JPH09163308A - Video server - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize high speed reproduction at a reproduction speed requested from a terminal equipment independently of dispersion in a key frame data size for each stream, to send a high speed reproduction frame at an equal interval and to reduce a response time from a reproduction request of the terminal equipment till transmission of a stream signal independently of the size of an access table. SOLUTION: A stream control section 60 is provided with a means 21 that obtains a key frame located in the vicinity of a reproduction position designated by a terminal equipment from an access table management section 4 and commands a read position of the key frame to a stream read section 2 and a means 22 that acquires a key frame data length from the access table management section 4, and also with a means instructing a transmission timing of each key frame to a stream transmission section 3 and a means instructing the access table management section 4 to acquire an address of the key frame from a stream storage means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video server device which realizes various special reproductions of encoded moving images more smoothly.

[0002]

2. Description of the Related Art In recent years, a video server device in a video-on-demand system, which stores a plurality of compression-encoded moving image signals in a storage medium such as a hard disk and is intended for multiple reproduction by a plurality of terminals, has been commercialized. It is in. In addition to normal reproduction, there is an increasing demand for fast-forward reproduction and rewind reproduction for moving image reproduction.

A conventional video-on-demand system will be described below. FIG. 8 shows the configuration of a conventional video-on-demand system. In FIG. 8, 1 is a storage medium hard disk, 1a is an AV stream, 1b is an access table, 2 is a stream reading unit, 3 is a stream transmitting unit, 4 is an access table managing unit, 5 is a command receiving unit, and 6 is a stream. The video server device VS is a control unit. 7 is a stream receiving unit, 8 is a command transmitting unit,
Reference numeral 9 is a decoder unit, 10 is an input control unit, and these constitute a terminal device ST. 11 is a monitor, 12
Is a speaker and 13 is an input device, which are connected to the terminal device ST.

FIG. 9 shows the above-mentioned conventional video server VS.
6 is a block diagram showing details of a stream control unit 6 in FIG. In FIG. 9, reference numeral 81 is a stream read position determining unit, and reference numeral 82 is a key frame skip number setting table.

FIG. 4A is a diagram for explaining a key frame read time interval during high speed reproduction in the conventional example. In FIG. 4A, 41, 42, and 43 are the key frames read out from the first, second, and third key frames, and a, b, and c are the key frames 41, 42, and 43, respectively.
This is the time for reading 43 at a constant bit rate.

FIG. 5A is a diagram for explaining a key frame read time interval during high speed reproduction in the conventional example. In FIG. 5A, n is the time for reading the storage unit block length at a constant bit rate, 51, 52, and 53 are the first, second, and third read key frames, a ′, b ′ and c ′ are key frames 5 respectively
This is the time for reading 1, 52, 53 at a constant bit rate and in units of storage blocks.

FIG. 7A is a diagram for explaining the operation of the access table management unit 4 in the conventional example. FIG.
In (a), 1b is an access table, and u is a time for reading the access table 1b at a constant bit rate.

FIG. 10A is a diagram for explaining the order of accumulated frames of the AV stream 1a, and FIG. 10B is a diagram for explaining the order of normal reproduction frames of the AV stream 1a.

The operation of the video server device configured as described above will be described below. A signal input from the input device 13 is converted into a reproduction position and a reproduction speed by the input control unit 10 and transmitted from the command transmission unit 8 to the command reception unit 5. The stream control unit 6 obtains the reproduction position and the reproduction speed received by the command receiving unit 5, the key frame read from the address of the key frame managed by the access table management unit 4 and the storage position of the key frame, and the stream reading unit 2 Instruct. Here, the stream read determination unit 81 uses the reproduction speed obtained from the command reception unit 5 and the key frame skip number setting table 8
2, the key frame interval, the key frame to be read from the encoding bit rate of the AV stream 1a, the reproduction position obtained from the command receiving unit 5, and the address of the key frame managed by the access table management unit 4 from the AV stream. The reading position of 1a is obtained and the stream reading unit 2 is instructed. The stream reading unit 2 reads the AV stream 1a at the specified read bit rate, and the read stream is the stream transmitting unit 3
Is transmitted to the stream receiving unit 7. The stream received by the stream receiving unit 7 is decoded by the decoder unit 9 and output from the monitor 11 as video and from the speaker 12 as audio.

The AV stream 1a is an international standard MPEG.
The video signal with audio is compression-encoded by and is stored in the frame order as shown in FIG. In the case of normal reproduction, the stream reading unit 2 stores the accumulated A
The entire V stream 1a is read and the stream transmission unit 3
Are transmitted and output to the monitor 11 in the frame order as shown in FIG. Further, in the case of high-speed reproduction, the stream reading unit 2 reads only the I frame that is the key frame, the stream transmitting unit 3 transmits only the key frame, and the frame order shown in FIG. 4A or FIG. It is output from 11.

For the sake of explanation, FIGS. 4, 5, and 10 show the frame types of I, P, and B and the display frame sequence numbers in normal reproduction for each frame. The frame type includes an intra-coded image in which I frame is intra-coded, a forward predictive coded image in which P frame is motion compensated inter-frame coded, and a bidirectional predictive code in which B frame is motion compensated inter-frame coded. It is a converted image.

[0012]

However, in the above-mentioned conventional example, when the data length of the key frame is different for each stream, even when the same key frame skip number is set when reading at a constant bit rate during high speed reproduction, reproduction is performed. There was a problem that the speed was not constant.

Further, in the above-mentioned conventional example, when the data length of each key frame is different in the stream, the time for reading or transmitting one key frame when reading or transmitting the stream at a constant bit rate during high speed reproduction. There was a problem that was not constant.

Further, in the above-mentioned conventional example, when the data length of each key frame is different in the stream, one key frame is read out when reading or transmitting for each fixed length block at a constant bit rate during high speed reproduction. There was a problem that the transmission time was not constant.

Further, in the above-mentioned conventional example, when the access table is acquired at a constant bit rate, all access tables are acquired immediately before the reproduction, so that the reproduction of the stream is actually started until the reproduction of the stream is actually started. There was a problem that the response time of was long.

The present invention solves the above-mentioned problems of the prior art, and is capable of realizing high-speed reproduction at a reproduction speed required by a terminal, regardless of variations in key frame data size for each stream. The first purpose is to provide.

A second object of the present invention is to provide a video server device capable of transmitting high-speed playback frames at regular intervals regardless of variations in key frame data size in a stream.

A third object of the present invention is to provide a video server device capable of shortening the response time from the reproduction request from the terminal to the transmission of the stream regardless of the size of the access table. To do.

[0019]

In order to achieve the first object, the video server device according to the present invention is such that a stream control unit obtains a key frame data length from an access table management unit. And a stream read position determination unit that selects a key frame to be extracted so as to maintain an arbitrary reproduction speed designated by the terminal device from the bit rate for reading the stream, the key frame interval, and the key frame data length acquired by the key frame data length calculation unit. With this, it is possible to provide a video server device capable of realizing high-speed reproduction at the reproduction speed required by the terminal, regardless of variations in the key frame data size for each stream.

In order to achieve the second object,
In the video server device according to the present invention, the stream control unit acquires the key frame data length calculation unit that acquires the key frame data length from the access table management unit, the bit rate for reading the stream, the key frame interval, and the key frame data length calculation unit. A stream read position determination unit that selects a key frame to be extracted so as to maintain an arbitrary playback speed specified by the terminal device based on the key frame data length, and a stream transmission timing setting unit that instructs the transmission timing of each key frame. , This allows
It is possible to provide a video server device capable of transmitting high-speed playback frames at regular intervals regardless of variations in key frame data size in a stream.

In order to achieve the third object,
The video server device of the present invention reads an access table from a hard disk for each page of an arbitrary data length or an arbitrary time, and reads a key frame from an arbitrary reproduction position designated by a terminal device in a stream control unit. Determine whether to acquire the next page of the access table from the stream read position determination unit that determines the position, the read position determined by the stream read position determination unit, and the access table page acquired by the access table management unit An access table page switching determination unit that instructs the access table management unit to shorten the response time from the playback request from the terminal to the stream transmission regardless of the size of the access table. Video server device It is possible.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION The invention according to claim 1 of the present invention is a stream storage means for storing a compression-coded stream, a stream reading means for reading a stream designated by a terminal device, and a read stream. In a video server device including stream transmitting means for transmitting a key frame to a terminal device, an access table managing means for managing an address of a key frame in a stream, a key frame data length calculating means for obtaining each key frame data length, and a terminal A stream read position determining means for determining a key frame located in the vicinity of a reproduction position designated by the device from the access table managing means, and instructing the stream reading means the read position of the key frame; Stream reading means From the bit rate for reading the stream, the encoding bit rate of the stream, the key frame interval, and the key frame data length acquired by the key frame data length calculation means, the stream is adjusted so as to maintain an arbitrary playback speed specified by the terminal device. A keyframe to be extracted is selected and is instructed to the stream reading means, the keyframe data length calculation unit acquires the data length of the keyframe from the access table management unit at an arbitrary interval, and the stream read position determination unit Based on the bit rate for reading the stream, the key frame interval, and the key frame data length acquired by the key frame data length calculation unit, the key frame to be extracted is moved to the reproduction speed closest to the arbitrary reproduction speed specified by the terminal during high speed reproduction. The stream reading section and touch the stream reading section. By also have different data length of the key frame for each stream, it is possible to realize a closest, and less smooth high-speed reproduction variation in reproduction speed for each stream to the playback speed requested by the terminal.

According to a second aspect of the present invention, the stream storage means for storing the compression-encoded stream, the stream reading means for reading the stream designated by the terminal device, and the read stream to the terminal device. In a video server device provided with a stream transmitting means for transmitting, an access table managing means for managing an address of a key frame in a stream, a key frame data length calculating means for obtaining each key frame data length, and a terminal device specify. Obtain the key frame located near the playback position from the access table management means,
A stream reading position determining means for selecting a key frame that satisfies the playback speed designated by the terminal device and instructing the stream reading means for the reading position of the key frame, and a stream for instructing the stream transmitting means of the transmission timing of each key frame. Transmission timing setting means, the stream transmission timing means, from the key frame length acquired by the key frame data length calculation means,
The transmission bit rate of the stream transmission means and the read bit rate of the stream reading means are controlled so that the transmission timing of each key frame to be transmitted becomes constant, and the stream transmission timing setting unit From the key frame data length acquired by the key frame data length calculation unit, set the transmission bit rate of the stream transmission unit and the read bit rate of the stream reading unit so that the transmission timing of each key frame transmitted during high-speed playback will be constant. By controlling
Even if the data length of each key frame is different in the stream, the interval of each key frame transmitted to the terminal at the time of high-speed reproduction becomes constant, and high-speed reproduction that is easier to see can be realized.

According to a third aspect of the present invention, stream accumulation means for accumulating a compression-encoded stream, stream reading means for reading a stream designated by the terminal device, and the read stream to the terminal device are provided. In a video server device provided with a stream transmitting means for transmitting, an access table managing means for managing an address of a key frame in a stream, a key frame data length calculating means for obtaining each key frame data length, and a terminal device specify. Obtain the key frame located near the playback position from the access table management means,
Stream read position determination means for instructing the stream read means of the read position of the key frame, and access table page switching for instructing the access table management means to obtain the address of the key frame managed by the access table management means from the storage means. The access table management unit divides and acquires the address of the key frame for each page of arbitrary data length or arbitrary time, and the access table page switching determination unit determines the key frame of the key frame being read by the stream reading unit. It is characterized by determining whether to obtain the next page from the address and instructing it to the access table management means, in which the access table management unit assigns the address of the key frame for each page of arbitrary data length or arbitrary time. Get to Stream read position determination section,
The process starts immediately after the access table management unit acquires the address of the key frame in page units, and the access table page switching determination unit determines the position of the key frame being processed by the stream read position determination unit and the access table management unit. By determining whether to acquire the address of the next key frame from the range of the address of the key frame to be acquired, and instructing the access table management unit, various playback is started without waiting for the completion of acquisition of the address of all key frames. Therefore, it is possible to shorten the response time from the stream reproduction request until the stream reproduction is actually started.

Next, a video server device according to the embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows the configuration of a video-on-demand system including the video server device of the present invention. In FIG. 1, 1 is a hard disk as a storage medium, 1a is an AV stream, 1b is an access table, 2 is a stream reading unit, 3 is a stream transmitting unit, 4 is an access table managing unit, 5 is a command receiving unit, and 60 is a stream. The video server device VS is a control unit. Reference numeral 7 is a stream reception unit, 8 is a command transmission unit, 9 is a decoder unit, and 10 is an input control unit, and these constitute a terminal device ST. 11 is a monitor,
Reference numeral 12 is a speaker and 13 is an input device, which are connected to the terminal device ST. The video server device of the present invention differs from the conventional example of FIG. 8 only in the stream control unit 60.

(First Embodiment) A video server apparatus according to the first embodiment of the present invention will be described below.
FIG. 2 shows the configuration of the stream control unit 60 of the video server device VS according to this embodiment. In FIG. 2, reference numeral 21 is a stream read position determination unit that obtains a key frame located near a reproduction position designated by the terminal ST from the access table management unit 4 and instructs the stream read unit 2 to read the key frame read position.
Reference numeral 2 is a key frame data length calculation unit that acquires the data length of the key frame from the accelerator table management unit 4 at arbitrary intervals.

With respect to the video server device configured as described above, the operation of the stream control unit 60 will be mainly described below. When the command reception unit 5 receives the reproduction position, the stream read position determination unit 21 determines, from the reproduction position and the address of the key frame acquired by the access table management unit 4 from the access table 1b stored in the hard disk 1, When the read position of the key frame in the vicinity of the designated playback position is determined and the command receiving unit 5 does not receive the playback position, the next read position of the designated key frame or consecutive read positions of the AV stream 1a is read. Then, the stream reading unit 2 is instructed.

Further, the stream read position determining unit 21
Is a key frame data length calculation unit 22 when the reproduction speed received by the command receiving unit 5 is discontinuous reproduction such as high speed reproduction.
Is calculated from the arbitrary number of key frame data lengths obtained from the access table 1b and the bit rate at which the stream reading unit 2 reads the AV stream 1a, and the time for reading the average data length of the key frames is obtained and assumed to be the key frame transmission time interval. Then, the key frame to be read next that satisfies the reproduction speed is specified from the assumed key frame transmission time interval, key frame interval, and frame frequency.
When the reproduction speed received by the command receiving unit 5 is continuous reproduction such as normal reproduction and slow reproduction, the key frame to be read next is not designated.

When the reproduction speed received by the command receiving unit 5 is discontinuous reproduction such as high-speed reproduction, specifically, the number of key frame data acquired from the access table 1b is a, and each key frame data length is Ai (i = 1,2, ...,
a), assuming that the bit rate at which the stream reading unit 2 reads the AV stream 1a is BR and the average data length of the key frame is KL, KL is calculated by the following equation. KL = (A1 + A2 + ... Aa) / a (1)

If KT is the time for reading the average data length of the key frame, KI is the key frame interval, FR is the frame frequency, NS is the number of key frame skips to the next key frame to be read, and PS is the playback speed.
And PS are calculated by the following equations. KT = KL ÷ BR (2) PS = (KI ÷ FR) × (NS + 1) ÷ KT (3) In the above equation, the designated reproduction speed is the reproduction speed PS.
The number of key frame skips NS that is closest to is obtained.
If the key frame interval KI is not constant here, the average value of the key frame intervals of the stream is calculated.

The stream reading unit 2 reads the key frame or continuous reading position of the AV stream 1a designated by the stream reading position determining unit 21 and sends it to the stream transmitting unit 3. The stream transmitter 3 transmits a stream to a terminal at regular time intervals.

As described above, according to the first embodiment, by providing the key frame data length calculation unit 22 in the stream control unit 60, the reproduction speed of high speed reproduction can be determined based on the key frame data length. Since the key frame to be read next is determined so as to keep it, even if the key frame data length differs for each stream, it is closest to the specified arbitrary playback speed, and the variation in playback speed for each stream is minimized. It can provide smooth high-speed playback.

(Second Embodiment) Next, a video server device according to a second embodiment of the present invention will be described.
FIG. 3 shows the configuration of the stream control unit 60 of the video server device VS according to the present embodiment. In FIG. 3, reference numeral 31 refers to a keyframe located near the playback position designated by the terminal ST from the access table management unit 4, and selects a keyframe satisfying the playback speed designated by the terminal device ST. A stream read position determination unit that indicates the read position to the stream read unit 2, 32 is a key frame data length calculation unit that acquires the data length of a key frame from the accelerator table management unit 4 at arbitrary intervals, and 33 is a stream transmission unit 3. It is a stream transmission timing setting unit for instructing the transmission timing of the key frame.

FIG. 4B is an explanatory diagram of the key frame read time interval during the first high speed reproduction in the present embodiment. In FIG. 4B, m is the time for reading the maximum key frame of the stream at a constant read bit rate. Further, FIG. 5B is an explanatory diagram of the key frame read time interval during the second high speed reproduction in the present embodiment. In FIG. 5B, n ′ is the time for reading the number of storage blocks at a constant bit rate when the key frame of the stream is included in the most storage unit blocks. The other symbols are the same as those described in the prior art.

With respect to the video server device configured as described above, the operation of the stream control unit 60 will be mainly described below. When the command reception unit 5 receives the reproduction position, the stream read position determination unit 31 specifies from the reproduction position and the address of the key frame that the access table management unit 4 acquires from the access table 1b stored in the hard disk 1 from the address. If the read position of the key frame near the specified reproduction position is determined and the command receiving unit 5 does not receive the reproduction position, the read position of the key frame specified to be read next or the continuous read position of the AV stream 1a is determined. Stream reading unit 2
To instruct.

Also, the stream read position determination unit 31
Is the key frame data length calculation unit 32 when the reproduction speed received by the command receiving unit 5 is discontinuous reproduction such as high speed reproduction.
All or an arbitrary number of key frame data lengths acquired from the access table 1b by the stream reading unit 2
Determines the maximum key frame read time m from the maximum bit rate for reading the AV stream 1a and sets it as the key frame transmission time interval, and instructs the stream transmission timing setting unit 33 to set the key frame transmission time interval, the key frame interval, and the frame frequency. Specifies the key frame to be read next that satisfies the playback speed. Command receiver 5
When the playback speed received by is continuous playback such as normal playback or slow playback, the key frame to be read next is not designated.

When the reproduction speed received by the command receiving unit 5 is discontinuous reproduction such as high-speed reproduction, specifically, the maximum key frame data length acquired from the access table 1b is A
m, and the bit rate at which the stream reading unit 2 reads the AV stream 1a is BR, the maximum key frame reading time m is calculated by the following equation. m = Am ÷ BR (4)

Further, if the key frame interval is KI, the frame frequency is FR, the number of key frame skips to the next key frame to be read is NS, and the reproduction speed is PS,
PS is calculated by the following formula. PS = (KI ÷ FR) × (NS + 1) ÷ m (5) In the above equation, the designated reproduction speed is the reproduction speed PS.
The number of key frame skips NS that is closest to is obtained.
If the key frame interval KI is not constant here, the average value of the key frame intervals of the stream is calculated.

The stream transmission timing setting unit 33
In the case of high-speed playback, the stream transmission unit 3 is instructed to transmit the key frame read by the stream reading unit 2 at the key frame transmission time interval specified by the stream reading position determination unit 31, and the timing for reading the next key frame is streamed. The reading unit 2 is instructed.

When the stream reading section 2 reads the AV stream 1a in units of arbitrary fixed-length blocks, the stream reading position determining section 31 determines that the playback speed received by the command receiving section 5 is discontinuous playback such as high-speed playback. In this case, the reproduction speed and the key frame data length calculation unit 3
Based on all or an arbitrary number of key frame addresses and data lengths 1 acquired from the access table 1b and the maximum bit rate at which the stream reading unit 2 reads the AV stream 1a, the AV stream 1 in which the key frames are arranged
The read time n'of the maximum fixed length block number of a is calculated,
This is set as the key frame transmission time interval, and the stream transmission timing setting unit 33 is instructed to specify the key frame to be read next from the key frame transmission time interval, the key frame interval, and the frame frequency.

Specifically, when the fixed length block including the key frame is the maximum number, the continuous read time of all fixed length blocks including the key frame is n ', the key frame interval is KI, the frame frequency is FR, If the number of key frame skips up to the next key frame to be read is NS and the reproduction speed is PS, PS is calculated by the following equation. PS = (KI ÷ FR) × (NS + 1) ÷ n ′ (6) In the above equation, the designated reproduction speed is the reproduction speed PS.
The number of key frame skips NS that is closest to is obtained.
If the key frame interval KI is not constant here, the average value of the key frame intervals of the stream is calculated.

As described above, according to this embodiment, by providing the stream control unit 60 with the stream transmission timing setting unit 33, the key frame transmission time interval is set to the maximum key frame read time or more during high speed reproduction. Therefore, even when the key frame data lengths are different in the stream, the transmission frame time interval becomes constant at the designated arbitrary reproduction speed, and it is possible to provide easier-to-read high-speed reproduction.

(Third Embodiment) Next, a video server device according to a third embodiment of the present invention will be described.
FIG. 6 shows the configuration of the stream control unit 60 of the video server device VS in this embodiment. In FIG. 6, reference numeral 61 denotes a stream read position determination unit 6 which obtains a key frame located near the reproduction position designated by the terminal ST from the access table management unit 4 and instructs the stream read unit 2 to read the read position of the key frame.
Reference numeral 2 is a key frame data length calculation unit that acquires the data length of the key frame from the accelerator table management unit 4 at arbitrary intervals, 63 is a stream transmission timing setting unit that instructs the stream transmission unit 3 about the transmission timing of each key frame, and 64 is The access table page switching determination unit instructs the access table management unit 4 to obtain the address of the key frame managed by the access table management unit 4 from the hard disk 1.

FIG. 7B is an operation explanatory diagram of the access table management unit 4 in the present embodiment. In FIG. 7B, 71 is the first page of the access table, 72
Is the second page of the access table, 73 is the third page of the access table, and 74 is the fourth page of the access table.
Page, 75 is the fifth page of the access table, 7
6 is the nth page of the access table, and t is the time for reading one page of the access table at a constant bit rate.

With respect to the video server device configured as described above, the operation of the stream control unit 60 will be mainly described below. When the command reception unit 5 receives the reproduction position, the stream read position determination unit 61 specifies from the reproduction position and the address of the key frame that the access table management unit 4 acquires from the access table 1b stored in the hard disk 1 from the address. If the read position of the key frame near the specified reproduction position is determined and the command receiving unit 5 does not receive the reproduction position, the read position of the key frame specified to be read next or the continuous read position of the AV stream 1a is determined. Stream reading unit 2
To instruct.

Further, the stream read position determination unit 61
Is a key frame data length calculation unit 62 when the reproduction speed received by the command receiving unit 5 is discontinuous reproduction such as high speed reproduction.
All or an arbitrary number of key frame data lengths acquired from the access table 1b by the stream reading unit 2
Determines the key frame transmission time interval from the maximum bit rate at which the AV stream 1a is read and instructs the stream transmission timing setting unit 63 to read the key that satisfies the reproduction speed from the key frame transmission time interval, the key frame interval, and the frame frequency. Specify the frame. When the reproduction speed received by the command receiving unit 5 is continuous reproduction such as normal reproduction and slow reproduction, the key frame to be read next is not designated.

The stream transmission timing setting unit 63
In the case of high-speed playback, the stream transmission unit 3 is instructed to transmit the key frame read by the stream reading unit 2 at the key frame transmission time interval specified by the stream reading position determination unit 61, and the timing for reading the next key frame is streamed. The reading unit 2 is instructed. When reading the access table 1b from the hard disk 1, the access table management unit 4 acquires it in page units for an arbitrary data length or an arbitrary time, and the access table page switching determination unit 64 is processing the stream read position determination unit 61 during processing. Playback position and access table management unit 4
Compares the position range of the page acquired by the above, determines whether to acquire the page of the next access table, and instructs the access table management unit 4.

For example, when the stream read position determination unit 61 receives a reproduction request, the access table page switching determination unit 64 reads the first page 71 of the access table so that the access table management unit 4 can read it.
To instruct. The access table management unit 4 reads from the hard disk 1 the first page 71 of the access table instructed by the access table page switching determination unit 64. The time required for reading is t. Since the acquisition of the access table is completed, the stream read position determination unit 61 starts the reproduction process. The access table page switching determination unit 64 acquires the second page of the next access table when the stream read position determination unit 61 processes the first key frame of the first page of the access table. Instruct 4. The operation of the access table management unit 4 is the same as above.

After that, the stream read position determining unit 61
However, a new page of the access table is newly acquired when the start position of the page of the second access table owned by the access table management unit 4 is passed, and the access table management unit 4 always acquires 0, 1 or 2 pages. Has an access table page.

As described above, according to the present embodiment, by providing the access table page switching determination section 61 in the stream control section 60, the reproduction can be started when only a part of the access table is acquired. The response time from the reproduction request to the start of reproduction can be shortened.

In each of the above embodiments, the arrangement method and reference method of the access table 1b of the access table management unit 4, the data size n of the fixed-length block, the division unit of the access table 1b, and the frame structure of the AV stream 1a are as follows. It is not limited to the above.
Although the storage medium is a hard disk, it may be an arrayed disk such as an optical disk, a magnetic tape, a semiconductor memory, or a RAID, or another arrayed storage medium. Furthermore, although the accumulation target is an AV stream,
It may be a video stream or an audio stream. In addition, the encoding method of the AV stream 1a is MPEG
However, JPEG or another system may be used. Further, if the bit rate at which the stream transmitting unit 2 transmits all or part of the AV stream 1a during high-speed reproduction or the bit rate at which the stream reading unit 2 reads part or all of the AV stream 1a is set higher than that in normal reproduction. Needless to say, smoother high-speed playback can be achieved. Furthermore, the AV stream 1a may be physically distributed and accumulated.

[0052]

As described above, according to the present invention, the first
In the case where the key frame data length differs from stream to stream, the key frame data length calculation means is provided to determine the key frame to be read next based on the key frame data length so as to maintain the high-speed playback speed. Also in the above, it is possible to realize smooth high-speed reproduction that is the closest to the specified arbitrary reproduction speed and has the minimum fluctuation in the reproduction speed for each stream.

Secondly, by providing the stream transmission timing setting means, the key frame transmission time interval is set to be equal to or longer than the maximum key frame read time at the time of high speed reproduction. Therefore, even when the key frame data lengths in the streams are different, The transmission frame time interval becomes constant at the designated arbitrary reproduction speed, and high-speed reproduction that is easier to see can be realized.

Thirdly, by providing the access table page switching judging means, the reproduction can be started when only a part of the access table is acquired, and the response time from the reproduction request to the reproduction start is shortened. The device can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a video-on-demand system including a video server device according to each embodiment of the present invention.

FIG. 2 is a block diagram of a stream control unit of the video server device according to the first embodiment of the present invention.

FIG. 3 is a block diagram of a stream control unit of the video server device according to the second embodiment of the present invention.

FIG. 4A is a schematic diagram for explaining a key frame read time interval during high speed reproduction in a conventional example. FIG. 4B is a key frame read time during first high speed reproduction according to the second embodiment of the present invention. Schematic diagram for explaining the intervals

FIG. 5A is a schematic diagram for explaining a key frame read time interval during high speed reproduction in a conventional example. FIG. 5B is a key frame read time during second high speed reproduction according to the second embodiment of the present invention. Schematic diagram for explaining the intervals

FIG. 6 is a block diagram of a stream control unit of a video server device according to a third embodiment of the present invention.

FIG. 7A is a schematic diagram for explaining the operation of the access table management unit in the conventional example. FIG. 7B is a schematic diagram for explaining the operation of the access table management unit in the third embodiment of the present invention.

FIG. 8: Video on / off including conventional video server device
Block diagram showing the configuration of the demand system

FIG. 9 is a block diagram of a stream control unit of a conventional video server device.

FIG. 10A is a schematic diagram for explaining an accumulation frame order of an AV stream, and FIG. 10B is a schematic diagram for explaining a normal reproduction frame order of an AV stream.

[Explanation of symbols]

1 hard disk 1a AV stream 1b access table 2 stream reading unit 3 stream transmitting unit 4 access table management unit 5 command receiving unit 6 and 60 stream control unit 7 stream receiving unit 8 command transmitting unit 9 decoder unit 10 input control unit 11 monitor 12 speaker 13 input device 21, 31, 61, 81 stream read position determination unit 22, 32, 62 key frame data length calculation unit 33, 63 stream transmission timing setting unit 64 access table page switching determination unit 41 first key frame 42 second Key frame 43 third key frame 51 first key frame 52 second key frame 53 third key frame 71 first page of access table 72 second page of access table 73 Access table third page 74 access table fourth page 75 access table fifth page 76 access table nth page a first keyframe read time b second keyframe read time c Read time of third keyframe m Read time of maximum keyframe n Read time of fixed length block a'Read time of fixed length block containing first keyframe b'Read of fixed length block containing second keyframe Read time c'Read time of fixed-length block including third keyframe n'Read time of maximum number of fixed-length block including keyframe t Read page time of access table

Claims (3)

[Claims] 1. A stream storage unit for storing a compression-encoded stream, a stream reading unit for reading the stream designated by a terminal device, and a stream transmitting unit for transmitting the read stream to the terminal device. In the video server device, access table managing means for managing the address of the key frame in the stream, key frame data length calculating means for obtaining each key frame data length, and a position near the playback position designated by the terminal device. A stream read position determining means for determining a key frame to be read from the access table managing means and instructing the stream reading means a read position of the key frame. From the bit rate for reading the stream, the encoding bit rate of the stream, the key frame interval, and the key frame data length acquired by the key frame data length calculation means, an arbitrary reproduction speed designated by the terminal device is maintained. A video server device, characterized in that a key frame to be extracted from the stream is selected, and the stream reading means is instructed. 2. A stream storage unit for storing a compression-encoded stream, a stream reading unit for reading the stream designated by the terminal device, and a stream transmitting unit for transmitting the read stream to the terminal device. In the video server device, access table managing means for managing the address of the key frame in the stream, key frame data length calculating means for obtaining each key frame data length, and a position near the playback position designated by the terminal device. Stream read position determining means for obtaining a key frame to be read from the access table managing means, selecting a key frame satisfying the reproduction speed designated by the terminal device, and instructing the stream reading means to read the key frame. The stream Stream transmitting timing setting means for instructing transmitting timing of each key frame to transmitting means, wherein the stream transmitting timing means transmits each key frame to be transmitted from the key frame length acquired by the key frame data length calculating means. A video server device, wherein a transmission bit rate of the stream transmitting means and a read bit rate of the stream reading means are controlled so that the timing becomes constant. 3. A stream storage means for storing a compression-coded stream, a stream reading means for reading the stream designated by the terminal device, and a stream transmitting means for transmitting the read stream to the terminal device. In the video server device, access table managing means for managing the address of the key frame in the stream, key frame data length calculating means for obtaining each key frame data length, and a position near the playback position designated by the terminal device. A key frame to be read from the access table management means, and a stream read position determination means for instructing the stream read means of the read position of the key frame; and an address of the key frame managed by the access table management means from the storage means. An access table page switching determination means for instructing the access table management means to obtain the access table management means,
Whether or not the address of the key frame is divided and acquired for each page of arbitrary data length or arbitrary time, and the access table page switching determination means acquires the next page from the address of the key frame being read by the stream reading means. A video server device, which makes a judgment and gives an instruction to the access table management means.