Patent Application
20090183223
1. Field of the Invention
The present invention relates to a video distribution system for digital broadcasting.
2. Description of Related Art
For example, patent reference 1 discloses, as a method of enabling a user to view and listen to a plurality of programs currently being broadcast simultaneously, a method of, in a conventional video distribution system in which a video distribution center broadcasts a program to one or more receivers via a network so that each user can view and listen to a broadcast program received by a receiver, collectively recording programs in the video distribution center, and providing a recorded program for each user via the network. Furthermore, patent reference 2 discloses a method of storing moving image data which a receiver has received in a recorder which is connected to the receiver via a network, and reading moving image data from the recorder according to a user's specification.
[Patent reference 1] JP, 2002-199318,A
[Patent reference 2] JP, 2005-20057,A
However, although patent reference 1 discloses a method for and a procedure for recording a program, patent reference 1 does not disclose any video-recording method of, in a case of enabling each user to view and listen to a plurality of programs, and recording them, taking into consideration the load on the network between the distribution center and the receiver at the time of distributing recorded data about the plurality of programs to the receiver, and any method of distributing the recorded data. A problem with the above-mentioned conventional video distribution system is therefore that in a case in which a user views and listens to or records a program distributed via the network by using one receiver, the network load increases when the receiver receives a plurality of streams simultaneously, and therefore a large network band is needed and this becomes a factor causing increase in the cost of the system.
Furthermore, because it is necessary to store the recorded data about a program which are recorded by the distribution center until the user who has made a request to record the program views and listens to the program, it is necessary to free up a large storage capacity for video-recording in the distribution center and this also becomes a factor causing increase in the cost of the system. A further problem is that both the network load at the time of distributing recorded data stored in a storage unit connected to the network to the receiver and a time period during which the recorded data are stored in the storage unit are dependent upon users.
The present invention is made in order to solve the above-mentioned problems, and it is therefore an object of the present invention to provide a video distribution system which can implement distribution of a stream with stability while limiting the number of streams which are distributed from a distribution center comprised of a stream distribution apparatus and a video-recording and distribution apparatus to a receiver to one.
In accordance with the present invention, there is provided a video distribution system including a stream distribution apparatus which distributes a plurality of programs, a video-recording and distribution apparatus which records and distributes a predetermined program, a receiver which receives a program distributed by the stream distribution apparatus, and a network which connects the stream distribution apparatus, the video-recording and distribution apparatus, and the receiver with one another, in which the video-recording and distribution apparatus includes: a recording control unit for recording the predetermined program; and a download distribution unit for distributing recorded data about the predetermined program which are recorded by the recording control unit, and the receiver includes: a stream receiving unit for receiving a program distributed from the stream distribution apparatus; a playback unit for playing back the program; a recording unit for recording the program; a recorded data reading unit for reading recorded data about the program which are recorded by the recording unit; and a download receiving unit for downloading the recorded data recorded by the video-recording and distribution apparatus, and in which, when the video distribution system carries out reception and video-recording of a plurality of programs, the stream receiving unit receives one of the programs which is distributed from the stream distribution apparatus, the recording unit outputs either a request to start recording of another one of the programs or a request to end recording of the other program to the recording control unit, the recording control unit records the other program according to either the recording start request or the recording end request, and the download receiving unit outputs a request to start downloading the other program to the download distribution unit after the stream receiving unit completes the reception of the one program.
According to the present invention, while the receiver is receiving a predetermined program, the recording unit outputs a recording start request and a recording end request to the recording control unit, the recording control unit records the predetermined program according to the recording start request and the recording end request, and the download receiving unit outputs the download start request to the download distribution unit after the receiver completes the reception of the predetermined program. Thus, the system can record a plurality of programs while the receiver limits the number of programs which the receiver receives simultaneously to one program.
Further objects and advantages of the present invention will be apparent from the following description of the preferred embodiments of the invention as illustrated in the accompanying drawings.
The video-recording and distribution apparatus 102 is comprised of a recording control unit 103, a download distribution unit 104, and a storage unit 105. According to a request inputted from the receiver 200, the recording control unit 103 receives a stream of a program which is distributed by the stream distribution apparatus 101 and the recorder 105 then stores the stream as recorded data. The storage unit 105 is comprised of, for example, a hard disk drive. The recording control unit 103 can delete the headers of the IP packets from the stream of the program which the recording control unit has received, and can store, as recorded data, only the coded data about the video, the audio, etc. of the program. According to a request inputted from the receiver 200, the download distribution unit 104 distributes the recorded data which the recording control unit 103 has stored in the storage unit 105 to the receiver 200.
The receiver 200 is comprised of a stream receiving unit 201, a playback unit 202, a recording unit 203, a recorded data reading unit 204, a download receiving unit 205, a user input unit 206, and a storage unit 207. The stream receiving unit 201 receives the stream of the program which is distributed from the stream distribution apparatus 101 included in the distribution center 100, and outputs the received stream to either the playback unit 202 or the recording unit 203. The playback unit 202 decodes the stream inputted from the stream receiving unit 201 into data about the video, the audio, etc. by using a coding method such as an H.264 coding method or an MPEG-2 coding method, and then plays back the data.
The recording unit 203 records a program according to a user's instruction inputted from the user input unit 206. In this embodiment, there can be the following two methods of recording a program: a method of recording a program in the storage unit 207 included in the receiver 200; and a method of recording a program in the storage unit 105 included in the video-recording and distribution apparatus 102 of the distribution center 100. In the case of recording a stream of a program in the receiver 200, the stream of the program which the stream receiving unit 201 has received is inputted to the recording unit 203 and is then recorded in the storage unit 207. In contrast, in the case of recording a program in the distribution center 100, when the recording unit 203 transmits a recording start request to the distribution center 100, a video-recording command for recoding the program is inputted to the recording control unit 103 and the program is then recorded in the storage unit 105.
The recorded data reading unit 204 reads the recorded data about the program recorded in the storage unit 207, and outputs the recorded data to the playback unit 202. The download receiving unit 205 downloads the recorded data about the program recorded in the distribution center 100. The receiver performs the download of the recorded data by transmitting a download start request to the download distribution unit 104 of the distribution center 100.
Next, the operation of the video distribution system in accordance with Embodiment 1 of the present invention will be explained.
The user of the receiver 200 inputs a setting command for viewing and listening to the program A and recording the program B via the user input unit 206 (step ST101). In step ST101, the recording unit 203 which has received the recording setting command transmits a recording start request to start video-recording of the program B to the video-recording and distribution apparatus 102 (step ST102). When the distribution start time of the programs A and B comes, the stream distribution apparatus 101 starts the distribution of the programs A and B (step ST103). The stream receiving unit 201 starts reception of the stream of the program A which the stream distribution apparatus starts distributing in step ST103, and outputs the stream received to the playback unit 202, so that the playback unit 202 plays back the program A (step ST104). On the other hand, the video-recording and distribution apparatus 102 to which the recording start request is transmitted in step ST102 starts video-recording of the program B by using the recording control unit 103 (step ST105).
When the distribution end time of the program A comes, the stream distribution apparatus 101 ends the distribution of the program A (step ST106). The receiver 200 then ends the reception and playback of the program A, and starts reception and video-recording of the program B. More specifically, the stream receiving unit 201 ends the reception of the program A and starts reception of the program B, and outputs the stream of the program B which the stream receiving unit has received to the recording unit 203, and the recording unit 203 then records the stream of the program B in the storage unit 207 (step ST107). The recording unit 203 further outputs a recording end request to end the recording of the program B to the video-recording and distribution apparatus 102 in order to end the video-recording of the program B using the recording control unit 103 (step ST108). The video-recording and distribution apparatus 102 ends the video-recording of the program B using the recording control unit 103 according to the recording end request transmitted thereto in step ST108 (step ST109). When the distribution end time of the program B comes, the stream distribution apparatus 101 ends the distribution of the program B (step ST110), the stream receiving unit 201 ends the reception of the program B, and the recording unit 203 ends the video-recording of the program B (step ST111).
Next, the download receiving unit 205 outputs a download distribution request to download the recorded data about the program B recorded in the storage unit 105 of the video-recording and distribution apparatus 102 (step ST112). The video-recording and distribution apparatus 102 carries out download distribution of the recorded data about the program B by using the download distribution unit 104 according to the download distribution request outputted thereto in step ST112 (step ST113). The download receiving unit 205 receives the recorded data about the program B distributed from the video-recording and distribution apparatus 102 and then outputs the received recorded data to the recording unit 203, and the recording unit 203 stores the recorded data in the storage unit 207 (step ST114).
In this case, because the stream of the latter half of the program B is already stored, as recorded data, in the storage unit 207, the stream of the first half of the program B recorded in the distribution center 100 is stored, as other recorded data, in the storage unit 207. As a method of storing the stream of the program B in the storage unit 207, there can be, for example, a method of combining the file of the first half recorded in the distribution center 100 and the file of the latter half recorded in the receiver 200, and then storing the combined fines as one stream, or a method of storing both the file of the first half and the file of the latter half separately, and then making the recorded data reading unit 204 read the stream of the latter half to start a playback of the latter half after completing a playback of the first half.
When the download receiving unit 205 completes the download of the program B (step ST115), the receiver 200 records the whole of the program B in the storage unit 207. As a result, the receiver 200 enables the user to view and listen to the program B. After completing the download distribution of the recorded data about the program B to the receiver 200, the video-recording and distribution apparatus 102 can delete the recorded data.
After the system carries out the series of processes in steps ST101 to ST115 as mentioned above, and the user of the receiver 200 views and listens to the program A, the user can view and listen to the program B recorded in the receiver 200. In this case, the receiver 200 receives only the program A in steps ST104 to ST107, receives only the program B in steps ST107 to ST111, and receives only the program B in steps ST114 and ST115. The receiver 200 can thus enable the user to view and listen to the program A and record the program B while limiting the number of programs which the receiver 200 receives simultaneously to one.
Next, an example of the recording start request and the recording end request which are transmitted from the recording unit 203 of the receiver 200 to the video-recording and distribution apparatus 102, the download distribution start request which is transmitted from the download receiving unit 205 to the video-recording and distribution apparatus 102, and a recording start response, a recording end response, and a download distribution start response which are transmitted respectively from the video-recording and distribution apparatus 102 to the receiver 200 in response to the above-mentioned requests will be shown with reference to
As shown in
The recording end request which the recording unit 203 transmits has a specified format consisting of a command type indicating that the request is a recording end request, a request ID, a recording ID, and a recording end time. By using the recording end request having this format, the recording unit 203 makes a request of the video-recording and distribution apparatus 102 to end the recording. The video-recording and distribution apparatus 102 to which the recording end request is inputted answers, as a recording end response to the recording end request, the request ID stored in the recording end request and a result indicating whether to accept the recording end request to the recording unit 203. The download distribution start request which the download receiving unit 205 transmits has a specified format consisting of a command type indicating that the request is a download distribution start request, a request ID, a user ID, a recording ID, and a distribution start time. By using the recording end request having this format, the download receiving unit 205 makes a request of the video-recording and distribution apparatus 102 to start download distribution. The video-recording and distribution apparatus 102 to which the download distribution starting request is inputted answers, as a download distribution start response to the download distribution start request, the request ID stored in the download distribution start request and a result indicating whether to accept the download distribution start request to the download receiving unit 205.
a) to 5(b) are diagrams showing in time sequence recorded data in the storage unit of the video distribution system in accordance with Embodiment 1 of the present invention, and show the positions of playback of the recorded data and a state in which the download of the recorded data is in process. In the above-mentioned explanation, the example in which the receiver 200 enables the user to start viewing and listening to the program B after the download of the program B is completed and the whole of the program B is recorded in the storage unit 207 included in the receiver 200 is shown. As an alternative, the receiver can play back the program B so as to make the user start viewing and listening to the program B during the download of the program B, as shown in
However, in a case in which the transfer rate at which the receiver plays back the program is higher than the transfer rate which the receiver downloads the program, if the playback start time of the program is too early, an underflow of the recorded data occurs and the playback of the program becomes discontinuous. Therefore, the time t at which the receiver starts a playback of the program after starting downloading the program is calculated from the transfer rate p of the download, the transfer rate q of the playback, and the size r of the recorded data about the program to be downloaded according to the following equation 1:
t=r/p−r/q(q>p), t=0(q<=p) (equation 1)
As mentioned above, in accordance with Embodiment 1 of the present invention, while the receiver receives a predetermined program, another program is recorded into the storage unit of the distribution center, and, after the receiver finishes the reception of the program, the receiver downloads the recorded data about the other program from the distribution center by using the download distribution unit, and records the recorded data therein. Therefore, after the user of the receiver finishes viewing and listening to the predetermined program, the user can view and listen to the other program recorded in the receiver. Thus, the system can record a plurality of programs while the receiver limits the number of programs which the receiver receives simultaneously to one program.
Furthermore, in accordance with Embodiment 1 of the present invention, the distribution center records only a part of the other program including from the head of this program only during a period of time which elapses until the distribution of the predetermined program which the receiver is receiving is completed. Therefore, as compared with a case in which the whole of the other program to be recorded is recorded in the distribution center, the capacity of the storage unit of the distribution center can be reduced. In addition, because the receiver automatically downloads the recorded data recorded in the storage unit of the distribution center when not receiving any stream, it is not necessary to store the recorded data recorded in the storage unit of the distribution center for a long time and it is therefore possible to use the storage unit efficiently and to reduce the cost of the system.
Furthermore, in accordance with Embodiment 1 of the present invention, while the receiver is receiving a program other than programs to be recorded and the load on the network is high, the distribution center records another program to be recorded and, after that, when the load on the network becomes low, the receiver receives the recorded data about the other program from the distribution center automatically. Therefore, the user of the receiver can view and listen to a plurality of programs which are broadcast simultaneously with an easy operation. In addition, in a case in which the video-recording done by the distribution center is a pay service, because the amount of storage in the distribution center which the user uses to record a desired program and the time required for the user to use the storage unit to record the desired program can be minimized, the charge for the use of the distribution center which increases in proportion to the used amount of and the usage time of storage of the distribution center can be reduced.
Next, the operation of the video distribution system in accordance with Embodiment 2 of the present invention will be explained.
After the receiver 200, in step ST111, completes the reception and video-recording of the program B, the seamless playback control unit 208 transmits a stream distribution start request to start distribution of a stream of the recorded data about the program B recorded in the video-recording and distribution apparatus 102 (step ST201). The video-recording and distribution apparatus 102 stream-distributes the recorded data about the program B by using the stream distribution unit 106 according to the stream distribution start request transmitted in step ST201 (step ST202). When the seamless playback control unit 208 receives the recorded data about the program B distributed from the video-recording and distribution apparatus 102, the seamless playback control unit 208 outputs the recorded data to the playback unit 202 and the playback unit 202 then plays back the recorded data about the program B (step ST203).
After the video-recording and distribution apparatus 102 completes the distribution of the stream of the recorded data about the program B (step ST204), the seamless playback control unit 208 included in the receiver 200 ends the reception of the stream of the program B, and, in order to continue to play back the recorded data about the program B recorded within the receiver 200 in steps S107 to S111, reads the recorded data about the program B via the recorded data reading unit 204, and outputs the recorded data to the playback unit 202. The playback unit 202 then plays back the recorded data about the program B (step ST205). After that, the playback unit 202 completes the playback of the recorded data about the program B (step ST206).
a) to 8(d) are diagrams showing the status of data in the seamless playback control unit of the video distribution system in accordance with Embodiment 2 of the present invention.
c) shows a state immediately before the seamless playback control unit 208 ends the reception and playback of the stream. When the seamless playback control unit 208 does not receive the stream during a fixed period of time, the seamless playback control unit 208 judges that the distribution of the stream is completed and starts reading the recorded data stored in the receiver 200. As a result, the playback unit 202 can play back both the recorded data in the distribution center 100 and the recorded data in the receiver 200 seamlessly.
Next, an example of a stream distribution start response which the video-recording and distribution apparatus 102 transmits to the receiver 200 in response to the stream distribution start request which is transmitted from the seamless playback control unit 208 of the receiver 200 to the video-recording and distribution apparatus 102 will be shown with reference to
As mentioned above, the video distribution system according to Embodiment 2 of the present invention includes the stream distribution unit for stream-distributing recorded data about a program, and the seamless playback control unit for performing a control operation to play back both the recorded data distributed by the stream distribution unit and recorded data in the receiver seamlessly. Therefore, the video distribution system can play back both the recorded data distributed by the stream distribution unit and recorded data in the receiver seamlessly. Furthermore, the user of the receiver can view and listen to both a program recorded in the distribution center and a program recorded in the receiver after viewing and listening to a predetermined program.
In above-mentioned Embodiment 2, the example in which the video-recording and distribution apparatus 102 is disposed in the distribution center 100 is shown. As an alternative, as in the case of
For example, when the receiver 200 downloads a program C under the usage of the network 300 as shown in
As mentioned above, the video distribution system according to this Embodiment 3 includes the leftover band detecting unit for measuring a leftover band which exists in the network, and carries out download reception of recorded data recorded in the distribution center using the leftover band. Therefore, even if the user of the receiver is viewing and listening to a program or the receiver is recording a program, the receiver can download another program when a leftover band exists in the network.
The structure of the recorded data management unit 107 will be explained with reference to
Recorded data which are actually stored in the storage unit 105 of the video-recording and distribution apparatus 102 when the receiver 200 has made program vide-recording requests as shown in
As mentioned above, because the video distribution system according to Embodiment 4 of the present invention is provided with the recorded data management unit for managing video-recording requests in which their channels and recording time zones overlap one another as a single video-recording request, the amount of recorded data which are stored in the storage unit can be reduced to a minimum.
Many widely different embodiments of the present invention may be constructed without departing from the spirit and scope of the present invention. It should be understood that the present invention is not limited to the specific embodiments described in the specification, except as defined in the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2008-006864 | Jan 2008 | JP | national |
