Viewing terminal and viewing control program

Abstract

To provide a viewing terminal capable of switching between a viewing form via communication and a viewing form via broadcast depending on a communication state when a moving image is viewed in a simultaneous distribution service of broadcast and communication.SOLUTION: A viewing terminal 9 includes a segment acquisition unit 91L that acquires segments of moving image content from a local distribution server of a home gateway 8, a segment acquisition unit 91H that acquires segments from a distribution server via a communication line 6, a clocking unit 921 that clocks a predetermined delay time, a segment switching acquisition unit 920 that requests segments via the segment acquisition unit 91H and requests and acquires segments that could not be acquired from the segment acquisition unit 91H within the delay time via the segment acquisition unit 91L, and a decoding processing unit 93 that decodes the segments acquired by the segment switching acquisition unit 920.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a viewing terminal and a viewing control program for viewing video content simultaneously distributed by broadcasting and communication.

Background Art

[0002] In recent years, simultaneous distribution services of broadcasting and communication (Internet) by broadcasters have begun, and the same video content (program) as the broadcast can be viewed on viewing terminals such as a PC (personal computer) and a smartphone connected to the Internet in the same time zone. In video distribution via the Internet, distribution methods using ABR (Adaptive bit-rate) technologies such as MPEG-DASH (Non-Patent Document 1) and HLS (Non-Patent Document 2) are often used.

[0003] In these methods, video content is encoded in a plurality of qualities with different bitrates and resolutions, and further divided into segment files of about several seconds. The viewing terminal determines which quality segment to acquire according to the changing congestion situation of the Internet. That is, the viewing terminal acquires a high-quality segment when the network situation is good, and acquires a low-quality segment when it is bad and plays it back. As a result, viewers can view a video with as high a quality as possible while suppressing video freezes and the like on the viewing terminal. The control for selecting the quality according to this network situation is called ABR control.

[0004] Particularly in recent years, CMAF (Non-Patent Document 3), which is a common container format for MPEG-DASH and HLS, has begun to be used. For example, Patent Document 1 discloses a technique for viewing video content by broadcasting on a viewing terminal such as a PC or a smartphone using CMAF. Specifically, the transmitting device transmits video content as MMT (MPEG Media Transport) packets by CMAF over a broadcast wave. Then, a receiving device equipped with an HGW (Home Gateway) receives the broadcast wave in the CMAF / MMT format and distributes the received CAMF to the viewing terminal via IP unicast from the distribution server owned by the receiving device itself. As a result, viewers can watch the content on a viewing terminal connected to the LAN (Local Area Network) within the home.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Non-Patent Documents

[0006]

Non-Patent Document 1

Non-Patent Document 2

Non-Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0007] In the conventional simultaneous distribution service of broadcasting and communication, in the form of viewing a video in CMAF format via communication (Internet), when there is sufficient communication bandwidth, it is possible to view the video with a quality higher than that of television broadcasting. On the other hand, in the conventional simultaneous distribution service, when the communication is congested, the video viewing via communication may have a lower quality than that of television broadcasting.

[0008] On the other hand, in the form of receiving a broadcast wave with a receiving device equipped with an HGW and viewing a video via a LAN, it is possible to view a video with the same quality as stable broadcasting. However, in this case, it is difficult to view a video with a quality higher than the broadcast bandwidth.

[0009] Therefore, an object of the present invention is to provide a viewing terminal and a viewing control program capable of switching between viewing forms via communication or via broadcasting according to the communication state in video viewing in a simultaneous distribution service of broadcasting and communication.

Means for Solving the Problems

[0010] In order to solve the above problems, a viewing terminal according to the present invention includes a local distribution server that stores video content distributed by a broadcast wave in units of segments, and a distribution server that distributes video with a higher bit rate than the video content simultaneously distributed with the video content via a communication line in units of segments. A viewing terminal that switches and acquires segments according to the communication state and plays them, and includes a broadcast segment acquisition unit, a communication segment acquisition unit, a timing unit, a segment switching acquisition unit, and a decoding processing unit.

[0011] In such a configuration, the viewing terminal acquires segments from the local distribution server in response to a request by the broadcast segment acquisition unit. Since the local distribution server acquires segments via a broadcast wave, the broadcast segment acquisition unit can stably acquire segments. In addition, the viewing terminal acquires segments from the distribution server in response to a request by the communication segment acquisition unit. Since the distribution server distributes segments via a communication line, the communication segment acquisition unit may have unstable segment acquisition depending on the communication state, but can acquire high-quality segments according to the bandwidth. In addition, the viewing terminal measures a predetermined delay time in response to an instruction by the timing unit.

[0012] Then, the viewing terminal instructs the timing unit to measure the delay time by the segment switching acquisition unit, and requests a segment via the communication segment acquisition unit. Then, for segments that could not be acquired from the communication segment acquisition unit within the delay time due to the communication state, the viewing terminal requests and acquires the segments via the broadcast segment acquisition unit by the segment switching acquisition unit. Then, the viewing terminal decodes the segments acquired by the segment switching acquisition unit by the decoding processing unit. Note that the viewing terminal can operate a computer with a program for causing the computer to function as each of the above-described units.

Effect of the Invention

[0013] According to the present invention, in video viewing in a simultaneous distribution service of broadcast and communication, the viewing mode via communication or broadcast can be switched according to the communication state.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0015] Hereinafter, embodiments of the present invention will be described with reference to the drawings. ≪Configuration of Video Distribution System≫ First, with reference to FIG. 1, the configuration of a video viewing system 100 according to an embodiment of the present invention will be described.

[0016] The video viewing system 100 simultaneously distributes video in units of segments by broadcast and communication (Internet), and selects high-quality segments at the viewing terminal 9 to play the video. The video viewing system 100 is composed of the device of the broadcasting station 1 and the device of the viewer 7 (inside the house). Here, only one device of the viewer 7 is shown, but actually there are a plurality according to the number of viewers. Also, between the device of the broadcasting station 1 and the device of the viewer 7, there are a transmitting station 5 for transmitting broadcast waves and a communication line 6 for transmitting communication data (packets).

[0017] <Configuration of the Device of the Broadcasting Station> The device of the broadcasting station 1 is composed of an encoder (live encoder) 2, a broadcast multiplexer 3, and a distribution server 4.

[0018] Encoder 2 encodes video content for simultaneous distribution in both broadcasting and communication (simultaneous distribution video content) into two types of bitrates and packages each encoding result in the form of CMAF (Common Media Application Format). Encoder 2 encodes the simultaneous distribution video content in units of a predetermined time length (segment length) at two different bitrates, namely a broadcast-quality bitrate and a bitrate higher than the broadcast quality. For example, here, Encoder 1 encodes a certain simultaneous distribution video content at two types of bitrates, with 2K (1920×1080 pixels) as the broadcast quality and 4K (3840×2160 pixels) as the quality higher than the broadcast quality, and the segment length is encoded as a fixed length of 1 second. For the sake of convenience, one of the two types of qualities (2K) is relatively called low quality and the other (4K) is called high quality.

[0019] Here, when the number of seconds elapsed from the service start time, which is a predetermined reference time, is t [seconds], as shown in FIG. 2, Encoder 2 encodes the low-quality (2K) segment S L as low t .m4s, and the high-quality (4K) segment S H as high t .m4s into segment data every 1 second.

[0020] Furthermore, Encoder 2 packages the segments in the form of CMAF for different qualities. That is, as shown in FIG. 3, Encoder 2 packages the HLS playlist (index L .m3u8), which is control information indicating the segment acquisition source, etc., and the MPD file (index L .mpd) for MPEG-DASH, and the low-quality segments (…,low t-1 .m4s,low t .m4s,low t+1 .m4s) into CMAF L to generate.

[0021] Also, as shown in FIG. 4, the encoder 2 generates a packaged CMAF with a playlist for HLS (index H .m3u8) and an MPD file for MPEG-DASH (index H .mpd), which are control information indicating the acquisition source of segments and the like, and high-quality segments (…, high t-1 .m4s, high t .m4s, high t+1 .m4s). H Note that since the configuration of CMAF (CMAF L , CMAF H ) is the same as the conventional configuration described in Non-Patent Document 3, a detailed description thereof is omitted. The encoder 2 outputs a low-quality CMAF L to the broadcast multiplexing device 3. Also, the encoder 2 outputs a high-quality CMAF H to the distribution server 4.

[0022] Note that when the encoder 2 outputs segments to the broadcast multiplexing device 3 and the distribution server 4, it may perform encoding by dividing the segments into finer granularity than the segments called chunks without waiting for the completion of encoding of the entire one segment. That is, the encoder 2 may subdivide and encode the segments by using an encoding (chunked encode) used in CMAF-ULL (Ultra Low Latency) and a chunked transfer encoding (CTE) of HTTP (Hyper Text Transfer Protocol). Thereby, the encoder 2 can suppress the encoding delay.

[0023] The broadcast multiplexing device 3 multiplexes the low-quality CMAF (CMAF L ) output from the encoder 2 into a broadcast signal and transmits it to the transmission station 5. ​The broadcast multiplexing device 3 multiplexes, for example, CMAF into a broadcast wave in the MMT (MPEG Media Transport) format (CMAF / MTT format). Since the CMAF / MTT format is an existing format, detailed description thereof is omitted. Also, in addition to CMAF, other transmission control signals (such as MMT-SI [Signaling Information]) are multiplexed into the broadcast wave, but since they are not directly related to the present invention, the description thereof is omitted.

[0024] Then, the broadcast multiplexing device 3 performs broadcasting by means of a broadcast wave via the transmission station 5, using, for example, STL / TTL which is a dedicated fixed wireless line for a broadcasting station. Note that STL (Studio to Transmitter Link) is a line connecting the broadcasting station 1 and the transmission station 5 (parent station). Also, TTL (Transmitter to Transmitter Link) is a line connecting between the transmission stations 5 (parent stations and relay stations).

[0025] The distribution server 4 distributes CMAF (CMAF H ) requested from the viewing terminal 9 via the communication line 6. The distribution server 4 can use a general HTTP server. The distribution server 4 stores the high-quality CMAF output from the encoder 2. H Then, the distribution server 4 transmits a segment corresponding to a request (HTTP request) from the viewing terminal 9 to the requester via the communication line 6. Note that for dispersing the load of the distribution server 4, a content delivery network (CDN: Contents Delivery Network) composed of a plurality of cache servers may be used for the communication line 6.

[0026] <In-house device configuration> The device of the viewer (inside the house) 7 is composed of a home gateway 8 and a viewing terminal 9. Note that the home gateway 8 and the viewing terminal 9 are connected by a home LAN via WiFi or the like. Also, the home gateway 8 may be incorporated in a television receiver (not shown). Further, the home gateway 8 may be incorporated in the viewing terminal 9. In that case, the viewing terminal 9 may communicate with the local distribution server of the home gateway 8 incorporated therein using a loopback address.

[0027] (Configuration of Home Gateway) The home gateway 8 receives low-quality CMAF (CMAF L ) by broadcast wave and distributes it to the viewing terminal 9. The home gateway 8 stores the low-quality CMAF received by broadcast wave L in a local distribution server 82 provided therein, and distributes segments corresponding to requests (HTTP requests) from the viewing terminal 9 to the viewing terminal 9.

[0028] Here, with reference to FIG. 5, a configuration example of the home gateway 8 will be described. As shown in FIG. 5, the home gateway 8 includes a demultiplexing unit 80, a CMAF analysis unit 81, and a local distribution server 82.

[0029] The demultiplexing unit 80 separates the multiplexed broadcast signal. The demultiplexing unit 80 separates CMAF (CMAF L ) multiplexed in the CMAF / MTT format on the broadcast wave. The demultiplexing unit 80 outputs the separated CMAF L to the CMAF analysis unit 81.

[0030] The CMAF analysis unit 81 analyzes the CMAF (CMAF L ) separated by the demultiplexing unit 80 and stores it in the local distribution server 82. Here, the CMAF analysis unit 81 writes the control information in CMAF (see FIG. 3) to the local distribution server 82. Furthermore, the CMAF analysis unit 81 analyzes the control information and writes the segment file to the position (address) on the local distribution server 82 corresponding to the acquisition destination of the segment set in the control information.

[0031] The local distribution server 82 stores CMAF (CMAF L ) and distributes segments in response to requests from the viewing terminal 9. The local distribution server 82 is an HTTP server, and in response to an HTTP request from the viewing terminal 9, it transmits the requested numbered segment from the low-quality CMAF L stored therein to the viewing terminal 9. With the configuration described above, the home gateway 8 can distribute segments of broadcast quality to the viewing terminal 9 by means of CMAF L multiplexed on the broadcast wave. Returning to FIG. 1, the description of the device of the viewer (inside the house) 7 will be continued.

[0032] (Configuration of the viewing terminal) The viewing terminal 9 acquires segments from a distribution server (including a cache server of a CDN) 4 or the home gateway 8 and performs playback. The viewing terminal 9 switches and acquires segments according to the communication state from the local distribution server 82 that stores video content distributed by broadcast wave in units of segments, and the distribution server 4 that distributes video content with a higher bit rate than the video content distributed by broadcast wave in units of segments via the communication line 6, and performs playback. Normally, the viewing terminal 9 acquires high-quality segments packaged in CMAF H from the distribution server 4 via the communication line 6. Then, when the segments acquired via the communication line 6 cannot be acquired even after a predetermined delay time has elapsed, the viewing terminal 9 acquires the corresponding segments from the home gateway 8.

[0033] Here, referring to FIG. 6, a configuration example of the viewing terminal 9 according to an embodiment of the present invention will be described. As shown in FIG. 6, the viewing terminal 9 includes an IF unit 90 (90 H , 90 L ), a segment acquisition unit 91 (91 H , 91 L ), an ABR control unit 92, and a decode processing unit 93.

[0034] The IF unit (communication control unit) 90 transmits and receives data (packets) by communication. The IF unit 90 can be configured by a general communication card (board) or the like. The IF unit 90 H performs packet transmission and reception between the segment acquisition unit 91 H and the distribution server (including the cache server) 4 (see FIG. 1) via the communication line 6. The IF unit 90 L performs packet transmission and reception between the segment acquisition unit 91 L and the local distribution server 82 (see FIG. 1) of the home gateway (HGW) 8.

[0035] The segment acquisition unit 91 acquires the segment requested by the ABR control unit 92 via the IF unit 90. The segment acquisition unit (communication segment acquisition unit) 91 H requests a high-quality segment from the distribution server (including the cache server) 4 via the communication line 6 by an HTTP request in response to an acquisition request from the ABR control unit 92, and acquires (downloads) it. The segment acquisition unit 91 H outputs the acquired segment to the ABR control unit 92. Also, the segment acquisition unit 91 H may be instructed by the ABR control unit 92 to cancel the acquisition of the requested segment. When the segment acquisition unit 91 H is instructed to cancel, it cancels the download of that segment.

[0036] Segment acquisition unit (broadcast segment acquisition unit) 91 L In response to an acquisition request from the ABR control unit 92, it requests and acquires low-quality segments from the local distribution server 82 of the home gateway 8 by means of an HTTP request. The segment acquisition unit 91 L outputs the acquired segments to the ABR control unit 92. Also, the segment acquisition unit 91 L may be instructed by the ABR control unit 92 to cancel the acquisition of the requested segment. When the segment acquisition unit 91 L is instructed to cancel, it cancels the download of that segment. If the download has been completed before cancellation, the segment is discarded by the ABR control unit 92.

[0037] The ABR control unit (adaptive bitrate control unit) 92 monitors the acquisition state of segments and performs control to acquire segments at an optimal bitrate (high quality or low quality). The ABR control unit 92 includes a segment switching acquisition unit 920 and a timing unit 921.

[0038] The segment switching acquisition unit 920 switches and acquires externally specified video content for each segment via the Internet (communication) or via broadcast according to the communication state. The segment switching acquisition unit 920 requests segments via the segment acquisition unit 91 H and, for segments that cannot be acquired by the segment acquisition unit 91 H within a predetermined delay time, acquires them via the segment acquisition unit 91 L . The segment switching acquisition unit 920 outputs the acquired segments to the decoding processing unit 93.

[0039] Basically, the segment switching acquisition unit 920 requests high-quality segments (high t .m4s) from the segment acquisition unit 91 HRequest and obtain it. After the segment switching acquisition unit 920 requests the segment at time t, it instructs the timer unit 921 to measure time for a predetermined period.

[0040] This predetermined time is set to "TL - offset" seconds when the target delay time TL [s] (for example, 3 seconds) for obtaining the segment via the communication line 6 and the time offset [s] (for example, 1 second) required to obtain the segment from the home gateway 8 are considered. Here, subtracting offset from TL is to ensure the time for obtaining the segment from the home gateway 8 in case the segment cannot be obtained from the communication line 6.

[0041] Note that the segment switching acquisition unit 920 may refer to the control information of CMAF H as information for obtaining the segment. Before obtaining the segment, the segment switching acquisition unit 920 H acquires the control information of CMAF. For example, when using the MPD file (index H .mpd) (see Figure 4) for MPEG - DASH as the control information, the segment switching acquisition unit 920 can utilize the information described in the "availabilityTime: delivery time", "target - latency: target delay time (TL)", and "representation: resolution, etc.", which are the attributes of the segment. Note that the offset value may be set as a parameter variable in advance.

[0042] When the segment switching acquisition unit 920 is notified of a timeout (elapse of the delay time "TL - offset" seconds) from the timer unit 921, if the download of the high - quality segment (high t .m4s) at time t has already been completed, it ignores the notification of this timeout. Alternatively, when the download of the segment at time t is completed, the segment switching acquisition unit 920 may instruct the timer unit 921 to stop the timer.

[0043] On the one hand, when the segment switching acquisition unit 920 is notified of a timeout from the timing unit 921, if the download of the high-quality segment (high t .m4s) at time t has not been completed yet, it requests the low-quality segment (low t .m4s) at the same time t from the segment acquisition unit 91 L .

[0044] After the segment switching acquisition unit 920 requests the low-quality segment (low t .m4s) at time t, if the download of the low-quality segment is completed before the download of the high-quality segment (high t .m4s) at the same time t is completed, it instructs the segment acquisition unit 91 H to cancel the acquisition of the high-quality segment (high t .m4s) at time t.

[0045] On the other hand, if the download of the high-quality segment (high t .m4s) at time t is completed before the download of the low-quality segment (low t .m4s) at time t is completed, the segment switching acquisition unit 920 instructs the segment acquisition unit 91 L to cancel the acquisition of the low-quality segment, and if the download of the low-quality segment has already been completed, it discards it. As a result, for two types of segments with different qualities at the same time t, the segment acquired first is output to the decoding processing unit 93, and when acquired simultaneously, the high-quality segment is preferentially output to the decoding processing unit 93.

[0046] The timing unit 921 measures a predetermined delay time. The timing unit 921 can be composed of a general timer. The timing unit 921 is instructed by the segment switching acquisition unit 920 to measure for "TL-offset" seconds, and after the elapse of the delay time, it notifies the segment switching acquisition unit 920 of a timeout. As a result, the ABR control unit 92 can normally acquire high-quality segments, and when communication delays occur due to congestion or the like, it can acquire low-quality segments by broadcast waves without delay.

[0047] The decoding processing unit 93 reproduces the segments downloaded by the ABR control unit 92. The decoding processing unit 93 includes a storage unit 930 and a decoding unit 931.

[0048] The storage unit 930 is a buffer (decoding buffer) that sequentially stores the segments downloaded by the ABR control unit 92. The storage unit 930 can be configured with a general storage medium such as a semiconductor memory. The segments stored in the storage unit 930 are sequentially read out by the decoding unit 931.

[0049] The decoding unit 931 decodes (decodes) the segments stored in the storage unit 930. The decoding unit 931 sequentially reads out the segments stored in the storage unit 930 and decodes them using a method corresponding to the encoding method of the segments, for example, segments in the MP4 format. The decoding unit 931 outputs the decoded video to a display device (monitor), not shown. With the configuration described above, the viewing terminal 9 can switch the viewing mode via communication or via broadcast according to the communication state in video viewing in the simultaneous distribution service of broadcast and communication.

[0050] <ABR Control Operation of Viewing Terminal> Next, with reference to FIG. 7 (refer to FIG. 6 as appropriate for the configuration), the operation of the viewing terminal 9 according to the embodiment of the present invention, mainly the ABR control operation performed by the ABR control unit 92, will be described.

[0051] In step S1, the segment switching acquisition unit 920 starts a request for the segment at time t via the Internet (communication) for the video content (simultaneous distribution video content) specified from the outside. Here, the segment switching acquisition unit 920 instructs the segment acquisition unit 91 H to request a segment. Then, the segment acquisition unit 91 H requests a high-quality segment (high t .m4s) from the distribution server (including the cache server) 4 via the communication line 6 by means of an HTTP request.

[0052] In step S2, the segment switching acquisition unit 920 causes the timer unit 921 to measure the time from time t for "TL-offset" seconds, and the segment acquisition unit 91 H starts acquiring (downloading) the segment (high t .m4s) at time t.

[0053] In step S3, the segment switching acquisition unit 920 determines whether the acquisition (download) of the segment at time t via the Internet (via the communication line 6) has been completed when "TL-offset" seconds have elapsed. Here, if the acquisition of the segment (high t .m4s) has been completed (Yes in step S3), in step S7, the segment switching acquisition unit 920 adds and stores the high-quality segment (high t .m4s) acquired in step S2 in the storage unit 930 of the decoding processing unit 93.

[0054] On the other hand, if the acquisition of the segment (high t .m4s) has not been completed when "TL-offset" seconds have elapsed (No in step S3), in step S4, the segment switching acquisition unit 920 requests and starts acquiring the low-quality segment (low t .m4s) at time t via broadcast. Here, the segment switching acquisition unit 920 instructs the segment acquisition unit 91 L to request a segment. Then, the segment acquisition unit 91 L requests the low-quality segment (lowt Start the acquisition (download) of (.m4s).

[0055] In step S5, the segment switching acquisition unit 920 determines again whether the acquisition of the segment at time t via the Internet has been completed. Here, if the acquisition of the segment (high t .m4s) has been completed (Yes in step S5), in step S6, the segment switching acquisition unit 920 cancels the request for the low-quality segment (low t .m4s) at time t via the home gateway. Here, the segment switching acquisition unit 920 instructs the segment acquisition unit 91 L to cancel the acquisition of the segment. Also, if the acquisition of the segment (low t .m4s) has also been completed, it discards this. Then, the segment switching acquisition unit 920 moves on to step S7. That is, when the acquisition of the segment via the Internet is completed at the time of "TL-offset" seconds elapsed (Yes in step S3), the segment switching acquisition unit 920 is the same as in step S2, and adds and stores the high-quality segment (high t .m4s) obtained in step S2 in the storage unit 930 of the decoding processing unit 93.

[0056] On the other hand, if the acquisition of the segment (high t .m4s) has not been completed yet (No in step S5), in step S8, the segment switching acquisition unit 920 determines whether the acquisition of the segment at time t via the home gateway has been completed. Here, if the acquisition of the segment (low t .m4s) has been completed (Yes in step S8), in step S9, the segment switching acquisition unit 920 cancels the request for the high-quality segment (high t .m4s) at time t via the Internet. Here, the segment switching acquisition unit 920 instructs the segment acquisition unit 91 H to cancel the acquisition of the segment.

[0057] In step S10, the segment switching acquisition unit 920 adds and stores the low-quality segments (low t .m4s) distributed by the broadcast acquired via the home gateway 8 in step S4 in the storage unit 930 of the decoding processing unit 93. On the other hand, when the acquisition of the segment (low t .m4s) is not completed (No in step S8), the segment switching acquisition unit 920 moves the operation back to step S5 again and repeats the determination until the acquisition of the segment at time t via the Internet or the home gateway is completed.

[0058] After the operation in step S7 or step S10, the segment switching acquisition unit 920 switches the time t to the next time t + 1, moves the operation to step S1, and starts requesting the segment at time t + 1. By repeating the above operations, the ABR control unit 92 changes the acquisition path according to the communication situation, acquires the segments without delay, and stores them in the storage unit 930 of the decoding processing unit 93. Then, the decoding processing unit 93 decodes the segments sequentially stored in the storage unit 930 by the decoding unit 931 and plays the video (not shown as a step).

[0059] As a result, the viewing terminal 9 can play a high-quality video via the Internet, and can surely play a video of the broadcast quality even when the communication situation deteriorates due to congestion or the like.

[0060] As described above, the embodiments of the present invention have been described, but the present invention is not limited to these embodiments. Here, when the download of the low-quality segments is completed earlier than the download of the high-quality segments, the segment switching acquisition unit 920 cancels the acquisition of the high-quality segments (step S9 in FIG. 7). However, even in this case, if the download of the high-quality segment is completed before the target delay time TL elapses, the segment switching acquisition unit 920 may preferentially store the high-quality segment in the storage unit 930 of the decoding processing unit 93.

[0061] Also, here, when the download of the high-quality segment is not completed until "TL-offset" seconds have elapsed, the segment switching acquisition unit 920 continues the download of the high-quality segment and requests a low-quality segment (step S4 in FIG. 7). However, in this case, in order to reduce the processing load or the load on the communication line, the segment switching acquisition unit 920 may request a low-quality segment and cancel the download of the high-quality segment.

[0062] Moreover, the viewing terminal 9 is not limited to a device that simply performs video playback, and may be incorporated into a personal computer (PC), a smartphone, or the like. Also, in the above-described embodiment, the viewing terminal 9 has been described as independent hardware. However, the present invention can also be realized by a program for causing hardware resources such as a CPU, a memory, and a hard disk included in a computer to function as the viewing terminal 9 described above. This program may be distributed via a communication line, or may be written on a recording medium such as a CD-ROM or a flash memory and distributed. Also, here, the high-quality segment has been described as 4K and the low-quality segment as 2K, but the two types of quality are not limited to this. For example, the high-quality segment may be 8K, and the low-quality segment may be 4K or 2K.

Explanation of Signs

[0063] 100 Video viewing system 1 Broadcasting station 2 Encoder 3 Broadcast multiplexing device 4 Distribution server 5 Transmission site 6 Communication line 7 Viewer 8 Home gateway 80 Multiplex separation unit 81 CMAF analysis unit 82 Local distribution server 9 Viewing terminal 90 IF unit (communication control unit) 91,91 H Segment acquisition unit (communication segment acquisition unit) 91,91 L Segment acquisition unit (broadcast segment acquisition unit) 92 ABR control unit (adaptive bitrate control unit) 920 Segment switching acquisition unit 921 Timing unit 93 Decoding processing unit 930 Storage unit 931 Decoder

Claims

1. A viewing terminal that obtains and plays segments by switching according to a communication state from a local distribution server that stores video content distributed by a broadcast wave in segment units, and a distribution server that distributes video content with a higher bit rate than the video content simultaneously distributed with the video content via a communication line in segment units, comprising: a broadcast segment acquisition unit that acquires segments from the local distribution server; a communication segment acquisition unit that acquires segments from the distribution server; a timing unit that measures a predetermined delay time; a segment switching acquisition unit that requests segments via the communication segment acquisition unit and, for segments that could not be acquired from the communication segment acquisition unit within the delay time, requests and acquires them via the broadcast segment acquisition unit; a decoding processing unit that decodes the segments acquired by the segment switching acquisition unit; A viewing terminal characterized by comprising the above.

2. The viewing terminal according to claim 1, wherein the delay time is a time obtained by subtracting a predetermined time for acquiring segments from the local distribution server from a predetermined target delay time for acquiring segments from the distribution server.

3. The viewing terminal according to claim 1, wherein when, after the elapse of the delay time, the segment switching acquisition unit has acquired the segment at a certain time from the communication segment acquisition unit before acquiring the segment at the certain time from the broadcast segment acquisition unit, the segment switching acquisition unit aborts the acquisition of the segment at the certain time by the broadcast segment acquisition unit or discards the segment acquired from the broadcast segment acquisition unit.

4. The viewing terminal according to claim 1, wherein when, after the elapse of the delay time, the segment switching acquisition unit has acquired the segment at a certain time from the broadcast segment acquisition unit and has not acquired the segment at the certain time from the communication segment acquisition unit, the segment switching acquisition unit aborts the acquisition of the segment by the communication segment acquisition unit.

5. A program for causing a computer to function as the viewing terminal according to any one of claims 1 to 4.

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