JPH04227387A - Track discrimination device - Google Patents

Abstract

PURPOSE:To identify a video track and an audio track with simple constitution. CONSTITUTION:A head 1 reproduces a magnetic disk on which a video track with a video signal recorded thereon and an audio track with an audio signal recorded thereon are provided. A synchronizing separator circuit 21 detects a vertical synchronizing signal from a reproduced signal. A CPU 12 identifies the video track or audio track from number of the vertical synchronizing signals detected for a prescribed period.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a track discrimination device suitable for use in, for example, an apparatus for reproducing video floppies (magnetic disks).

0002

2. Description of the Related Art In electronic still video cameras, not only video signals can be recorded on a magnetic disk, but also audio signals can be recorded if necessary.

FIG. 12 is a block diagram showing the configuration of an example of a conventional track discrimination device for such a magnetic disk.

The signal reproduced by the head 1 is amplified by a regenerative amplifier (PB AMP) 2, and then passed through a high-pass filter and equalizer (HPF&EQ) 3, a low-pass filter (LPF) 4, and a band-pass filter (
BPF) 5.

[0005] The high-pass filter and equalizer 3 are
The high-frequency components of the input signal are separated and equalized, and then output to the luminance signal demodulation circuit 6. The luminance signal demodulation circuit 6 performs FM demodulation on the input signal and outputs it to the luminance signal processing circuit 10 and the audio signal processing circuit 9. The luminance signal processing circuit 10 processes the input demodulated luminance signal and outputs it to the adder 13. Furthermore, the audio signal processing circuit 9 processes the input demodulated audio signal and outputs it to a circuit (not shown) via the switch 14.

[0006] Furthermore, this audio signal includes a flag indicating start or end and various control codes, and when these flags and control codes are detected in the audio signal processing circuit 9, the detection The result is output to the CPU 12.

The low-pass filter 4 separates low frequency components (FM color signal components) from the input signal and outputs them to the color signal demodulation circuit 7. The color signal demodulation circuit 7 demodulates the input FM color signal and outputs the demodulated output to the color signal processing circuit 11. The color signal processing circuit 11 processes the input demodulated color signal and outputs it to the adder 13.

Further, the bandpass filter 5 separates a signal (ID signal) in a predetermined frequency band from the input signal, and
It is output to the demodulation circuit 8. The ID demodulation circuit 8 demodulates the ID signal and outputs the demodulation result to the CPU 12. The CPU 12 generates a character signal etc. corresponding to the ID signal as necessary,
Output to adder 13. Note that the ID signal includes information such as the track number and the recording date and time of the video signal.

Adder 13 adds video signals from luminance signal processing circuit 10, color signal processing circuit 11, and CPU 12, and outputs the sum to a circuit (not shown) via switch 14.

Further, the CPU 12 determines whether the track being played back is a track on which a video signal is recorded or a track on which an audio signal is recorded, and controls the switch 14 according to a flowchart as shown in FIG. .

That is, when the head 1 reproduces a magnetic disk (not shown), the CPU 12 performs a process (step S1).
), the presence or absence of an ID is determined from the output of the ID signal demodulation circuit 8 (step S2). Since the ID (DPSK) signal is recorded on a video track (a track on which a video signal is recorded), the fact that this ID is detected means that the playback track is a video track. Therefore, at this time, the CPU 12 opens the upper contact of the switch 14 in the figure to mute the audio output (step S4).

On the other hand, if the playback track is an audio track, a flag or control code is recorded therein. Therefore, when these flags or control codes are detected, since the playback track is an audio track (a track on which audio signals are recorded), the CPU 12 opens the lower contact of the switch 14 in the figure, and the video Mute the signal (steps S3, S5)
.

In this way, the correct reproduction signal is automatically selected and output regardless of whether the reproduction track is a video track or an audio track.

[0014]

[0006] Conventional devices thus have the ability to detect the presence or absence of flags or control codes contained in an audio track, or alternatively to determine the presence or absence of an ID in a video track.
A video track or an audio track is determined based on the presence or absence of a signal. Therefore, in order to discriminate between tracks, it is necessary to use the outputs from the audio signal processing circuit and the ID signal demodulation circuit, which has the drawback of requiring a relatively long time.

The present invention has been made in view of the above situation, and it is an object of the present invention to enable easy discrimination of reproduced tracks without using an audio signal processing circuit or an ID signal demodulation circuit.

[0016]

[Means for Solving the Problems] The track discrimination device of the present invention includes a reproduction means for reproducing a video track on which a video signal is recorded or an audio track on which an audio signal is recorded, and an output of the reproduction means. A video signal processing means for separating and processing a video signal, a synchronization separation means for separating a vertical synchronization signal included in the video signal from the output of the video signal processing means, and an output of the synchronization separation means in a predetermined period. The present invention is characterized by comprising a discriminating means for discriminating between an audio track and a video track.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Before explaining the operation of this apparatus, the characteristics of the magnetic disk and the video and audio tracks recorded thereon will be explained.

As shown in FIG.
Tracks of books are provided, with the outermost track being the first track and the innermost track being the fiftieth track. An FM video signal is recorded on a predetermined one of these as a video track, and an FM audio signal is recorded on a predetermined one as an audio track.

Of these, the audio track is divided into four sectors as shown in FIG. 5, and independent information is recorded in each sector. The video track (a video track is not divided into sectors) contains an FM modulated video signal and a DPSK (Different) signal.
ntial Phase Shift Keyi
ng) The modulated ID code is frequency multiplexed and recorded. On the audio track, a time-base compressed audio signal is time-base multiplexed with a control code, and is further FM modulated and recorded.

[0020] A video signal is recorded in one field on one track, but in the NTSC system, one image is displayed in two fields (one frame).
The frame mode that displays one image on two tracks is standard, but in order to record more images, there is also a field mode that displays one image on one field, and you can select and use either of them. It has become.

FIG. 6 shows the bit arrangement of the ID code recorded together with the video signal. The vertical synchronization signal interval T is the time for one rotation of the disk, and the image is switched to the image of the next track at the switching position. It is now possible to Periods T1, T7, and T8 are periods for margins, and period T2 is an initial bit period representing a starting point.

Field/frame information, that is, selection information as to whether to use the above-mentioned frame mode or field mode is recorded in the period T3. When used in the frame mode, one frame ( In order to record the image information of 2 fields), information as to whether the information is recorded on the inner track or the outer track is also recorded.

[0023]In the period T4, information on the track number in which image information is recorded is recorded, in the period T5, date information is recorded, and in the period T6, information defined by the user can be recorded. In this embodiment, the number of the next video track, the playback time T set by the operator, and the recording mode (AV mode or normal mode (V mode or A mode)) are recorded.

Information recorded in one sector of an audio track is formatted as shown in FIG. Periods T1, T9, T10, T8, and T2 are pedestal levels representing reference levels, and during playback, these pedestal levels are clamped to a predetermined reference level and the levels (admonitions) of data in other periods are determined. It has become. Period T11
The start flag of T12 and the end flag of period T12 are used not only to determine the original start and end, but also to determine which type from type 1 to type 4 this sector belongs to, as will be described later.

The control code of period T13 is used to record various control information, as will be described later. The overlap information for the period T3 is used to ensure continuity of the audio information between sectors, since the audio information is composed of information of a plurality of sectors. Period T4 is a portion in which audio information is recorded.

As shown in FIG. 8, the sector type is identified by a combination of polarities of a start flag and an end flag. In other words, when the start flag is high level and the end flag is low level, type 1
Alternatively, it is set as type 2 (discrimination between type 1 and type 2 will be described later). Further, when the start flag is high level and the end flag is also high level, it is identified as type 3, and when the start flag is low level and the end flag is high level, it is identified as type 4.

The usage of this sector type is as shown in FIG. 9, where a type 1 sector indicates that it continues to the next sector on the track, and a type 2 sector indicates that it ends on that track but is specified. A type 3 sector indicates a jump to a sector, a type 3 sector indicates the end of a sequence, and a type 4 sector indicates that no audio information is recorded.

FIG. 10 shows an example of four sectors recorded on one track, and the first to third sectors are type 1 sectors because the next sector follows that sector on the track. The fourth sector is a type 3 sector because the sequence ends in this sector.

FIG. 11 shows another example of how four types of sectors are used, and one track is 0, 1, 2, 3.
It consists of four sectors, track numbers 5, 8, 11.
This is an example in which continuous audio information is recorded on each of the 13 tracks. Track 5 has two type 1 sectors, followed by a type 2 sector, and the type 2
A control code is recorded in the sector indicating that the next sector is the first sector of track 8. Since audio information is not recorded in the fourth sector of track 5, type 4 is assigned to it.

Track 8 has three type 1 sectors in succession, a type 2 sector is assigned to the fourth sector, and it is recorded in the control code that the next succeeding sector is the first sector of track 11.

Track 11 is arranged with one type 1 sector and one type 2 sector, and in the type 2 sector, it is recorded in the control code that the next sector is the first sector of track 13. . Type 4 is assigned to the remaining two sectors of track 11. Track 13 is assigned one type 3 sector, indicating that the sequence ends there.

The remaining three sectors of track 13 are assigned type 4 sectors. The sequence therefore begins at the first sector of track 5 and continues to the first sector of track 13, where it ends.

As shown in FIG. 11, when moving to the first sector of another track in the middle of a track, for example track 5, the type 2 of the third sector has a start flag and an end as shown in FIG. Both flags are at a high level, which is apparently the same as type 1. However, since the fourth sector is type 4 and unused, it is determined that it is type 2 rather than type 1.

Furthermore, when moving to the beginning of another track after using all the sectors of one track, as in track 8, the type 2 of the fourth sector appears to be type 1 from the flag configuration as described above. However, since sector 3 is the last sector in one track, it is determined that it is type 2.

Next, an embodiment of the track discrimination device of the present invention will be described with reference to FIG. FIG. 1 is a block diagram showing the configuration of an embodiment of the track discrimination device of the present invention, and parts corresponding to those in FIG. do.

In this embodiment, the luminance signal processing circuit 1
A part of the output of 0 (video signal processing means) is sent to the synchronous separation circuit 2.
1 (synchronization separation means), and the vertical synchronization signal is separated. The output of the synchronous separation circuit 21 is CP
It is supplied to U12. The other configurations are the same as in FIG. 12.

Next, referring to the flowchart of FIG.
Let's explain its operation. When the head 1 (playback means) plays a disc (not shown), if the playback track is an audio track, the audio signal processing circuit 9 (
An audio signal is output from the audio signal processing means), and if it is a video track, a luminance signal processing circuit 10 and a color signal processing circuit 1 are output.
The video signal processed by 1 (video signal processing means) is
It is output from the adder 13.

The CPU 12 first sets the time of the built-in timer to Tm (where Tm is an arbitrary value of V/2<Tm<V, and V is a period corresponding to one field), and then sets the time of the synchronous separation circuit 21 to Monitor the output (steps S11, S
12). When the synchronization separation circuit 21 generates a vertical synchronization signal detection output, the CPU 12 starts a timer (
Step S13). When the synchronization separation circuit 21 generates the detection signal of the vertical synchronization signal again before the timer elapses the set time Tm, the CPU 12 determines that the playback track is an audio track and turns off the lower switch in FIG. Then, the video signal is muted, the upper switch in the figure is turned on, and the audio signal is output (steps S14, S16,
S17).

If the synchronization separation circuit 21 does not generate the detection signal again until the timer measures the set time Tm, the playback track is determined to be a video track, the upper switch in the figure is turned off, and the audio signal is is muted, the lower switch is turned on, and the video signal is output (steps S14, S15).

Next, the relationship between track types and vertical synchronization signals will be explained. When the track currently being played is a video track, the luminance signal processing circuit 10 outputs a luminance signal as shown in FIG. 3A. Therefore, the synchronization separation circuit 21 outputs a synchronization separation output as shown in FIG. 3B once during one field period (during one rotation of the disk). Therefore, if the time Tm is set to a value smaller than 1V (Tm<V), the next detection signal will not be generated during the period until the time Tm is counted.

On the other hand, the audio track is divided into four sectors, as explained with reference to FIG. Therefore, when the reproduced track is an audio track, the output of the luminance signal processing circuit 10 includes, in addition to the original audio signal component, a signal that changes to a low level or a high level at the boundary of each sector, as shown in FIG. 3C. A start flag or end flag is generated. Among these, the flag that changes to a low level has the property of being detected as a vertical synchronization signal by the synchronization separation circuit 21, so the output of the synchronization separation circuit 21 is 4 times per rotation of the disk 21, as shown in FIG. 3D.
Occurs twice.

The above is a case where an audio signal of sufficient volume is recorded in all four sectors, but if an audio signal of sufficient volume is recorded in 3.5 sectors, the luminance signal processing circuit 10 The output of the synchronization separation circuit 21 and the output of the synchronization separation circuit 21 are as shown in FIGS. 3E and 3F. Similarly, the output of the luminance signal processing circuit 10 and the output of the sync separation circuit 21 are 1.5
When a low-level audio signal is recorded in a sector or 0.5 sector, or when almost no audio signal is recorded, the situation is as shown in FIGS. 3G to 3L, respectively.

That is, in any case, if the reproduced track is an audio track, the synchronization separation circuit 21 outputs at least four detection signals during one field (four sectors).

The longest time during which no detection signal is output is
As shown in FIG. 4, for example, an audio signal is recorded in the first sector (it is a type 1 or type 2 sector).
, no audio signal is recorded in the fourth sector (type 4)
(the second and third sectors may or may not record an audio signal), and approximately two sectors are played from the fourth sector to the first sector. (V/2) period (to be exact, a period slightly shorter than two sectors). Therefore, if the time Tm is set to be longer than two sectors (V/2<Tm), the detection signal will be generated at least once during the period Tm.

After all, if the time Tm is set to V/2<Tm<V, if a detection signal is generated even once during that period, it means that an audio signal has been recorded; If not, it means that a video signal is being recorded.

In this way, the type of track can be determined from the number (interval) of vertical synchronization signals.

Note that in the above, the synchronous separation circuit 21
is provided separately from the luminance signal processing circuit 10, but it is also possible to use one built into the luminance signal processing circuit 10.

[0048]

As described above, according to the track discrimination device of the present invention, the video track and the audio track are discriminated from the synchronization signal detected during a predetermined period, so that The type of truck can be quickly determined without reading the ID or control code.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of a track discrimination device of the present invention.

[Fig. 2] Flowchart explaining the operation of the embodiment shown in Fig. 1.

[Fig. 3] Waveform diagram of the outputs of the luminance signal processing circuit and the synchronization separation circuit in the embodiment of Fig. 1

FIG. 4 is a diagram explaining the playback timing of the disc flag used in the embodiment of FIG. 1;

FIG. 5 is an explanatory diagram of sectors of a disk used in the embodiment of FIG. 1.

[Fig. 6] A diagram showing the format of a DPSK signal that is frequency multiplexed on a video signal.

[Figure 7] Diagram showing the format of one sector of the signal written to the audio track

[Figure 8] Diagram explaining the types of sector types

[Figure 9] Diagram explaining the functions of sector types

FIG. 10 is a diagram showing an example of allocation of each sector in an audio track.

FIG. 11 is a diagram showing an example of consecutive sectors of multiple audio tracks.

FIG. 12 is a block diagram showing the configuration of an example of a conventional track discrimination device.

FIG. 13 is a flowchart explaining the operation of the example in FIG. 12;

[Explanation of symbols]

1 Head (reproduction means) 6 Luminance signal demodulation circuit 7 Color signal demodulation circuit (video signal processing means) 8 ID
Signal demodulation circuit (video signal processing means) 9 Audio signal processing circuit (audio signal processing means) 10 Luminance signal processing circuit (
Video signal processing means) 11 Color signal processing circuit (video signal processing means) 12 CPU (discrimination means)

Claims (1)

[Claims] 1. Reproducing means for reproducing a video track on which a video signal is recorded or an audio track on which an audio signal is recorded on a disc; and video signal processing for separating and processing a video signal from the output of the reproducing means. means, a synchronization separation means for separating a synchronization signal included in the video signal from the output of the video signal processing means, and discrimination of the audio track or the video track from the output of the synchronization separation means in a predetermined period. A track discriminating device comprising: discriminating means for performing a track discriminating operation.