JP5200415B2 - Receiving device, receiving method and transmitting / receiving method - Google Patents

Description

  The technical field relates to a content distribution system, a content distribution server, a content reception client, and a content recording / playback method via a network.

  Regarding the above technical field, for example, Japanese Patent Application Laid-Open No. H10-228707 has an issue of “to be able to check the progress of download, video playback position and disk capacity, and freely select video content playback timing” As a solution, “When content is requested from the transmission unit 111 to the video server, the content is transmitted from the video server, and the reception unit 112 acquires the content size. Then, the content size is compared with the disk capacity, and the disk capacity is insufficient. If there is not enough disk capacity, the receiving unit 112 acquires the content, the writing unit 113 writes the content to the disk 114, and the downloaded to the display unit 117. Show progress, content is ready for playback Is displayed on the display unit 117. When the user performs playback, the reading unit 115 reads the content from the disc 114, and the playback unit 116 causes the display unit 117 to display the playback position. ing.

JP 2002-290948 A

  In recent years, with an increase in capacity of network lines and an increase in capacity of hard disks, an IP television (IPTV) service that distributes images such as television programs and movies through an IP (Internet Protocol) network is being realized. There are roughly three types of viewing modes for IP broadcast programs: streaming viewing for viewing in real time, download viewing for viewing after downloading, and progressive download viewing for playback while downloading both.

  Japanese Patent Application Laid-Open No. 2004-228561 discloses a technical idea about progressive download that displays the progress of download during progressive download and displays that the content is reproducible when the content is reproducible.

  However, the above-described Patent Document 1 does not clearly indicate a specific means for determining whether or not the content can be reproduced. In particular, there is a problem that it is not considered that the timing at which viewing is possible differs depending on the content and the network environment. In addition, there is a problem that it is not possible to fast-forward the content being watched for progressive download.

Therefore, a content distribution system, a content distribution server, a content reception client, and a content recording / playback method that are more convenient for progressive download are provided.

  For example, a content distribution system including a server that distributes content via a network and a content reception client that receives, distributes, and plays back the content distributed from the content distribution server. At the time, hint information on the encoded average bit rate of the content is added to the playback control metafile, and when the content receiving client is instructed to perform progressive playback, the margin is taken into consideration to determine whether playback is possible to the end, Start playback if playback is possible.

In other words, information is added to the downloaded metafile in preparation for progressive download (viewing during downloading). In particular,
(1) The content distribution server adds the encoded average bit rate hint information to the reproduction control metafile and distributes it, and the content receiving client reproduces to the end in consideration of the margin when the progressive reproduction is instructed. Judge whether it is possible and start playback if possible.
(2) The content distribution server distributes the content by adding the stream reproduction control information, and causes the content receiving client to download the content. The content receiving client prohibits fast-forwarding and fast-reverse when playing back a content without stream playback control information during downloading.

  According to the above means, it is possible to provide a content distribution system, a content distribution server, a content reception client, and a content recording / playback method that are easy to use.

  Hereinafter, an example (example) of an embodiment suitable for the present invention will be described with reference to the drawings. However, application of the present invention is not limited to this embodiment.

  FIG. 2 shows an example of a network configuration in the present embodiment. In this content distribution system, a content distribution server 201 and content reception clients 202 to 204 are connected through a network 200.

  FIG. 1 is a block diagram showing a configuration example of the content recording / playback apparatus 1 corresponding to the content receiving clients 202 to 204 of FIG.

  The content recording / playback apparatus 1 includes data and metadata (download control metafile and playback control) of video content (for example, programs such as movies, sports and news) broadcast from the content distribution server 201 and the like via the Internet (communication line). (Including a metafile) is received through the LAN adapter 121, and the received data is recorded in the storage unit 119 such as a hard disk or an optical disk via the recording / playback control unit 103. The content recording / playback apparatus 1 receives a TV broadcast (for example, terrestrial digital broadcast) with the antenna 101 and selects a desired program with the tuner 102. The selected program is recorded in the storage unit 119 such as a hard disk or an optical disc via the recording / playback control unit 103. A recorded program can be searched for a scene including the keyword and reproduced by inputting the keyword. Various signal processing is involved for recording and reproduction, but is omitted in FIG.

  The audio input unit 117 separates an audio signal from the acquired content, sequentially converts the audio signal, and inputs the digital signal to the program processing unit 104 via the interface 108. Various information such as the sampling frequency of audio and the number of channels when converted into a digital signal are also transferred from the audio input unit 117 to the program processing unit 104. Of course, the information set by the program processing unit 104 may be given to the audio input unit 117.

  The video input unit 118 separates the video signal from the acquired content, sequentially converts the video signal, and inputs the digital signal to the program processing unit 104 via the interface 108. Various information such as the sampling frequency of the video when converted into a digital signal is also transferred from the video input unit 118 to the program processing unit 104. Of course, the information set by the program processing unit 104 may be given to the video input unit 118.

A separation unit is provided at a branch point before the audio input units 117 and 118. Further, the metadata may also be separated by this separation unit.

The metadata received by the LAN adapter 121 roughly includes a reproduction control metafile and stream reproduction control information.
The playback control metafile is received by the receiving client from the content distribution server prior to downloading the content. The reproduction control metafile includes information necessary for starting the content. Specifically, the playback control metafile includes creation date and time, encrypted / unencrypted content type, license link information, content title, content overview, content encoded average bit rate hint information, and the like. .

On the other hand, the stream reproduction control information is received together with the content body by the receiving client when the content body is downloaded from the content distribution server. The stream reproduction control information is used for fast reverse and fast forward. The stream reproduction control information includes information regarding the time stamped content file and information indicating the byte position from the beginning of the file corresponding to the time information in the segmentation data. In particular, since position information relating to an I frame that does not require other frame information to be reconstructed is included, it is possible to fast forward and fast reverse by referring to the information relating to this I frame.

  The program processing unit 104 performs progressive download from the hint information of the encoded average bit rate of the content included in the playback control metafile received through the LAN adapter 121 and the average bit rate of the reception speed at the client. It is determined whether or not playback is possible. Details will be described later with reference to FIG. Note that progressive download is a download or playback format (mode) for playback while downloading.

  The program processing unit 104 acquires, for example, position information of each I frame of the video signal to be recorded / reproduced from the stream reproduction control information included in the content received through the LAN adapter 121, and transmits it to the recording / reproduction control unit 103. The image of the frame number can be skipped (fast forward, fast reverse) and played back.

  In addition, when the content received through the LAN adapter 121 does not include stream reproduction control information, fast forward and fast reverse can be prohibited. As stream reproduction control information, information having a stream resource time axis and byte position mapping information, for example, SCI (Streaming Control Information) described in the ARIB standard TR-B27 can be used.

  In the program processing unit 104, a signal received through the LAN adapter 121 is temporarily input to the memory 107, and the CPU 106 performs a reproduction permission determination process, an I frame position analysis process, and the like. The processing program is stored in the auxiliary storage unit 105, and the CPU 106 reads it out as appropriate, transfers it to the memory 107, and processes it. The contents of the processing program have the functional configuration shown in FIGS. Various data and calculation results created by the processing are stored in the memory 107 and referred to as necessary. Various information such as processing results can also be stored in the auxiliary storage unit 105. In the present embodiment, the program is configured to be executed by the CPU, but may be executed by a plurality of LSIs or all may be executed by hardware.

  A display device 120 such as a PDP or LCD displays the output content of the program processing unit 104 via the interface 111. The speaker 113 outputs an audio signal input to the program processing unit 104 via the interface 110, or outputs an audio signal stored in the memory 107 in response to a user request. The input device 115 includes a pointing device such as a mouse, a numerical input device such as a keyboard, and a voice input device such as a microphone, and issues instructions to the program processing unit 104 via the interface 114.

The configuration of the content recording / playback apparatus is not limited to the configuration shown in FIG. 1, and the broadcast receiving unit such as the tuner 102, the storage unit 119, the video / audio output unit such as the display device 120 and the speaker 113 is the device. It can be built-in or external.

  FIG. 3 is a schematic diagram illustrating an example of a data table of information related to an I frame necessary for fast forward and fast reverse in the stream reproduction control information.

  When the time stamp information (for example, the value of the clock counter for controlling the relative input time to the decoder included in the video input unit 118) and the corresponding address information from the beginning of the content is transmitted from the content distribution server. The reception client stores the received content in the storage unit 119 added to the content stream.

When the program processing unit 104 reads out the content stored in the storage unit 119, the program processing unit 104 reads out the I frame information that is a combination of the time stamp and the address, so that the receiving client can control playback of fast forward and fast reverse. Become. The time stamp, information, and address information may be read when the content is stored in the storage unit 119. The timing for reading the time stamp, information, and address information is not limited to this embodiment.

  FIG. 4 is an example of a screen configuration output to the display device 120, particularly a screen being downloaded. The program presentation screen 4 includes a mini screen 41 that displays a program that is currently being downloaded, a program broadcast information display screen 42 that presents information related to a program that is currently available for download, a video operation button group 43, and a TV column switching button 44. , A keyword search screen switching button 45, a recording list display switching button 46, and an electronic program guide display area 47. When a channel displayed on the program broadcast information screen 42 is selected, the selected channel is highlighted 48. The progress of the download is presented on the progressive bar 49. When playback is possible during progressive download, the program presentation screen 4 becomes a recorded content playback screen 5 shown in FIG.

  FIG. 5 is an example of a screen configuration that is output to the display device 120, and is particularly a screen when playback is possible during download. When playback is possible in progressive download, the playback control button group 51 is enabled as shown in FIG. In this embodiment, the playback control button group 51 is displayed when playback is possible. However, when the playback control button group 51 is always displayed and playback is not possible, It goes without saying that the operation of the reproduction control button group 51 may not be accepted, or the reproduction control button group 51 may not be operated. Needless to say, the screen configuration is not limited to this.

  FIG. 6 is a flowchart showing an example of processing when the content recording / playback apparatus 1 performs fast forward and fast reverse playback (special playback).

  This flowchart is started when a fast-forward / fast-reverse playback instruction is input from the user during playback.

  In process step S61, first, fast forward and fast reverse are prohibited.

In processing step S62, it is determined whether or not stream reproduction control information having information related to the I frame necessary for fast forward and fast reverse is added to the content.
If it is determined in step S62 that the table in FIG. 3 is not present, the data table in FIG. 3 is not created, and fast-forward and fast-reverse are prohibited.

  If the playback control information is added to the content, the process proceeds to step S63. If the playback control information is not added to the content, the process ends.

  In process step S63, the prohibition in S61 is canceled, fast forward and fast reverse reproduction are permitted, and the process ends.

This flowchart can be changed. For example, S61 may be removed, and fast-forward and fast-reverse may be prohibited when No in S62.

  FIG. 7 is a flowchart showing an example of processing in which the content recording / playback apparatus 1 determines whether to play back content during progressive download.

  In process step S71, it transmits to the content delivery server 201 so that content download may be started, and content download is started.

  In processing step S72, the bit rate at the time of reproduction is obtained from the hint information of the encoded average bit rate of the content added to the reproduction control metafile. For example, if there is a description of 10 Mbps in the hint information of the encoded average bit rate of the content, it can be seen that the encoded average bit rate of the content is 10 Mbps.

  In processing step S73, the average bit rate of the reception speed at the client is calculated based on the received content file size and the elapsed time from the start of progressive download, taking the network line and server performance into consideration.

  In the processing step S74, the average bit rate at the time of reproduction calculated based on the hint information of the reception average bit rate of the client and the encoded average bit rate of the content is compared. When the average bit rate of the reception speed at the client exceeds the average bit rate at the time of reproduction, the process proceeds to processing step S75, and when it does not exceed, the process proceeds to processing step S76. Details of the determination in step S74 will be described with reference to FIG.

  FIG. 8 is a diagram showing the relationship between content download and playback bit rate in the present invention. Fig. 8- (a) shows the case where the average bit rate of the reception speed at the client is larger than the encoded average bit rate of the content. Fig. 8- (b) shows the case where the average bit rate of the reception speed at the client is the content. This shows a case where it is smaller than the coding average bit rate.

  Hereinafter, a method for determining whether or not playback is possible during progressive download will be described with reference to FIG. f (t) represents the relationship between the file size of the content downloaded through the network line and the elapsed time. The slope of f (t) represents the average bit rate of the reception speed at the client. tm indicates the estimated time for content download completion.

  g (t) represents the relationship between the content playback file size and the elapsed time.

  The slope of g (t) represents the average bit rate at the time of reproduction obtained from hint information of the encoded average bit rate of the content added to the reproduction control metafile. ta represents the content reproduction start time, and tb represents the content reproduction completion time. (tb-ta) indicates the playback time of the content.

  When the average bit rate of the reception speed at the client is larger than the encoded average bit rate of the content, the progressive download reproduction start time ta can be set to an arbitrary time.

  On the other hand, if the average bit rate of the receiving speed at the client is smaller than the encoded average bit rate of the content, first calculate the expected download completion time tm from the average bit rate of the receiving speed at the client and the total content capacity. To do. In this embodiment, the total content capacity value is explicitly given from the content distribution server as a response to the communication protocol in the communication process between the content distribution server and the receiving client, but is acquired from the content distribution server. The total content capacity value may be described in the playback control metafile. Note that the method for acquiring the value of the total content capacity is not limited to the present embodiment. Next, tb is set so that the expected content reproduction completion time tb is tb = tm. Next, the content reproduction startable time ta is calculated by subtracting the content length (reproduction time) from the content reproduction completion expected time tb. The content reproduction startable time ta is compared with the current time, and it can be determined that the reproduction can be performed when the reproduction startable time has passed the current time. In this embodiment, the content length (reproduction time) is calculated from the encoded average bit rate and the entire capacity. In the communication process between the content distribution server and the receiving client, the response of the communication protocol from the content distribution server. It may be explicitly acquired as a result.

  In process step S75, the reproduction is permitted and the process proceeds to process step S81.

  In process step S76, the content download completion time tm is estimated.

  In process step S77, the reproduction end time tb of the content is estimated.

  In process step S78, the reproduction start time ta of the content is estimated.

  In processing step S79, it is determined whether or not the content reproduction start time ta is positive. If the content reproduction start time ta is positive, the process proceeds to processing step S75, and if not, the process proceeds to processing step S80.

  In process step S80, reproduction is prohibited and the process proceeds to process step S81.

  In process step S81, it is determined whether the download of the content is completed. If the download is complete, the process ends. If the download has not been completed, the process returns to process step S72 to continue the process.

The figure which shows the structural example of a content receiving client Diagram showing an example of network configuration Diagram showing an example of the structure of a data table Example of content receiving client screen # 1 Content receiving client screen example 2 A flowchart showing an example of processing for determining whether or not special playback is possible during downloading The flowchart which shows the process example of the decision | availability of the reproduction | regeneration of the content reproduction in downloading The figure which shows the relationship between the reception bit rate of content, playback bit rate, and playback start time

Explanation of symbols

1. Content recording / playback apparatus (content receiving client),
101 ... antenna,
102 ... Tuner,
103. Recording / playback control unit,
104 ... program processing section,
105. Auxiliary storage unit,
106 ... CPU,
107: Memory,
113 ... Speaker,
115 ... input device,
117 ... voice input unit,
118 ... Video input section,
119 ... Storage section,
120: display device 200 ... network 201 ... content distribution server 202 ... content receiving client 1

Claims (3)

A receiving device that receives video content distributed from the outside and metadata of the video content,
The metadata distributed from the outside includes reproduction bit rate information indicating a bit rate at the time of reproduction of the moving image content, and position information of the I frame of the moving image content,
A receiver that receives the video content and the metadata of the video content;
A recording unit for recording the moving image content received by the receiving unit;
A playback unit that plays back the video content recorded by the recording unit;
If the receiving speed of the video content being received is faster than the bit rate at the time of playback indicated by the playback bit rate information, the playback of the video content is allowed to be played back by the playback unit. And
If the position information of the I frame can be acquired , fast forward or fast reverse playback using only the I frame of the video content is permitted,
And a moving image content processing unit that prohibits playback of the fast-forward or fast-reverse of the moving image content if the position information of the I frame cannot be acquired. A receiving method for receiving video content distributed from the outside and metadata of the video content,
The metadata distributed from the outside includes reproduction bit rate information indicating a bit rate at the time of reproduction of the moving image content, and position information of the I frame of the moving image content,
Receiving the video content and metadata of the video content;
Record the received video content,
For the video content being received, if the reception speed of the video content being received is faster than the playback bit rate indicated by the playback bit rate information, the recorded video content can be played back,
If the position information of the I frame can be acquired , fast forward or fast reverse playback using only the I frame of the video content is permitted,
If the position information of the I frame cannot be acquired, the fast forward or fast reverse playback of the moving image content is prohibited. A transmission / reception method in which video content and metadata of the video content are distributed, and the distributed video content and metadata of the video content are received,
The metadata is distributed including reproduction bit rate information indicating a bit rate at the time of reproduction of the moving image content and I frame position information of the moving image content,
Receiving the video content and metadata of the video content;
Record the received video content,
For the video content being received, if the reception speed of the video content being received is faster than the playback bit rate indicated by the playback bit rate information, the recorded video content can be played back,
If the position information of the I frame can be acquired , fast forward or fast reverse playback using only the I frame of the video content is permitted,
If the position information of the I frame cannot be acquired, the fast-forward or fast-reverse playback of the moving image content is prohibited.

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