(19) United States
`(12) Patent Application Publication (10) Pub. No.: US 2004/0052371 A1
`Watanabe
`(43) Pub. Date:
`Mar. 18, 2004
`
`US 200400.52371A1
`
`(54) CONTENT PROVIDINGAPPARATUS AND
`CONTENT PROVIDING METHOD
`(76) Inventor: Koichiro Watanabe, Saitama (JP)
`Correspondence Address:
`Ronald P Kananen
`Rader Fishman & Grauer
`Suite 501
`1233 20th Street NW
`Washington, DC 20036 (US)
`
`(21) Appl. No.:
`
`10/398,580
`
`(22) PCT Filed:
`(86) PCT No.:
`
`Jul. 26, 2002
`PCT/JP02/07587
`
`Foreign Application Priority Data
`(30)
`Aug. 15, 2001 (JP)...................................... 2001-246345
`
`Publication Classification
`
`(51) Int. Cl. ............................................. H04N 7/167
`(52) U.S. Cl. .............................................................. 380/233
`
`ABSTRACT -
`(57)
`The present invention is applied to distribution of music and
`VideoS via the Internet. Single Stream content is divided into
`a plurality of parts A to D in a time-Series manner, and a first
`part A is transmitted via Stream distribution, and remaining
`parts B to D are transmitted via buffering distribution such
`that decoding of a receiver's Side can be started upon end of
`decoding an immediately preceding part.
`
`TRANSMISSION START
`REPRODUCTION START
`
`
`
`ON END
`REPRODUCT
`T ME
`
`TRANSMISSION
`
`RECEPTION
`
`(C)
`
`REPRODUCTION
`
`-1-
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`

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`Patent Application Publication Mar. 18, 2004
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`Patent Application Publication Mar. 18, 2004 Sheet 2 of 5
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`Patent Application Publication Mar. 18, 2004 Sheet 3 of 5
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`Patent Application Publication Mar. 18, 2004 Sheet 4 of 5
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`Patent Application Publication Mar. 18, 2004 Sheet 5 of 5
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`US 2004/0052371 A1
`
`Mar. 18, 2004
`
`CONTENT PROVIDING APPARATUS AND
`CONTENT PROVIDING METHOD
`
`BACKGROUND OF THE INVENTION
`0001) 1. Technical Field
`0002 The present invention relates to a content providing
`apparatus and a content providing method, and can be
`applied, for example, to distribution of music and VideoS via
`the Internet. In the present invention, Single Stream content
`is divided into a plurality of parts in a time-Series manner,
`and a first part is transmitted via Stream distribution, whereas
`remaining parts are transmitted via buffering distribution
`Such that decoding of a receiver's Side can be started upon
`end of decoding an immediately preceding part, whereby the
`stream content is distributed with a high reliability and
`latency can be reduced remarkably as compared to that in the
`conventional art.
`0003 2. Background Art
`0004 Conventionally, to distribute information such as
`music, films, etc. whose content changes with time (here
`inafter called stream content), it is designed to use a method
`of providing Stream content while its data is being received
`(hereinafter called Stream distribution), and a method of
`providing a user with Stream content after its data is tem
`porarily buffered (hereinafter called buffering distribution).
`0005) That is, in the stream distribution, as shown in FIG.
`1, a transmitter's Side transmits Stream content to a client at
`a transfer rate that is Substantially the same as a reproduction
`speed (FIG.1(A)), and a receiver's side buffers the received
`data in an amount large enough to decode the Stream content
`(FIG. 1(B)) for sequential decoding (this process on the
`receiver's Side is called Stream reception as corresponding to
`the stream distribution). In the case of this method, the
`Stream content transmitted by the transmitter can be repro
`duced only to a very Small delay time required for data
`transmission and decoding (FIG. 1(C)), whereby a latency
`between the Start of receiving the Stream content and the
`Start of actually reproducing it can be reduced, thereby
`allowing the Stream content to be provided Smoothly.
`0006 By contrast, in the buffering distribution, as shown
`in FIG. 2, a transmitter's Side transmits Stream content at a
`rate irrelevant to a reproduction speed (FIG. 2(A)). A
`recipient receives the Stream content, bufferS all the received
`stream content (FIG. 2(B)), and thereafter decodes the
`buffered stream content to provide a user with the decoded
`stream content (FIG. 2(C)) (this process on the receivers
`Side is hereinafter called buffering reception as correspond
`ing to the buffering distribution). In the case of this method,
`there is a shortcoming that a relatively long time interval is
`required between the Start of receiving the content and the
`Start of actually reproducing it. However, in the case of this
`method, all the stream content is received and buffered in
`advance prior to its reproduction, and this allows an error
`recovery technique, Such as error correction or retransmis
`sion request processing in TCP/IP, to be applied, whereby
`the Stream content can be distributed with a correspondingly
`higher reliability.
`0007. In the buffering distribution, it is so designed that
`Single Stream content is decomposed into a plurality of parts
`to be transmitted Sequentially, whereby to reduce the latency
`
`between the Start of receiving the Stream content and the
`Start of actually reproducing it.
`0008 That is, in the case of this method, as shown in
`FIG. 3, a transmitter's side divides single stream content
`into, for example, four parts A to D in a time-Series manner,
`and transmits these parts Ato D sequentially (FIG.3(A)). In
`response thereto, a receiver's Side receives and buffers these
`parts A to D, and, upon completion of receiving one part,
`Starts reproducing this part. Thus, it is So designed that after
`having buffered the first part A, the receiver's side starts
`decoding a part whose reception is completed while buff
`ering another part, whereby to reduce the latency (FIGS.
`3(B) and (C)).
`0009. Thus, the buffering distribution has a merit that
`stream content can be distributed with a high reliability, but
`does involve a problem of generating the latency. For this
`reason, a user, who has requested Stream content, cannot
`listen to a demonstration of the content during the latency
`period. Incidentally, as explained with reference to FIG. 3,
`even when Single Stream content is divided and distributed
`as a plurality of parts, the latency does exist before reception
`of the first part is completed.
`DISCLOSURE OF THE INVENTION
`0010. The present invention has been made in consider
`ation of the above points, and attempts to propose a content
`providing apparatus and a content providing method by
`which stream content is distributed with a high reliability
`and latency can be reduced remarkably as compared to that
`in the conventional art.
`0011. In order to solve the above problem, the present
`invention is applied to a content providing apparatus for
`transmitting predetermined Stream content to a client.
`Among a plurality of parts formed by time-Series division of
`Single Stream content, a first part is transmitted via Stream
`distribution, and remaining parts are transmitted via buffer
`ing distribution Such that decoding of a receiver's Side can
`be started upon end of decoding an immediately preceding
`part.
`0012. The stream distribution exhibits an extremely low
`latency but has a demerit of low reliability, whereas the
`buffering distribution exhibits a high latency but has a merit
`of high reliability. Thus, according to the configuration of
`the present invention, the first part is transmitted via the
`Stream distribution, and the remaining parts are transmitted
`via the buffering distribution such that decoding of the
`receiver's Side can be started upon end of decoding an
`immediately preceding part, whereby while reproducing the
`first part after an extremely low latency, buffering of the
`Succeeding parts can be completed, thereby allowing the
`parts Subsequent to the first part to be reproduced without
`interruption. Thus, Stream content can be provided, ensuring
`a high reliability.
`0013 Further, the present invention is applied to a con
`tent providing apparatus for receiving Stream content trans
`mitted by a predetermined server to provide a user with the
`received Stream content. The Stream content is divided into
`a plurality of parts in a time-Series manner to be transmitted
`by the Server, and the content providing apparatus receives
`a first one of the parts via Stream reception to be provided to
`the user, and buffer-receives a rest of the parts in a manner
`decodable upon completion of decoding an immediately
`preceding part.
`
`-7-
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`

`

`US 2004/0052371 A1
`
`Mar. 18, 2004
`
`0.014 Thus, according to the configuration of the present
`invention, the proceSS performed by the receiver's Side
`permits the Stream content to be provided at a low latency
`and ensuring a high reliability.
`0.015
`Still further, the present invention is applied to a
`content providing method of transmitting predetermined
`Stream content to a client. Among a plurality of parts formed
`by time-Series division of Single Stream content, a first part
`is transmitted via the Stream distribution, and remaining
`parts are transmitted via the buffering distribution Such that
`decoding of a receiver's Side can be started upon end of
`decoding an immediately preceding part.
`0016. According to the configuration of the present
`invention, a content providing method can be provided, by
`which stream content is distributed with a high reliability
`and latency can be reduced remarkably as compared to that
`in the conventional art.
`0017 Still further, the present invention provides a con
`tent providing method of receiving Stream content transmit
`ted by a predetermined Server to provide a user with the
`received Stream content. The Stream content is divided in to
`a plurality of parts in a time-Series manner to be transmitted
`by the Server, and the content providing method includes
`receiving a first one of the parts via Stream reception to be
`provided to the user, and buffer-receiving a rest of the parts
`in a manner decodable upon completion of an immediately
`preceding part.
`0.018. According to the configuration of the present
`invention, a content providing method can be provided, by
`which stream content is distributed with a high reliability
`and latency can be reduced remarkably as compared to that
`in the conventional art.
`
`BRIEF DESCRIPTION OF DRAWINGS
`FIG. 1 is a characteristic curve diagram for
`0.019
`explaining conventional Stream distribution;
`0020 FIG. 2 is a characteristic curve diagram for
`explaining conventional buffering distribution;
`0021
`FIG. 3 is a characteristic curve diagram for
`explaining buffering distribution in which Single Stream
`content is divided into a plurality of parts,
`0022 FIG. 4 is a block diagram showing a distribution
`System according to an embodiment of the present inven
`tion; and
`0023 FIG. 5 is a characteristic curve diagram for
`explaining the distribution of stream content in FIG. 4.
`
`BEST MODES FOR CARRYING OUT THE
`INVENTION
`0024. Embodiments of the present invention are
`described below in detail with reference to the drawings
`whenever appropriate.
`0025 (1) Configuration of an Embodiment
`0.026
`FIG. 4 is a block diagram showing a distribution
`System according to an embodiment of the present inven
`tion. In this distribution System 1, a client 2 is a computer
`connected to a network Such as the Internet, and is a
`receiving unit of content. A Service Server 3 functions as an
`
`HTTP server and renders services such as presentation of
`providable content by access from the client 2. A content
`Server 4 provides Stream content by Similar access from the
`client 2.
`0027. Here, the content server 4 divides single stream
`content for distribution into a plurality of parts in a time
`Series direction, and distributes a first part via the Stream
`distribution and remaining parts are transmitted via the
`buffering distribution Such that a receiver's Side can perform
`reproduction upon completion of reproducing an immedi
`ately preceding part; i.e., the receiver's Side can complete
`buffering upon completion of decoding an immediately
`preceding part.
`0028. That is, in this embodiment, as shown in FIG. 5,
`Single Stream content is arranged in time-Series manner and
`divided into four parts A to D. Here, the parts A to D are
`formed such that they are related to each other to have their
`reproduction time doubled Sequentially in the time-Series
`direction. Among these parts A to D, the content Server 4
`transmits the first part A via the stream distribution. The
`parts B to D Subsequent to the first part A are Sequentially
`transmitted via the buffering distribution. Further, when
`transmitting the first part A, the content Server transmits the
`Subsequent part B concurrently (FIG. 5 (A)).
`0029. Thus, it is so designed in this embodiment that
`while receiving and decoding the first part A, the receiver's
`side receives and buffers the Subsequent part B so that the
`Subsequent part B can be reproduced upon completion of
`reproducing the part A. Further, it is So designed that while
`reproducing the part B in this way, the Subsequent part C is
`received and buffered So that the Subsequent part C can be
`reproduced upon completion of reproducing the part B. By
`enabling the receiver's Side to perform these processes, the
`content Server 4 is designed Such that a reproducer's Side can
`reproduce the Successive parts A to D without interruption
`whereby to reduce the latency remarkably after a request is
`made.
`0030. In order to do so, thus the client 2 requests the
`content Server 4 to distribute Stream content based on a menu
`offered by access to the service server 3. Then the client 2
`concurrently receives the first and Second parts A and B
`transmitted in this way, and decodes the first part A to
`provide a user with the decoded part A, and buffers the
`Second part B. Further, upon completion of decoding the first
`part A, the client 2 starts decoding the Second part B, and
`also receives and buffers the Subsequently transmitted third
`part C. Further, upon completion of decoding the Second part
`B, the client 2 starts decoding the third part, and also starts
`receiving and buffering the fourth part, and upon completion
`of decoding the third part C, it starts decoding the fourth part
`D.
`0.031) (2) Operation of the Embodiment
`0032. In the above configuration, this distribution system
`1 operates such that the client 2 is provided with a list or the
`like of content for distribution by access to the service server
`3, and Stream content is provided from the content Server 4
`by access following this list.
`0033. In this way of providing the content, among four
`parts A to D formed by dividing Single Stream content in a
`time-Series manner, the content Server 4 provides the first
`part A and Subsequent part B via the Stream distribution and
`
`-8-
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`

`US 2004/0052371 A1
`
`Mar. 18, 2004
`
`the buffering distribution, respectively, and the Subsequent
`parts C and D via the buffering distribution. Further, the
`parts B to Dother than the first part are distributed such that
`upon end of decoding an immediately preceding part, a
`receiver's Side can decode a Succeeding part for reproduc
`tion.
`0034. Thus, the receivers side can stream-receive the first
`part A, whereby the Stream content can be provided to the
`user with extremely low latency period. Further, while
`providing the user with the first part A in this way, the
`receiver's Side buffer-receives the Subsequent part B, i.e.,
`receives and buffers the part B, and Starts decoding the part
`B upon completion of decoding the part A, whereby the
`Successive parts A and B can be provided to the user without
`interruption.
`0035) Further, while providing the user with the part B in
`this way, the receiver's side receives and buffers the Subse
`quent part C, and upon completion of decoding the part B,
`it starts decoding the part C. Further, while providing the
`user with the part C, the receiver's side receives and buffers
`the Subsequent part D, and upon end of decoding the part C,
`it starts decoding the part D. Thus, this embodiment ensures
`a low latency and allows the Successive parts A to D to be
`provided to the user without interruption. At this time, the
`parts B to D other than the first part are provided via the
`buffering distribution, whereby recovery processing for
`transmission error can be performed whenever necessary, to
`ensure a high reliability.
`0036 (3) Advantages of the Embodiment
`0037 According to the above configuration, single
`Stream content is divided into a plurality of parts in a
`time-Series manner, and a first part is transmitted via the
`Stream distribution, and remaining parts are transmitted via
`the buffering distribution such that decoding of a receiver's
`Side can be started upon end of decoding an immediately
`preceding part, whereby the Stream content is distributed
`with a high reliability and latency can be reduced remark
`ably as compared to that in the conventional art.
`0038 (4) Second Embodiment
`0039. In this embodiment, the first part Aaccording to the
`above-described first embodiment is distributed via unicast
`and the remaining parts B to D via multicast.
`0040 Here, unicast means a process of distributing one
`item of Stream content to one client exclusively, whereas
`multicast means a process of distributing one item of Stream
`content to a plurality of clients in common. In a distribution
`via the multicast, the content Server 4 transmits the plurality
`of parts C and D Sequentially and cyclically, and each client
`buffer-receives these parts C and D Sequentially and Selec
`tively.
`0041. Thus, it is so designed in this embodiment that
`stream the distribution of the first part is performed via
`unicast to allow the latency to be reduced accordingly.
`0.042
`Further, it is so designed that the buffering distri
`bution of the remaining parts is performed via multicast to
`prevent a bandwidth required for transmission from increas
`ing.
`Further, the plurality of parts are each transmitted
`0.043
`Sequentially and cyclically to implement a distribution via
`
`the multicast, whereby it is designed to prevent the band
`width required for transmission from increasing even if the
`number of clients is increased.
`0044) (5) Other Embodiments
`0045. Note that while the cases where single stream
`content is distributed by division into four parts have been
`described in the above-described embodiments, the present
`invention is not limited thereto. By dividing Single Stream
`content into Such various parts as necessary, advantages
`similar to those of the above-described embodiments can be
`obtained.
`0046. Further, while the cases where parts to be buffer
`distributed are sequentially received and buffered have been
`described in the above-described embodiments, the present
`invention is not limited thereto. What matters is that it is
`arranged that upon end of decoding an immediately preced
`ing part, buffering is completed So that decoding can be
`Started. AS long as it is So arranged, even when a first part
`and Subsequent Second and third parts may be received
`concurrently, advantages Similar to those of the above
`described embodiments can be obtained.
`0047 As described above, according to the present
`invention, Single Stream content is divided into a plurality of
`parts in a time-Series manner, and a first part is transmitted
`via the Stream distribution, and remaining parts are trans
`mitted via the buffering distribution such that decoding of a
`receiver's Side can be started upon completion of decoding
`an immediately preceding part, whereby the Stream content
`is distributed with a high reliability and latency can be
`reduced remarkably as compared to that in the conventional
`art.
`
`Industrial Applicability
`0048. The present invention relates to a content providing
`apparatus and a content providing method, and can be
`applied, for example, to distribution of music and VideoS via
`the Internet.
`
`Description of Numerals
`0049) 1. Distribution System
`0050 2. Client
`0051) 3. Service Server
`0.052
`4. Content Server
`
`1. (Amended) A content providing apparatus for trans
`mitting predetermined Stream content to a client, character
`ized in that:
`among a plurality of parts formed by time-Series division
`of Single Stream content,
`only a first part is transmitted via Stream distribution; and
`remaining parts are transmitted via buffering distribution
`Such that decoding of a receiver's Side can be Started
`upon end of decoding an immediately preceding part.
`2. The content providing apparatus as claimed in claim 1,
`wherein Said Stream distribution is a distribution via unicast.
`3. The content providing apparatus as claimed in claim 1,
`wherein said buffering distribution is a distribution via
`multicast.
`
`-9-
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`

`US 2004/0052371 A1
`
`Mar. 18, 2004
`
`4. (Amended) A content providing apparatus for receiving
`Stream content transmitted by a predetermined Server to
`provide a user with the received Stream content, character
`ized in that:
`Said Stream content is divided into a plurality of parts in
`time-Series manner to be transmitted by Said Server; and
`Said content providing apparatus receives only a first one
`of Said parts via Stream reception to be provided to the
`user, and
`buffer-receives a rest of Said parts in a manner decodable
`upon completion of decoding an immediately preced
`ing part.
`5. (Amended) A content providing method of transmitting
`predetermined Stream content to a client, characterized by
`comprising:
`among a plurality of parts formed by time-Series division
`of Single Stream content,
`transmitting only a first part via Stream distribution, and
`
`transmitting remaining parts via buffering distribution
`Such that decoding of a receiver's Side can be Started
`upon end of decoding an immediately preceding part.
`6. (Amended) A content providing method of receiving
`Stream content transmitted by a predetermined Server to
`provide a user with the received Stream content, character
`ized in that:
`Said Stream content is divided into a plurality of parts in
`time-Series manner to be transmitted by Said Server; and
`Said content providing method comprises:
`receiving only a first one of Said parts via Stream
`reception to be provided to the user; and
`buffer-receiving a rest of Said parts in a manner decod
`able upon completion of decoding an immediately
`preceding part.
`
`-10-
`
`