JP2017225164A - Receiving device, receiving method, transmitting device, transmitting method, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the real-time property of reproduced content data while minimizing discontinuity of content data stored after a receiving device receives it at a time of communication delay or processing delay at the receiving device.SOLUTION: A receiving device for receiving, from a transmitting device, one or more segments into which content data is divided requests a prescribed number of segments from a newest segment in reproduction order among one or more segments indicated in a play list if a mode of the receiving device is a streaming reproduction mode.SELECTED DRAWING: Figure 4

Description

The present invention relates to a technique for dividing content data into a plurality of segment data and transmitting each segment data from a transmission device to a reception device.

In recent years, streaming technologies for transmitting and receiving content data in real time, such as network cameras and video conferencing systems, have been put into practical use. With the streaming technology, it is possible to simultaneously reproduce the received content data while receiving the content data.

As such streaming technology, HTTP Live Streaming (Non-Patent Document 1), MPEG-DASH (Non-Patent Document 2), and the like have been standardized. In each of these standards, the transmission device generates a plurality of segment data by dividing content data such as video data and audio data at predetermined time intervals. Further, the transmission device transmits metadata (referred to as a playlist) including location information of each generated segment data, reproduction order, and the like to the reception device. The receiving device acquires segment data based on the location information of each segment data, the playback order, and the like described in the received playlist. As described above, in each of the above-described standards, content data can be streamed by continuously transmitting and receiving playlists and segment data at predetermined time intervals between the transmission device and the reception device.

Also, as a conventional technique that enables streaming of content data, a method has been proposed in which audio / video content is segmented into a plurality of small clips and downloaded and played back simultaneously (Patent Document 1). Patent Document 1 describes storing metadata of a plurality of small clips in a local storage device and starting reproduction of the plurality of small clips. Thereby, the content of the first clip of the plurality of small clips can be displayed while the second clip of the plurality of small clips is being downloaded.

IETF draft HTTP Live Streaming draft-pantos-http-live-streaming-09 ISO / IEC 2309-1

Special table 2008-523718 gazette

However, the above-described conventional technique has a problem that the real-time property of the reproduced video is deteriorated due to a communication delay between the transmission device and the reception device, a processing delay of the reception device, and the like. For example, in the above-described prior art, when a communication delay between the transmission device and the reception device, a processing delay of the reception device, or the like occurs, the transmission and reception timing of the playlist and segment data in the transmission device It may be later than the generation timing. In such a case, the transmission device generates more segment data than the segment data to be transmitted. Therefore, it is necessary to control the segment data transmitted and received by the transmission device or the reception device.

Therefore, by transmitting and receiving only the segment data having a lower playback order among the plurality of segment data generated by the transmission device, the delay is eliminated, and the real-time property of the content data reproduced after reception by the reception device is Secured. However, in this case, among the plurality of segment data generated by the transmission device, since the higher order segment data is not transmitted / received, content data stored after reception by the reception device is discontinuous. is there.

The present invention has been made to solve the above-described problems.

The receiving apparatus of the present invention has the following configuration.

That is, a receiving device that receives one or a plurality of segments into which content data is divided from a transmitting device, wherein the receiving device receives a playlist in which information on segments that can be transmitted by the transmitting device is described, and the receiving When the mode of the apparatus is a streaming playback mode in which a reception process for receiving a segment from the transmission apparatus and a playback process for reproducing a segment from the transmission apparatus are performed in parallel, the play received by the reception unit is performed. Requesting means for requesting a predetermined number of segments from the segment with the newest playback order among the one or a plurality of segments indicated by the list, and the receiving means responds to the request by the requesting means. A segment is received from the transmitting device.

Moreover, the transmission device of the present invention has the following configuration.

That is, a transmitting device that transmits a playlist describing information on one or more segments into which content data is divided to a receiving device, wherein a determination unit that determines a mode of the receiving device and a mode of the receiving device are , When the determination means determines that it is a streaming playback mode in which a reception process for receiving a segment from the transmission apparatus and a reproduction process for reproducing a segment from the transmission apparatus are performed in parallel, When there are a plurality of segments that have not been transmitted to the receiving device, a generating unit that generates a playlist that does not include information on the segment with the oldest playback order among the plurality of segments that have not been transmitted to the receiving device, and the generating unit Transmitting means for transmitting the generated playlist to the receiving device.

According to the present invention, discontinuity is minimized when content data received by the receiving device is stored during communication delay or processing delay of the receiving device, and real-time performance is improved when reproducing the content data received by the receiving device. be able to.

The figure which shows the connection form of the transmitter 100 of Embodiment 1 and Embodiment 2, and the receiver 102 1 is a block diagram illustrating an example of an internal configuration of a transmission device 100 according to a first embodiment. The flowchart which shows an example of the production | generation procedure of the play list in the production | generation part 216 of the transmitter 100 of Embodiment 1. FIG. FIG. 3 is a block diagram illustrating an example of an internal configuration of the reception apparatus 102 according to the first embodiment. 7 is a flowchart illustrating an example of a segment data reception control processing procedure in the reception apparatus 102 according to the first embodiment. The figure which shows the transmission / reception process of each segment data in case the video data is not preserve | saved between the transmission apparatus 100 and the receiving apparatus 102 of Embodiment 1 with progress of time. The figure which shows the transmission / reception process of each segment data in the case of preserve | saving video data between the transmission apparatus 100 and the receiving apparatus 102 of Embodiment 1 with progress of time. A block diagram showing an example of an internal configuration of transmitting apparatus 800 of Embodiment 2. The flowchart which shows an example of the production | generation procedure of the play list in the production | generation part 216 of the transmitter 800 of Embodiment 2. FIG. The figure which shows the transmission / reception processing of each segment data when not storing video data between the transmission apparatus 800 and the reception apparatus 102 of Embodiment 2 with time progress.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. The configurations shown in the following embodiments are merely examples, and the present invention is not limited to the illustrated configurations.

<Embodiment 1>
Processing of the entire system of this embodiment will be described with reference to FIG.

FIG. 1 is a diagram illustrating an example of a connection form between a transmission device 100 and a reception device 102 according to the present embodiment. In the present embodiment, the transmission device 100 and the reception device 102 are connected to each other via the network 101.

The transmission device 100 and the reception device 102 divide the segment data acquired by dividing the content data at predetermined time intervals and metadata including reproduction section information related to each segment data (hereinafter referred to as a playlist). Respectively. Thereby, the transmission device 100 and the reception device 102 perform streaming of content data. Content data refers to video data, audio data, and the like. In the present embodiment, an example in which the transmission device 100 transmits video data as content data to the reception device 102 will be described below, but the present invention is not limited to this. That is, the same processing method can also be used when the transmitting apparatus 100 transmits audio data as content data to the receiving apparatus 102. The playlist is metadata in which the reproduction order, location information (URL, etc.), reproduction time, etc. of each segment data are described. In the present embodiment, the text-based M3U8 format is used as the playlist format. Details of the playlist in the M3U8 format will be described later with reference to FIG.

The network 101 includes, for example, the Internet, a wired LAN (Local Area Network), or a wireless LAN (Wireless LAN). In the present embodiment, the network 101 is assumed to be a wired LAN or a wireless LAN as a home network, but the present invention may be of any communication standard, scale, and configuration. That is, as a communication standard of the network 101, WAN (Wide Area Network), ad hoc network, Bluetooth (registered trademark), Zigbee (registered trademark), UWB (Ultra Wide Band), or the like may be used.

The transmission device 100 transmits a playlist and segment data based on the playlist acquisition request and the segment data acquisition request transmitted from the reception device 102 via the network 101. Examples of the transmission apparatus 100 include a camera, a video camera, a smartphone, a mobile phone, and a PC (Personal Computer), but the present invention is not limited to this. That is, the transmission apparatus 100 only needs to satisfy a hardware configuration and a module configuration described later. Further, the video data transmitted by the transmission device 100 may be generated within the transmission device 100, or may be generated by another server device or the like and transmitted to the transmission device 100.

The receiving device 102 receives a playlist transmitted from the transmitting device 100 via the network 101 (metadata reception) and receives segment data (segment reception). Further, in the present embodiment, the receiving device 102 has a function of playing back and storing received video data. Note that the video data received by the receiving apparatus 102 may be transmitted to another apparatus for reproduction and storage. Examples of the receiving device 102 include a smartphone, a mobile phone, a PC, and a television, but the present invention is not limited to this. That is, the receiving apparatus 102 only needs to satisfy the hardware configuration and module configuration described later. Further, there may be only one receiving apparatus 102 connected to the network 101, or a plurality of receiving apparatuses may exist.

Next, the transmission device 100 according to the present embodiment will be described with reference to FIGS. 2 and 3.

FIG. 2 is a block diagram illustrating an example of an internal configuration of the transmission device 100 according to the present embodiment.

Reference numeral 201 denotes a central processing unit (CPU) that comprehensively controls each unit described below. Reference numeral 202 denotes a RAM which functions as a main memory, work area, and the like for the CPU 201. A ROM 203 stores a control program executed by the CPU 201 and the like. An operation unit 204 receives user instructions, and includes buttons, a mode dial, and the like.

Reference numeral 205 denotes an imaging unit that receives light information (signal) of a subject by a sensor (imaging device), A / D converts the received signal, and acquires video data. An image processing unit 206 performs image processing using video data acquired by the imaging unit 205 or video data output from the digital signal processing unit 211. A bus 207 serves as a transfer path for various data. For example, the video data acquired by the imaging unit 205 is sent to a predetermined processing unit via the bus 207.

A display control unit 208 controls display of images and characters displayed on the display unit 209. Reference numeral 209 denotes a display unit that displays images and characters acquired by the imaging unit 205, and for example, a liquid crystal display is used. The display unit 209 may have a touch screen function. In that case, a user instruction using the touch screen can be handled as an input of the operation unit 204. An imaging unit control unit 210 controls the imaging system based on an instruction from the CPU 201 such as focusing, opening / closing a shutter, and adjusting an aperture. A digital signal processing unit 211 performs various types of processing such as white balance processing, gamma processing, and noise recommendation processing on video data received from the imaging unit 205 via the bus 207.

An encoder unit 212 compresses and encodes video data output from the imaging unit 205 or the digital signal processing unit 211 using the MPEG-2 system (hereinafter referred to as encoding) and multiplexes the data using the MPEG-2TS system. Each segment data is generated. MPEG-2 is an abbreviation for Moving Picture Experts Group-2. Generally, since video data has a large amount of information, encoded data is used when transmitting and receiving video data via a network. MPEG-2 TS is an abbreviation for Moving Picture Experts Group-2 Transport Stream. MPEG-2 TS is a container format for multiplexing and transmitting encoded video data. In the present embodiment, the encoder unit 212 divides the encoded video data into segment data at predetermined time intervals. The video data dividing method is not limited to every predetermined time interval, and can be divided by any method. In other words, it may be divided every predetermined information amount interval.

An external memory control unit 213 is an interface for connecting to a personal computer (hereinafter referred to as a PC) and other media (for example, a hard disk, a memory card, a CF card, an SD card, a USB memory).

A communication control unit 214 controls the communication unit 215. The communication control unit 214 performs communication control for a video distribution request from the receiving device 102 and communication control for video data transmitted to the receiving device 102. Details of the communication control processing in the communication control unit 214 will be described later.

A communication unit 215 acquires the playlist generated by the reception device 102 generation unit 216 and the segment data generated by the encoder unit 212, and transmits the playlist and the segment data to the reception device 102. The communication unit 215 receives control information transmitted from the receiving device 102. In the present embodiment, the communication unit 215 uses HTTP (Hyper Text Transfer Protocol) as a communication protocol.

Reference numeral 216 denotes a generation unit that generates a playlist including reproduction section information related to the segment data generated by the encoder unit 212. Details of the playlist generation processing in the generation unit 216 will be described later.

The constituent elements of the transmission apparatus 100 exist in addition to the processing units described above, but are not the main points of the present invention, and thus the description thereof is omitted.

Next, details of playlist generation processing by the transmission apparatus 100 of the present embodiment will be described.

FIG. 3 is a flowchart illustrating an example of a playlist generation processing procedure in the generation unit 216 of the transmission device 100 according to the present embodiment.

First, the generation unit 216 determines whether segment data is generated in the encoder unit 212 (step S301). In the present embodiment, the generation unit 216 determines whether or not generation of segment data divided at predetermined time intervals in the encoder unit 212 has been completed.

When it is determined in step S301 that segment data has been generated (YES in step S301), the generation unit 216 adds reproduction section information regarding the newly generated segment data to the playlist (step S302). On the other hand, if it is determined in step S301 that segment data has not been generated (NO in step S301), the process of step S303 is performed.

In step S303, the generation unit 216 determines whether there is segment data that has been transmitted to the receiving apparatus 102 among the segment data indicated in the playlist.

If it is determined in step S303 that there is segment data that has been transmitted (YES in step S303), the generation unit 216 deletes the playback section information related to the transmitted segment data from the playlist (step S304).

When it is determined in step S303 that there is no segment data that has been transmitted (NO in step S303) or when the processing in step S304 is completed, the generation unit 216 determines whether or not the streaming is finished (step S305). . Here, the generation unit 216 determines whether the operation unit 204 has received a user's instruction to end streaming, or determines whether the communication unit 215 has received a streaming end request from the receiving device 102. It is possible to determine termination.

If it is determined in step S305 that the streaming is not to be terminated, the process returns to step S301, and the subsequent playlist generation process for the segment data is performed. An example of the generated playlist will be described later with reference to FIG.

Next, the receiving apparatus 102 of this embodiment is demonstrated using FIG.4 and FIG.5.

FIG. 4 is a block diagram illustrating an example of an internal configuration of the receiving apparatus 102 according to the present embodiment.

Reference numeral 401 denotes a central processing unit (CPU) that comprehensively controls each unit described below.

A RAM 402 functions as a main memory, work area, and the like for the CPU 401.

A ROM 403 stores a control program executed by the CPU 401 and the like.

Reference numeral 404 denotes an operation unit that receives user instructions, and includes buttons, a mode dial, and the like.

A storage unit 405 stores the video data received by the communication unit 412 via the external memory control unit 410.

A bus 406 serves as a transfer path for various data. For example, video data received by the communication unit 412 is sent to a predetermined processing unit via the bus 406.

A display control unit 407 controls display of images and characters displayed on the display unit 408.

Reference numeral 408 denotes a display unit that displays images and characters received by the communication unit 412. For example, a liquid crystal display is used. The display unit 408 may have a touch screen function. In that case, a user instruction using the touch screen can be handled as an input of the operation unit 404.

Reference numeral 409 denotes a decoder unit. The decoder unit 409 demultiplexes the video data received by the communication unit 412 using the MPEG-2 TS system, and further decodes the demultiplexed video data using the MPEG-2 system.

Reference numeral 410 denotes an external memory control unit, which is an interface for connecting to a PC and other media (for example, a hard disk, a memory card, a CF card, an SD card, and a USB memory).

A communication control unit 411 controls the communication unit 412. The communication control unit 411 performs communication control on video data received from the transmission device 100 and a video distribution request and control information transmitted to the transmission device 100. Details of the communication control processing in the communication control unit 411 will be described later with reference to FIG.

A communication unit 412 receives a playlist and segment data transmitted from the transmission device 100 and transmits control information to the transmission device 100.

Reference numeral 413 denotes a segment data control unit, which analyzes the playback order, location information (URL, etc.), playback time (time length), etc. of each segment data from the playlist transmitted from the transmission device 100, and receives the received segment data. Control.

Next, details of video data reception control by the receiving apparatus 102 according to the present embodiment will be described.

FIG. 5 is a flowchart illustrating an example of a segment data reception control processing procedure in the reception apparatus 102 according to the embodiment.

First, the communication control unit 411 transmits a playlist acquisition request (hereinafter, “playlist request”) to the transmission device 100 (step S501). Here, it is assumed that an HTTP GET method is used for transmission of the playlist request, and the URL of the playlist request is notified from the transmission apparatus 100 in advance. Also, although the transmission timing of the playlist request is arbitrary, it is possible to reduce useless communication by transmitting it in accordance with the time interval at which segment data is generated.

Next, the communication unit 412 receives the playlist transmitted from the transmission device 100 based on the playlist request in step S501 (step S502).

Subsequently, the segment data control unit 413 determines whether or not reproduction section information regarding a plurality of segment data is described in the playlist received by the communication unit 412 in step S502 (step S503).

In the present embodiment, the transmission device 100 periodically generates segment data at predetermined time intervals. Therefore, the transmission timing of the playlist request in the receiving apparatus 102 is delayed from the generation timing of the segment data in the transmitting apparatus 100 due to a communication delay between the transmitting apparatus 100 and the receiving apparatus 102, a processing delay of the receiving apparatus 102, and the like. Sometimes. In such a case, playback section information relating to a plurality of segment data is described in the playlist generated by the transmission apparatus 100. On the other hand, when the generation timing of the segment data in the transmission device 100 and the transmission timing of the playlist request in the reception device 102 coincide with each other, reproduction section information related to single segment data is included in the playlist generated in the transmission device 100. Is described.

If it is determined in step S503 that the playback section information of a plurality of segment data is described in the playlist (YES in step S503), the segment data control unit 413 determines whether to store the video data received by the receiving apparatus 102. Is determined (step S504). Here, the segment data control unit 413 determines whether or not to store the video data received by the receiving apparatus 102 by determining the storage mode (save information) selected by the user using the operation unit 404 and set in the RAM 402. Can be determined. The present invention is not limited to this. That is, a storage mode is set in advance in the RAM 402 or the like, and the segment data control unit 413 determines whether or not to store the video data received by the receiving apparatus 102 based on the storage mode set in the RAM or the like. Also good. Whether the receiving apparatus 102 stores the video data received by the receiving apparatus 102 based on whether or not the receiving apparatus 102 is in a streaming playback mode that simultaneously receives the video data and plays back the received video data. You may judge. That is, when the receiving apparatus 102 is in the streaming playback mode, it is determined that the video data received by the receiving apparatus 102 is not stored. On the other hand, when the receiving apparatus 102 is not in the streaming playback mode, it is determined to store the video data received by the receiving apparatus 102.

If it is determined in step S504 that the video data received by the receiving apparatus 102 is to be stored (YES in step S504), the segment data control unit 413 performs the process in step S505. In step S505, the segment data control unit 413 selects segment data that has not been received and has the highest playback order from the playback section information related to the plurality of segment data described in the playlist, and selects the segment data of the selected segment data. Send an acquisition request. The segment data acquisition request is hereinafter referred to as a segment data request. The playback order is included in the playback section information related to each segment data described in the playlist, and the segment data having the highest playback order is the first of the plurality of segment data described in the playlist. Indicates segment data to be reproduced. Further, as in the present embodiment, when the segment data is generated in the same order as the playback order in the encoder unit, the segment data with the highest playback order is the segment data generated the oldest in the encoder unit. It shows that. For this reason, in this embodiment, the segment data with the highest reproduction order, that is, the segment data generated the oldest in the encoder unit is referred to as the oldest segment data.

The segment data request in step S504 also uses the HTTP GET method in the same manner as the playlist request in step S501. Thereby, in step S504, the segment data control unit 413 refers to location information such as URL information related to the segment data described in the playlist received in step S502, and transmits a segment data request.

In step S506, the communication unit 412 receives the segment data transmitted from the transmission device 100 based on the segment data request transmitted in step S505.

In step S507, the segment data control unit 413 determines whether the segment data received in step S506 is the lowest segment data in the reproduction order among the plurality of segment data described in the playlist received in step S502. Determine. The segment data with the lowest playback order indicates the segment data to be played back last among the plurality of segment data described in the playlist. Furthermore, when each segment data is generated in the same order as the playback order in the encoder unit as in this embodiment, the segment data with the lowest playback order is the segment data generated most recently in the encoder unit. Indicates. For this reason, in this embodiment, the segment data with the lowest reproduction order, that is, the segment data newly generated in the encoder unit is referred to as the latest segment data.

If it is determined in step S507 that the received segment data is the latest segment data in the playlist (YES in step S507), the decoder unit 409 and the display unit 408 decode and reproduce the segment data (step S507). S508).

Further, the storage unit 405 stores the segment data of the video data received in step S506 (step S509), and ends the segment data reception process.

On the other hand, when it is determined in step S507 that the received segment data is not the latest segment data in the playlist (NO in step S507), the storage unit 405 only stores the segment data (step S510). Then, the process returns to step S505 to receive unreceived segment data, and steps S505 to 507 are repeated. That is, in this case, the decoder unit 409 and the display unit 408 do not decode and reproduce the segment data.

Through the processing in steps S507 to S509, the video data received by the receiving apparatus 102 is reproduced by performing decoding and reproduction processing only on predetermined segment data at the time of communication delay and processing delay when the video data is stored. Discontinuity of video data can be minimized. In addition, when the video data received by the receiving apparatus 102 is stored, the above processing is performed, so that the real-time property of the reproduced video data can be improved.

Also, the description returns to step S503 and step S504.

If it is determined in step S503 that the playback section information regarding the plurality of segment data is not described in the playlist (NO in step S503), the segment data control unit 413 performs the process of step S511. Also, when it is determined in step S504 that the receiving apparatus 102 does not store the video data (NO in step S504), the segment data control unit 413 performs the process in step S511.

In step S511, the segment data control unit 413 selects the segment data having the lowest playback order or the segment data higher by a predetermined number from the lowest order from the playback section information regarding the plurality of segment data described in the playlist. Further, the segment data control unit 413 transmits a segment data request based on the selected segment data. Further, the segment data that is higher in the playback order by the predetermined number from the lowest order indicates the segment data that is to be played back a predetermined number of times from among the plurality of segment data described in the playlist. The predetermined number is set based on a delay time allowed in the reproduction of the received video data, and is set in the RAM 402 in the present embodiment.

Here, by setting the segment data request to always select the latest segment data, it is possible to eliminate the delay compared to selecting the oldest segment data, and to realize streaming of video data with high real-time characteristics. it can. Also, by setting so that the segment data that is higher by a predetermined number from the lowest playback order is selected, streaming that takes into account the delay time allowed by the user in video data playback can be realized.

In step S512, the communication unit 412 receives the segment data transmitted from the transmission device 100 based on the segment data request transmitted in step S511.

In step S513, the decoder unit 409 and the display unit 408 decode and reproduce the segment data received in step S512.

Through the processing of each step S511 to 513, at the time of communication delay and processing delay when the video data received by the receiving apparatus 102 is not stored, transmission / reception and decoding of the oldest segment data and segment data exceeding the set allowable delay time, Control not to play. For this reason, when the video data received by the receiving apparatus 102 is not stored, the real-time property of the reproduced video can be improved. In addition, communication bandwidth can be saved and processing load can be reduced.

Next, transmission / reception processing of video data between the transmission device 100 and the reception device 102 according to the present embodiment will be described with reference to FIGS. 6 and 7.

FIG. 6 is a diagram illustrating an example of transmission / reception processing of each segment data between the transmission device 100 and the reception device 102 when the video data received by the reception device 102 is not stored according to the present embodiment over time. is there.

Each step S601-603 has shown the production | generation timing of the segment data 1, the segment data 2, and the segment data 3, respectively. In the present embodiment, the generation timing of the segment data 1 to 3 is constant at a predetermined time interval. That is, it is assumed that the time interval between step S601 and step S602 is the same as the time interval between step S602 and step S603.

Step S604 indicates transmission / reception of video data in the transmission device 100 and the reception device 102 when no communication delay in the network 101 or processing delay in the reception device 102 has occurred.

First, the receiving apparatus 102 transmits a playlist request to the transmitting apparatus 100 (step S608), and the transmitting apparatus 100 that has received the playlist request transmits a playlist response (hereinafter, “playlist response”) to the receiving apparatus 102. (Step S609).

Reference numeral 605 denotes a playlist that is transmitted and received between the transmission apparatus 100 and the reception apparatus 102 after the segment data 1 is generated in the transmission apparatus 100. The playlist 605 is metadata indicating segment data that can be received by the receiving apparatus 102 among the plurality of segment data generated by the encoder unit 212.

In the present embodiment, the play list 605 describes playback time and location information as playback section information related to the segment data 1. As shown in FIG. 6, the first line “#EXTINF: 1” of the playlist 605 indicates that the playback time of the segment data 1 is 1 second, and “http: // xxx / segment1” on the second line. .Ts ”indicates the location information (URL) of the segment data 1.

Next, the receiving apparatus 102 transmits an acquisition request for the segment data 1 to the transmitting apparatus 100 based on the content of the received playlist 605 (step S610). Then, the transmission apparatus 100 that has received the segment data 1 acquisition request transmits the segment data 1 to the reception apparatus 102 (step S611).

Step S606 indicates transmission / reception of video data in the transmission device 100 and the reception device 102 when a communication delay occurs in the network 101. As shown in FIG. 6, in the playlist request (step S612) transmitted from the receiving apparatus 102 after the segment data 2 is generated by the transmitting apparatus 100 (step S602), the segment data 3 is generated by the transmitting apparatus 100 (step S612). It arrives after step S603).

Reference numeral 607 denotes a playlist transmitted from the transmission device 100 in this case (when communication delay occurs in the network 101 as shown in FIG. 6). The play list 607 describes reproduction section information (reproduction time and URL) regarding the segment data 2 and the segment data 3. Specifically, “#EXTINF: 1” in the first and third lines of the playlist 607 indicates that the reproduction time of the segment data 2 and the segment data 3 is 1 second, respectively. In addition, “http: //xxx/segment2.ts” on the second line indicates the URL of the segment data 2, and “http: //xxx/segment3.ts” on the fourth line indicates the URL of the segment data 3. As described above, the playback section information related to the segment data 1 described in the playlist 605 received by the receiving apparatus 102 in step S609 is deleted from the playlist 607. In the playlist 607 received by the receiving apparatus 102 in step S613, playback section information related to the segment data 2 and the segment data 3 newly generated by the transmitting apparatus 100 is added.

Next, the receiving apparatus 102 determines that playback section information regarding a plurality of segment data is described in the received playlist 607, and further determines that it is a setting that does not store video data. For this reason, the receiving apparatus 102 transmits an acquisition request for the segment data 3 whose playback order is lower among the plurality of segment data corresponding to the playback section information described in the playlist 607 to the transmitting apparatus 100 (step S100). S614). In the present embodiment, since the encoder unit generates each segment data in the same order as the reproduction order, the segment data having a lower reproduction order indicates segment data newly generated in the encoder unit.

Then, the transmission apparatus 100 that has received the segment data 3 acquisition request transmits the segment data 3 to the reception apparatus 102 (step S615).

As described above, in the present embodiment, when the playback section information related to a plurality of segment data is described in the playlist 607, the receiving apparatus 102 is the segment data 2 whose playback order is higher among the plurality of segment data. Do not decrypt and play. For this reason, according to this embodiment, when the video data received by the receiving apparatus 102 is not stored, the delay can be eliminated and the real-time property of the video data to be reproduced can be ensured. Further, by selecting the segment data to be reproduced, it is possible to reduce the processing load in decoding and reproduction as compared with the case of reproducing all the segment data.

On the other hand, FIG. 7 is a diagram illustrating an example of transmission / reception processing of each segment data between the transmission device 100 and the reception device 102 when the video data received by the reception device 102 is stored according to the embodiment over time. It is. In FIG. 7, the same sequence parts as those in FIG.

Step S <b> 701 indicates transmission / reception of video data in the transmission device 100 and the reception device 102 when a communication delay occurs in the network 101. Similarly to the case where the receiving device 102 does not store the video data received by the receiving device 102 shown in FIG. 6, the receiving device 102 creates a playlist 607 in which the reproduction section information related to the segment data 2 and the segment data 3 is described in step S613. Receive.

Next, the receiving apparatus 102 determines that the playback section information related to the plurality of segment data is described in the playlist 607 received in step S613, and further determines that it is a setting for storing video data. . For this reason, the receiving apparatus 102 transmits to the transmitting apparatus 100 an acquisition request for the segment data 2 having a higher playback order among the plurality of segment data corresponding to the playback section information described in the playlist 607 (step S100). S702). In the present embodiment, since the encoder unit generates each segment data in the same order as the playback order, the segment data having a higher playback order indicates the segment data generated earlier in the encoder unit.

Then, the transmission device 100 that has received the acquisition request for the segment data 2 transmits the segment data 2 to the reception device 102 (step S703).

Subsequently, the receiving apparatus 102 sends an acquisition request to the transmitting apparatus 100 for the segment data 3 whose playback order is lower by the transmitting apparatus 100 among the plurality of segment data corresponding to the playback section information described in the playlist 607. Transmit (step S704). Then, the transmitting apparatus 100 that has received the segment data 3 acquisition request transmits the segment data 3 to the receiving apparatus 102 (step S705).

When the video data received by the receiving apparatus 102 is stored according to the present embodiment described above, the segment data 2 with the higher playback order is stored without being decoded and played back, and the segment data with the lower playback order is stored. 3 is controlled to perform decoding and reproduction and storage. Thereby, the real-time property of the reproduced video data can be improved while ensuring the continuity of the stored video data. Further, by selecting the segment data to be reproduced, it is possible to reduce the processing load in decoding and reproduction as compared with the case of reproducing all the segment data.

As described above, the segment data reception control process of the receiving apparatus 102 according to the present embodiment determines the segment data to which the acquisition request is transmitted according to whether or not the video data received by the receiving apparatus 102 is to be saved. Thereby, when the video data received by the receiving apparatus 102 is stored in the receiving apparatus 102 at the time of communication delay or processing delay of the receiving apparatus 102, discontinuity of the video data to be stored can be minimized. Further, it is possible to improve the real-time property of video data to be reproduced when the video data received by the receiving device 102 is not stored in the receiving device 102.

<Embodiment 2>
In the above-described embodiment, the receiving apparatus 102 is configured to control reception of video data. On the other hand, in the present embodiment, control is performed so that segment data to be transmitted by the transmission device 100 is determined based on a storage mode indicating whether or not the video data received by the reception device 102 is to be stored.

FIG. 8 is a block diagram illustrating an example of an internal configuration of the transmission apparatus 800 according to the present embodiment. As illustrated in FIG. 8, the transmission device 800 according to the present embodiment includes a storage mode determination unit 801. In FIG. 8, the same reference numerals are assigned to the same processing units as those in FIG. Next, details of playlist generation processing by the transmission apparatus 800 of the present embodiment will be described.

FIG. 9 is a flowchart illustrating an example of a playlist generation processing procedure in the generation unit 216 of the transmission device 800 according to the present embodiment. Note that, in FIG. 9, steps that perform the same processing as in FIG.

After the generation unit 216 adds the playback section information of the newly generated segment data to the playlist (step S302), the storage mode determination unit 801 indicates whether or not to store the received video data from the reception device 102. The storage mode is acquired (step S901). Here, for example, the storage mode determination unit 801 determines whether or not to store the video data received by the reception device 102 by receiving the playback section information regarding the storage mode selected by the user using the operation unit 404 from the reception device 102. Can be determined.

Subsequently, the storage mode determination unit 801 determines whether to store the video data received by the receiving apparatus 102 from the storage mode acquired in step S901 (step S902).

If it is determined in step S902 that the receiving apparatus 102 stores the video data (YES in step S902), the generation unit 216 performs the process in step S303.

On the other hand, when it is determined in step S902 that the receiving apparatus 102 does not store the video data (NO in step S902), the generation unit 216 performs the process of step S903. In step S903, the generation unit 216 deletes the playback section information related to the oldest segment data from the playback section information related to the plurality of segment data described in the playlist.

The playlist generated by the transmission apparatus 800 of the present embodiment by the processing of each of steps S901 to S903 is a playback section related to newly generated segment data at the time of communication delay and processing delay when the reception apparatus 102 does not store video data. Only information is listed. When the receiving apparatus 102 stores video data, the playlist generated by the transmission apparatus 800 according to the present embodiment is the same as the playlist generated by the transmission apparatus 100 according to the first embodiment.

Next, video data transmission / reception processing between the transmission apparatus 800 and the reception apparatus 102 according to the present embodiment will be described with reference to FIG.

FIG. 10 is a diagram illustrating an example of transmission / reception processing of each segment data between the transmission device 800 and the reception device 102 when the video data received by the reception device 102 is not stored according to the present embodiment over time. is there. In FIG. 10, the same sequence parts as those in FIG.

Note that the relationship between the transmission / reception data of the transmission device 800 and the reception device 102 when the reception device 102 according to the present embodiment stores video data is the same as in FIG.

Step S <b> 1001 indicates transmission / reception of video data in the transmission device 800 and the reception device 102 when a communication delay occurs in the network 101. As for the playlist request (step S612) transmitted from the receiving apparatus 102 after the segment data 2 is generated (step S602), the segment data 3 is generated by the transmitting apparatus 800 as in the first embodiment ( It is assumed that it arrives after step S603).

In step S <b> 1002, the transmission device 800 and the reception device 102 transmit / receive information regarding the storage mode set in the reception device 102.

Further, in step S1003, the transmission device 800 and the reception device 102 transmit and receive the playlist generated by the generation unit 216 of the transmission device 800. In the playlist 1003, only the playback section information related to the segment data 3 is described, and the playback section information related to the segment data 2 is deleted.

Subsequently, the reception apparatus 102 transmits an acquisition request for the segment data 3 described in the playlist 1003 to the transmission apparatus 800 (step S1005). Then, the transmission device 800 that has received the acquisition request for the segment data 3 transmits the segment data 3 to the reception device 102 (step S1006).

As described above, the transmission apparatus 800 according to the present embodiment generates a playlist so as to switch the segment data transmitted by the transmission apparatus 800 according to whether or not the video data received by the reception apparatus 102 is to be stored. As a result, when the video data received by the receiving apparatus 102 is stored at the time of communication delay or processing delay of the receiving apparatus 102, discontinuity of the video data stored can be minimized. Further, it becomes possible to improve the real-time property of the video data to be reproduced when the video data received by the receiving device 102 is not stored at the time of communication delay or processing delay of the receiving device 102. Further, by selecting the segment data to be reproduced, it is possible to reduce the processing load in decoding and reproduction as compared with the case of reproducing all the segment data.

<Embodiment 3>
In the first embodiment and the second embodiment, the processing units 212, 214, 216, 409, 411, 413, 801 shown in FIGS. 2, 4, and 8 are configured by hardware. Explained as a thing. However, the processing performed by the processing units 212, 214, 216, 409, 411, 413, and 801 shown in these drawings may be executed by a computer program.

In this case, the CPU 201 in FIG. 2 controls the entire computer using computer programs and data stored in the RAM 202 and the ROM 203, and performs each process described above as being performed by the transmission apparatus according to the above-described embodiment. Run. That is, the CPU 201 functions as each processing unit 212, 214, 216.

The CPU 401 in FIG. 4 controls the entire computer using computer programs and data stored in the RAM 402 and the ROM 403, and executes each process described above as performed by the receiving apparatus according to the above-described embodiment. . That is, the CPU 401 functions as each processing unit 409, 411, 413.

Further, the CPU 201 in FIG. 8 controls the entire computer using computer programs and data stored in the RAM 202 and the ROM 203, and executes each process described above as performed by the transmission apparatus according to the above-described embodiment. . That is, the CPU 201 functions as each processing unit 212, 214, 216, 801.

The operation in the above-described configuration is controlled by the CPUs 201 and 401 centering on the operation described in the above flowchart.

<Other embodiments>
In each of the above-described embodiments, MPEG-2 is used as the video data encoding / decoding method, but the present invention is not limited to MPEG-2, and MPEG-4 AVC / H. It is possible to use other video data encoding / decoding methods such as H.264 and VC-1.

In each of the above-described embodiments, MPEG-2 TS is used as a container format for encoded video data. However, the present invention is not limited to MPEG-2, and other container formats suitable for streaming such as MP4 format and MOV format. It is also possible to use.

In the above-described embodiments, the M3U8 format is used as the playlist format. However, the playlist format is not limited to the M3U8 format, and other playlist formats such as the M3U format and the WPL format can also be used.

In each of the above-described embodiments, each playlist 605, 607, and 1003 describes the reproduction time and location information of the segment data as metadata indicating the segment data that can be received by the receiving apparatus 102. However, the present invention is not limited to this. That is, each playlist 605, 607, 1003 may include, for example, segment data playback time, location information (URL, address information, etc.), playback order, termination information, etc., and it is not necessary to include all of them. .

Further, in each of the above-described embodiments, the segment data to be transmitted by the transmission device 100 is determined based on the storage mode indicating whether or not the video data received by the reception device 102 is stored. Not. That is, segment data to be transmitted by the transmission apparatus 100 may be determined based on whether or not the video data received by the reception apparatus 102 is in a mode for reproducing in real time. Therefore, when the video data received by the receiving apparatus 102 is in a mode for reproducing in real time, the transmitting apparatus 100 is configured to acquire segment data whose playback order is lower than that in the mode for not reproducing the video data in real time. In addition, the receiving apparatus 102 may be controlled.

Further, the segment data to be transmitted by the transmission device 100 may be determined based on whether or not the reception device 102 is in a mode that allows a delay in receiving video data. Therefore, when the receiving apparatus 102 is in a mode that permits a delay in receiving video data, the transmitting apparatus 100 and the receiving apparatus are configured so as to acquire segment data having a higher playback order than in a mode that does not permit the delay. 102 may be controlled.

Furthermore, the segment data to be transmitted by the transmission device 100 may be determined based on whether or not the video data received by the reception device 102 is in a mode for reproducing all video data without interruption. Therefore, in a mode in which all video data received by the receiving apparatus 102 is reproduced without interruption, the transmitting apparatus 100 and the transmission apparatus 100 are configured to acquire segment data having a higher reproduction order than in a mode in which all the video data is not reproduced. The receiving device 102 may be controlled.

In each of the above-described embodiments, when the segment data to be transmitted by the transmission device 100 is determined based on the storage mode indicating whether or not the video mode received by the reception device 102 is to be stored, it is described in the playlist. However, the present invention is not limited to this. That is, the segment data to be transmitted by the transmission apparatus 100 is determined using other orders such as the segment data generation order in the transmission apparatus 100 and the segment data recording order in the reception apparatus 102 instead of the segment data reproduction order. It doesn't matter.

In each of the embodiments described above, HTTP is used as a data transfer protocol. However, the protocol is not limited to HTTP, and other protocols in the same layer of the OSI reference model, such as HTTPS, TCP, UDP, etc., or other protocols in another layer are used. It is possible.

Further, in each of the above-described embodiments, the transmission device 100 and the transmission device 800 include the imaging unit 205 as illustrated in FIGS. 2 and 8, but the present invention is not limited to this. That is, instead of the imaging unit 205, an acquisition unit that acquires video data may be included. In this case, the video data acquired by the acquisition unit is sent to a predetermined processing unit via the bus 207 in the same manner as the video data acquired by the imaging unit 205.

In each of the above-described embodiments, the transmission device 100 and the transmission device 800 include the encoder unit 212 as illustrated in FIGS. 2 and 8, but the present invention is not limited to this. That is, instead of the encoder unit 212, a segment acquisition unit that acquires segment data may be included. In this case, segment data generated by another device outside the transmission device 100 is acquired by the segment acquisition unit. The segment data acquired by the segment acquisition unit is sent to a predetermined processing unit via the bus 207 in the same manner as the segment data generated by the encoder unit 212.

The present invention can also be realized by executing the following processing. That is, software (program) that realizes the functions of the above-described embodiments is supplied to a system or apparatus via a network or various storage media, and a computer (or CPU, MPU, etc.) of the system or apparatus reads the program. It is a process to be executed.

Claims (17)

A transmission device that transmits a playlist describing information on one or more segments into which content data is divided to a reception device,
Determining means for determining a mode of the receiving device;
The determining unit determines that the mode of the receiving device is a streaming playback mode in which a receiving process for receiving a segment from the transmitting device and a playback process for playing back a segment from the transmitting device are performed in parallel. If there are a plurality of segments that have not been transmitted to the receiving device, information on one or more segments out of the plurality of segments that have not been transmitted to the receiving device, and information on the segment with the oldest playback order Generating means for generating a playlist not including
A transmission apparatus comprising: transmission means for transmitting the playlist generated by the generation means to the reception apparatus.   The transmission device according to claim 1, wherein the transmission unit transmits a segment designated by the reception device among one or a plurality of segments indicated by the playlist to the reception device.   When the determination unit determines that the mode of the receiving device is another mode different from the streaming playback mode, the generating unit is configured to play information in which information on a plurality of segments not transmitted to the receiving device is described. The transmission apparatus according to claim 1 or 2, wherein the list is generated.   The generation unit generates a playlist in which information of a plurality of segments not transmitted to the reception device is described when the determination unit determines that the mode of the reception device is a storage mode for storing the segment. The transmission device according to claim 1 or 2. A receiving device that receives from a transmitting device one or more segments into which content data is divided,
Receiving means for receiving a playlist in which information of segments that can be transmitted by the transmitting device is described;
When the reception device mode is a streaming playback mode in which a reception process for receiving a segment from the transmission device and a reproduction process for reproducing a segment from the transmission device are performed in parallel, the reception unit receives the segment. Requesting means for requesting a predetermined number of segments from the segment with the newest playback order among the one or a plurality of segments indicated by the playlist,
The receiving device is a receiving device that receives a segment according to a request from the requesting device from the transmitting device.   The requesting unit requests the one or more segments indicated by the playlist in an order corresponding to the playback order when the mode of the receiving device is a mode different from the streaming playback mode. The receiving device described.   If the mode of the receiving device is a mode different from the streaming playback mode, the requesting unit requests all of the one or more segments indicated by the playlist received by the receiving unit to the transmitting device. The receiving device according to claim 5 or 6.   When the mode of the receiving device is a storage mode for storing segments received from the transmitting device, the requesting unit transmits all the one or more segments indicated by the playlist received by the receiving unit. The receiving device according to claim 5 or 6, wherein the receiving device requests the device.   The receiving apparatus according to claim 5, wherein the predetermined number includes one.   10. The one or more segments requested by the requesting unit when the receiving device is in a mode different from the streaming playback mode is a segment not received by the receiving device. The receiving device according to item. A transmission method for transmitting a playlist describing information on one or more segments into which content data is divided to a receiving device,
A determination step of determining a mode of the receiving device;
The determination step determines that the mode of the receiving device is a streaming playback mode in which a receiving process for receiving a segment from the transmitting device and a playback process for playing back a segment from the transmitting device are performed in parallel. If there are a plurality of segments that have not been transmitted to the receiving device, information on one or more segments out of the plurality of segments that have not been transmitted to the receiving device, and information on the segment with the oldest playback order A generation step of generating a playlist not including
A transmission device that transmits the playlist generated by the generation step to the reception device.   12. The transmission method according to claim 11, wherein in the transmission step, a segment designated by the reception device among one or a plurality of segments indicated by the playlist is transmitted to the reception device. A reception method for receiving one or a plurality of segments into which content data is divided from a transmission device,
A playlist receiving step for receiving a playlist in which information of segments that can be transmitted by the transmitting device is described;
When the mode of the receiving device is a streaming playback mode in which a receiving process for receiving a segment from the transmitting device and a playback process for playing back a segment from the transmitting device are performed in parallel, the playlist receiving step A requesting step for requesting a predetermined number of segments from the segment with the newest playback order among the one or more segments indicated by the received playlist;
A segment receiving step of receiving a segment according to a request from the requesting step from the transmitting device.   14. When the mode of the receiving device is a mode different from the streaming playback mode, the requesting step requests the one or more segments indicated by the playlist in an order corresponding to the playback order. The receiving method described in 1.   When the mode of the receiving device is a storage mode for storing segments from the transmitting device, in the requesting step, the one or more segments indicated by the playlist are requested in an order corresponding to the playback order. The receiving method according to claim 13.   The program for operating a computer as each means of the transmission apparatus of any one of Claims 1 thru | or 4.   A program for causing a computer to operate as each unit of the receiving device according to any one of claims 5 to 10.

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