JP3443944B2 - Video signal transmission device, video signal transmission system, and video signal transmission method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal transmission device used in a so-called VOD system for reproducing and transmitting a desired video among a plurality of videos recorded on the transmission side according to designation from the reception side. The present invention relates to a video signal receiving device, a video signal transmission system, and a video signal transmission method.

[0002]

2. Description of the Related Art A cable television station is provided with an image recording device in which many images such as movies are recorded in the MPEG system, an image designated by a viewer is reproduced from the image recording device, and the image is designated. VOD provided to viewers individually
(Video On Demand) system is under consideration. In the VOD system, a video signal transmitting device of a cable television station and a video signal receiving device of a viewer are connected via a communication line of a public communication network such as a telephone line. A VO that wants to operate a video recording device of a cable TV station as if it were its own VTR device.
There is a request from the viewer of the D system. Therefore, V
In the OD system, a viewer can operate a receiver at home to perform operations such as playback start, fast forward, rewind, fast rewind and stop on a video recording device of a cable television station. Need to be kept.

[0003]

In the VOD system, when a viewer performs an operation such as fast-forwarding and fast-rewinding an image on the image recording device of a cable television station, the data speed of the image signal reproduced from the image recording device. There is a problem that (bit rate) becomes faster. When the data speed reproduced from the video recording device becomes faster, it exceeds the data speed (capacity of the communication line) that can be transmitted by the communication line connecting the video signal transmission device of the cable TV station and the video signal reception device of the viewer. It may end up.

In such a case, in the VOD system, unlike the operation for the VTR device at home, the viewer operates the video signal transmission device of the cable television station while operating the fast-forward and fast-rewind while watching the video in the middle. Could not be done. That is, instead of performing a fast-forward operation on the VTR device at home, the viewer transmits to the video signal transmission device of the cable television station, the video signal of "minutes and seconds before or minutes and seconds after" (jump). There is a problem that only the method) can be operated. If only an operation such as fast-forwarding of the image by the jump method can be performed, the viewer cannot operate while looking for the desired part while looking at the intermediate image, and there is a problem that it is difficult to find the desired part of the image. In addition, the VOD system, which allows only such operations for the viewer, is inconvenient to use.

The present invention has been made in view of the above-mentioned problems of the prior art, and allows a viewer of a VOD system to operate a video signal transmission device of a cable television station as if it were a home VTR device. An object of the present invention is to provide a video signal transmission device, a video signal reception device, a video signal transmission system, and a video signal transmission method which are easy to use. In particular, the present invention allows video signals to be transmitted to a video signal transmission device of a cable television station such as fast-forwarding the video while the viewer is watching the video in the middle, and it is easy to search for a desired portion of the video signal. An object of the present invention is to provide a device, a video signal receiving device, and a video signal transmitting method.

[0006]

In order to achieve the above-mentioned object, a video signal transmission apparatus of the present invention is connected to a receiving side via a transmission line, and an intra-frame encoded signal and an inter-frame encoded signal are encoded. A video signal transmission device for reproducing and transmitting an encoded video signal designated by the receiving side from a recording medium in which a plurality of encoded video signals encoded so as to include signals are recorded, the receiving side According to the control signal transmitted from, the reproduction means for reproducing the encoded video signal from the recording medium at a normal data rate, or at a data rate higher than the normal data rate, in a forward direction or a reverse direction, The intra-frame coded signal is sequentially extracted from the coded video signal reproduced at the high data rate, and the extracted intra-frame coded signal is included in the transmission band of the transmission path. Signals extractor, which extended the time axis as
In accordance with the time axis expansion means and the control signal, the encoded video signal reproduced by the reproduction means, or the signal extraction /
And a transmission means for selecting the intra-frame coded signal extracted by the time axis expansion means and expanded in the time axis, and transmitting it as a transmission signal to the reception side via the transmission path.

Preferably, the encoded video signal is MPE
It is formatted in the G system, and the signal extraction / time axis expansion means detects the header indicating the intra-frame coded signal in the MPEG system format and extracts the intra-frame coded signal. Preferably, it further comprises control signal receiving means for receiving the control signal transmitted via the transmission path.

In the video signal transmission system of the present invention, the video signal transmission device and the video signal reception device are connected via the transmission path. The video signal receiving device receives the control signal and transmits the control signal to the video signal transmitting device via the transmission line, and a transmission signal transmitted from the transmission device. Display means for receiving and displaying.

According to the video signal transmission method of the present invention, a coded video signal including an intra-frame coded signal and an inter-frame coded signal is transmitted at a normal data rate according to the control signal sent from the receiving side, and At a data rate higher than the data rate of, and at least an intra-frame coded signal is sequentially extracted from the coded video signal of the fast data rate to obtain a coded video signal of a normal data rate or the fast data rate. The intra-frame coded signal extracted from the coded video signal is transmitted to the receiving side.

[0010]

The reproducing means of the video signal transmitting apparatus of the present invention allows the VOD system to watch the video signal recorded on the recording medium such as a magneto-optical disk by the MPEG system through a transmission line such as a public telephone line. According to the control signal sent from the person's video signal receiving device, bidirectional reproduction is performed, for example, at a data rate in the case of normal reproduction and at a higher data rate than usual in the case of fast-forwarding. The signal extraction / time axis expansion means extracts an intra-frame coded signal (intra frame signal) from at least a video signal having a higher data rate than usual among the video signals reproduced by the reproduction means,
The extracted intra frame is expanded on the time axis so as to fit in the transmittable frequency band of the transmission path. According to the control signal, the transmission means selects an intra-frame signal which is extracted from a video signal of a normal data rate or a video signal of a data rate higher than the normal data rate and which is time-axis expanded, and transmits it as a transmission signal. It is transmitted to the receiving side via the path.

The control signal transmitting means of the video signal receiving apparatus of the present invention generates a control signal from the control information input by the viewer or the like from the operation terminal or the like, and transmits the control signal to the video signal transmitting apparatus via the transmission line. To the other side. The receiving means receives the video signal or the intra-frame coded signal sent from the video signal transmission device. The display means visualizes and displays the signal received by the receiving means.

[0012]

EXAMPLES Examples of the present invention will be described below. First, the configuration of the VOD system 1 of the present invention will be described with reference to FIG. FIG. 1 is a diagram showing a configuration of a VOD system 1 of the present invention. The VOD system 1 shown in FIG. 1 displays many images such as movies on a cable television station, for example, "International standard of multimedia encoding (edited by Hiro Yasuda, published by Maruzen Co., Ltd., issued June 30, 1991)." A video recording device (REC) 10 for recording in the MPEG system disclosed on pages 126 to 156 of (Reference 1) is prepared, and a video signal specified by a viewer is transmitted as a video signal transmission device (VTM) 20.
Is a so-called VOD (Video On Demand) system in which the video is reproduced from the video recording device 10 and individually provided to the designated viewer via the communication line 30.

In the VOD system 1, when a viewer inputs operation information to the terminal device 60, the cable television station is transmitted via the video signal receiving device 40, the communication line 30, and the video signal transmitting device (VRC) 20. The video recording device 10 is operated as if it were a VTR device at home, and the transmitted video can be displayed on the monitor 50.

As shown in FIG. 1, the VOD system 1 is
A cable television station 2 including a video recording device 10 and a video signal transmitting device 20, a video signal receiving device 40, and a monitor 50.
And a subscriber device 3 including a terminal device 60, and a communication line 30 connecting the cable television station 2 and the subscriber device 3. Although FIG. 1 shows a case where the cable television station 2 and the subscriber device 3 are connected to each other in a one-to-one manner, in reality, the VOD system 1 connects the communication line 30 to one cable television station 2. A large number of subscriber apparatuses 3 are connected via the above. The video recording device 10 records a large number of videos such as movies on a recording medium such as a magneto-optical disk, a VTR tape or a hard disk as a video signal of the MPEG system, and a video recording device control signal RC of the video signal transmission device 20. The video signal transmission device 2 reads one video signal or a plurality of video signals from the recording medium at the same time and controls the video signal VR as a video signal VR.
Output for 0.

The video signal transmission device 20 controls the video recording device 10 via the video recording device control signal RC, and VOD
A video signal requested by a viewer of the system 1 is read out as a video signal VR at a normal data rate (bit rate), an MPEG video signal is reproduced from the video signal VR, for example, QAM modulation is performed, and communication is performed. It is transmitted to the subscriber device 3 via the line 30. When the viewer of the VOD system 1 requests the video recording device 10 for an operation such as fast-forwarding, the video signal transmission device 20 causes the video recording device 10 to operate via the video recording device control signal RC. The video signal requested by the viewer of the VOD system 1 is read out as the video signal VR in the forward or reverse direction at a higher data rate than usual. Further, the video signal transmission device 20 reproduces an MPEG video signal from the video signal VR and extracts an intra-frame coded signal (intra-frame signal) from the reproduced MPEG video signal. The extracted intraframe signal has a low data rate,
That is, the data is converted to the upper limit (capacity) of the data rate that can be transmitted by the communication line 30 and transmitted to the subscriber device 3 via the communication line 30. The detailed configuration of the video signal transmission device 20 will be described later with reference to FIG.

The communication line 30 is a communication line such as a telephone line of a public network, and is a normal data rate MPEG system video signal or a high data rate MPEG system video signal transmitted from the video signal transmission device 20. Intra-frame coded signals extracted from (hereinafter, signals relating to video transmitted on the communication line 30 are collectively referred to as “transmission signal”).
, And the video signal transmission device 20 and the communication line 3
The control signal between 0 and 0 is transmitted. Video signal receiver 40
Generates a video signal RVO from the transmission signal transmitted from the video signal transmission device 20 over the communication line 30, and displays it on the monitor 50. In addition, the video signal receiving device 40 is a cable television station
The control signal (control signal in the up direction) designating the operation of the video recording device 10 is transmitted to the video signal transmission device 20 through the communication line 30, and conversely, the control signal is transmitted from the video signal transmission device 20 to the communication line 30. A control signal (downward control signal) sent via the control signal is received, and processing is performed based on this control signal. The detailed configuration of the video signal receiving device 40 will be described later with reference to FIG.

The monitor 50 is an image display device such as a color television, and displays the video signal RVO input from the video signal receiving device 40. Terminal device (TERM)
Reference numeral 60 denotes a terminal equipped with a keyboard and a liquid crystal display device, for example.
Enter the information (operation information) that specifies the operation for.
The operation information input to the terminal device 60 is output to the video signal receiving device 40.

Hereinafter, referring to FIG. 2, the video signal transmission device 2
The configuration and operation of 0 will be described. FIG. 2 is a diagram showing the configuration of the video signal transmission device 20 shown in FIG. As shown in FIG. 2, the video signal transmission device 20 includes a reproduction circuit 200,
Switch circuit (SW1) 202, intra frame signal extraction circuit (IPE) 204, FIFO circuit (FF) 20
6. Multiplexing circuit (MUX) 208, modulation circuit (MOD)
210, control circuit 220 and demodulation circuit (DEMOD)
It is composed of 230.

The reproducing circuit 200 is controlled from the video signal VR read from the recording medium by the video recording device 10 under the control of the control circuit 220 via the video recording device control signal RC.
The MPEG type video signal MPS is generated and output to the intra-frame signal extraction circuit 204 and the contact a of the switch circuit 202. The intra-frame signal extraction circuit 204, according to the control of the control circuit 220 via the control signal IPC, outputs at least the video signal VR at a data rate faster than usual, when the video recording device 10 outputs the video signal VR.
The intra frame signal is extracted from the video signal MPS and output to the contact b of the switch circuit 202. The switch circuit 202 includes a control circuit 220 via a control signal SWC.
In accordance with the control of 1., the video signal MPS input to the contact a from the reproduction circuit 200 or the intra frame signal IPS input to the contact b from the intra frame signal extraction circuit 204 is selected, and FI is selected as the switch output signal SWS.
Output to the FO circuit 206.

The FIFO circuit 206, under the control of the control circuit 220 via the signal FFC, switches the switch circuit 202.
The video signal MPS input as the switch output signal SWS via the switch circuit 2 at the same data rate.
The data rate of the intra frame signal IPS input as the switch output signal SWS via 02 is reduced to F
The IFO output signal FFS is output to the multiplexing circuit 208. The intra-frame signal extraction circuit 204
A method for separating an intra-frame signal from an MPEG video signal, a method for reducing the data rate of the extracted intra-frame signal by the FIFO circuit 206, and the like will be described later with reference to FIGS. 4 and 5.

The multiplexing circuit 208 multiplexes the downlink control signal input as the control signal RCS from the control circuit 220 with the FIFO output signal FFS to generate a multiplexed signal MUS.
To the modulation circuit 210. This control signal RCS is transmitted to the video signal receiving device 40, and is displayed on the monitor 50 by the video signal receiving device 40 as various messages from the cable television station 2 to the viewer of the VOD system 1, or from the cable television station 2. The transmission signal transmitted to the subscriber unit 3 is MPE.
G system video signal itself or extracted MPE
It is used, for example, to identify whether the video signal of G system is an intra-frame signal. The modulation circuit 210 uses the multiplexed signal MU.
S is, for example, QAM-modulated to generate a modulation signal RVC,
It is transmitted to the video signal receiving device 40 of the subscriber device 3 via the communication line 30.

The demodulation circuit 230 demodulates the upstream control signal transmitted as the control signal TCS via the communication line 30 and outputs it to the control circuit 220 as the control signal TC. The control circuit 220 is a control computer including a CPU and its peripheral circuits,
Processing is performed based on the control signal TC input from the demodulation circuit 230, and each control signal IPC, SWC, FFC, RC
The intra-frame signal extraction circuit 204, the switch circuit 202, the FIFO circuit 206, and the video recording device 10 are controlled via the. It also generates a downlink control signal,
The control signal RCS is output to the multiplexing circuit 208.

Hereinafter, referring to FIG. 3, the video signal receiving device 4
The configuration and operation of 0 will be described. FIG. 3 is a diagram showing a configuration of the video signal receiving device 40 shown in FIG. As shown in FIG. 3, the video signal receiving device 40 includes a demodulation circuit (DEMO).
D) 400, separation circuit (DEMUX) 402, MPEG
It is composed of a decoder (DECODE) 404, a control circuit 410 and a modulation circuit (MOD) 420. The demodulation circuit 400 demodulates the transmission signal transmitted as the modulation signal RVC via the communication line 30 and the control signal in the up direction (control signal RCS in the video signal transmission device 20) to obtain a demodulation signal DMS and a control signal RCS. Output to the separation circuit 402.

The separation circuit 402 separates the demodulated signal DMS into a transmission signal and an upstream control signal, and outputs the respective signals to the MPEG decoder 404 and the control circuit 410 as a video signal DRV and a control signal RCS.
Under the control of the control circuit 410 via the control signal DCC, the MPEG decoder 404 decodes the transmission signal input as the video signal DRV to generate the video signal RVO, and displays it on the monitor 50.

The control circuit 410 is a control computer composed of a CPU and its peripheral circuits,
The operation information input as the terminal input signal TRMS from the terminal device 60 and the control signal RC from the separation circuit 402.
Processing is performed based on the downlink control signal input as S, the MPEG decoder 404 and the terminal device 60 are controlled via the control signals DCC and TRMC, and an uplink control signal (control signal TC) is generated. Modulation circuit 42
Output for 0. The control signal TC is used in the video signal transmission device 20 to allow the viewer of the VOD system 1 to select a video signal or to cause the video recording device 10 to perform fast-forwarding or the like. The modulation circuit 420 converts the control signal TC input from the control circuit 410 into, for example, QAM.
The modulated signal is transmitted as a control signal TCS to the video signal transmission device 20 via the communication line 30.

The operations of the intra-frame signal extraction circuit 204 and the FIFO circuit 206 of the video signal transmission device 20 will be described below with reference to FIGS. 4 and 5. Figure 4
It is a figure which shows the signal format of the video signal of an MPEG system, (A) shows the format of a video sequence layer, (B) shows the format of the GOP layer shown to (A), (C) is a picture layer. Shows the format of.
FIG. 5 shows the intra-frame signal extraction circuit 2 shown in FIG.
04 and a diagram showing the operation of the FIFO circuit 206,
4A shows the format of the GOP layer of the MPEG video signal shown in FIG. 4B reproduced at a normal data speed, and FIG. 4B shows the format of the GOP layer reproduced at a higher data speed than usual. GOP of the MPEG video signal shown in B)
The format of a layer is shown, (C) shows the intra-frame signal I extracted by the intra-frame signal extraction circuit 204.
PS indicates (PS), and (D) indicates an intra frame signal (FIFO output signal FFS) whose data rate has been slowed (time axis expanded) by the FIFO circuit 206.

A video signal of one MPEG system is composed of several video sequence layers. That is,
As shown in FIG. 4A, the header H is followed by a plurality of GOs.
P _j (j is an integer) follows. As shown in FIG. 4B, each GOP _j is composed of a header H and eight frames of frame signals P, B, I, P, B, B, P, and B. Here, the frame signal P indicates a forward predictive coded signal, the frame signal B indicates both predictive coded signals, and the frame signal I indicates an intraframe coded signal (intra frame signal).

Of these frame signals, the frame signal I is an intra-frame coded signal, and therefore, the MPEG decoder 4 of the video signal receiving apparatus 40 independently of other frames.
It can be visualized by 04. VOD system 1
Has been invented paying attention to this point, and causes the video recording apparatus 10 to read the video signal VR at a data rate faster than usual to reproduce an MPEG video signal, and to use an intra frame from this video signal. Only the signal (frame signal I) is extracted, the time axis expansion of the frame signal I is performed by utilizing the idle time of the frame signals P and B that are not transmitted, and the data rate of the transmission signal is reduced below the capacity of the communication line 30. Make a transmission. That is, the video signal transmission device 20 is configured to transmit to the subscriber device 3 the video on the way until the user of the VOD system 1 finds the desired video at a data rate equal to or lower than the capacity of the communication line 30. There is. Therefore,
Unlike operations such as fast-forwarding by the jump method in the conventional VOD system, the viewer of the VOD system 1 operates the video recording device 10 of the cable television station 2 as if he / she operates the VTR device at home. By looking at the video in the middle and performing operations such as fast-forwarding, the desired video can be located.

Each frame signal I, P, B is shown in FIG.
The format is as shown in (1), and the content of the header H is different for each of the frame signals I, P, and B. The intra-frame signal extraction circuit 204 can detect whether the frame signal is the frame signal I, P, or B by identifying the content of the header H, and can extract the frame signal I. it can.

When the video signal is read by the video recording device 10 at a normal data rate, the video signal VR (..., DB _i , DB _{i + 1} , ...) Is generated at the timing as shown in FIG. 5 (A). To be done. When the video signal is read out by the video recording device 10 at this data rate, the video signal MPS obtained by reproducing the video signal VR is directly transmitted to the video signal receiving device 40 via the communication line 30. be able to.
On the other hand, when the video recording device 10 is caused to read the video signal at a higher data rate than usual, the video signal VR is generated at the timing shown in FIG. 5B. When the video signal is read by the video recording device 10 at this data rate, the video signal MPS obtained by reproducing the video signal VR exceeds the capacity of the communication line 30, and therefore the video signal receiving device 40 is used as it is. Not to be transmitted to.

Therefore, the intra-frame signal extraction circuit 2
04, only the intra frame signal (frame I) is extracted from the video signal VR shown in FIG.
An intra frame signal IPS as shown in (C) is generated. This signal is expanded on the time axis by the FIFO circuit 206 to generate a FIFO output signal FFS as shown in FIG. Since the FIFO output signal FFS does not exceed the capacity of the communication line 30, it can be transmitted to the video signal receiving device 40 on the communication line 30.

The operation of the VOD system 1 will be described below with reference to the drawings. First, the operation of the VOD system 1 when transmitting an MPEG video signal read from the video recording device 10 at a normal data rate will be described. The viewer inputs predetermined operation information to the terminal device 60,
Select the desired video. The operation information input to the terminal device 60 is input to the control circuit 410 as a terminal input signal TRMS. The control circuit 410 uses the terminal input signal TRMS.
Is processed to generate a control signal TC for transmitting to the cable television station 2 that the movie A is selected and reproduced at a normal speed, and is output to the modulation circuit 420. The modulation circuit 420 QAM-modulates the control signal TC and transmits the video signal transmission device 2 of the cable television station 2 via the communication line 30.
Transmit to 0.

Demodulation circuit 230 of video signal transmission device 20
QAM demodulates the transmitted control signal TCS and outputs the control signal TC to the control circuit 220. The control circuit 220 performs processing based on the control signal TC, controls the video recording device 10 via the video recording device control signal RC, and causes the movie A to be read from the recording medium at a normal data rate. Further, the control circuit 220 controls the switch circuit 202 via the control signal SWC to select the contact a and controls the FIFO circuit 206 via the signal FFC to multiplex the switch output signal SWS at the same data rate. The circuit 208 is made to output. Further, the control circuit 220 generates a control signal RCS for notifying that the transmission signal to the subscriber unit 3 is a video signal of a normal speed, and outputs it to the multiplexing circuit 208.

The image read from the recording medium is shown in FIG.
The video signal VR as shown in (A) is input to the reproduction circuit 200 of the video signal transmission device 20. Reproduction circuit 20
0 reproduces a video signal of the MPEG system from the video signal VR and outputs it as a video signal MPS to the switch circuit 202. At this time, the intra-frame signal extraction circuit 204 may or may not be operating. The video signal MPS is sent to the FIFO circuit 2 via the switch circuit 202.
It is input to the multiplexing circuit 208 as it is, and is passed as it is as a FIFO output signal FFS. The multiplexing circuit 208 includes a FIFO output signal FFS and a control signal RCS.
And are multiplexed, and as a multiplexed signal MUS, the modulation circuit 210
Output to. The modulation circuit 210 uses the multiplexed signal MU.
The communication line 30 modulates S by QAM and outputs it as a modulation signal RVC.
The video signal is transmitted to the video signal transmission device 20 via the.

The modulated signal RVC transmitted from the video signal transmission device 20 is demodulated by the demodulation circuit 4 of the video signal reception device 40.
QAM demodulation by 00 and output to the separation circuit 402 as a demodulation signal DMS. The separation circuit 402 separates the demodulation signal DMS into a control signal RCS and a video signal DRV, and these signals are respectively controlled by the control circuit 410 and MPE.
It outputs to the G decoder 404. Here, the video signal DRV is the same as the FIFO output signal FFS in the video signal transmission device 20. The control circuit 410 processes the control signal RCS to recognize that the video signal DRV is a normal MPEG video signal, and controls the MPEG decoder 404 via the control signal DCC to perform normal MPEG.
The operation of decoding the video signal of the system to generate the video signal RVO is performed. The MPEG decoder 404 decodes the video signal DRV according to the control of the control circuit 410 via the control signal DCC, and displays the video signal RVO on the monitor 50. This is the end of the description of the operation of the VOD system 1 when transmitting an MPEG video signal read from the video recording device 10 at a normal data rate.

Next, the operation of the VOD system 1 in the case of transmitting the MPEG type video signal read from the video recording device 10 at a higher data rate than usual will be described. As described above, the viewer watching the MPEG video signal read from the video recording device 10 at the normal data rate inputs predetermined operation information to the terminal device 60,
For example, operation information for performing a fast-forward operation is input to the video recording device 10. The operation information input to the terminal device 60 is input to the control circuit 410 as a terminal input signal TRMS. The control circuit 410 processes the terminal input signal TRMS to generate a control signal TC for informing the cable television station 2 that the video recording device 10 is to perform the fast forward operation, and outputs the control signal TC to the modulation circuit 420. Modulation circuit 42
0 transmits the control signal TC to the video signal transmission device 20 of the cable television station 2 by QAM-modulating it through the communication line 30.

Demodulation circuit 230 of video signal transmission device 20
QAM demodulates the transmitted control signal TCS and outputs the control signal TC to the control circuit 220. The control circuit 220 performs a process based on the control signal TCS, controls the video recording device 10 via the video recording device control signal RC, and performs a fast-forward operation in a direction in which the recording medium has a higher data speed than usual. Read from. The control circuit 220 also controls the switch circuit 20 via the control signal SWC.
2 is controlled to select the contact b, and F is set via the signal FFC.
The IFO circuit 206 is controlled to expand the intra frame signal IPS as shown in FIG.
The O output signal FFS is generated. Further, the control circuit 220 notifies the control signal R that the transmission signal to the subscriber device 3 is a video signal for fast-forwarding.
The CS is generated and output to the multiplexing circuit 208.

The image read from the recording medium is shown in FIG.
The video signal VR as shown in (B) is input to the reproduction circuit 200 of the video signal transmission device 20. Reproduction circuit 20
0 reproduces the video signal of the MPEG system from the video signal VR and outputs it as the video signal MPS to the intra-frame signal extraction circuit 204. The intra-frame signal extraction circuit 204 extracts the intra-frame signal from the video signal MPS, generates the intra-frame signal IPS as shown in FIG. 5C, and outputs the intra-frame signal IPS to the contact b of the switch circuit 202. The intra-frame signal IPS is input to the FIFO circuit 206 via the switch circuit 202, expanded on the time axis, and then the FI as shown in FIG.
The FO output signal FFS is input to the multiplexing circuit 208. The multiplexing circuit 208 multiplexes the FIFO output signal FFS and the control signal RCS, and outputs them as the multiplexed signal MUS to the modulation circuit 210. The modulation circuit 210 QAM-modulates the multiplexed signal MUS and transmits it as a modulated signal RVC to the video signal transmission device 20 via the communication line 30.

The modulated signal RVC transmitted from the video signal transmission device 20 is demodulated by the demodulation circuit 4 of the video signal reception device 40.
QAM demodulation by 00 and output to the separation circuit 402 as a demodulation signal DMS. The separation circuit 402 separates the demodulation signal DMS into a control signal RCS and a video signal DRV, and these signals are respectively controlled by the control circuit 410 and MPE.
It outputs to the G decoder 404. Here, the video signal DRV is the same as the FIFO output signal FFS in the video signal transmission device 20. The control circuit 410 processes the control signal RCS, and outputs M when the video signal DRV is fast-forwarding.
The control signal D is recognized by recognizing that it is a PEG type video signal.
The MPEG decoder 404 is controlled via the CC to perform an operation of decoding a video signal consisting only of an intra frame signal to generate a video signal RVO. The MPEG decoder 404 has a control circuit 410 via a control signal DCC.
The video signal DRV is decoded according to the control of 1. and the video signal RVO is displayed on the monitor 50. With the above, the MPE read from the video recording device 10 at a higher data rate than usual
The description of the operation of the VOD system 1 when transmitting a G system video signal is finished.

By configuring the VOD system 1 as described above, the viewer of the VOD system 1 can use the video recording device 10 of the cable television station 2 as if it were a VTR at home.
Operations such as fast-forwarding can be performed at intervals as if the apparatus were operated. Therefore, the VOD system 1 is very convenient for the viewer. In addition, although it is possible to improve the usability for the viewer in this way, the VOD system 1 adds the intra-frame signal extraction circuit 204 and the switch circuit 202 to the conventional VOD system and changes the configuration of the MPEG decoder. Then
This can be easily realized simply by changing the programs of the control circuits on the cable television station 2 side and the subscriber device 3 side.

The VOD system 1 can also support an operation of reading an image from the image recording apparatus 10 at a data rate faster than usual, for example, fast rewinding. Video signal transmitter 20 and video signal receiver 4 of VOD system 1
Each component of 0 can be replaced with another circuit having an equivalent function or software means having an equivalent function and performance as much as possible. Further, the communication line 30 does not necessarily have to be a public network, but simply the video signal transmission device 20 and the video signal reception device 40.
It may be a cable for connecting the above or a local network. Also, the modulation method in the VOD system 1 is QAM.
Not limited to this, for example, an AM method or an FM method may be used. In addition to the embodiments described above, the VOD system 1 of the present invention can have various configurations, for example, as in the modification shown here.

[0042]

As described above, according to the present invention, V
A viewer of the OD system can operate the video signal transmission device of the cable television station as if it were a home VTR device. Therefore, according to the present invention, it is possible to provide a VOD system that is very convenient for the viewer. Further, according to the present invention, a viewer can perform an operation such as fast-forwarding of a video on a video signal transmission device such as a cable television station while watching a video in the middle.
Therefore, it is easy for the viewer of the VOD system to search for a desired portion of the video despite the operation such as fast-forwarding the video to the video signal transmission device such as a cable television station.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a VOD system of the present invention.

FIG. 2 is a diagram showing the configuration of the video signal transmission device shown in FIG.

FIG. 3 is a diagram showing a configuration of the video signal receiving device shown in FIG.

FIG. 4 is a diagram showing a signal format of a video signal of an MPEG system, (A) shows a format of a video sequence layer, (B) shows a format of a GOP layer shown in (A), and (C). ) Indicates the format of the picture layer.

5 is a diagram showing operations of the intra-frame signal extraction circuit and the FIFO circuit shown in FIG. 2, where (A) is the MPEG shown in FIG. 4 (B) reproduced at a normal data rate.
Shows the format of the GOP layer of the video signal of the system,
(B) is reproduced at a higher data rate than usual.
The format of the GOP layer of the MPEG video signal shown in (B) is shown, (C) shows the intra frame signal IPS extracted by the intra frame signal extraction circuit,
(D) shows an intra-frame signal (FIFO output signal FFS) whose data rate has been slowed (time-axis expanded) in the FIFO circuit.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... VOD system 1, 2 ... Cable television station, 3 ... Subscriber device, 10 ... Video recording device, 20 ... Video signal transmission device, 200 ... Reproducing circuit, 202 ... Switch circuit, 204
... Intra-frame signal extraction circuit, 206 ... FIFO circuit, 208 ... Multiplexing circuit, 210 ... Modulation circuit, 220 ...
Control circuit, 230 ... Demodulation circuit, 30 ... Communication line, 40 ...
Video signal receiving device, 400 ... Demodulation circuit, 402 ... Separation circuit, 404 ... MPEG decoder, 410 ... Control circuit, 4
20 ... Modulation circuit, 50 ... Monitor, 60 ... Terminal device

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Claims (6)

(57) [Claims] 1. A receiver is connected via a transmission line,
The encoded video signal designated by the receiving side is reproduced from the recording medium in which a plurality of encoded video signals encoded so as to include the intra-frame encoded signal and the inter-frame encoded signal are recorded, and the reception side is reproduced. A video signal transmission device for transmitting the encoded video signal from the recording medium at a normal data rate according to a control signal transmitted from the receiving side,
Or at a data rate faster than the normal data rate,
Reproducing means for reproducing in a forward direction or a reverse direction, and sequentially extracting the intra-frame encoded signal from the encoded video signal reproduced at the high data rate, the extracted intra-frame encoded signal, A signal extracting / time axis expanding means for expanding the time axis so as to be included in the transmission band of the transmission path; and an encoded video signal reproduced by the reproducing means according to the control signal, or the signal extracting / time axis expanding means. Select the intra-frame coded signal extracted and expanded in the time axis,
A video signal transmission device , comprising: transmission means for transmitting a transmission signal to the reception side via the transmission path. 2. The coded video signal is formatted according to the MPEG system, and the signal extraction / time axis expansion means detects a header indicating an intra-frame coded signal of the MPEG system format to detect the frame. The video signal transmission device according to claim 1 , wherein the intra-coded signal is extracted. Wherein further comprising a control signal receiving means for receiving the control signal transmitted through the transmission path, the video signal transmission apparatus according to claim 1 or 2. 4. A video signal transmission system having a video signal transmission device and a video signal reception device connected via a transmission line, wherein the video signal transmission device is an intra-frame coded signal and an inter-frame coded signal. Video signal transmission in which a coded video signal designated by the video signal receiving device is reproduced from a recording medium in which a plurality of coded video signals encoded to include signals are recorded and transmitted to the video signal receiving device. A device, wherein the encoded video signal is transmitted from the recording medium at a normal data rate, or at a data rate higher than the normal data rate, in a forward direction according to a control signal transmitted from the video signal receiving apparatus. Alternatively, a reproducing means for reproducing in the reverse direction, and the intra-frame encoded signal is sequentially extracted from the encoded video signal reproduced at the high data rate, and the extracted signal is extracted. A coded video signal reproduced by the reproduction means according to the control signal, and a signal extraction / time axis expansion means for expanding the encoded coded signal in the time axis so as to be included in the transmission band of the transmission path, or Selecting the intra-frame encoded signal extracted by the signal extraction / time axis expansion means and expanded in the time axis;
And a control signal receiving unit for receiving the control signal transmitted via the transmission line, the transmission unit transmitting the transmission signal as a transmission signal to the video signal receiving device via the transmission line. The device receives the control signal, transmits the control signal to the video signal transmission device via the transmission path, and receives the transmission signal transmitted from the transmission device. A video signal transmission system comprising: a display unit for displaying. 5. A coded video signal containing an intra-frame coded signal and an inter-frame coded signal at a normal data rate and at a data rate higher than the normal data rate in accordance with a control signal sent from a receiving side. Playback at a speed, at least the intraframe coded signal is sequentially extracted from the coded video signal at the high data rate, and the extracted intraframe coded signal is transmitted through a transmission band of a transmission line.
And time between base decompression to be included in frequency in accordance with said control signal, said coded video signal or said
A video signal transmission method for selecting an intra-frame encoded signal that has been time-axis expanded and transmitting the selected signal to the reception side via the transmission path . 6. The encoded video signal is formatted according to the MPEG system, and in the step of performing the signal extraction / time axis expansion, the M
The video signal transmission method according to claim 5, wherein a header indicating an intra-frame coded signal of a PEG format is detected and the intra-frame coded signal is extracted.