JPH0519775B2 - - Google Patents

Description

[Detailed description of the invention]

FIELD OF THE INVENTION The present invention relates to a method for detecting an absolute position on a tape, and more particularly, to a method for detecting an absolute position on a videotape using a CUE signal. Prior art and its problems In order to detect the absolute position of a videotape, a CUE signal having a predetermined frequency is recorded on the audio track of the videotape, and a reference position is set on the videotape according to the detection of the frequency of the CUE signal. A method is known in which the absolute position is determined by determining the absolute position. However, in this conventional method, the position is determined by simply detecting a single predetermined frequency, and therefore it may malfunction due to sounds that exist in the natural world. For this reason, general audio and CEU
It was not possible to mix signals. Therefore, for example, one of the two audio tracks of a videotape is used exclusively for the CUE signal, and a track exclusively for the CUE signal is provided. Furthermore, according to the conventional method, the reference position was determined by detecting a predetermined frequency, so for example, if the reference position is determined while playing a videotape at high speed, a CUE signal may be recorded. There was also a problem that the position on the videotape where the camera was placed and the determined reference position were misaligned. Means for Solving the Problems The present invention has been made in view of the above-mentioned situation. According to the present invention, the above-mentioned problems can be solved by converting a CUE signal having a predetermined waveform and a predetermined time width into a video signal. recording on the audio track of the tape, playing the videotape in the forward direction at a first playback speed, and generating numerical values at predetermined time intervals according to the waveform of the audio signal obtained by the playback; When the generated value matches the value corresponding to the waveform of the CUE signal a predetermined number of times in succession, the videotape is played forward at a second playback speed that is slower than the first playback speed. By playing and then detecting a numerical value that does not correspond to the CUE signal,
The problem is solved by providing a method for detecting the absolute position of a videotape, which is characterized by resetting a counter for the CTL signal. Embodiments Next, preferred embodiments of the present invention will be described with reference to the accompanying drawings. First, FIG. 1 shows a system implementing the method according to the preferred embodiment of the present invention, which system comprises a conventional VTR (video tape recorder) 10
, a control device 12 connected to a VTR 10, and a television broadcasting section 14. The VTR10 has a normal configuration and receives video signals by playing a videotape.
VID, a first audio signal AUD-1, a second audio signal AUD-2, and a CTL signal CTL.
For example, the CTL signal is converted to normal playback speed,
It is a short rectangular pulse generated every 1/30 seconds. The control device 12 includes an audio distributor 16, a binarization circuit 18, a pulse counter 20, a CPU (central processing unit) 22, and a CTL counter 24. The audio distributor 16 receives one of the audio signals, for example, the second audio signal AUD-2, from the VTR 10,
This is sent to the television broadcasting section 14 and the binarization circuit 18. The binarization circuit 18 converts the second audio signal AUD-2 sent from the audio distributor 16 into a binarized signal. The pulse counter 20 counts the pulses from the binarization circuit 18 every time the CTL signal CTL is generated, sends the counting result to the CPU 22, and is controlled by the CPU 22 to set and reset. The CTL counter 24 receives the CTL signal from the VTR 10, counts it, and sends the counting result to the CPU 22.
At the same time, it is controlled by the CPU 22 for setting and resetting. The television broadcasting section 14 is a television broadcasting section such as that used in general broadcasting stations, and has a function of broadcasting according to video and audio signals from, for example, a VTR. According to the present invention, the mechanism described above operates as follows. First, as shown in Figure 2, on the videotape,
As a CUE signal, for example, an audio signal of 440 Hz is recorded on one of the audio tracks for about 15 seconds at normal playback speed. When determining the absolute position of the videotape according to this CUE signal, the VTR 10
The videotape is played back at a high playback speed, for example at 5x speed. With this, the VTR 10 receives the video signal VID,
First audio signal AUD-1, second audio signal AUD
-2, and generates the CTL signal CTL. Video signal VID and first audio signal AUD-1
is sent directly to the television broadcast section 14, and the second
The audio signal AUD-2 is sent to the television broadcasting section 14 via the audio distributor of the control device 12. However, the television broadcasting section 14 is not yet ready to broadcast according to these signals. The CTL signal CTL is sent to the CTL counter 24, via which this signal is sent to the CPU 22. However, at this stage, the CTL counter 24 is under the control of the CPU 22 and the CTL signal CTL
It is not yet ready to count. The second audio signal AUD-2 is sent to the binarization circuit 18 of the control device 12 via the audio distributor,
This circuit converts the audio signal into a plurality of binary signals corresponding to the waveform, that is, rectangular pulses, and sends them to the pulse counter 20. Under the control of the CPU 22, the pulse counter 20 counts 2 pulses at predetermined time intervals, for example, every 1/30th of a second.
The digitized signals are totaled, that is, the number of pulses is counted. The number of counted pulses corresponds to the waveform of the audio signal. Numerical examples of the number of sampled pulses expressed in hexadecimal are shown in Tables 1 and 2 below. This is an example of a 440 Hz CUE signal, a 15-20 KHz normal audio signal, a 5x playback speed, and a 30 Hz sampling frequency. Table 1 shows the results when playing at a constant speed of 5x.
This is an example of binarized data of a CUE signal and an audio signal, and Table 2 shows the CUE signal that was binarized during 5x playback.
This is an example of data of a CUE signal and a binary signal of an audio signal when 10 pieces of signal data are detected and then reproduced at the same speed.

【table】

[Table] Such sampling data is sent to the CPU 22. The CPU 22 determines the waveform of the CUE signal (for example, 400Hz).
sine curve)) (e.g. “49”)
In response to a predetermined number of consecutive detections, for example 10 or more, a control signal is sent to the VTR 10 to cause the VTR 10 to play back at a low speed, for example at the same speed. Ten
CUE the signal by receiving it more than once.
Recognize it as a signal. 2 depending on the frequency of the CUE signal
Even if the value of the converted signal is 49 (in the case of 5x speed), a measurement error will actually occur, so for example, if you receive a value of 47 to 4A, it will match the value that corresponds to the waveform of the CUE signal. Suppose we did. When, for example, 10 numerical values corresponding to the waveform of the CUE signal are detected consecutively, the playback at 5x speed is changed to playback at 1x speed. Since the CUE signal has a certain time length, even if the corresponding binary signal is received 10 times or more as described above, the corresponding binary signal will continue to be received. Thereafter, when the CUE signal CUE ends, a binary signal corresponding to, for example, a normal audio signal is detected. In accordance with the detection of the binary signal corresponding to this normal audio signal, the CTL counter 24
Reset. Thereby, the end point of the CUE signal CUE is used as the reference point (FIG. 2) for the absolute position of the videotape, and the absolute position of the videotape is determined. By recording a predetermined program at the end point of the CUE signal CUE or at a predetermined interval from the end point, the predetermined program can be broadcast at a desired time. A flowchart of a method according to a preferred embodiment of the present invention is shown in FIG. Effects According to the present invention, the CUE signal can be recorded on the audio track, so there is no need to use a track dedicated to the CUE signal. For example, even if the audio track is a two-channel videotape, the audio can be transmitted in stereo. According to the present invention, the start point of the CUE signal is detected at high speed playback, the end point of the CUE signal is detected at low speed, and the reference position of the videotape is determined.
The reference position can be determined quickly and accurately, and there is no malfunction.

[Brief explanation of the drawing]

FIG. 1 is a simplified diagram of a system for implementing a method in accordance with a preferred embodiment of the present invention. FIG. 2 is a diagram showing an audio waveform during playback. FIG. 3 is a diagram showing a binarized audio waveform. FIG. 4 is a diagram showing the waveform of the CTL signal. FIG. 5 is a flowchart of a method according to a preferred embodiment of the invention. 10...VTR, 12...control device, 14...
Television broadcasting section, 16...Audio distributor, 1
8...Binarization circuit, 20...Pulse counter, 2
2...CPU, 24...CTL counter.

Claims (1)

[Claims] 1. A CUE signal having a predetermined waveform and a predetermined time width is recorded on an audio track of a videotape, and the videotape is played forward at a first playback speed; A numerical value corresponding to the waveform of the obtained audio signal is generated at a predetermined time interval, and when the generated numerical value matches the numerical value corresponding to the waveform of the CUE signal a predetermined number of times in a row, the corresponding value is determined. Playing the videotape forward at a second playback speed that is slower than the first playback speed, and then resetting a counter for the CTL signal by detecting a value that does not correspond to the CUE signal. A videotape absolute position detection method characterized by: