JP2921956B2 - Method and apparatus for searching audio signal - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video floppy disk used as a recording medium of an electronic still video camera or the like, and more particularly, to a method and an apparatus for searching for an audio signal recorded on the disk. .

[Prior Art] In this type of video floppy disk, each track on which an audio signal is recorded is usually divided into four sectors, and the cueing of the audio signal is disclosed in Japanese Patent Application Laid-Open No. 1-269292. As described above, the audio signal recorded in the sector located at the head of each track is demodulated and sequentially output as audio.

The audio signal is approximately 20 per track depending on the compression ratio.
It is possible to record and reproduce in each mode of seconds, about 10 seconds and about 5 seconds. Since one track is composed of four sectors as described above, the recording and reproducing time per sector in each mode is about 5 seconds, about 2.5 seconds and about 2.5 seconds, respectively.
1.2 seconds.

[Problems to be solved by the invention]

However, if audio is recorded in a mode of about 5 seconds per track in each of the above modes, for example, since the playback time is as short as about 1.2 seconds, the reproduced audio becomes difficult to hear, and a desired track is searched. There is a problem that it becomes difficult to do.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an audio signal search method and an audio signal search method which make it possible to easily search for a necessary track reliably regardless of a mode in which audio is recorded.

[Means for solving the problem]

The search method according to the present invention reproduces an audio signal recorded on a recording medium at a predetermined compression ratio, and searches for an audio signal by performing cueing of a series of audio signals. The reproduction amount for cueing the audio signal is changed so as to increase as the compression ratio decreases.

Further, a search device according to the present invention is a device for searching for an audio signal recorded on a recording medium at a predetermined compression ratio, and a means for detecting that the audio signal is recorded on the recording medium, It is characterized by comprising means for detecting the head of the audio signal, means for detecting the compression ratio of the audio signal, and means for reproducing the audio signal from the head by a reproduction amount that increases as the compression ratio decreases.

〔Example〕

 Hereinafter, the present invention will be described with reference to the illustrated embodiments.

FIG. 3 is a circuit diagram of a disk recording / reproducing apparatus to which an audio signal searching method and apparatus according to one embodiment of the present invention are applied. The system controller 11 is a conventionally known microcomputer that controls the entire apparatus. The system controller 11 includes an operation unit 12 for performing various operations and a voice search button.
13 and a stop button 14 are connected. Further, a display unit 15 for performing various displays is connected to the system controller 11.

The video recording / reproducing circuit 16 is controlled by the system controller 11, divides a video signal input via a video camera or the like (not shown) into a color difference signal and a luminance signal, and FM-modulates each signal. To record. The video recording / reproducing circuit 16 is also connected to a video output terminal. By connecting a reproducing device (not shown) to this terminal, the video recorded on the video floppy disk D can be viewed. The switch 17 is controlled by the system controller 11, and is closed on the video recording / reproducing circuit 16 side when recording and reproducing video, and is closed on the audio recording / reproducing circuit 31 described later when recording and reproducing audio.

The disk drive comprises a magnetic head 21 and this magnetic head 21
And a spindle motor 23 for rotating and driving the video floppy disk D.
A servo circuit 24 for controlling the driving of the motor 23; and a PG coil 25 for detecting the rotational angle position of the video floppy disk D. The PG coil 25 is connected to the servo circuit 24, and the servo circuit 24 and the tracking circuit 22 are connected to the system controller 11. Video floppy disk D
Is controlled by the system controller 11 and 3600 rpm
Rotate with.

Next, a circuit for recording and reproducing audio will be described.

The audio recording / reproducing circuit 31 is a circuit that performs FM modulation, FM demodulation, and the like, and is connected to the magnetic head 21 via the switch 17. The emphasis circuit 32 is a circuit for emphasizing the high frequency range of the audio signal transmitted from the audio memory 33 at the time of recording the audio on the disk D and outputting it to the audio recording / reproducing circuit 31. The low pass filter 34 and the D / A conversion It is connected to the audio memory 33 via the device 35. The de-emphasis circuit 36 is a circuit that suppresses the high frequency range of the audio signal output from the audio recording / reproducing circuit 31 at the time of reproducing the audio recorded on the disk D, and via a low-pass filter 37 and an A / D converter 38. Connected to the audio memory 33.

The microphone 41 is connected to a switch 45 via an amplifier 42, and the speaker 43 is connected to a switch 45 via an amplifier 44. The switch 45 is controlled by the system controller 11, and is closed on the amplifier 42 side of the microphone when recording audio and closed on the amplifier 44 side of the speaker when reproducing audio. The switch 45 is connected to a noise reduction circuit 46, and the noise reduction circuit 46 is connected to a low-pass filter 47. The low-pass filter 47 is connected to an A / D converter 51 and a D / A converter 52 via a switch 48, and the A / D converter 51 and the D / A converter 52
Connected to. The switch 48 is controlled by the system controller 11 and is closed on the A / D converter 51 side when recording audio.
It is closed on the D / A converter 52 side when sound is reproduced. Note that the noise reduction circuit 46 and the low-pass filter 47 are also controlled by the system controller 11.

Voice memory 33, A / D converters 51 and 38 and D / A converter 52,
The timing control circuit 53 is connected to 35. This timing control circuit 53 is controlled by the system controller 11 and cooperates with the audio memory 33, the A / D converters 51 and 38 and the D / A converters 52 and 35 to record and reproduce the sound of the disk D.
The audio signal is compressed or expanded with respect to the time axis.

When recording the sound, the sound input from the microphone 41 is input to the A / D converter 51 through the amplifier 42, the noise reduction circuit 46, and the low-pass filter 47. This audio signal is time-compressed by the operation of the A / D converter 51, the audio memory 33, and the timing control circuit 53, is D / A-converted by the D / A converter 35, passes through the low-pass filter 34, and passes through the emphasis circuit. The high frequency is emphasized by 32, FM-modulated by the audio recording / reproducing circuit 31, and recorded on the disk D.

Also, at the time of audio reproduction, the audio signal recorded on the disk D is FM-demodulated by the audio recording / reproduction circuit 31,
The high frequency band is suppressed by the de-emphasis circuit 36, and is passed through the low-pass filter 37 and the A / D converter 38.
Stored in 3. The audio signal stored in the audio memory 33 includes the audio memory 33, the timing control circuit 53, and the D / A
The signal is time-expanded by the operation of the converter 52 and output as an analog signal, passes through the low-pass filter 47, the noise reduction circuit 46, and the amplifier 44, and is reproduced by the speaker 43.

As described above, the audio signal is recorded on one track on the video floppy disk D rotating at 3600 rpm, so that the time axis is compressed. In addition, at the time of reproduction, the time axis is expanded corresponding to the compression ratio.

FIG. 4 shows a video floppy disk D used in the disk recording / reproducing apparatus of FIG. The video floppy disk D is, for example, a 2-inch magnetic disk. The 1st to 50th tracks from the outside of the video floppy disk D are recording tracks on which video and audio are recorded, and nothing is recorded on the 51st track.
The third track is a cue track for recording a so-called cue signal. The track on which the audio signal is recorded is divided into four sectors.

FIG. 5 shows the relationship between tracks and sectors on the video floppy disk D. In this example, the sixth, seventh, ninth, tenth,
Video signals are recorded on 12 tracks, and audio signals are recorded on tracks 5, 8, 11, and 13. The video signal is recorded with one track as one unit. On the other hand, the track on which the audio signal is recorded is divided into four sectors, and the audio signal is recorded with one sector as a unit. It is formed.

The recording format of the signal in the sector containing the audio signal is 4
There are two types. Type 1 (FIG. 5) is a sector in which audio signals are also recorded in subsequent sectors, type 2
(FIG. 5) is a sector following a track where the audio signal is different, type 3 (FIG. 5) is a sector at the end of a series of audio signals, and type 4 (FIG. 5) is an audio signal recorded. No sector. That is, in the example of FIG. 5, the audio signal is transmitted from the sector # 2 to the eighth track of the fifth track.
Following the track, the process is continued from the sector # 3 of the eighth track to the eleventh track, followed by the sector # 1 of the eleventh track to the sector # 0 of the thirteenth track. That is, a series of audio signals are recorded over predetermined tracks of the fifth, eighth, eleventh, and thirteenth tracks.

FIG. 6 schematically shows a state of recording a signal in one sector including an audio signal. In each sector, a signal that starts with the start flag F1 and ends with the end flag F2 is recorded. At the end of the start flag F1,
A control code C1 for recording various information is recorded, and an audio waveform signal C2 is recorded between the control code C1 and the end flag F2.

As shown in FIG. 6, type 1 of the signal recording format is indicated by the start flag F1 being a high level signal and the end flag F2 being a low level signal. Type 2 is also indicated by the start flag F1 being a high level signal and the end flag F2 being a low level signal.
It differs from Type 1 in that the next sector in the same track is not Type 3. Type 3 is indicated by the fact that both the start flag F1 and the end flag F2 are low level signals, and type 4 is indicated by the fact that the start flag F1 is a low level signal and the end flag F2 is a high level signal.

FIG. 1 is a flowchart showing a first method for searching for an audio signal. This routine is started by pressing the voice search button 13.

In step 101, it is determined whether or not the magnetic head 21 currently faces the 50th track of the video floppy disk D, that is, the innermost track of the recording tracks.
Is determined. The video floppy disk D is read from the outer peripheral side toward the inner peripheral side, and the magnetic head 21
When it is located on the track, this routine ends because the reading of the recording track has been completed.

If the 50th track has not been played yet,
Tracked in step 102, the magnetic head 21
Is moved to one inner track. In step 103, it is determined whether the track to be reproduced is a track on which an audio signal is recorded. This is determined by an output signal from a synchronization signal separation circuit (not shown). Since the synchronization signal separation circuit detects the start flag F1 and the end flag F2 as vertical synchronization signals, if the currently reproduced track is an audio track, more synchronization signals are detected than if the track is a video track. Step if the track is not the track on which the audio signal was recorded
Returning to 101, if the track is a track on which an audio signal is recorded, in step 104, by reading the control code C1 (FIG. 6), it is determined whether it is the beginning of a sequence, that is, a series of audio signals. In the control code C1 in each sector of the series of audio signals, the track number and the sector number of the first sector are recorded,
By reading this, it is determined whether the sector is the head of a series of audio signals. If the currently playing track is not the beginning of a series of audio signals, the process returns to step 101.If the track is the beginning of a series of audio signals,
Step 105 and subsequent steps are executed.

In step 105, a time limit is set in a timer (not shown), and in step 106, the timer is started.

Next, in step 111, reproduction of the audio signal is started. In step 112, it is determined whether or not the stop button 14 (FIG. 3) has been pressed. If the stop button 14 has been pressed, the timer is stopped in step 119, and this routine is forcibly terminated in this state. If not, steps 113 and subsequent steps are executed. That is, it is determined whether the currently reproduced sector is type 3 or not, that is, whether it is the last of a series of audio signals. Type 3
If not, the timer started in step 106 is checked in step 114, and it is determined whether or not the time is over, that is, whether or not the time limit set in step 105 has elapsed. If the time limit has not elapsed, it is determined in step 115 whether or not the sector currently being reproduced is type 2, that is, whether or not the audio signal follows a sector on another track. If the type is not type 2, the process returns to step 111 as it is. In the case of type 2, the magnetic head 21 is tracked to a subsequent track in step 116, and the process returns to step 111.

Steps 111 to 116 are repeatedly executed, and audio signals are reproduced for some sectors. Thereafter, if it is determined in step 113 that the sector being reproduced is type 3 or if it is determined in step 114 that the predetermined time has elapsed, reproduction of the audio signal is stopped in step 117, and
At 118, the timer is stopped. Then, the routine returns to step 101, where the same processing as described above is repeatedly executed, and the reproduction of the next series of audio signals, that is, cueing is performed.

As described above, the present embodiment is configured to reproduce the audio signal for a fixed time regardless of the compression ratio in recording the audio signal. Therefore, even in a mode in which about 5 seconds of audio is recorded per track, a reproduction time of, for example, about 2.5 seconds is secured. (In this embodiment, the predetermined time is 2.5 seconds.) For this reason, the reproduction time is long enough to hear the sound, and it becomes easy to search for a desired track. Further, according to this embodiment, even if audio signals of different recording modes are mixed on one video floppy disk, the audio signals can be reproduced for a certain period of time, so that a desired track can be reliably searched. Can be.

FIG. 2 is a flowchart showing a second method for searching for a voice signal. This routine is started by pressing a voice search button 12.

The processing of steps 201, 202, 203 and 204 is the same as that of steps 101, 102, 103 and 104 in FIG. 1, respectively, and a description thereof will be omitted.

In step 205, a reference value N indicating the number of sectors to be reproduced is set to "1". This is merely an example, and may be set to “2” or more as needed. In step 206, the audio signal is in the first mode (a mode in which approximately 20 seconds of audio is recorded per track).
It is determined whether or not it has been recorded. If it is not the first mode, it is determined in step 207 whether or not the audio signal is recorded in the second mode (a mode in which approximately 10 seconds of audio is recorded per track). In the case of the second mode, in step 208, the reference value N is changed to 2N. If it is not the second mode, that is, if it is the third mode (a mode in which about 5 seconds of audio is recorded per track), the reference value N is changed to 4N in step 209.

Next, at step 210, the counter M is set to "1", and at step 211 and thereafter, sound reproduction is performed.

In step 211, one sector is reproduced and the audio is reproduced. In step 212, the stop button 14 (third
Is determined to be pressed, and if it is pressed, this routine is forcibly terminated in this state, but if it is not pressed, step 213 and subsequent steps are executed. First, in step 213, it is determined whether or not the currently reproduced sector is type 3, that is, whether or not it is the last of a series of audio signals. If it is type 3, since the series of audio signals has been completed, the process immediately returns to step 201. If it is not type 3, in step 214, it is determined whether or not the counter M has reached the reference value N. The counter M is the reference value N
, That is, when the reproduction of a predetermined number of sectors has been completed, the process returns to step 201, and the next audio cue is performed.

On the other hand, if the reproduction of the predetermined number of sectors has not been completed and the counter M has not reached the reference value N, the counter M is incremented by “1” in step 215, and then in step 216, It is determined whether or not the currently reproduced sector is type 2, that is, whether or not the audio signal follows a sector of another track. If the type is not type 2, the process returns to step 211 as it is. In the case of type 2, the magnetic head 21 is tracked to a subsequent track in step 217, and the process returns to step 211.

Steps 211 to 217 are repeatedly executed, and audio signals are reproduced for a predetermined number of sectors. Step 213
If it is determined at step 214 that the sector being reproduced is of type 3 or if it is determined at step 214 that reproduction of a predetermined number of sectors has been completed, the routine returns to step 201 and performs the same processing as described above. Are repeatedly executed to reproduce the next series of audio signals.

As described above, the present embodiment is configured such that the reproduction amount (the number of sectors to be reproduced) of the audio signal can be changed in accordance with the compression ratio in recording the audio signal. For this reason, the number of sectors reproduced is increasing. That is, the reproduction time is constant (5 seconds) regardless of the audio recording mode. Therefore, even in a mode having a small compression ratio in which about 5 seconds of sound is recorded per track, the reproduction time is sufficiently long, the sound can be easily heard, and the desired track can be reliably recorded. Can be searched. Further, according to the present embodiment, even if audio signals of different recording modes are mixed on one video floppy disk, the number of sectors corresponding to each mode is always reproduced, so that a desired track can be reliably searched. be able to.

In each of the above embodiments, a video floppy disk is used as a recording medium. However, the present invention is not limited to this, and can be applied to an apparatus using a magnetic tape or a magnetic drum as a recording medium. .

〔The invention's effect〕

As described above, according to the present invention, an effect is obtained that a desired track can be reliably searched regardless of the mode (compression ratio) in which sound is recorded.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a first method for searching for an audio signal, FIG. 2 is a flowchart showing a second method for searching for an audio signal, and FIG. 3 is a voice according to an embodiment of the present invention. FIG. 4 is a circuit diagram showing a disk recording / reproducing apparatus to which the signal search method and apparatus are applied, FIG. 4 is a diagram showing a video floppy disk, FIG. 5 is a diagram showing a relationship between tracks and sectors of the video floppy disk, FIG. FIG. 3 is a diagram schematically illustrating a recording state of an audio signal in one sector. D: Video floppy disk

Claims (4)

(57) [Claims] 1. A method for reproducing an audio signal recorded on a recording medium at a predetermined compression ratio and searching for an audio signal by performing a cueing of a series of audio signals, wherein the compression ratio is detected.
A method for retrieving an audio signal, characterized by changing a reproduction amount for cueing the audio signal so as to increase as the compression ratio decreases. 2. The recording medium according to claim 1, wherein said recording medium is divided into a plurality of sectors, and the number of sectors reproduced for cueing changes according to said compression ratio. The search method of the audio signal described in. 3. An apparatus for retrieving an audio signal recorded on a recording medium at a predetermined compression ratio, comprising: means for detecting that the audio signal is recorded on the recording medium; Means for detecting the compression ratio of the audio signal, and means for reproducing the audio signal from the beginning by a reproduction amount that increases as the compression ratio decreases. Search device. 4. The recording medium according to claim 1, wherein said recording medium is divided into a plurality of sectors, and said audio signal reproducing means reproduces an audio signal by a number of sectors changed according to said compression ratio. Item 3. The audio signal search device according to item 3.