JPS62279505A - Reproducing device for recorded signals - Google Patents

Abstract

PURPOSE:To output reproduced sounds which are not inconvenient to hearing by combining the reproduced sound signal of a system other than time compression PCM sound recording system and a delayed PCM sound signal through a PCM sound recording A/D converter and a digital memory. CONSTITUTION:A time compression PCM sound reproduced signal like an FM sound signal, which is recorded while being multiplexed with a PCM video signal, reproduced by a rotary head HA 21, an FM sound reproducing process circuit 24, etc., or an AM sound signal reproduced from the signal recorded on a tape in the lengthwise direction by a head HB and the reproduced sound signal of another system are supplied to A/D converters 12 and 13 used for time compression PCM sound signal recording through switches 10 and 9 respectively. A/D-converted reproduced sound signals are delayed through digital memories 32 and 31, and the reproduced sound signal of another system is combined with the delayed reproduced time compression PCM sound signal, and the reproduced sound in each system is outputted as a sound which is not inconvenient to hearing.

Description

DETAILED DESCRIPTION OF THE INVENTION 3. Detailed Description of the Invention Field of Industrial Application The present invention relates to an apparatus for recording and reproducing a television signal consisting of a video signal and an audio signal on a tape-shaped p-recording medium.

2. Description of the Related Art A device for recording and reproducing television signals on a magnetic tape will be explained using an 8 mm video as an example.

As shown in Figure 2, the 8mm video tape recording format is such that the video signal is recorded on tracks diagonal to the longitudinal direction of the tape &1. a2. A3... are recorded one field at a time by a rotating head, and the audio signal can be recorded in the following three ways. One is to frequency multiplex the audio signal with the video signal as an FM modulated wave.
a 2 p a 3 J...The second method of recording on a track is to time-compress the audio signal with PCM...
The third method is to record the audio signal sequentially using a rotating head, as shown in the following method.The third method is to record the audio signal as a longitudinal track AUX-1 at the end of the tape using an alternating current bias.

Now, in the audio signals recorded by the above three methods in the above apparatus, a problem arises in which there is a difference in delay time depending on the recording method. That is, in the case of FM modulation recording and AC bias recording, the time delay due to signal processing can be ignored, but in the case of time compression PCM recording, the audio signal is stored in memory in units of 1 field (1,"so seconds), The signal processing time is 1.6 to 2 fields because signal processing is required to read out at high speed, compress the time, record, and when playing back, store it in the memory again, read it out slowly, and return to the original time axis. This results in a time delay of 20 to 30 seconds compared to the audio signal obtained by the above two recording methods.Therefore, highly related multi-channel audio signals can be recorded in two ways, including the PCM recording method. When recording and playing back using the above recording method, a time difference may occur, causing audible inconvenience.Also, when recording an audio signal related to a video signal using PCM, the audio signal may be delayed by 20 to 30 m5ec with respect to the video signal. Generally, it is not a practical problem even if the audio related to the video is delayed by about 30 m5ec, but it is a problem in a strict sense.

Problems to be Solved by the Invention As a method for solving these problems, a method has been proposed in which an auxiliary playback head for PCM audio is used to reproduce the audio signal recorded in PCM in advance of the video signal reproduction timing. has been done. However, the method of using an auxiliary head requires the addition of two expensive magnetic heads, as well as the addition of two channels of rotary transformers.
The reproduction preamplifier circuit also has the disadvantage of being complicated and expensive, as it requires two additional channels.

By the way, in a video tape recorder such as an 8 mm video tape recorder, as shown in FIG. 1, the recording track by the rotary head and the position of the audio signal recording head in the longitudinal direction of the tape are usually set in a specific relationship. That is, in the diagonal recording track of the tape recorded by the rotating head,
The distance X from the 1800 position, that is, the 21st point of the video signal recording by the rotary head, to the 22nd position of the audio signal recording head is specified, so that the audio signal playback timing during compatible playback between decks is constant. stipulated.

A PCM audio signal recorded on an extension of a video signal recording track is recorded with a time delay due to time compression processing during recording, and a time delay occurs again during playback due to time expansion processing.

As a method of correcting the relative delay time Δt that occurs between the recording and reproduction of the PCM audio signal and the audio signal that is recorded and reproduced without time delay, the method shown in FIG. 3 can be considered. As a method of correcting the relative time difference between the audio signal recorded on the track and the audio signal recorded in PCM, the position of the playback head is adjusted so that the playback time Δt The distance Δ2 (ΔR=vpi Δt') corresponding to Δt is
, v t is the tape speed).

In this case, especially in a reproduction-only machine, it is very effective to simply shift the geometrical position of the reproduction head.

In another method, if the position of the tape longitudinal recording trunk playback head is left at the 22 points shown in FIG. 3, it is necessary to electrically delay the playback signal, but this is the most efficient electrical delaying method. This method converts the signal into a digital signal and uses digital memory. An A/D converter is required to delay it as a digital signal, but the A/D converter used during recording in the PCM recording/playback signal processing system is not required during playback; It is effective to convert the signal into a digital signal using a /D converter and delay it.

The present invention is designed to reduce the amount of PC generated by time-axis compression/expansion processing when an audio signal is recorded as a time-compressed PCM signal together with other signals such as in an 8mm videotape format.
It is an object of the present invention to provide a recording/reproducing device which solves the problem of M recorded audio signals being delayed from other signals recorded together by electrical processing.

Means for Solving the Problems The present invention provides an audio signal reproduced through a system other than time-compressed PCM audio recording using an A/D converter used in the recording system for the time-compressed PCM signal. This recording and reproducing apparatus is characterized in that the time-compressed PCM signal is converted into a digital signal, delayed using a digital memory, and the delay time is matched with the delayed reproduced audio signal in the recording and reproducing signal processing system for the time-compressed PCM signal.

According to the above-mentioned configuration, the present invention allows the delay time of the audio signal reproduced through the separate system and the time-compressed PCM signal to be transferred to the shared A/D.
Matching is achieved by digitizing using a converter and delaying using digital memory.

FIG. 1 shows a circuit block of an embodiment of the present invention.

1 is a video input terminal, 2 is a recording signal processing circuit including an FM modulator, and 3 is an adder. Four audio signals are input to input terminals 4, 6, . It is input from θ, 7.

The audio signal input from 4 passes through the FM audio recording signal processing circuit 8, is added to the FM video signal at the adder 3, and is led to the switch circuit 16. - The signals input to the 10,000-man terminal 6.6 are guided through switches 9.10 to A/D converters 11 and 12, respectively, converted into digital signals, guided through switches 13.14 to the PCM processor 15, and further It is led to switch 16. The switch 16 connects the signal from the adder 3 and the PCM processor 15.
The signal is then switched and recorded on the tape through the recording amplifier 17, switch 18, and rotary head HA, as shown in FIG. 1, for example. - The audio input to the terminal 7 is bias-recorded as a track in the longitudinal direction of the tape at the end of the tape by the head HB through the recording process circuit 19 and the switch 2o.

During reproduction, the signal reproduced from the head HA passes through the head amplifier 21 and is then guided to circuits 22, 24, and 25.

The signal demodulated by the playback video processing circuit 22 is guided to an output terminal 23. FM audio playback process circuit 2
The reproduced audio signal demodulated through the switch 4 is guided to the switch 10. The two-channel audio signal processed by the PCM reproduction signal processing circuit 25 is sent to the D/A converter 26.
and 27 to be decoded and reproduced signals are obtained at terminals 28 and 29. On the other hand, the audio signal recorded in the longitudinal direction of the tape is reproduced by the head HB, passes through the switch 20, is guided to the reproduced signal processing circuit 3Q, and its output is guided to the switch 9. During playback, the reproduced audio signals led to switches 9 and 10 are led to A/D converters 11 and 12, respectively, where they are converted into PCM signals, and are led through switches 13 and 14 to memory circuits 31 and 32, respectively, where they are specified. After being delayed for a period of time, an audio signal is obtained which is led to the D/A converters 33 and 34. In addition, the memory circuit 31゜3
The delay time in step 2 is configured to approximately match the delay time in the signal processing circuit in PCM audio recording and reproduction. In this way, the A/D converter 1 is used as a means for delaying the FM audio reproduction signal and the reproduction signal by the fixed head.
1.12 can be shared, there is no need to newly install an A/D converter, which is the most costly component in digital processing, and only a memory circuit and a D/A converter are required, which is a great advantage in terms of cost.

As described above, the time difference between the audio signal recorded and reproduced using time-compressed PCM and the audio signal recorded and reproduced through other systems can be effectively eliminated in this manner.

Note that when the delay times of the audio signals are matched in this way, the video signal advances relative to the audio signal. As a means to eliminate the time difference between the audio signal and the video signal, a memory circuit (A/D,
D/A, including memory, etc. Il, J-
c-If-) bm Suna Irininu, HP Although not included, a similar memory circuit was inserted between input terminal 1 and recording processor 2 (distributed to both the input side and output side).
You can also use a method that halves the amount of memory by using it twice. Another possibility is to digitally process the video recording processor and video playback processor and record analog data.In this case, since both processors have A/D converters, you can easily record the video by simply adding memory. The signal can be delayed to match the timing of the audio signal. Digital memory is becoming cheaper due to advances in IC technology, and it can be expected to be cheaper than using a conventional advance playback head for PCM audio.

Effects of the Invention In a device in which a video tape recorder records an audio signal together with a video signal as a time-compressed PCM signal using a rotary head, the audio signal is also recorded on the same recording medium through other systems. Audio signals recorded and reproduced as time-compressed PCM signals are delayed by the time required for time compression/expansion processing compared to audio signals recorded through other systems.

As a means for correcting the time difference between this PCM time-compressed recording signal and a signal recorded and reproduced by another system, the present invention provides a means for correcting the time difference between this PCM time-compressed recording signal and a signal recorded and reproduced by another system. A/D converter to be used, converts the signal into a digital memory circuit,
A D/A converter is added to delay the signal and the delay time is combined with the playback audio signal delayed by PCM recording sickle playback.In this case, the most expensive A/D converter is the one used in the PCM time compression recording system. A that can be done
/D converter can be used during reproduction, the cost of the delay circuit system can be made very low, and it is possible to perform delay without deterioration.

[Brief explanation of the drawing]

FIG. 1 is a circuit block diagram of an embodiment of the present invention, FIG. 2 is a recording pattern diagram for 8 mm video, and FIG. 13 is a tape pattern diagram. 11.12...-A/D converter, 31
．． 32...--Memory circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
Figure 3 ΔL FCI'1-A

Claims (1)

[Claims] When recording a television signal containing at least a video signal and an audio signal on a tape-shaped recording medium, the video signal is sequentially recorded as a recording trajectory diagonal to the longitudinal direction of the tape, and the audio signal is recorded on the diagonal track of the video signal recording. A method of recording the audio signal sequentially as a time-compressed PCM signal on the extension of the recording tape, and bias recording the audio signal as a recording track in the tape longitudinal direction at the end of the recording tape, and recording the audio signal as an FM signal.
In an apparatus for recording an audio signal on the same recording medium through a system different from the time-compressed PCM audio by at least one of the methods of modulating and frequency multiplexing recording with the video signal, the time-compressed PCM audio An audio signal reproduced through a system other than recording is converted into a digital signal using an A/D converter used in the recording system of the time-compressed PCM signal, and is delayed using a digital memory, A recording/reproducing apparatus characterized in that the delay time is matched with a reproduced audio signal delayed in a recording/reproducing signal processing system for a time-compressed PCM signal.