When the movement amount of the main program channel area reaches a predetermined first threshold value, the processor is played back in the one adjacent program channel area adjacent to the end of the movement direction of the main program channel area. Controlling the transmit / receive interface and the display to end reception and playback of adjacent program channels,
When the amount of movement of the main program channel region reaches a predetermined second threshold, the processor, the other adjacent program channel region adjacent to the end of the main program channel region opposite to the moving direction Controlling the transmit / receive interface and the display to start reception and playback of an adjacent program channel further adjacent to the other adjacent program channel being played back in
When the other adjacent program channel region adjacent to the end of the main program channel region in the direction opposite to the moving direction reaches the initial position of the main program channel region, the other adjacent program channel A channel is received and played back at the high bit rate, and the main program channel played back in the main program channel region moved to the initial position of the one adjacent program channel region is received and played back at the low bit rate. A method of playing a video stream, comprising: controlling the transmission / reception interface and the display. The video stream reproduction method according to claim 6, wherein
The video stream playback method, wherein the at least three video streams of the different contents are distributed from the content distribution server by designating the main program channel according to a program guide. The video stream reproduction method according to claim 8,
The program guide lists contents distributed in the past by the content distribution server, and by specifying the content distributed in the past according to the program guide, the content distributed in the past is sent from the content distribution server. User terminal to be delivered. The video stream reproduction method according to claim 6, wherein
The at least three video streams of the different content are delivered from the content delivery server according to a protocol selected from the group consisting of a real time transport protocol (RTP), an HTTP live streaming (HLS) protocol, and an MPEG-DASH protocol. , Video stream playback method. A program for causing a user terminal, which includes a memory and a processor, connected to a content distribution server via a communication network to execute a method of reproducing at least three video streams of different contents, the method comprising:
Receiving at least one of the three video streams of the different content at the transmit / receive interface from the content distribution server via the communication network, wherein at least one of the three video streams is received at a high bit rate. The remaining of the three video streams are received at a low bit rate,
The at least one of the three video streams received at the high bit rate is played as a main program channel in the main program channel region of the display, and the at least one of the three video streams received at the low bit rate Replaying the rest of the as adjacent program channels in at least two adjacent program channel regions, each adjacent to a pair of opposing ends of the main program channel region of the display,
The main program channel region is a video stream playback program that can move in either direction of the at least two adjacent program channel regions in response to a user operation for switching program channels. 12. The video stream playback program according to claim 11, wherein the video stream playback method includes:
The amount of movement of the main program channel area when the main program channel area moves in the direction of one of the at least two adjacent program channel areas in response to a user operation. Monitoring steps,
When the movement amount of the main program channel area reaches a predetermined first threshold value, the processor is played back in the one adjacent program channel area adjacent to the end of the movement direction of the main program channel area. Controlling the transmit / receive interface and the display to end reception and playback of adjacent program channels,
When the amount of movement of the main program channel region reaches a predetermined second threshold, the processor, the other adjacent program channel region adjacent to the end of the main program channel region opposite to the moving direction Controlling the transmit / receive interface and the display to start reception and playback of an adjacent program channel further adjacent to the other adjacent program channel being played back in
When the other adjacent program channel region adjacent to the end of the main program channel region in the direction opposite to the moving direction reaches the initial position of the main program channel region, the other adjacent program channel A channel is received and played back at the high bit rate, and the main program channel played back in the main program channel region moved to the initial position of the one adjacent program channel region is received and played back at the low bit rate. A video stream playback program comprising: controlling the transmission / reception interface and the display. The video stream playback program according to claim 11, wherein
The video stream playback program, wherein the at least three video streams of the different contents are distributed from the content distribution server by designating the main program channel according to a program guide. The video stream playback method according to claim 13,
The program guide lists contents distributed in the past by the content distribution server, and by specifying the content distributed in the past according to the program guide, the content distributed in the past is sent from the content distribution server. User terminal to be delivered. The video stream playback program according to claim 11, wherein
The at least three video streams of the different content are delivered from the content delivery server according to a protocol selected from the group consisting of a real time transport protocol (RTP), an HTTP live streaming (HLS) protocol, and an MPEG-DASH protocol. , Video stream playback program.