CA1097798A - System for recording and/or reproducing a television signal - Google Patents
System for recording and/or reproducing a television signalInfo
- Publication number
- CA1097798A CA1097798A CA352,427A CA352427A CA1097798A CA 1097798 A CA1097798 A CA 1097798A CA 352427 A CA352427 A CA 352427A CA 1097798 A CA1097798 A CA 1097798A
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Abstract
ABSTRACT OF THE DISCLOSURE
A system for recording and/or reproducing a television signal containing a video signal component and a sound signal component is improved to establish long-time recording and reproducing, in which the video signal component is periodically sampled, for example, at every other frame period and the sound signal component and a delayed sound signal component obtained by means of an one-frame delay device by which the sound signal component is delayed by one frame period are alternately sampled at the first half and the second half of each line period in the duration of the sampled frame period in order to be recorded on a recording medium and be reproduced from the record-ing medium In reproducing, each recorded frame of the video signal component is reproduced twice continuously together with the sound signal component and the reproduced sound signal component is sampled at the first half of each line period in the duration of the first reproduction of the recorded frame and at the second half of each line period in the duration of the second reproduction of the same frame.
A system for recording and/or reproducing a television signal containing a video signal component and a sound signal component is improved to establish long-time recording and reproducing, in which the video signal component is periodically sampled, for example, at every other frame period and the sound signal component and a delayed sound signal component obtained by means of an one-frame delay device by which the sound signal component is delayed by one frame period are alternately sampled at the first half and the second half of each line period in the duration of the sampled frame period in order to be recorded on a recording medium and be reproduced from the record-ing medium In reproducing, each recorded frame of the video signal component is reproduced twice continuously together with the sound signal component and the reproduced sound signal component is sampled at the first half of each line period in the duration of the first reproduction of the recorded frame and at the second half of each line period in the duration of the second reproduction of the same frame.
Description
1~7 798 BACKGROUND OF THE INVENTION
Field of the Invention This invention relates generally to a system for recording and/or reproducing a composite television signal con-taining a video signal component and a sound signal component, and more particularly to a recording and/or reproducing system for achieving long-time recording of the television signal and/
or reproducing of the television signal recorded for the purpose of long-playback.
Description of the Prior Art Various sytems have been proposed for recording a television signal on a recording medium such as a magnetic tape, rotatable magnetic sheet, rotatable optical disc and the like, and reproducing the recorded television signal in the composite form or in the form of separated video signal, sound
Field of the Invention This invention relates generally to a system for recording and/or reproducing a composite television signal con-taining a video signal component and a sound signal component, and more particularly to a recording and/or reproducing system for achieving long-time recording of the television signal and/
or reproducing of the television signal recorded for the purpose of long-playback.
Description of the Prior Art Various sytems have been proposed for recording a television signal on a recording medium such as a magnetic tape, rotatable magnetic sheet, rotatable optical disc and the like, and reproducing the recorded television signal in the composite form or in the form of separated video signal, sound
-2-lQq7798 signal and other signals. To cite an example of the system utilizing the rotatable optical disc, generally each frame component of the television signal is optically recorded on the rotating disc having a predetermined turning speed at each turn of the latter and, as a result, a plurality of one-frame circular tracks are formed on the disc with a predetermined space between adjacent ones. Precisely speaking, each of these tracks continues to the next onè to form a single recorded spiral track inclusively In reproducing, the recorded disc is turned at the same speed as the turning in recording and each recorded frame component of the television signal is reproduced at each turn of the disc sequentialy from the recorded spiral track.
Ill such a previously proposed system~ a certain circular area on the surface of the rotatable disc is consumed at every turn of the disc so asto form the circl-1ar track, on which one frzme component of the television signal is recorded, with the space provided for separating the track from adjacent circular tracks. Accordingly, the total recording time is restricted by the dimention of a portion of the surface of the disc where is available for formingthe recording track Generally, it is difficult to allow a diameter of the rotatQble disc to be immoderately large and it is restricted to be suitably small, for example, 10 to 15 inches. As a result of this, the total recording time is lilnited to be relatively short~ for example, 30 minutes for a disc of 12 inch diameter.
To elongate the recording time, some attempts have been proposed on the prior art recording and reproducing systems. According to one of those attempts, for example, the rotation speed of the disc is reduced so as to recordplural frame components of the television signal on a single circular track which is formed during one turn of the disc or, according to another attempt, the space between each pair of adjacent circular tracks, that is, a pitch of the spiral track is reduced so as to increase the track density on the surface of the disc.These attempts, however, require a recording mechanism to have extremely accurate operation witn very complicated and sensitive controls which may be realized with many difficulties, besides result in deteriorations in the quality lQ~7~798 of reproduced signals. Therefore, the elongation of the recording time with satisfaction has not been accomplished by the previously proposed attempts SUI~IARY OF THE INVENTION
It is an object of the present invention to provide an improved system for recording and/or reproducing a television signal which can realize the long-time recording and/or reproducing without the above mentioned dis-advantages in the prior art systems.
Another object of the present invention is to provide an improved recording system for recording a television signal on a recording medium with reduced consumption of the recording area of the recording medium so as to elongate the tot 1 recording time Further object of the D~tion is to provide an improved reproduc-ing system for reproducing a television signal recorded on a recording medium with reduced consumption thereof for the purpose of long-playback.
According to one example of the system of the present invention, first~ a composite television signal is separated to a video signal component and a sound signal component, and the sound signal component is derived directly and through a delay circuit at which the sound signal component is delayed by one frame period of the video signal component. The delayed sound signal component is sampled at the first (or second) half of every line period of the video signal and the original (undelayed) sound signal component is sampled at the second(or first half of every line period, then both sampled sound signal components are mixed with each other. The mixed sound signal component is mixed with the video signal component The mixed video and sound sign~1 components are sampled, for example, at every other frame period and recorded on a recording medium to form a circular recorded track at every duration of the sampled frame period.In consequence, the recording is done at every other frame period and~ thereforethe consumption of the recording area of the recording medium is reduced. This results in the elongation of the recording time. In reproducing, the recorded lQ~7798 signal on each circular reoorded track, which contains the video signal com-ponent of one frame and the mixed sound signal component, is reproduced twi oe continuously. The reproduced mixed sound signal component is sampled at the first (or second) half of every line period in the duration of the first reproduced frame of the video signal component and also sampled at the second (or first) half of every line period in the duration of the second reproduced frame, which is repeatedly reproduced, of the video signal oomponent. Accord-ingly, the continuous reproduced video signal component in which each pair of successive frames are the same as each other and the reproduced sound signal component oorresponding to each frame of the reproduced video signal component are obtained. Since the difference between every tWD successive frames of the original video signal component is negligible, the reprodu oe d video signal conponent which consists of every other original frame and its replica provided in succession is substantially same as the original video signal component and does not have any substantial deterioration. Further, although the reproduced sound signal component is sampled at every half line period, this does not result in any substantial deterioration in reproduced sound because the sam~
pling frequency is sufficiently high.
There is provided a system for recording on a record-ing medium a television signal containing a sound signal and a video signal divided into line periods and periods of longer periodic duration, said system comprising:
means for delaying the extracted sound signal by one periodic duration of the video signal;
first sampling means for sampling the delayed sound signals at periods corresponding to one half of each line period and for sampling the undelayed sound signal at periods correspond-ing to the other half of each line period;
mixing means connected to said sampling means to receive and mix the sampled delayed sound signal with the sampled undelayed sound signal to produce a mixed sound signal;
~,~ , 10"7798 second sampling means connected to receive the video signal and to receive the mixed sound signal to sample both the extracted video signal and the mixed sound signal at every other period corresponding to said one periodic duration of the video signal to produce segments of television signal;
and recording means connected to said second sampling means for intermittently recording said segments comprising sampled video and mi~ed sound signals on the recording medium.
More particularly, there is provided:-a system for reproducing a television signal con-taining a sound signal and a video signal recorded on a record-ing medium in the form of a plurality of recording tracks each recording one segment of the television signal of a predeter-mined periodic duration, the video signal being divided into line periods and periods of longer periodic duration, comprising:
reproducing means for reproducing each of said segments of television signal recorded on the respective record-ing tracks twice in succession:
extraction means for extracting separately video and sound signals from each of the picked up segments to pro-vide continuous reproduced video and sound signals;
sampling means for sampling said reproduced sound signal during one half of each line period of the video signal reproduced in the first reproduction of each recorded segment and also sampling the reproduced sound signal during the other half of each line period of the video signal reproduced in the second reproduction of the same segment; and means for filtering the sampled sound signal.
- 5a-lQ97798 There is further provided:-a system for recording and reproducing a television signal containing video and sound signals comprising:
means for extracting separately the video signal and the sound signal from the television signal the video signal being divided into line periods and periods of longer duration;
means for delaying the extracted sound signal by one periodic duration of the video signal;
first sampling means for sampling the delayed sound signals at periods corresponding to the first half of each line period in the video signal, and for sampling the undelayed sound signals at periods corresponding to the second half of each line period in the video signal, respectively;
means for mixing the sampled delayed sound signal with the sampled undelayed sound signal to produce a mixed sound signal;
second sampling means for sampling both the extracted video signal and the mixed sound signal at every other period corresponding to said one periodic duration of the video signal to produce spaced segments of television signal;
means for intermittently recording said segments comprising sampled video and mixed sound signals on the record-ing medium;
means for reproducing each of said segments of television signal recorded on the recording medium twice in succession;
means for extracting separately video and sound signals fxom each of the picked up segments to provide continuous -5b-lQg7798 reproduced video and sound signals;
means for sampling said reproduced sound signal at periods corresponding to the first half o each line period of the v~deo signal reproduced in the first reproduction of each recorded segment and sampling at periods corresponding to the second half of each line period of the video si~nal reproduced in the second reproduction of the same segment; and means for ~iltering the sampled reproduced sound sig~al.
Other objects~ features and advantage~ of the present invention will be apparent from 'he following description taken in conjunction with the accompanying drawings.
B RIEF DESCRIPTION OF THE DRAWING S
Fig, 1 is a ~chematic block diagram showing an esample of a television signal recording system according to the present invention.
Fig, 2 is a schematic block diagram showing an exasnple of a television signal reproducing system according to the present invention.
- Figs, 3A to 3E are schematic waveforms used for e~cplanation of the recording system shown in Fig, 1, Figs. 4A and 4B are schematic waveforms used for e~cplanation of the reproducing system shown in Fig. 2.
--5c--- 10"7798 DESCRIPTION OF THE PREFERRED EMBODIMENT
One example of the recording system for a television signal accord~
ing to the present invention is shown in Fig. 1 In the figure, 1 designates an input terminal to which a composite television signal consisting of a video signal and a sound signal is applied. The input terminai 1 is connected to the input terminal of a video signal circuit 2 which produces at its output terminal a video signal component contained in the television signal as shown in Fig 3A. The output terminal of the video circuit 2 is connected to the input terminal of a mixer circuit 3 to supply the video signal component to the latter The input terminal 1 is also connected to the input terminal of a sound signal circuit 4 which produces at its output terminal a sound signal component contained in the television signal as shown in Fig. 3B The output terminal of the sound circuit 4 is connected to one of the input terminals of a sound signal sampling gate circuit 6 and also to the other input terminal thereof through a frame delay circuit 5 which delays a signal supplied thereto by, for example, 1/30 seconds or one frame period of the video signal. Thus, the gate circuit 6 is supplied at the same time with the sound signal shown in Fig. 3B
and the sound signal delayed from the former by, for example, one frame period of the video signal shown in Fig. 3C.
The input termin~1 1 is further connected to the input terminal of a synchronizing signal separating circuit 7 which produces at its one output terminal a horizontal synchronizing signal and at its other output terminal a vertical synchronizing signal The former output terminal of the synchronizing signal separating circuit 7 is connected to a horizontal synchronizing signal supplying terminal of the sound signal sampling gate circuit 6 to supply the horizontal synchronizing signal to the latter. Thus, the gate circuit 6 is con-trolled with the horizontal synchronizing signal and operated to sampling-gate the sound signal, which is delayed by, for example, one frame period of the video signal ~s shown in Fig. 3C, during the first half period of each horizontal period (line period) H and the sound signal, vvhich is undelayed as shown in lQ97798 Fig. 3B, during the latter half period of each line period H For this reasonJ
both the sound signals shown in Figs 3B and 3C are alternately and sequentially sampling-gated by the sound signal sampling gate circuit 6 at every half line period.
The output terminal of the gate circuit 6 is connected through a -sound signal mixing circuit 8 to the input terminal of the mixer circuit 3. Thatis, two sampled signals obtained at the output terminal of the gate circuit 6 are mixed in the mixing circuit 8 and the mixed signal of the two sampled signals is applied to the mixer circuit 3. As described previously, the mixer circuit 0 3 is supplied also with the video signal~ so that it mixes the sampled signal with the video signal. The output terminal of the mixer circuit 3 is connected to the inpùt ter~ninal of a sampling gate circuit 9 which is connected, at its vertical synchronizing signal supplying terminal, with the latter output termin~of the synchronizing signal separating circuit 7 to be supplied with the vertical synchronizing signal from the separator circuit 7. In this case, the gate cir-cuit 9 is controlled with the ver~cal synchronizing signal and operated to sampling-gate the mixed signal of the video signal and sampled signal from the mixer circuit 3 at, for example, every other one frame period of the video signal. In other words, the sampling gate circuit 9 operates to cut off the mixed !0 signal from the mixer circuit 3 during, for example, the first one frame period of the video signal; to pass therethrough the mixed signal during the following one fram0 period; to cut off the same during the following one frame period;
and to pass therethrough the following one frame period, which is repeated successively. As a result, the gate circuit 9 can produce at its output termi-!5 nal a mixed signal of a sampled video signal shown in Fig. 3D, which contains only b-, d- and f- frame components of the video signal shown in Fig. 3A, and a sampled sound signal shown in Fig 3E In this case, the sampled sound signal shown in Fig. 3E contains a sound signal component delayed by, for example, one frame period of the video signal as described above, so that the 0 sampled sound signal mixed with, for example, the b-fr~ne component of the lQ97798 video signal contains the sound signal component corresponding to the b-frame component of the video signal and the sound signal component ahead of the formerby one frame period or corresponding to the a- frame component of the video signal The output terminal of the sampling gate circuit 9 is connected -to the input terminal of a modulating circuit 10 to supply the mixëd signal passed through the gate circuit 9 to the latter. Thus, the modulating circuit 10 mod-ulates a carrier applied thereto with the mixed sign~1. The modulated signal from the modulating circuit 10 is supplied to a recording device R to be recorded on a recording medium such as a rotatable disc (not shown). This recording is carried out such that a light beam or electron beam is modulated with the signal from the modulating circuit 10 and the recording is performed by the modulated light or electron beam on the rotatable disc optically or electronically .
The latter output terminal of the synchronizing signal separating circuit 7 is connected through a control signal generating network 11 for recording to the input terminal of a tracking control system 12 for recording whose output signal is supplied to the recording device R to control. for example, a light beam (or electron beam) scanning the surface of the rotatable disc in the recording device R so as to carry out an optic~l record (electronic record) That is, the vertical synchronizing signal is applied to the control sign 1 generating network 11 and the control signal generated therefrom is applied to the tracking control system 12 to control the latter.
In the recording device Fc, the relative relation between the rotat-able disc and, for example, the light beam scanning the surface thereof is selected such that, at every time when the rotatable disc is rotated by one turn and consequently the light beam scans the surface of the rotatable disc by one turn, a signal of one frame period is recorded on the rotatable disc as a circular record track. In this case, the light beam is controlled by the control syStem 12 to form a recorded track at every other one rotation of the rotatable disc and during the recordings the light beam is moved in the radius direction of the disc by a predetermined pitch. It is preferred that when the light beam is moved in the radius direction, the light beam is controlled not to carry out any recording The light beam is modulated at every other frame period in accordance with the successive operation of the sampling gate cir-cuit 9 that it cuts off the mixed signal from the mixer circuit 3 during, for example, the first one frame period of the video signal, then passes the mixed signal therethrough during the next one frame period, and so on as described previously to form circular recorded tracks on the rotatable disc successively.
That is, the light beam is moved by the predetermined pitch in the radius direc-tion of the rotatable disc without forming any recorded track during the time period when the mixed signal from the mixer circuit 3 is cut off by the gate circuit 9, but modulated with the signal from the modulating circuit 10 and stopped to scan the rotatable disc in accordance with the rotation thereof to form a circular recorded track thereon of the signal from the modulating cir-cuit 10 at the rate of one frame by one turn during the time period when the next mixed signal is transmitted through the gate circuit 9.
With the recording system of the present invention constructed as above, when the television signal containing the video signal shown in Fig. 3A
and the sound signal shown in Fig 3B is supplied to the input terminal 1, the sampled video signal shown in Fig. 3D and the sampled sound signal shown in Fig 3E can be recorded on the rotatable disc in superimposed state. In this case, the recording is performed at every other turn of the rotatable disc or every other one frame period of the video signal~ so that the consumed amount of the rotatable disc is reduced by 1/2 as cc~npared with the case where a television signal is recorded as it is and hence a long-time recording (two times) can be realized.
An example of the reproducing system according to the present invention for the signal recorded on, for example, the rotatable disc as described above will be described with reference to Fig 2 and Figs 4A and 4B.
~Q"7798 In Fig 2, P designates a play-back de~ice with which the carrier signal modulated with the mixed signal of the sampled video signal and sampled sound signal and recorded on the recording medium or rotatable disc is repro-duced by, for example, a light beam (not shown) optically and then supplied to an input termin~l 13 of the reproducing system. The input terminal 13 is connected to the output terminal of a demodulating or demodulator circuit 14 which produces at its output terminal demodulated output signals of the mixed signal of the sampled video signal and sampled sound signal. The output ter-minal of the demodulator circuit 14 is connected to the input terminal of a synchronizing signal separating circuit 15 which produces at its one output terminal the vertical synchronizing sign~l and at its other output terminal the horizontal synchronizing signal The former output terminal of the separator s~ircuit 15 is connected through a control signal generating circuit 16 for reproducing to the input terminal of a tracking control system 17 for reproduc-1 5 ing which will control, for example, the light beam scanning the recorded - rotatable disc for optical playback. That is, the vertical synchronizing signal is fed to the control signal generator circuit 16, and the control signal gener-ated therefrom is fed to the tracking control system 17 to control the same.
At this time, in the playback device P the light beam scans the same circular recorded track on the disc~ which is rotating at a predetermined rotating number, by two times. This scanning manner is carried out for each circular recorded track. In this caset the signal recorded on the respective tracks of the disc is reproduced at the rate of one frame period at one turn of the disc Thus, the modulated signal corresponding to the b-frame component of the video signal shown in Fig. 3A is reproduced twice. Similarly, the modulated signals corresponding to the d-and f- frame components of the video signal are repro-duced twice, respectively. As a result, the input terminal 13 is supplied with the modulated signals sequentially such that it is supplied with the modulated signal corresponding to the b- frame component of the video signal twice and then with the modulated signal corresponding to the d-frame component of the lQ"7798 video signal twice. Thus, at the output terminal of the demodulator circuit 14 there are respectively obtained twice a mixed signal of the b-frame component of the video signal and the sampled sound sign:~l corresponding thereto, a mixedsign~1 of the d-frame component of the video signal and the sampled sound signal corresponding thereto, and so on, which are repeated twice and sequen-tially ~ ~ A, The output terminal of the demodulator circuit 14 is connected through a video signal reproducing circuit 18 to the input terminal of a video monitor 19 to supply the reproduced video signal component in the mixed signals obtained at the output terminal of the demodulator circuit 14 to the video moni-tor 19. Therefore, the video monitor 19 is supplied with the video signal shown in Fig. 4A and a reproduced picture is diplayed thereon. In this case, the reproduced video signals are such that the a-, c- and e-frame components of the original video signal shown in Fig 3A are replaced with respective one frame components of the video signal following thereto or the b-, d- and f-frame components of the video signal, respectively. In a practical picturç, however, the picture is not chang~d so abruptly and hence the difference betweenthe following two frame video signals can be neglected, so that even if one frame component of the video signal is reproduced twice as described above, a reproduced picture does not become unnatural for a viewer The output terminal of the demodulator circuit 14 is connected through a sound signal detecting circuit 20 to the input terminal of a sound signal sampling gate circuit 21 to thereby detect the sampled sound signal in the mixed signal ~rom the demodulator circuit 14 and supply the sampled sound signal to the sound signal sampling gate circuit 21. Further, the latter output terminal of the synchronizing signal separator 15 is connected through a sam--pling signal generating circuit 22 to the sampling signal input terminal of the gate circuit 21. Thus, the horizontal synchronizing signal is fed to the sam-pling signal generator 22 which then produces at its output terminal a sampling signal, and this sampling signal is fed to the gate circuit 21 to control the same.
_ 1 1 _ The gate circuit 21 is so controlled that it sampling-gates a signal to be sam-pled at every repeating reproduction of one frame video signal in delayed state by 1/2 line period. That is, by the light beam scanning the same recorded track on the disc twice as described above, in the case that, for example, the b-frame component of the video signal is sequentially reproduced twice as shown in Fig. 4A, the gate circuit 21 sampling-gates only the sound signal corres-ponding to the a-frame component of the video signal contained in the sampled signal during the reproduction of the former half period of the b-frame com-ponents, while upon the reproduction of the latter half period of the b-frame components the gate circuit 21 sampling-gates only the sound signal corres-ponding to the b-frame component of the video signal presenting at delayed state by a half line period from the sound signal corresponding to the a-frame component of the video signal.
The output terminal of the gate circuit 21 is connected through a low pass filter 23 to the input terminal of a speaker 24, so that the output sign~l from the gate-circuit 21 is made as a sequential signal by the low pass filter 23 and then fed to the speaker 24. Thus, when, for example, the former half of the b-frame components of the video signal is reproduced, the sound signal corresponding to the video signal component ahead of the b-frame com-ponent by one frame period or to the a-frame component is reproduced, while when the latter half of the b-frame components is reproduced, the sound signal corresponding to the b-frame component is reproduced. That is, the original sound signal shown in Fig. 3B is reproducedJ as it is, as shown in Fig. 4B.
The reproducing system of the invention constructed as above~
the signal, which is formed by modulating the carrier signal with the mixed signal of the video signal and sound signal shown in Figs 3D and 3E and recorded on a recording medium such as the rotatable disc for a long period of time, is reproduced by, for example, the light beam, the video monitor 19 is supplied with the video signal shown in Fig. 4A, and the speaker 24 is supplied with the sound signal corresponding to the video signal shown in Fig.4B, lQ97798 so that the monitor 19 and speaker 24 reproduce a picture and a sound which are substantially same as those upon recording, respectively.
As déscribed above, with the systems according to the present invention, long-time recording and reproducing of a television signal can be carried out only by improving the signal system and control system of the recordin~ and reproducing systems.
In the above description, the video signal is superimposed with the sound signal which is obtained by alternately and sequentiaLly sampling the sound signals corresponding to two frames of the above video signal at every 1/2 line period and composing the sound signals~ the mixed signal is sampled at every other frame,-and then recorded. It is, howerver, also possible that the video signal of one frame is sampled at every two frame; a sound signal is obtained by alternately and sequentially sampling the respectivesound signals of two frames at every 1/2 line period during the period of the sampled video signal and composing the same; the above sampled video and sound signals are superimposed with each other; and then recorded.
It will be easily understood from the above example that in place of the above frame the similar sampling can be performed at every field (one frame consists of two fields) It will be apparent that many modifications and variations could be effected by one sldlled in the art without departing from the spirits or scope of the novel concepts of the present invention, so that the scope of ~e inven-tion should be determined by the appended claims.
Ill such a previously proposed system~ a certain circular area on the surface of the rotatable disc is consumed at every turn of the disc so asto form the circl-1ar track, on which one frzme component of the television signal is recorded, with the space provided for separating the track from adjacent circular tracks. Accordingly, the total recording time is restricted by the dimention of a portion of the surface of the disc where is available for formingthe recording track Generally, it is difficult to allow a diameter of the rotatQble disc to be immoderately large and it is restricted to be suitably small, for example, 10 to 15 inches. As a result of this, the total recording time is lilnited to be relatively short~ for example, 30 minutes for a disc of 12 inch diameter.
To elongate the recording time, some attempts have been proposed on the prior art recording and reproducing systems. According to one of those attempts, for example, the rotation speed of the disc is reduced so as to recordplural frame components of the television signal on a single circular track which is formed during one turn of the disc or, according to another attempt, the space between each pair of adjacent circular tracks, that is, a pitch of the spiral track is reduced so as to increase the track density on the surface of the disc.These attempts, however, require a recording mechanism to have extremely accurate operation witn very complicated and sensitive controls which may be realized with many difficulties, besides result in deteriorations in the quality lQ~7~798 of reproduced signals. Therefore, the elongation of the recording time with satisfaction has not been accomplished by the previously proposed attempts SUI~IARY OF THE INVENTION
It is an object of the present invention to provide an improved system for recording and/or reproducing a television signal which can realize the long-time recording and/or reproducing without the above mentioned dis-advantages in the prior art systems.
Another object of the present invention is to provide an improved recording system for recording a television signal on a recording medium with reduced consumption of the recording area of the recording medium so as to elongate the tot 1 recording time Further object of the D~tion is to provide an improved reproduc-ing system for reproducing a television signal recorded on a recording medium with reduced consumption thereof for the purpose of long-playback.
According to one example of the system of the present invention, first~ a composite television signal is separated to a video signal component and a sound signal component, and the sound signal component is derived directly and through a delay circuit at which the sound signal component is delayed by one frame period of the video signal component. The delayed sound signal component is sampled at the first (or second) half of every line period of the video signal and the original (undelayed) sound signal component is sampled at the second(or first half of every line period, then both sampled sound signal components are mixed with each other. The mixed sound signal component is mixed with the video signal component The mixed video and sound sign~1 components are sampled, for example, at every other frame period and recorded on a recording medium to form a circular recorded track at every duration of the sampled frame period.In consequence, the recording is done at every other frame period and~ thereforethe consumption of the recording area of the recording medium is reduced. This results in the elongation of the recording time. In reproducing, the recorded lQ~7798 signal on each circular reoorded track, which contains the video signal com-ponent of one frame and the mixed sound signal component, is reproduced twi oe continuously. The reproduced mixed sound signal component is sampled at the first (or second) half of every line period in the duration of the first reproduced frame of the video signal component and also sampled at the second (or first) half of every line period in the duration of the second reproduced frame, which is repeatedly reproduced, of the video signal oomponent. Accord-ingly, the continuous reproduced video signal component in which each pair of successive frames are the same as each other and the reproduced sound signal component oorresponding to each frame of the reproduced video signal component are obtained. Since the difference between every tWD successive frames of the original video signal component is negligible, the reprodu oe d video signal conponent which consists of every other original frame and its replica provided in succession is substantially same as the original video signal component and does not have any substantial deterioration. Further, although the reproduced sound signal component is sampled at every half line period, this does not result in any substantial deterioration in reproduced sound because the sam~
pling frequency is sufficiently high.
There is provided a system for recording on a record-ing medium a television signal containing a sound signal and a video signal divided into line periods and periods of longer periodic duration, said system comprising:
means for delaying the extracted sound signal by one periodic duration of the video signal;
first sampling means for sampling the delayed sound signals at periods corresponding to one half of each line period and for sampling the undelayed sound signal at periods correspond-ing to the other half of each line period;
mixing means connected to said sampling means to receive and mix the sampled delayed sound signal with the sampled undelayed sound signal to produce a mixed sound signal;
~,~ , 10"7798 second sampling means connected to receive the video signal and to receive the mixed sound signal to sample both the extracted video signal and the mixed sound signal at every other period corresponding to said one periodic duration of the video signal to produce segments of television signal;
and recording means connected to said second sampling means for intermittently recording said segments comprising sampled video and mi~ed sound signals on the recording medium.
More particularly, there is provided:-a system for reproducing a television signal con-taining a sound signal and a video signal recorded on a record-ing medium in the form of a plurality of recording tracks each recording one segment of the television signal of a predeter-mined periodic duration, the video signal being divided into line periods and periods of longer periodic duration, comprising:
reproducing means for reproducing each of said segments of television signal recorded on the respective record-ing tracks twice in succession:
extraction means for extracting separately video and sound signals from each of the picked up segments to pro-vide continuous reproduced video and sound signals;
sampling means for sampling said reproduced sound signal during one half of each line period of the video signal reproduced in the first reproduction of each recorded segment and also sampling the reproduced sound signal during the other half of each line period of the video signal reproduced in the second reproduction of the same segment; and means for filtering the sampled sound signal.
- 5a-lQ97798 There is further provided:-a system for recording and reproducing a television signal containing video and sound signals comprising:
means for extracting separately the video signal and the sound signal from the television signal the video signal being divided into line periods and periods of longer duration;
means for delaying the extracted sound signal by one periodic duration of the video signal;
first sampling means for sampling the delayed sound signals at periods corresponding to the first half of each line period in the video signal, and for sampling the undelayed sound signals at periods corresponding to the second half of each line period in the video signal, respectively;
means for mixing the sampled delayed sound signal with the sampled undelayed sound signal to produce a mixed sound signal;
second sampling means for sampling both the extracted video signal and the mixed sound signal at every other period corresponding to said one periodic duration of the video signal to produce spaced segments of television signal;
means for intermittently recording said segments comprising sampled video and mixed sound signals on the record-ing medium;
means for reproducing each of said segments of television signal recorded on the recording medium twice in succession;
means for extracting separately video and sound signals fxom each of the picked up segments to provide continuous -5b-lQg7798 reproduced video and sound signals;
means for sampling said reproduced sound signal at periods corresponding to the first half o each line period of the v~deo signal reproduced in the first reproduction of each recorded segment and sampling at periods corresponding to the second half of each line period of the video si~nal reproduced in the second reproduction of the same segment; and means for ~iltering the sampled reproduced sound sig~al.
Other objects~ features and advantage~ of the present invention will be apparent from 'he following description taken in conjunction with the accompanying drawings.
B RIEF DESCRIPTION OF THE DRAWING S
Fig, 1 is a ~chematic block diagram showing an esample of a television signal recording system according to the present invention.
Fig, 2 is a schematic block diagram showing an exasnple of a television signal reproducing system according to the present invention.
- Figs, 3A to 3E are schematic waveforms used for e~cplanation of the recording system shown in Fig, 1, Figs. 4A and 4B are schematic waveforms used for e~cplanation of the reproducing system shown in Fig. 2.
--5c--- 10"7798 DESCRIPTION OF THE PREFERRED EMBODIMENT
One example of the recording system for a television signal accord~
ing to the present invention is shown in Fig. 1 In the figure, 1 designates an input terminal to which a composite television signal consisting of a video signal and a sound signal is applied. The input terminai 1 is connected to the input terminal of a video signal circuit 2 which produces at its output terminal a video signal component contained in the television signal as shown in Fig 3A. The output terminal of the video circuit 2 is connected to the input terminal of a mixer circuit 3 to supply the video signal component to the latter The input terminal 1 is also connected to the input terminal of a sound signal circuit 4 which produces at its output terminal a sound signal component contained in the television signal as shown in Fig. 3B The output terminal of the sound circuit 4 is connected to one of the input terminals of a sound signal sampling gate circuit 6 and also to the other input terminal thereof through a frame delay circuit 5 which delays a signal supplied thereto by, for example, 1/30 seconds or one frame period of the video signal. Thus, the gate circuit 6 is supplied at the same time with the sound signal shown in Fig. 3B
and the sound signal delayed from the former by, for example, one frame period of the video signal shown in Fig. 3C.
The input termin~1 1 is further connected to the input terminal of a synchronizing signal separating circuit 7 which produces at its one output terminal a horizontal synchronizing signal and at its other output terminal a vertical synchronizing signal The former output terminal of the synchronizing signal separating circuit 7 is connected to a horizontal synchronizing signal supplying terminal of the sound signal sampling gate circuit 6 to supply the horizontal synchronizing signal to the latter. Thus, the gate circuit 6 is con-trolled with the horizontal synchronizing signal and operated to sampling-gate the sound signal, which is delayed by, for example, one frame period of the video signal ~s shown in Fig. 3C, during the first half period of each horizontal period (line period) H and the sound signal, vvhich is undelayed as shown in lQ97798 Fig. 3B, during the latter half period of each line period H For this reasonJ
both the sound signals shown in Figs 3B and 3C are alternately and sequentially sampling-gated by the sound signal sampling gate circuit 6 at every half line period.
The output terminal of the gate circuit 6 is connected through a -sound signal mixing circuit 8 to the input terminal of the mixer circuit 3. Thatis, two sampled signals obtained at the output terminal of the gate circuit 6 are mixed in the mixing circuit 8 and the mixed signal of the two sampled signals is applied to the mixer circuit 3. As described previously, the mixer circuit 0 3 is supplied also with the video signal~ so that it mixes the sampled signal with the video signal. The output terminal of the mixer circuit 3 is connected to the inpùt ter~ninal of a sampling gate circuit 9 which is connected, at its vertical synchronizing signal supplying terminal, with the latter output termin~of the synchronizing signal separating circuit 7 to be supplied with the vertical synchronizing signal from the separator circuit 7. In this case, the gate cir-cuit 9 is controlled with the ver~cal synchronizing signal and operated to sampling-gate the mixed signal of the video signal and sampled signal from the mixer circuit 3 at, for example, every other one frame period of the video signal. In other words, the sampling gate circuit 9 operates to cut off the mixed !0 signal from the mixer circuit 3 during, for example, the first one frame period of the video signal; to pass therethrough the mixed signal during the following one fram0 period; to cut off the same during the following one frame period;
and to pass therethrough the following one frame period, which is repeated successively. As a result, the gate circuit 9 can produce at its output termi-!5 nal a mixed signal of a sampled video signal shown in Fig. 3D, which contains only b-, d- and f- frame components of the video signal shown in Fig. 3A, and a sampled sound signal shown in Fig 3E In this case, the sampled sound signal shown in Fig. 3E contains a sound signal component delayed by, for example, one frame period of the video signal as described above, so that the 0 sampled sound signal mixed with, for example, the b-fr~ne component of the lQ97798 video signal contains the sound signal component corresponding to the b-frame component of the video signal and the sound signal component ahead of the formerby one frame period or corresponding to the a- frame component of the video signal The output terminal of the sampling gate circuit 9 is connected -to the input terminal of a modulating circuit 10 to supply the mixëd signal passed through the gate circuit 9 to the latter. Thus, the modulating circuit 10 mod-ulates a carrier applied thereto with the mixed sign~1. The modulated signal from the modulating circuit 10 is supplied to a recording device R to be recorded on a recording medium such as a rotatable disc (not shown). This recording is carried out such that a light beam or electron beam is modulated with the signal from the modulating circuit 10 and the recording is performed by the modulated light or electron beam on the rotatable disc optically or electronically .
The latter output terminal of the synchronizing signal separating circuit 7 is connected through a control signal generating network 11 for recording to the input terminal of a tracking control system 12 for recording whose output signal is supplied to the recording device R to control. for example, a light beam (or electron beam) scanning the surface of the rotatable disc in the recording device R so as to carry out an optic~l record (electronic record) That is, the vertical synchronizing signal is applied to the control sign 1 generating network 11 and the control signal generated therefrom is applied to the tracking control system 12 to control the latter.
In the recording device Fc, the relative relation between the rotat-able disc and, for example, the light beam scanning the surface thereof is selected such that, at every time when the rotatable disc is rotated by one turn and consequently the light beam scans the surface of the rotatable disc by one turn, a signal of one frame period is recorded on the rotatable disc as a circular record track. In this case, the light beam is controlled by the control syStem 12 to form a recorded track at every other one rotation of the rotatable disc and during the recordings the light beam is moved in the radius direction of the disc by a predetermined pitch. It is preferred that when the light beam is moved in the radius direction, the light beam is controlled not to carry out any recording The light beam is modulated at every other frame period in accordance with the successive operation of the sampling gate cir-cuit 9 that it cuts off the mixed signal from the mixer circuit 3 during, for example, the first one frame period of the video signal, then passes the mixed signal therethrough during the next one frame period, and so on as described previously to form circular recorded tracks on the rotatable disc successively.
That is, the light beam is moved by the predetermined pitch in the radius direc-tion of the rotatable disc without forming any recorded track during the time period when the mixed signal from the mixer circuit 3 is cut off by the gate circuit 9, but modulated with the signal from the modulating circuit 10 and stopped to scan the rotatable disc in accordance with the rotation thereof to form a circular recorded track thereon of the signal from the modulating cir-cuit 10 at the rate of one frame by one turn during the time period when the next mixed signal is transmitted through the gate circuit 9.
With the recording system of the present invention constructed as above, when the television signal containing the video signal shown in Fig. 3A
and the sound signal shown in Fig 3B is supplied to the input terminal 1, the sampled video signal shown in Fig. 3D and the sampled sound signal shown in Fig 3E can be recorded on the rotatable disc in superimposed state. In this case, the recording is performed at every other turn of the rotatable disc or every other one frame period of the video signal~ so that the consumed amount of the rotatable disc is reduced by 1/2 as cc~npared with the case where a television signal is recorded as it is and hence a long-time recording (two times) can be realized.
An example of the reproducing system according to the present invention for the signal recorded on, for example, the rotatable disc as described above will be described with reference to Fig 2 and Figs 4A and 4B.
~Q"7798 In Fig 2, P designates a play-back de~ice with which the carrier signal modulated with the mixed signal of the sampled video signal and sampled sound signal and recorded on the recording medium or rotatable disc is repro-duced by, for example, a light beam (not shown) optically and then supplied to an input termin~l 13 of the reproducing system. The input terminal 13 is connected to the output terminal of a demodulating or demodulator circuit 14 which produces at its output terminal demodulated output signals of the mixed signal of the sampled video signal and sampled sound signal. The output ter-minal of the demodulator circuit 14 is connected to the input terminal of a synchronizing signal separating circuit 15 which produces at its one output terminal the vertical synchronizing sign~l and at its other output terminal the horizontal synchronizing signal The former output terminal of the separator s~ircuit 15 is connected through a control signal generating circuit 16 for reproducing to the input terminal of a tracking control system 17 for reproduc-1 5 ing which will control, for example, the light beam scanning the recorded - rotatable disc for optical playback. That is, the vertical synchronizing signal is fed to the control signal generator circuit 16, and the control signal gener-ated therefrom is fed to the tracking control system 17 to control the same.
At this time, in the playback device P the light beam scans the same circular recorded track on the disc~ which is rotating at a predetermined rotating number, by two times. This scanning manner is carried out for each circular recorded track. In this caset the signal recorded on the respective tracks of the disc is reproduced at the rate of one frame period at one turn of the disc Thus, the modulated signal corresponding to the b-frame component of the video signal shown in Fig. 3A is reproduced twice. Similarly, the modulated signals corresponding to the d-and f- frame components of the video signal are repro-duced twice, respectively. As a result, the input terminal 13 is supplied with the modulated signals sequentially such that it is supplied with the modulated signal corresponding to the b- frame component of the video signal twice and then with the modulated signal corresponding to the d-frame component of the lQ"7798 video signal twice. Thus, at the output terminal of the demodulator circuit 14 there are respectively obtained twice a mixed signal of the b-frame component of the video signal and the sampled sound sign:~l corresponding thereto, a mixedsign~1 of the d-frame component of the video signal and the sampled sound signal corresponding thereto, and so on, which are repeated twice and sequen-tially ~ ~ A, The output terminal of the demodulator circuit 14 is connected through a video signal reproducing circuit 18 to the input terminal of a video monitor 19 to supply the reproduced video signal component in the mixed signals obtained at the output terminal of the demodulator circuit 14 to the video moni-tor 19. Therefore, the video monitor 19 is supplied with the video signal shown in Fig. 4A and a reproduced picture is diplayed thereon. In this case, the reproduced video signals are such that the a-, c- and e-frame components of the original video signal shown in Fig 3A are replaced with respective one frame components of the video signal following thereto or the b-, d- and f-frame components of the video signal, respectively. In a practical picturç, however, the picture is not chang~d so abruptly and hence the difference betweenthe following two frame video signals can be neglected, so that even if one frame component of the video signal is reproduced twice as described above, a reproduced picture does not become unnatural for a viewer The output terminal of the demodulator circuit 14 is connected through a sound signal detecting circuit 20 to the input terminal of a sound signal sampling gate circuit 21 to thereby detect the sampled sound signal in the mixed signal ~rom the demodulator circuit 14 and supply the sampled sound signal to the sound signal sampling gate circuit 21. Further, the latter output terminal of the synchronizing signal separator 15 is connected through a sam--pling signal generating circuit 22 to the sampling signal input terminal of the gate circuit 21. Thus, the horizontal synchronizing signal is fed to the sam-pling signal generator 22 which then produces at its output terminal a sampling signal, and this sampling signal is fed to the gate circuit 21 to control the same.
_ 1 1 _ The gate circuit 21 is so controlled that it sampling-gates a signal to be sam-pled at every repeating reproduction of one frame video signal in delayed state by 1/2 line period. That is, by the light beam scanning the same recorded track on the disc twice as described above, in the case that, for example, the b-frame component of the video signal is sequentially reproduced twice as shown in Fig. 4A, the gate circuit 21 sampling-gates only the sound signal corres-ponding to the a-frame component of the video signal contained in the sampled signal during the reproduction of the former half period of the b-frame com-ponents, while upon the reproduction of the latter half period of the b-frame components the gate circuit 21 sampling-gates only the sound signal corres-ponding to the b-frame component of the video signal presenting at delayed state by a half line period from the sound signal corresponding to the a-frame component of the video signal.
The output terminal of the gate circuit 21 is connected through a low pass filter 23 to the input terminal of a speaker 24, so that the output sign~l from the gate-circuit 21 is made as a sequential signal by the low pass filter 23 and then fed to the speaker 24. Thus, when, for example, the former half of the b-frame components of the video signal is reproduced, the sound signal corresponding to the video signal component ahead of the b-frame com-ponent by one frame period or to the a-frame component is reproduced, while when the latter half of the b-frame components is reproduced, the sound signal corresponding to the b-frame component is reproduced. That is, the original sound signal shown in Fig. 3B is reproducedJ as it is, as shown in Fig. 4B.
The reproducing system of the invention constructed as above~
the signal, which is formed by modulating the carrier signal with the mixed signal of the video signal and sound signal shown in Figs 3D and 3E and recorded on a recording medium such as the rotatable disc for a long period of time, is reproduced by, for example, the light beam, the video monitor 19 is supplied with the video signal shown in Fig. 4A, and the speaker 24 is supplied with the sound signal corresponding to the video signal shown in Fig.4B, lQ97798 so that the monitor 19 and speaker 24 reproduce a picture and a sound which are substantially same as those upon recording, respectively.
As déscribed above, with the systems according to the present invention, long-time recording and reproducing of a television signal can be carried out only by improving the signal system and control system of the recordin~ and reproducing systems.
In the above description, the video signal is superimposed with the sound signal which is obtained by alternately and sequentiaLly sampling the sound signals corresponding to two frames of the above video signal at every 1/2 line period and composing the sound signals~ the mixed signal is sampled at every other frame,-and then recorded. It is, howerver, also possible that the video signal of one frame is sampled at every two frame; a sound signal is obtained by alternately and sequentially sampling the respectivesound signals of two frames at every 1/2 line period during the period of the sampled video signal and composing the same; the above sampled video and sound signals are superimposed with each other; and then recorded.
It will be easily understood from the above example that in place of the above frame the similar sampling can be performed at every field (one frame consists of two fields) It will be apparent that many modifications and variations could be effected by one sldlled in the art without departing from the spirits or scope of the novel concepts of the present invention, so that the scope of ~e inven-tion should be determined by the appended claims.
Claims (4)
FOLLOWS:
1. A system for reproducing a television signal con-taining a sound signal and a video signal recorded on a record-ing medium in the form of a plurality of recording tracks each recording one segment of the television signal of a predeter-mined periodic duration, the video signal being divided into line periods and periods of longer periodic duration, comprising:
reproducing means for reproducing each of said segments of television signal recorded on the respective re-cording tracks twice in succession:
extraction means for extracting separately video and sound signals from each of the picked up segments to pro-vide continuous reproduced video and sound signals;
sampling means for sampling said reproduced sound signal during one half of each line period of the video signal reproduced in the first reproduction of each recorded segment and also sampling the reproduced sound signal during the other half of each line period of the video signal reproduced in the second reproduction of the same segment; and means for filtering the sampled sound signal.
reproducing means for reproducing each of said segments of television signal recorded on the respective re-cording tracks twice in succession:
extraction means for extracting separately video and sound signals from each of the picked up segments to pro-vide continuous reproduced video and sound signals;
sampling means for sampling said reproduced sound signal during one half of each line period of the video signal reproduced in the first reproduction of each recorded segment and also sampling the reproduced sound signal during the other half of each line period of the video signal reproduced in the second reproduction of the same segment; and means for filtering the sampled sound signal.
2. A system for reproducing according to Claim 1, further comprising control means for controlling said reproducing means with a control signal so as to reproduce each recording track twice in succession and sequentially one after another.
3. A system for reproducing according to Claim 2, wherein said control means comprises extracting means for extract-ing a synchronizing signal from the reproduced segments and means for generating said control signal in response to the synchroniz-ing signal.
4. A system for reproducing according to Claim 2, wherein said segment of the video signal is a frame.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA352,427A CA1097798A (en) | 1975-06-19 | 1980-05-22 | System for recording and/or reproducing a television signal |
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP74657/75 | 1975-06-19 | ||
| JP50074657A JPS51150222A (en) | 1975-06-19 | 1975-06-19 | Recording method |
| CA254,789A CA1093680A (en) | 1975-06-19 | 1976-06-14 | System for recording and/or reproducing a television signal |
| CA352,427A CA1097798A (en) | 1975-06-19 | 1980-05-22 | System for recording and/or reproducing a television signal |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1097798A true CA1097798A (en) | 1981-03-17 |
Family
ID=27164518
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA352,427A Expired CA1097798A (en) | 1975-06-19 | 1980-05-22 | System for recording and/or reproducing a television signal |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1097798A (en) |
-
1980
- 1980-05-22 CA CA352,427A patent/CA1097798A/en not_active Expired
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