JP2003348548A - Stream distribution system and method, and stream receiving apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a video from being stopped or resent from a different scene even when starting a stream distribution corresponding to a change of a band in which a video communication on a network is possible. <P>SOLUTION: In the stream distribution from a video transmitting apparatus (server) 1 through a network 2 to a stream receiving apparatus (client) 3, not a single stream but a plurality of streams of different bands are synchronously distributed simultaneously and on the client side where respective streams are received, the respective streams are held for a fixed period individually by data queues (0) 3b and (1) 3c. In accordance with receiving statuses of the respective streams, namely, in accordance with a change in the utilized band of the network, streams to be outputted on an output device such as television or personal computer are switched for the unit of a frame by a switching part 3f. <P>COPYRIGHT: (C)2004,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technology for streaming video data from a video distribution device to a video reproduction device via a network such as the Internet.
In particular, the present invention relates to a technology that enables stable stream distribution even when a communication band of a network between a video distribution device and a video reproduction device changes every moment due to, for example, the network communication status of another party. .

[0002]

2. Description of the Related Art In recent years, for example, ISDN (Integrated Servo
vices Digital Network) and ADSL (Asymmetric Digi)
With the spread of high-speed data transfer technologies such as tal Subscriber Line), it has become easy to use stream distribution of moving image (video) data on the Internet.

In a system for performing such a stream distribution, a video distribution device (server) and a video reproduction device (client) are installed remotely over a network, and the video distribution server side transmits the network transfer speed (client). p
bs, bit rate), contents to be provided for distribution are generated (higher-quality contents are generated for high-speed use), and the video playback client selects and receives contents suitable for the connection speed.

[0004] However, the communication band (transfer speed) between the video distribution server and the video reproduction client changes every moment due to the network communication status of the other party, and therefore, when high-quality content is distributed. Network bandwidth may be reduced and movement may be jerky or stopped.

[0005] As a conventional technique for addressing such a problem, for example, "Microsoft Windows" has been proposed.
As in the case of the “sMedia (registered trademark)” technology, there is a technology in which the stream grade is switched according to a change in the band.

However, in this technique, the client receives one video stream most suitable for the current bandwidth condition. That is, during stream distribution,
When the available bandwidth decreases, the server automatically detects the change and switches to a stream data stream for lower bandwidth, and when the bandwidth is improved, the server returns to the original. Switching to a bandwidth stream for distribution.

For this reason, in this technique, the transition timing of the stream is long, and the transition cannot be performed smoothly. As a result, when performing a band transfer, stop the stream being delivered,
Streams of different bands are distributed, and when the stream is changed, the distribution is temporarily stopped, and it takes time to resume (resume), and the video is damaged.

[0008]

The problem to be solved in the prior art is that, when the band in which video communication on the network can be performed changes and the system shifts to stream distribution according to the change, video stoppage, The point is that retransmission from a different scene occurs.

[0009] An object of the present invention is to solve the problems of the prior art and to enable stable stream distribution of video contents over the Internet or the like.

[0010]

In order to achieve the above object, according to the present invention, when a stream is distributed from a video transmission side device (server) to a video reproduction side device (client), each of the bands is not a single stream. On the client side, which simultaneously synchronizes and distributes a plurality of different streams and receives each stream, holds each stream individually for a certain period of time, and according to the reception status of each stream, that is, according to a change in the bandwidth used by the network. The stream output from an output device such as a television or a personal computer is switched in frame units. As described above, when the video reproducing apparatus (client) simultaneously receives and temporarily accumulates a plurality of different streams of different bands distributed from the video transmitting apparatus (server), and reproduces and outputs the streams. To compensate for the loss in one stream on a frame basis, to stop the stream in the band where the loss frequently occurs and switch to the stream in the band without loss, or when there is no loss, the stream in the higher band Can be adjusted.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram showing an example of the configuration of a stream distribution system according to the present invention, and FIG.
And FIG. 3 is an explanatory diagram showing an example of a state transition processing operation of the stream distribution system in FIG.

In FIG. 1, reference numeral 1 denotes a video transmitting apparatus for distributing video contents in a stream, 2 denotes a network, 3 denotes a stream receiving apparatus for receiving video contents via a network, and 4 denotes a stream signal output from the stream receiving apparatus 4. Decoder 5 and decoder 4
This is a receiver that reproduces a video from an output signal from a TV.

Hereinafter, a system for performing stream distribution according to the present invention via the Internet will be described as an example.
To the Internet, stream receiving device 3 and decoder 4
The receiver 5 is described as a video viewer terminal (client device) including a personal computer.

The video distribution server and the client device include a CPU (Central Processing Unit), a main memory,
It has a computer configuration including a display device (receiver 5), an input device, and an external storage device. After a program or data recorded on, for example, a CD-ROM is installed in the external storage device via a driving device, the external storage device The functions of the respective processing units in the video transmitting device 1 and the stream receiving device 3 are executed by reading from the device into the main memory and processing by the CPU.

That is, the video transmission device 1 is provided with a stream distribution processing unit 1a, and the stream reception device 3 is provided with a reception processing unit 3a and data queues (0) 3b, (2).
3c, a time stamp management unit 3d, and a switching unit 3f.

In such a configuration, when the video distribution server (video transmission device 1) streams the video content to the requesting client device (video viewer terminal), the video distribution server 1a uses the stream distribution processing unit 1a to provide a single stream. Instead, a plurality of streams each having a different band are synchronously distributed at the same time. In this example, it is assumed that two streams, “Stream # 0” and “Stream # 1”, are simultaneously distributed in a keyframe synchronous manner.

On the side of the client device (stream receiving device 3), the streams which have been simultaneously keyframe-synchronizedly distributed in this manner are received by the reception processing unit 3a, divided for each stream, and the data queue (0) 3
b and the data queue (1) 3c.

The data queue (0) 3b and the data queue (1) 3c are composed of buffers having a FIFO (First In First Out, First In First Out) structure.
“0” is stored in a predetermined position of the data queue (0) 3b,
"eam # 1" at a predetermined position of the data queue (1) 3c,
It is stored in a time series for a certain period, and is output in order at a certain time interval.

In the time stamp management unit 3d, the stream data (“Stream # 0”, “S #”) in each of the data queue (0) 3b and the data queue (1) 3c
stream # 1 ”) is managed by the time stamp 3e, and based on this management information, each stream data from the reception processing unit 3a is stored in the data queue (0) 3.
b and the data queue (1) 3c are stored at respective predetermined positions.

The switching unit 3f includes a data queue (0) 3
b and the data queue (1) 3c is to switch the stream that is constantly output from each of them. In this example,
In particular, referring to the management content based on the time stamp 3e of the time stamp management unit 3d, switching control of stream output is performed.

For example, when "Stream # 0" from the data queue (0) 3b is selected and output, as a result of referring to the time stamp management unit 3d, the output target position of the data queue (0) 3b is determined. When the frame loss is detected, the frame of “Stream # 1” at the position of the data queue (1) 3c is selected and the output is switched.

The stream output from the switching unit 3f in this manner is converted by the decoder 4 so that it can be reproduced by the receiver 5, sent to the receiver 5, and reproduced by the receiver 5.

In the example shown in FIG. 1, the data is reproduced in the order of reproduction by the receiver 5 in correspondence with the time stamps T (n-1, n, n + 1, n + 2, n + 3,...) In the time stamp management section 3d. The queue (0) 3b has D (0,
n-1), D (0, n), D (0, n + 1), D (0,
n (2 + 2), D (0, n + 3),..., and D (1, n−1), D (1, n), D
(1, n + 1), D (1, n + 2), D (1, n +
3),... Are accumulated without loss.

The processing operation according to the present invention of the stream receiving apparatus 3 having such a configuration will be described with reference to FIG.

In FIG. 2, "Stream # 0"
And "Stream # 1" simultaneously receive and transmit lost data in a system that receives the data.

"Stream # 0" and "Stream #
"1" are two streams having different bands (transmission bit rates), and "Stream # 0" and "Stream # 1", which have been simultaneously and synchronously distributed, have a data queue (0) 3b and a data queue (b). (1) The data queue (0) 3b and the data queue (1) 3c hold the data in time series in each of the data queues (3c) and output the data queues in a constant manner.

Each stream output from the data queue (0) 3b and the data queue (1) 3c is arbitrarily switched by the switching unit 3f and output to the decoder 4.
The data is converted by the decoder 4 so that it can be reproduced by the receiver 5, passed to the receiver 5, and reproduced by the receiver 5. The switching operation control of the stream by the switching unit 3f is performed according to the contents of the management information based on the time stamp 3e of the time stamp management unit 3d.

The actual data "S" of the delivered stream
“Stream # 0” and “Stream # 1” are delivered synchronously and without any loss at the time of transmission from the transmission source. However, in the network 2, a delay occurs due to, for example, traffic concentration in a transit node, and data exchange is performed. Or a lack occurs.

In this example, in a normal state, "Stream
m # 0 ”, the time stamp T (n−1, n,
Data D (0, n−) corresponding to (n + 1, n + 2,...)
1), D (0, n), D (0, n + 1), D (0, n +
2), D (0, n + 3),..., D (0, n + 11),.
At a predetermined position in the data queue (0) 3b,
Regarding “Stream # 1”, data D (1, n−
1), D (1, n), D (1, n + 1), D (1, n +
2), D (1, n + 3),..., D (1, n + 11),.
Is buffered at a predetermined position in the data queue (1) 3c,
At the time of reception, it is synchronously transferred to the receiver 5.

By providing the buffer as described above,
Jitter on the network ("delay") is absorbed by an amount equal to the length of the buffer length. That is, there is a possibility that data may be exchanged in time series due to jitter on the network, and even if the time series is disturbed in this way, the data queues (0) 3b and (1) 3c may be used to transfer data from the receiver 5 to the receiver 5.
If delayed data arrives before the transfer to
It is inserted into the data queues (0) 3b and (1) 3c at positions corresponding to the time stamp 3e managed by the time stamp management unit 3d.

The delay data is stored in the data queue (0) 3b,
(1) The maximum wait time before insertion into 3c is the queue length (data count) of data queues (0) 3b and (1) 3c.
And the time stamp interval.

As described above, the data (stream) synchronously distributed from the transmission source is disturbed by passing through the network 2, but the data arriving within a predetermined finite time is transmitted to the data queue (0) 3 b, ( 1) In 3c, all are stored along the synchronization sequence of the source.

However, if data does not arrive within a predetermined finite time, "St" output to the decoder 4 and the receiver 5 is output.
Data loss occurs in "stream # 0" or "Stream # 1". In this example, in the switching unit 3f, based on the management information of the data storage status of the data queues (0) 3b and (1) 3c based on the time stamp 3e by the time stamp management unit 3d, the data queues (0) 3b,
(1) The occurrence of data loss in 3c is detected.

For example, upon detecting the occurrence of data loss in the data queue (0) 3b being selected for stream output to the decoder 4, the switching unit 3f switches the stream output source to the decoder 4 to the data queue (1). ) 3c
And outputs the data at the corresponding position in the data queue (1) 3c to the decoder 4.

In the following, such a switching operation is judged from the quality of the image, and the data (stream) stored in the data queue (0) 3b is the data queue (1) 3
An example will be described in which it is determined that priority is given to data stored in c.

As described above, when the quality of the video stored in the data queue (0) 3b is higher than that of the stream stored in the data queue (1) 3c, the data queue (0) 3b has the same time stamp value. When there is the data of (1), the switching unit 3f selects the data of the data queue (0) 3b and outputs it to the decoder 4.

For example, with respect to T (n) of the time stamp 3e, in the data queue (0) 3b, D (0,
n), and D (1, n) in the data queue (1) 3c, so that the decoder 4 and the receiver 5 have D (0, n) on the data queue (0) 3b side. Is transferred.

However, T (n +
In (1), D (0,
n + 1) does not exist. In FIG. 2, such data loss is indicated by oblique lines.

In this case, the switching unit 3f switches the data output source from the data queue (0) 3b to the data queue (1).
3c, and outputs the data D (1, n + 1) at the same position in the data queue (1) 3c to the decoder 4.

Further, T (n) of the next time stamp 3e
+2), D (0,3) in the data queue (0) 3b
n + 2), the switching unit 3f returns the data output source from the data queue (1) 3c to the data queue (0) 3b, and the D on the data queue (0) 3b side.
(0, n + 2) is output to the decoder 4 and the receiver 5.

However, T (n +
6), in both the data queue (0) 3b and the data queue (1) 3c, the data D (0, n +
6), D (1, n + 6) does not exist, resulting in loss.

By repeating such an operation, in this example, the data transfer is performed according to the time stamp T (n-1).
.. T (n + 11),... Corresponding to D (0, n−1), D (0, n), D (0, n).
(1, n + 1), D (0, n + 2), D (1, n +
3), D (0, n + 4), D (0, n + 5), missing, D
(0, n + 7), D (0, n + 8), D (0, n +
9), D (1, n + 10), D (0, n + 11),.

The missing data generated at T (n + 6) of the time stamp 3e is, for example, re-interpolated from the preceding and following data D (0, n + 5) and D (0, n + 7).
This is dealt with by assigning invalid data.

Although the minimum unit of data required for reproduction has been described as one data here, if two data units are the minimum units required for reproduction, the video data sequence to be transferred to the receiver 5 is D (0, n-1), D (0, n), D
(1, n + 1), D (1, n + 2), D (1, n +
3), D (0, n + 4), D (0, n + 5), missing, D
(0, n + 7), D (0, n + 8), D (0, n +
9), D (1, n + 10), D (0, n + 11),. That is, the number of continuous data required for reproduction may be arbitrary.

Next, another operation example of the stream distribution system in FIG. 1 will be described with reference to FIG.

In the example of FIG. 3, a case where the bandwidth (transfer bit rate) of the stream to be reproduced is shifted higher or lower by one rank in accordance with the distribution state of the video content (stream) on the network. Show.

The video contents are stored in video Mov (n) (n =
1, 2,..., N, M; 1 ≦ N ≦ M).

The basic state is shown by a steady state ST (N). In this steady state ST (N), the video Mov (N) 1
If the book is in a stable state of distribution and there is no problem, distribution is performed in this state.

According to the change of the external situation, whether the state is ST (N-1) where Mov (N-1) having one smaller band is distributed,
ST (N) that delivers Mov (N + 1) with one larger band
+1) Transition to the state. At this time, in order to prevent the video from being interrupted or disturbed in the viewer terminal even for a moment, in this example, a buffer corresponding to the time required for the operation to switch the video is prepared, and the video data is Of the delivery status of

(1-1) First, transition to the deteriorated state (ST
(N) → STd (N) → ST (N−1)) will be described.

In the steady state ST (N), if data is lost or a video data packet delayed by a certain amount or more occurs at the time of being taken into the buffer, the state shifts to the deterioration transition preparation state STd (N).

In this deterioration transition preparation state STd (N),
In addition to receiving the Mov (N) being reproduced by the receiver, reception of the video Mov (N-1) one rank lower than that is started.

After the reception of the video Mov (N-1) is started (in the deterioration transition preparation state STd (N)), a fixed period Tw is set.
And the video Mov (N) and the video Mov (N-1)
In the event that data is lost again or a certain amount of delay occurs again,
The distribution of the video Mov (N) is stopped, and the video Mov (N-
One rank lower steady state ST (N) that performs only the reception of 1)
It shifts to -1) and becomes stable.

(1-2) Next, the return to the original steady state (ST (N) → STd (N) → ST (N)) will be described.

In the deterioration transition preparation state STd (N),
The video Mov (N) and the video Mov (N-
If no loss is found in the data of 1), the video Mov (N
The distribution of -1) is stopped and the operation returns to the steady state ST (N).

(2-1) Next, transition to the improved state (ST)
(N) → STu (N) → ST (N + 1)) will be described.

In the steady state ST (N), if no video data packet is lost or delayed by a certain amount or more at the time of being taken into the buffer during the fixed period Tu, the state shifts to the improvement transition preparation state Stu (N). I do.

In this improvement transition preparation state STu (N),
In addition to receiving the Mov (N) being reproduced by the receiver, reception of the video Mov (N + 1) one rank higher than that is started. After the reception of this video Mov (N + 1) starts, Mov (N + 1)
(N) and Mov (N + 1) when no data loss or a certain delay or more occurs in a certain period Tv,
The distribution of (N) is stopped, and the state shifts to the one-rank higher steady state ST (N + 1) where only Mov (N + 1) is received, and is stabilized.

(2-1) Next, the return to the original steady state (ST (N) → STu (N) → ST (N)) will be described.

In the improvement transition state STu (N), if any of the data of the video Mov (N) and the video Mov (N + 1) is lost during a certain period Tv, the video Mov
The distribution of (N + 1) is stopped, and the process returns to the steady state ST (N).

The steady state ST (N + 1) one rank higher
To the basic steady state ST (N), and 1
The transition from the steady state ST (N-1) under the rank to the basic steady state ST (N) is performed in the same manner.

As described above, in the example of FIG. 3, normally, one image is received in a steady state, and the state shifts to the deterioration transition preparation state or the improvement transition preparation state according to the change of the network. In accordance with the data reception status in this state, transition to the original stable state or transition to the stable state one rank higher or one rank lower is performed.

As described above with reference to FIGS. 1 to 3, in this example, video contents are transmitted from the video distribution server (video transmission device 1) via the Internet (network 2) to the video viewer terminal (stream reception terminal). In a system that distributes a stream to the apparatus 3, the decoder 4, and the receiver 5), the video distribution server arbitrarily selects the same video content in a plurality of M-stage bands and outputs the video data Mo.
v (N) (1 ≦ N ≦ M; M is an integer) is stream-distributed. For example, an image Mov (N-
1) The main stream of the video Mov (N) in the band one rank lower than the video Mov (N + 1) in the band one rank lower than the N + 1 grade, and an arbitrary number of sub-streams other than the main stream. Output synchronously from the server. Then, the video viewer terminal receives the main stream and the sub-stream, and holds them separately in a buffer for a certain period of time, so that the
Switch streams without interruption

For example, in the video viewer terminal, a state in which only the video Mov (N) of the N grade band, which is the main stream, is received is defined as a steady state ST (N), and a substream corresponding to the video Mov (N) is defined as a substream. , M (m =
1 ,,, N-1; m is an integer) The video Mo of the band below the rank
Degradation transition preparation state STd for receiving v (N−m)
(N−m + 1) and an improved transition preparation state STu (N + p−1) of a state in which the video Mov (N + p) of the band on the p (p = 1,..., M−N; p is an integer) rank is received. State transition.

In the steady state ST (N), if there is no lack in the main stream data for a certain period Tu, the improved transition preparation state STu (N + p-1) in which the sub-stream video Mov (N + p) is also synchronously received at the same time. ) (P
= 1,..., M−N), and if there is no delay or loss in the main stream data and the sub-stream data for a fixed period Tv in the improved transition preparation state STu (N + p−1), Stream Video Mov
(N) is replaced with the video Mov (N + p), the reception of the main stream Mov (N) is stopped and the steady state S
The process proceeds to T (N + 1).

The improvement transition preparation state STu (N + p−
In 1), if a delay or loss occurs in the main / sub stream data for a certain period Tv, the reception of Mov (N + p) as the sub stream is stopped and the stationary state ST
Return to (N).

In the steady state ST (N), if a delay or loss occurs in the main stream video Mov (N), the lower-rank video Mov (Nm) (m = 1, 2, N-1) and receive the same, and shift to the deterioration transition preparation state STd (N-m-1). In this deterioration transition preparation state STd (N-m-1), a certain period Tw If the main / sub stream data is delayed or missing at
The video stream Mov (N-m), which is the main stream, is stopped by replacing v (N) with Mov (N-m) of the sub-stream video, and shifts to the steady state ST (N-m).

Then, the deterioration transition preparation state STd (N-m
In -1), if no delay or loss has occurred in the main / sub stream data for a certain period Tw, the reception of the sub stream video Mov (N-m) stops and returns to the steady state ST (N). .

As described above, in the present embodiment, when a stream is distributed from the video transmission side device (server) to the video reproduction side device (client), not a single stream but a plurality of streams having different bands are synchronously distributed simultaneously. On the client side receiving each stream, each stream is individually held for a certain period of time, and the output of a television, a personal computer, or the like is changed according to the reception status of each stream, that is, according to a change in the bandwidth used by the network. The stream output by the device is switched in frame units.

As described above, the video reproducing apparatus (client) simultaneously receives and temporarily accumulates a plurality of different streams of different bands distributed from the video transmitting apparatus (server), thereby reproducing the image. When outputting, the loss in one stream is compensated by the other stream in frame units, the stream in the band where the loss frequently occurs is stopped and switched to the stream in the band without loss, or when there is no loss Can make adjustments to switch to a higher bandwidth stream.

The present invention is not limited to the examples described with reference to FIGS. 1 to 3 and can be variously modified without departing from the gist thereof. For example, in this example,
The system for performing stream distribution according to the present invention through the Internet has been described as an example, and the video transmission device 1 has been described as a video distribution server, the network 2 has been described as the Internet, and the stream reception device 3, the decoder 4, and the receiver 5 have been described as personal computers (clients). Alternatively, a dedicated device may be provided as the stream receiving device 3, and the decoder 4 and the receiver 5 may be configured as a television receiver. As described above, by configuring the stream receiving device 3 with a dedicated device, the data queues (buffers) 3b and 3c and the like are configured as hardware, and higher-speed processing can be performed. In addition, FDDI (Fiber-Distri
buted Data Interface).

In this example, “Stream # 0” and “Strm #”, which have different bands (transmission bit rates), respectively, are used.
Although the description has been made assuming that two streams of “eam # 1” are simultaneously and synchronously distributed, the present invention is also applicable to simultaneous and synchronous distribution of three or more streams by increasing the number of data queues (buffers).

In this example, a plurality of streams to be simultaneously and synchronously distributed are generated for different bands. For example, “Stream # 0” and “St
Assuming that the stream # 1 is the same (distributing at the same compression rate and the same bit rate and bandwidth), the data is duplicated, and the normal frame in the stream # 1 is replaced with the normal frame in the stream # 1 instead of the lost frame in the stream # 0. The stream may be complemented by using the stream.

Further, a timer capable of adjusting the timing of switching the stream or an adjuster capable of setting the conditions may be used to obtain a more appropriate and high-quality image.

In the computer configuration example of this embodiment, the CR-ROM is used as a recording medium.
(Flexible Disk) may be used as a recording medium. As for the installation of the program, the program may be downloaded and installed via a network via a communication device.

[0077]

According to the present invention, even when the band capable of performing video communication on the network changes and the system shifts to stream distribution according to the change, video stoppage and retransmission from different scenes do not occur. In addition, stable stream distribution of video content through the Internet or the like can be performed.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration example of a stream distribution system according to the present invention.

FIG. 2 is an explanatory diagram illustrating an example of a processing operation of the stream receiving device in FIG. 1;

FIG. 3 is an explanatory diagram showing an example of a state transition processing operation of the stream distribution system in FIG. 1;

[Explanation of symbols]

1: video transmission device, 1a: stream distribution processing unit, 2:
Network, 3: stream receiving device, 3a: reception processing unit, 3b: data queue (0), 3c: data queue (1), 3d: time stamp management unit, 3e: time stamp, 3f: switching unit, 4: decoder 5: Receiver.

Claims (6)

[Claims] 1. A system for streaming video content from a video transmission device to a video viewer terminal via a network, wherein the video transmission device generates a plurality of streams for each band from the same video content. Means for synchronously distributing, wherein the video viewer terminal individually retains each of the distributed streams for a certain period of time and outputs them on a first-in first-out basis; and a second means for detecting a change in the communication speed of the network. And a third means for switching a stream output from the first means in response to a detection result of the change in the transfer rate of the network by the second means. Delivery system. 2. A system for streaming distribution of video contents from a video transmission device to a video viewer terminal via a network, wherein the video transmission device generates a plurality of streams from the same video content and synchronously distributes the streams. Means for holding the distributed streams individually for a certain period of time and outputting the data on a first-in first-out basis, and detecting data loss in each stream held by the first means. And a third means for outputting the data of another stream when outputting a stream in which data loss has been detected by the second means. 3. A stream delivery method for a system for streaming video content from a video transmission device to a video viewer terminal via a network, wherein the video transmission device transmits a plurality of streams for each band from the same video content. Generating and synchronously distributing, wherein the video viewer terminal receives one of the streams distributed from the video transmission device as a main stream, and stores the received main stream in a storage device for a predetermined period of time. Holding and outputting on a first-in first-out basis; detecting a data loss in the storage device of the main stream; and if the data loss of the main stream does not occur at a predetermined time Tu, the data is higher than the main stream. Improvement transition level in which a first substream for a band is additionally received and stored in a storage device And when the data loss or the data delay of the first sub-stream and the main stream does not occur at the predetermined time Tv in the improvement transition preparation state, the reception of the main stream is stopped. A step of shifting to a steady state in which the first sub-stream is output as a first-in first-out stream as a main stream, and data loss or data delay of the first sub-stream and the main stream is predetermined in the improvement transition preparation state. And a transition to a steady state in which the reception of the first sub-stream is stopped and the reception of the main stream and the first-in first-out output are continued when the occurrence occurs at time Tv. 4. The stream distribution method according to claim 3, wherein the video viewer terminal receives data of the main stream and outputs data on a first-in first-out basis. When the occurrence has occurred, a step of additionally receiving a second sub-stream for a band lower than the main stream and shifting to the deterioration transition preparation state in which the second sub-stream is held in the storage device; When data loss or data delay of the stream and the main stream occurs at a predetermined time Tw, the reception of the main stream is stopped, and a transition is made to a steady state in which the second sub-stream is output as a first-in first-out stream as a main stream. And the data loss of the second sub-stream and the main stream in the deterioration transition preparation state. Or if the data delay does not occur in the predetermined time Tw, the step of stopping the reception of the second sub-stream and transitioning to a steady state in which the reception of the main stream and the output on a first-in first-out basis are continued. A stream distribution method characterized by the above-mentioned. 5. A stream receiving apparatus for receiving a stream of video content distributed from a video transmission device via a network, wherein the video transmission device generates the same video content for each band in the video transmission device. The first to receive multiple distributed streams
Means for individually holding each received stream for a certain period of time and outputting the data on a first-in first-out basis, third means for detecting a change in the communication speed of the network, and the network by the third means And a fourth means for switching the stream output from the second means in accordance with the detection result of the change in the transfer rate. 6. A stream receiving apparatus for receiving a stream of video content distributed from a video transmission device via a network, wherein the video transmission device generates a stream generated from the same video content in the video transmission device. Means for receiving a plurality of streams, which have been received, second means for holding each of the received streams individually for a fixed period of time and outputting on a first-in first-out basis, and data loss in each stream held by the second means. Third to detect
And a fourth means for outputting the data of another stream when outputting a stream for which data loss has been detected by the third means.