Magnetic tape recording/reproducing apparatus for digital video signals and associated digital sound signals, and corresponding recording/reproducing method

Abstract: A magnetic tape recording/reproducing apparatus (31) comprises two picture memories (36a, 36b). At the time of recording, a digital video signal converted by A/D converter (36) is stored in one picture memory (36a) in a first time period. Digital sound signals converted by A/D converters (32, 33) are stored in the other picture memory (36b) in a second time period. The digital video signal stored in one picture memory (36a) is read out in the second time period, to be recorded on a magnetic tape (42). The digital sound signals stored in the other picture memory (36b) are read out in the second time period, to be recorded of the magnetic tape (42). At the time of reproduction, the digital video signal recorded on the magnetic tape (42) is read out in the second time period, to be stored in either one of the picture memories (36a, 36b). The digital video signal recorded on the picture memory is read out in the first time period, to be outputted through a D/A converter (51). The digital sound signals recorded on the magnetic tape (42) are outputted through D/A converters (47, 48).

Description: The present invention relates generally to an apparatus and method for recording/reproducing digital signals, and more particularly to a magnetic tape recording/reproducing apparatus and method capable of recording/reproducing a still picture and a sound signal e.g. on/from a so-called digital audio tape as digital signals. Conventionally, a magnetic tape recording/ reproducing apparatus referred to as DAT (Digital Audio Tape recording/reproducing apparatus) has been known which is used for recording a sound signal on a magnetic tape as a digital signal and reproducing the digital signal. In such a magnetic tape recording/ reproducing apparatus, information for correcting errors referred to as parity can be simultaneously recorded. As a result, even if a part of information recorded is dropped, the original sound can be faithfully reproduced and a sound having very low noise can be obtained. In the above described magnetic tape recording/reproducing apparatus, the operating manner is selected among a two channel mode, a four channel mode and the like, corresponding to a sound signal to be recorded. In the two channel mode, two types of sound signals to be made acoustic by two speakers arranged in the left front and the right front of a listener are recorded on a magnetic tape. In the four channel mode, four types of sound signals corresponding to four speakers arranged in the left front, the right front, the left rear and the right rear of a listener are recorded thereon. In the above described conventional magnetic tape recording/reproducing apparatus, a sound signal can be recorded. However, a video signal representing a still picture, together with the sound signal, can not be recorded and reproduced. It has therefore been suggested to provide a magnetic tape recording/reproducing apparatus capable of recording/reproducing a video signal, together with a sound signal, on/from a magnetic tape as digital signals. The present inventors assume one example of a structure of such an apparatus. This structure, useful for understanding the present invention, is illustrated in Fig. 1. In the magnetic tape recording/reproducing apparatus shown in Fig. 1, a four channel mode is used as its operation mode. Sound signals are assigned to two channels out of four channels, and a video signal is assigned to the remaining two channels. The sound signal corresponding to a speaker arranged in the right front of a listener is inputted from an input terminal TR, while the sound signal corresponding to a speaker arranged in the left front thereof is inputted from an input terminal TL. The video signal is inputted from an input terminal TV. The sound signals inputted from the input terminals TR and TL are respectively converted into, for example, 12-bit digital sound signals D1 and D2 by analogue/digital (referred to as A/D hereinafter) converters 1 and 2, to be serially provided to lines 3 and 4. The A/D converters 1 and 2 convert analogue signals into digital signals at a sampling frequency of 32 kHz. The digital sound signals D1 and D2 provided to the lines 3 and 4 are respectively applied to input terminals 51 and 52 of a switch 5. The video signal inputted from the input terminal TV is converted into, for example, a 8-bit digital video signal D3 by an A/D converter 6, to be applied to a data bus 7 in parallel. The A/D converter 6 converts analogue signals into digital signals at a sampling frequency of 14.3 MHz. This digital video signal D3 is applied to a picture memory 8a from the data bus 7. The digital video signal D3 corresponding to a video signal of one field is stored in a picture memory 8a in 1/60 second. When writing of the digital video signal D3 corresponding to the video signal of one field to the picture memory 8a is completed, the digital video signal stored is applied to a parallel/serial (referred to as P/S hereinafter) converter 9 through the data bus 7. The digital video signal applied to the P/S converter 9 is serially provided to an input terminal 53 of the switch 5. The two types of digital sound signals and the digital video signal provided to the input terminals 51, 52 and 53 are selectively applied to an output terminal 54 of the switch 5. The digital signal applied to the output terminal 54 is applied to a recording signal processing portion 11 through a line 10. The recording signal processing portion 11 performs signal processing such as modulation and addition of information for correcting errors such as parity on the digital signal inputted. The digital signal processed in the recording signal processing portion 11 is recorded on a magnetic tape 12. At the time of reproduction, the digital signal read out from the magnetic tape 12 is inputted to a reproduction signal processing portion 13. The reproduction signal processing portion 13 performs signal processing such as demodulation and error correction processing by parity or the like, to provide two types of digital sound signals and the digital video signal. The digital sound signals and the digital video signal provided from the reproduction signal processing portion 13 are applied to an input terminal 154 of a switch 15 through a line 14. The switch 15 has output terminals 151, 152 and 153. The digital sound signals are respectively provided to the output terminals 151 and 152. The digital video signal is provided to the output terminal 153. The digital sound signals provided to the output terminals 151 and 152 are respectively converted into analogue sound signals by digital/analogue (referred to as D/A hereinafter) converters 16 and 17 and then, respectively provided to output terminals TR1 and TL1. The digital video signal provided to the output terminal 153 are applied to a serial/parallel (referred to as S/P hereinafter) converter 18. The digital video signal applied to the S/P converter 18 is applied to the data bus 7 in parallel, for example, 8 bits at a time. The digital video signal is applied to either one of the picture memories 8a and 8b connected to the data bus 7. The digital video signals of one field are stored in each of the picture memories 8a and 8b. From the picture memories 8a and 8b which have each already stored the digital video signals of one field, the digital video signals stored are applied to a D/A converter 19 through the data bus 7. The digital video signals are converted into an analogue video signal by the D/A converter 19, to be provided to an output terminal TV1. More specifically, the digital video signals from the S/ P converter 18 are written in one of the picture memories 8a and 8b. On this occasion, the digital video signals stored in the other picture memory are read out to the D/A converter 19. When a writing operation of the digital video signals of one field to the above described one picture memory is completed, an output of the above described one picture memory is applied to the D/A converter 19. On this occasion, writing of the digital video signals from the S/P converter 18 is initiated. In the above described manner, outputs of the picture memories 8a and 8b are alternately applied to the D/A converter 19. As a result, a still picture which is changed for each constant time period is displayed by a display such as a CRT (cathode-ray-tube). As described in the foregoing, sampling frequencies in the A/D converters 1 and 2 are, for example, 32 kHz. Sound signals inputted from the input terminals TR and TL respectively correspond to speakers arranged in, for example, the right front and the left front of the listener. Two channels are assigned to the video signal inputted from the input terminal TV. Correspondingly, the output terminal 54 and the input terminals 51, 52 and 53 are sequentially electrically connected in the switch 5. A switching operation of the switch 5 is performed in response to, for example, a sampling signal having the above described frequency 32 kHz. In a period of one cycle of the sampling signal, the input terminal 51 is selected in a period of the first one-fourth cycle, the input terminal 52 is selected in a period of the subsequent one-fourth cycle, and the input terminal 53 is selected in a period of the subsequent one-half cycle. Each of the input terminals 51, 52 and 53 thus selected and the output terminal 54 are electrically connected to each other. As a result, in a period of one cycle of the sampling signal, (12 x 4)-bit digital signals are inputted to the recording signal processing portion 11. The digital video signal corresponding to a still picture of one screen must be stored in the picture memory 8a. Therefore, an output of the A/D converter 6 in, for example, a period of one field, i.e., a period of 1/60 second, must be stored. Thus, storage capacity of the picture memory 8a is represented by the following equation: 14.3(MHz) x 8(bits) x 1/60(sec) = 1.911(Mbits) Furthermore, digital video signals read out to the recording signal processing portion 11 from the picture memory 8a per second are represented by the following equation: 32(kHz) x 12(bits) x 2 = 768(kbits/sec) Thus, the following time is required to read out digital video signals of one field to the recording signal processing portion 11: 1.911(Mbits)/768(kbits/sec) = 2.49(sec) It takes 1/60 second to write the digital video signal of one field in the picture memory 8a. Therefore, the digital video signals representing a still picture of one screen are recorded on the magnetic tape 12 in approximately 2.5 seconds. Thus, a sound signal can be made acoustic and a still picture which is changed every approximately 2.5 seconds can be displayed by reproducing this magnetic tape 12 having the digital video signals and the digital sound signals recorded thereon. As described in the foregoing, it takes approximately 2.5 seconds to record the still picture of one screen on the magnetic tape 12. This is the same in reproduction of information recorded on the magnetic tape 12. More specifically, at the time of reproduction, the digital video signal of one field is inputted to the reproduction signal processing portion 13 in approximately 2.5 seconds. Thus, it takes approximately 2.5 seconds to store the digital video signal of one field in the picture memory 8a during reproduction. As described in the foregoing, after storage of the digital video signals of one field in the picture memory 8a is completed, the digital video signals stored are applied to the D/A converter 19. However, in a period during which a digital video signal is being written in the picture memory 8a, the digital sound signals corresponding to the digital video signal being written are respectively provided to the output terminals TR1 and TL1 from the D/A converters 16 and 17. Therefore, a video signal delayed by approximately 2.5 seconds from the sound signals provided to the output terminals TR1 and TL1 is provided to the output terminal TV1. As a result, a reproducing operation is performed with a picture and a sound not corresponding to each other. To allow the reproduction of a picture and a corresponding sound in synchronism with each other, JP-A-62-213491 discloses a magnetic recording and reproducing device which is provided with a delay circuit. This circuit delays the sound signal prior to recording by a time interval necessary to bring the picture and sound in synchronism with each other during reproduction. This device has the disadvantage that the delay circuit requires an extra memory to hold the sound signal to be delayed in addition to two memories for the picture signal. Such a memory is expensive and increases the power consumption of the device. Further devices for recording and reproducing still picture video signals and an accompanying sound signal (recorded in time-compressed form) are disclosed in US-4 602 295 and US-4 725 897. It is an object of the invention to provide a particularly simple method and apparatus for recording and reproducing a still picture video signal and a sound signal on/from a magnetic tape, wherein synchronism between the video signal and the sound signal during reproduction is achieved. This object is solved by the apparatuses of claims 1, 6 or 8 and the method of claim 7. Generally, at the time of recording a real-time sound signal and a video unit signal corresponding to a still picture of one screen, are recorded on the magnetic tape. Since a predetermined time period is required to record the video unit signal on the magnetic tape as digital signals, a time lag occurs between recording of the video signal and recording of the sound signal. In addition, at the time of reproduction, the real-time sound signal and the video unit signal corresponding to a still picture of one screen are reproduced from the magnetic tape. Since a predetermined time period is required to reproduce the video unit signal recorded as a digital signal, a time lag occurs between reproduction of the video signal and reproduction of the sound signal. In a magnetic tape recording/reproducing apparatus according to an embodiment of the present invention, recording of the sound signal is delayed by a time period corresponding to a predetermined time period required to record the video unit signal and a predetermined time period required to reproduce the video unit signal. Thus, at the time of reproduction, the corresponding relation between the video unit signal and the sound signal is maintained. In a magnetic tape recording/reproducing apparatus according to an embodiment of the present invention, at the time of recording, the video unit signal is sequentially written in at least one of the plurality of storing means in a first time period, and the content of the storing means is read out to be recorded on the tape in a second time period longer than the first time period. At the time of reproduction, the video unit signal reproduced from the tape is sequentially written in any of the plurality of storing means in the second time period. From the storing means in which the video unit signal has been written, the video signal stored is read out in the first time period, to be reproduced. At the time of recording, the sound signal is sequentially written in the second time period in at least one of the remaining storing means which is not used for writing/reading of the video signal. After this writing operation is completed, the sound signal stored is read out in the second time period, to be recorded. The first time period is substantially shorter than the second time period. Therefore, when the sound signal is stored in any of the plurality of storing means at the time of recording, the sound signal is recorded on the magnetic tape after a delay of approximately the second time period from the video signal. Consequently, at the time of reproduction, the video unit signal is written in any of the plurality of storing means in the second time period. When the video signal stored is read out from the storing means after completion of this writing operation, a sound signal corresponding to the video signal read is read out from the magnetic tape, to be made acoustic. Thus, the corresponding time relation between picture and sound is maintained during reproduction. As described in the foregoing, according to the present invention, there is provided a magnetic tape recording/reproducing apparatus having a simple structure capable of recording/reproducing the video unit signal and the sound signal on/from the magnetic tape as digital signals while maintaining the corresponding relation therebetween. Therefore, the magnetic tape recording/reproducing apparatus can be very convenient. By way only of example, an embodiment of the present invention will be described with reference to the accompanying drawings, in which: Fig. 1 is a block diagram of the assumed structure of a magnetic tape recording/reproducing apparatus already described which is useful for understanding the present invention; Fig. 2 is a block diagram showing a basic structure of a magnetic tape recording/reproducing apparatus according to an embodiment of the present invention; and Fig. 3 is a timing chart for explaining an operation of the magnetic tape recording/reproducing apparatus shown in Fig. 2. Referring to the drawings, the embodiment of the present invention will be described in detail. Fig. 2 is a block diagram showing a basic structure of a magnetic tape recording/reproducing apparatus according to an embodiment of the present invention. This magnetic tape recording/reproducing apparatus can perform recording and reproducing operation in a so-called four channel mode, in which sound signals corresponding to four speakers respectively arranged in, for example, the left front, the right front, the left rear and the right rear of a listener are recorded and reproduced. In this embodiment, two channels out of four channels are assigned to sound signals, and the remaining two channels are assigned to a video signal. More specifically, the sound signals recorded and reproduced in this magnetic tape recording/reproducing apparatus are two types of sound signals corresponding to two speakers respectively arranged in the right front and the left front of a listener. A magnetic tape recording/reproducing apparatus 31 shown in Fig. 2 comprises a recording portion 100, a reproducing portion 200, and picture memories 36a and 36b. The recording portion 100 comprises A/D converters 32, 33 and 36, an S/P converter 34, a P/S converter 37, a switch 39, a switching control signal generating circuit 80, and a recording signal processing portion 41. The reproducing portion 200 comprises D/A converters 47, 48 and 51, an S/P converter 49, a switch 46, a switching control signal generating circuit 81, and a reproduction signal processing portion 43. Two types of analogue sound signals are inputted to the magnetic tape recording/reproducing apparatus 31 from input terminals R0 and L0. The analogue sound signals are respectively applied to the A/D converters 32 and 33. In the A/D converters 32 and 33, the analogue sound signals inputted are sampled at a sampling frequency of, for example, 32kHz, to be converted into 12-bit digital sound signals d1 and d2. The digital sound signals d1 and d2 from the A/D converters 32 and 33 are serially applied to the S/P converter 34. The digital sound signals applied to the S/P converter 34 are applied to a data bus 35 as a 8-bit parallel digital sound signal d4. On the other hand, an analogue video signal is applied to the A/D converter 36 through an input terminal V0. In the A/D converter 36, the analogue video signal inputted is sampled at a sampling frequency of, for example, 14.3 MHz, to be converted into a 8-bit digital video signal d3. The digital video signal d3 is applied to the data bus 35 in parallel. The digital video signal d3 is written in one 36a of the picture memories 36a and 36b which are storing means connected to the data bus 35. A still picture of one screen is represented by a video signal in a period of one field, i.e., a period of 1/60 second. Thus, it takes 1/60 seconds to write the digital video signal d3 corresponding to one screen in the picture memory 36a. The digital sound signal d4 applied to the data bus 35 from the S/P converter 34 is written in the other memory 36b which is not used for storing the digital video signal d3. The digital sound signal d4 written in the picture memory 36b is not read out until the digital sound signal d4 is written in all storage regions of the picture memory 36b. When storage of the digital sound signal d4 to all the regions of the picture memory 36b is completed, the digital sound signal is read out in the order stored, to be applied to the data bus 35. The digital sound signal read out to the data bus 35 is applied to the P/S converter 37. On the other hand, the digital video signal stored in the picture memory 36a are applied to a P/S converter 38 through the data bus 35. The digital sound signals serially provided from the P/S converter 37 are applied to input terminals 91 and 92 of the switch 39. The digital video signal serially provided from the P/S converter 38 is applied to an input terminal 93 of the switch 39. In the switch 39, an output terminal 94 and the input terminals 91, 92 and 93 are electrically connected sequentially and cyclically. A digital signal d5 thus provided to a line 40 from the output terminal 94 is applied to the recording signal processing portion 41. In the recording signal processing portion 41, processing such as modulation and addition of information such as parity for correcting errors is performed with respect to the digital signal d5 inputted. The digital signals thus processed are recorded on a magnetic tape 42 by a rotary head (not shown) or the like. At the time of reproduction, the digital signals recorded on the magnetic tape 42 are applied to the reproduction signal processing portion 43 from the rotary head. In the reproduction signal processing portion 43, processing such as demodulation and error correcting processing referencing parity or the like is performed. A digital signal d6 thus reproduced is applied to an input terminal 64 of the switch 46 through a line 44. In the switch 46, output terminals 61 and 62 are respectively connected to the D/A converters 47 and 48, and an output terminal 63 is connected to the S/P converter 49. By a switching operation as described below, in the switch 46, the input terminal 64 and the output terminals 61, 62 and 63 are electrically connected sequentially and cyclically. In the above described manner, digital sound signals d7 and d8 corresponding to speakers arranged in the right front and the left front of a listener are respectively applied to the D/A converters 47 and 48. The digital sound signals d7 and d8 are respectively converted into analogue sound signals in the D/A converters 47 and 48, to be provided to output terminals R1 and L1. A digital video signal d9 is applied to the S/P converter 49 through the output terminal 63 of the switch 46. The digital video signal d9 inputted to this S/P converter 49 is converted into a parallel digital video signal d10 8 bits at a time, to be applied to the data bus 35. This digital video signal d10 is inputted to either one of the picture memories 36a and 36b. On this occasion, a digital video signal which has already been stored in the other of the picture memories 36a and 36b is applied to the D/A converter 51 from the data bus 35 through a line 50. More specifically, in a period during which the digital video signal d10 is written in either one of the picture memories, the digital video signal stored in the other picture memory is read out in 1/60 second. Consequently, an analogue video signal representing a still picture which corresponds to the digital video signals stored in the other picture memory is continuously provided to an output terminal V1 connected to the D/A converter 51. The above described reading processing is cyclically performed. Such an analogue video signal is inputted to a display such as a CRT (cathode-ray tube), the still picture being displayed on a display screen thereof. A switching operation in the switch 39 is controlled by switching control signals LR and LR1 generated from the switching control signal generating circuit 80. A switching operation in the switch 46 is controlled by switching control signals LR and LR1 generated from the switching control signal generating circuit 81. Fig. 3 is a timing chart for explaining an operation of the magnetic tape recording/reproducing apparatus 31. (1) and (2) in Fig. 3 respectively indicate switching control signals LR and LR1 applied to the switch 39 (or 46), and (3) in Fig. 3 indicates a switching operation of the switch 39 (or 46). (4) in Fig. 3 indicates the digital signal d5 (or d6) provided to the output terminal 94 (or the input terminal 64) of the switch 39 (or 46), and (5) in Fig. 3 indicates a clock signal CK1 generated inside of the recording signal processing portion 41 (or the reproduction signal processing portion 43). Meanwhile, (3) in Fig. 3 indicates the change in the input terminals 91, 92 and 93 (or the output terminals 61, 62 and 63) connected to the output terminal 94 (or the input terminal 64) of the switch 39 (or 46). When the switching control signals LR and LR1 are both at a low level, the output terminal 94 (or the input terminal 64) of the switch 39 (or 46) is connected to the input terminal 91 (or the output terminal 61). When the switching control signal LR1 is at the low level and the switching control signal LR is at a high level, the output terminal 94 (or the input terminal 64) is connected to the input terminal 92 (or the output terminal 62). When the switching control signal LR1 is at the high level, the output terminal 94 (or the input terminal 64) is connected to the input terminal 93 (or the output terminal 63). In a period W1 from the time t1 to the time t2, the switching control signals LR and LR1 are both at the low level, so that the output terminal 94 is connected to the input terminal 91. Consequently, digital sound signals are applied to the recording signal processing portion 41 from the P/S converter 37. In this period W1, the digital sound signal applied to the recording signal processing portion 41 corresponds to a speaker arranged in, for example, the right front of a listener. The digital signal d5 provided to the line 40 from the output terminal 94 is accepted inside of the recording signal processing portion 41 bit by bit in synchronization with the rise of the clock signal CK1. In a period W2 from the time t2 to the time t3, the switching control signal LR is at the high level and the switching control signal LR1 is at the low level. Consequently, in this period W2, the digital sound signals provided to the input terminal 92 from the P/S converter 37 are accepted in the recording signal processing portion 41. The digital sound signals correspond to a speaker arranged in the left front of a listener. In a period W3 from the time t3 to the time t5, the switching control signal LR1 becomes the high level. Consequently, the output terminal 94 of the switch 39 is connected to the input terminal 93. Consequently, in this period W3, digital video signals from the P/S converter 38 are inputted to the recording signal processing portion 41 bit by bit. At the time t4, the switching control signal LR rises. Thus, the switching control signal LR becomes the high level in a period from the time t4 to the time t5. However, in a period during which the switching control signal LR1 is at the high level, a switching operation is not performed in the switch 39 in response to the change in the switching control signal LR. As described in the foregoing, sampling frequencies in the A/D converters 32 and 33 are set to, for example, 32kHz. Correspondingly, the switching control signal LR1 has a frequency of 32 kHz. In addition, since the analogue sound signals inputted to the A/D converters 32 and 33 are converted into 12-bit digital sound signals d1 and d2, the digital sound signals accepted in the recording signal processing portion 41 in the periods W1 and W2 are respectively 12-bit digital signals. Thus, the digital video signals accepted in the recording signal processing portion 41 in the period W3 become 24-bit digital signals. Each of the picture memories 36a and 36b has a storage capacity P in which a digital video signal corresponding to an analogue video signal of one field can be stored. Since a period of one field is 1/60 second, the sampling frequency in the A/D converter 36 is 14.3 MHz, and the digital video signal d3 sampled and converted is an 8-bit digital signal, the storage capacity P is as follows: P = 14.3(MHz) x 8(bits) x 1/60(sec) = 1.911(Mbits) On the other hand, since the switching control signal LR1 has a frequency of 32 kHz and 24-bit digital video signals are inputted to the recording signal processing portion 41 in a period of one cycle of the switching control signal LR1, the amount R of data of the digital video signal read out from the picture memory 36a for one second is as follows: R = 32(kHz) x 24(bits) = 768(kbits/sec) Thus, time found from the following equation is required to read out all digital video data stored in the picture memory 36a to the recording signal processing portion 41: P/R = 2.49(sec) Thus, the analogue video signal inputted from the input terminal V0 is recorded on the magnetic tape 42 through the recording signal processing portion 41 in a time period found from the following equation: 2.49(sec) + 1/60(sec) = 2.5(sec) On the other hand, the analogue sound signals inputted from the input terminals R0 and L0 are stored once in the picture memory 36b. The time represented by the foregoing equation (6), i.e., 2.49 seconds is required to write in the picture memory 36b a digital sound signal having an amount of data corresponding to the storage capacity P of the picture memory 36b. When the digital sound signals are written in all the storage regions of the picture memory 36b, the digital sound signals are read out to the P/S converter 37 in the order written. Thus, the digital sound signals provided to the input terminals 91 and 92 of the switch 39 from the P/S converter 37 are delayed by approximately 2.5 seconds from the sound signals inputted from the input terminals R0 and L0. In the above described manner, any one of the digital video unit signal is recorded on the magnetic tape 42 and then, the digital sound signal associated with said one digital video unit signal is recorded on the magnetic tape 42 interspersed with the following digital video unit signal. More specifically, the digital sound signal associated with said one digital video unit signal recorded on the magnetic tape 42 is recorded on the magnetic tape 42 after a delay of approximately 2.5 seconds from the start of recording of said one digital video unit signal. Description is now made of an operation of the magnetic tape recording/reproducing apparatus at the time of reproduction. Digital signals read out from the magnetic tape 42 by a rotary head or the like are applied to the reproduction signal processing portion 43, to be serially provided bit by bit to the line 44 in synchronization with the falling edge of the clock signal CK1. In the period W1, the digital signal d6 is applied to the D/A converter 47 as the digital sound signal d7. In the period W2, the digital signal d6 is applied to the D/A converter 48 as the digital sound signal d8. In the period W3, the digital signal d6 is applied to the S/P converter 49 as the digital video signal d9. More specifically, the digital signal d6 provided to the line 44 in the periods W1 and W2 respectively corresponds to speakers arranged in the right front and the left front of a listener. The digital signal d6 provided to the line 44 in the period W3 corresponds to the digital video signal. The digital video signal d10 outputted from the S/P converter 49 is sequentially written in, for example, one 36a of the picture memories. The time of approximately 2.5 seconds is required to write the digital video signal of one field in the picture memory 36a, like the above described time required to read out the digital video signals to the recording signal processing portion 41 from the picture memory 36a. When writing of the digital video signal of one screen is completed, all digital video data stored in the picture memory 36a in which writing thereof is completed are inputted to the D/A converter 51 through the line 50 in 1/60 seconds. Such an operation is repeatedly performed. In a period during which digital video data of one still picture are read out from the picture memory 36a, a digital video signal of the next still picture is written in the other picture memory 36b. Thus, in a period during which digital video data of one still picture are read out from one of the picture memories 36a and 36b, the digital video signal of the next still picture is written in the other of the picture memories 36a and 36b. Consequently, in a display connected to the output terminal V1, a still picture which is changed for each period of approximately 2.5 seconds or more is displayed. Analogue sound signals corresponding to the digital sound signals d7 and d8 out of the digital signals d6 provided to the line 44 from the reproduction signal processing portion 43 are respectively outputted from the output terminals R1 and L1 without delay. On the other hand, since the digital video signal d9 is stored once in the picture memories 36a and 36b, the analogue video signal represented by the digital video signal d9 is provided to the output terminal V1 after a delay of approximately 2.5 seconds. However, as described above, digital sound data corresponding to the digital video signal representing a given still picture are recorded on the magnetic tape 42 after a delay of approximately 2.5 seconds from the start of recording of the digital video signal. Consequently, the video signal provided to the output terminal V1 and the sound signals provided to the output terminals R1 and L1 at the time of reproduction are in the same corresponding relation as the corresponding relation between the video signal and the sound signals inputted from the input terminals V0, R0 and L0 at the time of recording. Thus, the content recorded is reproduced while maintaining the corresponding time relation between a picture and a sound. In the above described manner, in a so-called DAT (Digital Audio Tape Recording/reproducing Apparatus) or the like, a sound signal can be recorded as a digital signal and a video signal representing a still picture can be recorded as a digital signal. As a result, the operation of the DAT or the like is very convenient. Although in the above described embodiment, description was made of a magnetic tape recording/reproducing apparatus comprising two picture memories capable of storing digital video signals of one screen, it should be noted that a number of picture memories is not limited to two. For example, three or more picture memories may be provided, in which case recording of a sound signal and a video signal representing a still picture according to digital signals is also achieved. Furthermore, although in the above described embodiment, description was made of a magnetic tape recording/reproducing apparatus in a four channel mode, it should be noted that the present invention can be also applied to a magnetic tape recording/reproducing apparatus in a two channel mode. In this case, it is necessary to assign one channel to recording and reproduction of a video signal. In addition, in the magnetic tape recording/reproducing apparatus in a four channel mode, one channel may be assigned to recording and reproduction of a video signal. Although an embodiment of the present invention has been described and illustrated in detail, it is clearly understood that the same is by way of illustration and example only and the scope of the present invention is limited only by the terms of the appended claims.

Claims: A signal recording/reproducing apparatus for recording and reproducing on/from a magnetic tape a video signal and a sound signal as digital signals, the video signal comprising a sequence of unit signals each representing a still picture and having a duration equivalent to a first time period, the sound signal representing audio corresponding to the still pictures of the video signal, a still picture being associated with a portion in time of the sound signal, the apparatus comprising: recording means (100) for, in respect of each video unit signal and in said sequence, individually writing the video unit signal into a first one (36a) of a plurality of storing means (36a,36b) and then individually reading the video unit signal out therefrom, for recording on the tape in such a manner that the video signal is expansively converted so that each recorded video unit signal has a duration equivalent to a second time period longer than the first, and for writing the associated sound signal into a second one (36b) of said storing means (36a,36b) and then reading the sound signal out therefrom, for recording on the tape with a delay approximately equivalent to said second time period such that the sound recording starts after the recording of the associated video unit signal is accomplished; and reproducing means (200) for reproducing the recorded video signal by, in respect of each recorded video unit signal and in the recorded sequence, individually writing the video unit signal reproduced from the tape into one of said plurality of storing means (36a,36b) and then individually reading the video unit signal out therefrom, for reproduction in such a manner that the read out video unit signal is compressively converted to have a duration equivalent to said first time period, and for reproducing the associated sound signal from the tape directly without use of the plurality of storing means; said second one (36b) of the plurality of storing means (36a,36b) serving to store the sound signal during recording and the video signal during reproduction. The signal recording/reproducing apparatus according to claim 1, wherein: said recording means (100) comprises first analogue/digital converting means (36) for converting said video unit signal into a digital video unit signal at a first sampling frequency, second analogue/digital converting means (32,33) for converting said associated sound signal into an associated digital sound signal at a second sampling frequency lower than said first sampling frequency, and recording processing means (41) for recording said digital video unit signal and said associated digital sound signal on the tape; and said reproducing means (200) comprises reproduction processing means (43) for reproducing said recorded digital video unit signal and said recorded associated digital sound signal from the tape, first digital/analogue converting means (51) for converting the reproduced digital video unit signal into an analogue video signal at said first sampling frequency, and second digital/analogue converting means (47,48) for converting the reproduced associated digital sound signal into an analogue sound signal at said second sampling frequency; said first one (36a) of said plurality of storing means (36a,36b) storing once said digital video unit signal from said first analogue/digital converting means (36) to subsequently read out and apply the same to said recording processing means (41) at the time of video recording, said second one (36b) of said plurality of storing means (36a,36b) storing once said associated digital sound signal from said second analogue/digital converting means (32,33) to subsequently read out and apply the same to said recording processing means (41) at the time of sound recording, and said first one and said second one of said plurality of storing means (36a,36b) alternately storing successive ones of said digital video unit signals from said reproduction processing means (43) to subsequently read out and apply the successive signals from said first and second storing means to said first digital/analogue converting means (51) at the time of reproduction. The signal recording/reproducing apparatus according to claim 2, further comprising: first switching means (39) for alternately applying to said recording processing means (41) at a predetermined frequency said digital video unit signal from said first one (36a) of said plurality of storing means (36a,36b) and said associated digital sound signal from said second one (36b) of said plurality of storing means (36a,36b), and second switching means (46) for alternately applying said digital video unit signal and said associated digital sound signal from said reproduction processing means (43) to one of said plurality of storing means (36a,36b) and to said second digital/analogue converting means (47,48), respectively, at a predetermined frequency. The signal recording/reproducing apparatus according to claim 3, wherein said first analogue/digital converting means (36) outputs said digital video unit signal as parallel data, and said second analogue/digital converting means (32,33) outputs said associated digital sound signal as serial data, and which further comprises: first serial/parallel converting means (34) for converting the serial associated digital sound signal from said second analogue/digital converting means (32,33) into parallel data to apply the same to said second one of said plurality of storing means (36a,36b), first parallel/serial converting means (37) for converting the parallel associated digital sound signal applied from said second one of said plurality of storing means (36a,36b) into serial data to apply the same to said first switching means (39), second parallel/serial converting means (38) for converting the parallel digital video unit signal applied from said first one of said plurality of storing means (36a,36b) into serial data to apply the same to said first switching means (39), and second serial/parallel converting means (49) for converting the serial digital video unit signal applied from said second switching means (46) to parallel data to apply the same to one of said plurality of storing means (36a,36b). The signal recording/reproducing apparatus according to claim 2, wherein said second analogue/digital converting means comprises two analogue/digital converters (32,33), and said second digital/analogue converting means comprises two digital/analogue converters (47,48), said sound signal comprising two channels. A signal recording/reproducing apparatus for recording and reproducing on/from a magnetic tape a video signal and a sound signal as digital signals, the video signal comprising a sequence of unit signals each representing a still picture and having a duration equivalent to a first time period, the sound signal representing audio associated with the still pictures of the video signal, the apparatus comprising means (100,200) for recording and reproducing said video unit signals such that, in respect of each video unit signal and in said sequence, the video unit signal is individually written into a first one (36a) of a plurality of storing means (36a,36b) and then individually read out therefrom, for recording on the tape in such a manner that the video is expansively converted so that each recorded video unit signal has a duration equivalent to a second time period longer than said first time period, and, in respect of each recorded video unit signal and in the recorded sequence, the video unit signal reproduced from the tape is individually written into one of said plurality of storing means (36a,36b) and then individually read out therefrom, for reproduction in such a manner that each of said video unit signals has a duration equivalent to said first time period, and for recording and reproducing said sound signal such that, in respect of each video unit signal, the associated sound signal is written into a second one (36b) of said plurality of storing means (36a,36b) and read out therefrom for recording on the tape after a delay approximately equivalent to the second time period such that the sound recording starts after the recording of the associated video unit signal is accomplished, and for directly reproducing the recorded associated sound signal without use of the plurality of storing means, at the time of reproduction, said second one (36b) of the plurality of storing means serving to store the sound signal during recording and the video signal during reproduction. A method for recording and reproducing on and from a magnetic tape a video signal and a sound signal as digital signals, the video signal comprising a sequence of unit signals each representing a still picture and having a duration equivalent to a first time period, the sound signal representing audio corresponding to the still pictures of the video signal, a still picture being associated with a portion in time of the sound signal, the method comprising the steps of: in respect of each video unit signal and in said sequence, writing the video unit signal into a first one (36a) of a plurality of storing means (36a,36b) and then individually reading the video unit signal out therefrom, for recording on the tape in such a manner that the video signal is expansively converted so that each recorded video unit signal has a duration equivalent to a second time period longer than the first; writing the associated sound signal into a second one (36b) of said storing means (36a,36b) and then reading the sound signal out therefrom, for recording on the tape with a delay approximately equivalent to said second time period such that the sound recording starts after the recording of the associated video unit signal is accomplished; reproducing the recorded video signal by, in respect of each recorded video unit signal and in the recorded sequence, individually writing the video unit signal reproduced from the tape into one of said plurality of storing means (36a,36b) and then individually reading the video unit signal out therefrom, for reproduction in such a manner that the read out video unit signal is compressively converted to have a duration equivalent to said first time period; and reproducing the recorded associated sound signal from the tape directly without use of the plurality of storing means; said second one (36b) of the plurality of storing means (36a,36b) being used to store the sound signal during recording and the video signal during reproduction. A system for recording and reproducing both sound and associated video still pictures in digital form on and from a magnetic tape, said system requiring a sum of first and second predetermined time periods for both the recording and reproducing of video still data corresponding to a still picture, in which system there is provided a plurality of storing means (36a,36b) for storing video and sound signals and means (100,200) for recording and reproducing sound and video data to and from the tape, said video still data being stored in one (36a) of said storing means in said first time period and subsequently read out therefrom in said second time period for recording said video still data on the tape in a time-expanded manner, and the sound data associated with said video still data being stored in another (36b) of said storing means and subsequently read out therefrom for recording on the tape, storage of the sound data serving to delay the recording of the sound data with respect to the start of recording of the associated video still data substantially by the sum of said first and second predetermined time periods, the recorded video still data being reproduced in a time-compressed manner by storage in one of the storing means (36a,36b) and subsequent read-out therefrom, and the associated sound data being reproduced from the tape directly without storage, so as substantially to coordinate the reproduction of the stills and associated sound.

Inventors: HAIKAWA YUKIHIKO, JUSO HIROMI, NISHIDA SYUZO, HAIKAWA, YUKIHIKO, JUSO, HIROMI, NISHIDA, SYUZO
Applicants: SHARP KK, SHARP KABUSHIKI KAISHA
Application year: 1989
Main classification: H04N1
IPC codes: H04N9, G11B20, H04N1, H04N5