JP3191850B2 - Motion detection circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motion detecting circuit used in a device (MUSE decoder) for decoding a television signal subsampled between two frames, such as a MUSE system, and more particularly to a laser disk or the like. A motion detection circuit suitable for use in a MUSE decoder using a non-broadcast recording medium as a signal source.

[0002]

2. Description of the Related Art In recent years, high-definition television (hereinafter, HDTV) broadcasting by the MUSE system has been in full swing. M
For details of the USE system, see various documents (for example, “M
USE-Hi-Vision transmission method ", published by Yuichi Ninomiya, published by the Institute of Electronics, Information and Communication Engineers). Here, only the outline of processing not directly related to the present invention will be described.

In the MUSE method, offset subsampling (decimation) is performed between fields and between frames on the encoding side. Therefore, in order to reproduce a still image on the decoding side, four fields of M
It is necessary to synthesize (interpolate between frames and between fields) from the USE signal. However, if this still image processing is performed on a portion where an image is moving, a multiplex image is obtained.
The moving part is detected from the SE signal.
An image is composed (field interpolation) from signals for one field. Therefore, the MUSE decoder has
Motion detection processing for discriminating between a moving image portion and a still image portion is required.

Here, a schematic configuration and operation of the MUSE decoder will be described. FIG. 5 is a block diagram showing a schematic configuration of the MUSE decoder. In FIG. 5, a MUSE signal input from an input terminal 1 is input to a motion detecting circuit 2, a moving image processing circuit 3, a still image processing circuit 4, and an audio decoding processing circuit 6. The moving image processing circuit 3 synthesizes an image from a signal for one field (field interpolation), and the still image processing circuit 4 synthesizes an image from a signal for four fields (frame interpolation and field interpolation). Motion detection circuit 2
Detects a moving portion of the image, and inputs a motion detection signal indicating the amount of motion of the image to the mixing circuit 5. The mixing circuit 5 mixes the signal subjected to the moving image processing and the signal subjected to the still image processing at a ratio corresponding to the amount of motion.

If the output of the motion detection circuit 2 is k, the output of the moving picture processing circuit 3 is m, and the output of the still picture processing circuit 4 is s,
The output y of the mixing circuit 5 is given by the following equation. y = k × m + (1−k) × s (1) where k satisfies the condition of 0 ≦ k ≦ 1, and is 0 for a complete still image and 1 for a complete moving image.

On the other hand, the audio decoding processing circuit 6 decodes an audio signal. That is, since the MUSE signal is configured as shown in FIG. 9, the audio decoding processing circuit 6 decodes the audio signal from the signal time-division multiplexed to the line numbers 3 to 46 and 565 to 608.

In the motion detection circuit 2, it is preferable to detect a motion amount based on a difference between pixels in one frame. However, the MUSE signal has one sampling cycle because the sampling pattern makes one cycle in a period of four fields (two frames).
Since the same sample point does not exist between frames, motion detection becomes difficult. However, even if the sample points do not match, the MU
Since the SE signal has no sub-sample aliasing component with respect to the low-frequency component, it is possible to detect motion for one frame with respect to the low-frequency component of the image. But,
For the high frequency component of the image, it is necessary to detect the amount of motion from the difference between the two frames where the sample points match.

[0008] Due to the nature of such a MUSE signal, the MU
The conventional motion detection circuit 2 in the SE decoder is configured as shown in FIG. Here, the configuration and operation of the conventional motion detection circuit 2 will be described. In FIG. 6, a MUSE signal S0 input from an input terminal 10 is sequentially input to frame memories 11 and 12, and a signal S2 delayed by one frame and a signal S4 delayed by two frames are obtained. The signal S0 of the current frame and the signal S4 of two frames before are input to the subtractor 13, and the difference between them is obtained. The output of the subtractor 13 is input to an absolute value (ABS) circuit 14 and converted into an absolute value, thereby obtaining a two-frame detection signal Δ04 which is a motion detection component between two frames. The two-frame detection signal Δ04 is stored in the field memories 21, 22, 2
3 and sequentially delayed by one field
15, Δ26 and Δ37 are obtained.

On the other hand, the subtracter 15 receives the signal S0 of the current frame and the signal S2 of the previous frame, and calculates the difference between them. The output of the subtractor 15 is input to a low-pass filter (LPF) 16 to extract only low-frequency components. The output of the LPF 16 is input to an absolute value (ABS) circuit 17 and converted into an absolute value, thereby obtaining a one-frame detection signal Δ02 which is a motion detection component between one frame. This one-frame detection signal Δ02 is input to the field memory 24, and a signal Δ13 delayed by one field is obtained.

The two-frame detection signal .DELTA.04 obtained as described above and the delayed signals .DELTA.15, .DELTA.26, .DELTA.
37, the one-frame detection signal Δ02 and the signal Δ13 obtained by delaying the one-frame detection signal Δ02 are input to the arithmetic circuit 25, and the final motion detection signal k is generated. The arithmetic circuit 25 receives, for example, the input signal groups Δ04, Δ15, Δ26, Δ37, and Δ0.
2, and the maximum value at the time of Δ13 is output.

The operation of the above-described conventional motion detection circuit 2 will be further described with reference to a waveform diagram shown in FIG.
In FIG. 7, it is assumed that the object is moving in the direction of the arrow. S
7, S6, S5, S4, S3, S2, S1, S0 are signals from the previous seven fields to the current field, respectively.
The objects are X7, X6, X5, X4, X3, X2
X1, X0. When the object is a low-frequency component image, the one-frame detection signal Δ02 and the two-frame detection signal Δ04 are as illustrated. Note that the fact that the one-frame detection signal Δ02 is a low-frequency component is illustrated by a semicircle. One-frame detection signal Δ02 is the absolute value of the low-frequency component of the difference between signal S0 and signal S2, and two-frame detection signal Δ04 is the absolute value of the difference between signal S0 and signal S4.

Signals Δ15 and Δ2 obtained by delaying the two-frame detection signal Δ04 by one to three fields
6, Δ37, and the signal Δ13 obtained by delaying the one-frame detection signal Δ02 by one field are as shown in the figure. The final motion detection signal k having the maximum value at each point in these signals is as shown in the figure. That is, when the detection signal k is expressed by an equation, k = max (| f (S2-S0) |, | f (S3-S1) |, | S4-S0 |, | S5-S1 |, | S6-S2 | , | S7−S3 |) (2) Here, f () is a transfer function of the LPF 16,
max () means a function for extracting the maximum value of the arguments.

As described above, the maximum value of the detection signals for four fields is used because the still image processing of the MUSE decoder synthesizes the signals with a total of four fields of the field three fields before the current field. This is because moving image processing must be performed when motion is detected in any of the four fields. That is, if the motion detection signal is lost in any one of the fields, the image portion becomes a multiplex image.

[0014]

By the way, at present, MU
The main signal sources of the SE system include satellite broadcasting and laser disks. The biggest difference between the two signal sources is the presence or absence of special reproduction. In the case of a laser disk, special playback such as pause, frame advance, fast forward, and the like can be performed, whereas a broadcast system has no feature. In the trick play, a problem is particularly caused in the case of a pause. Hereinafter, this problem will be described.

In the MUSE system, since the sampling pattern has a period of four fields, in order to reproduce an original still image during a pause, the laser disk needs to repeatedly output signals for four fields. But,
If there is a moving object in the image, that portion is detected as a motion, and the image that moves in a four-field cycle flickers, making the viewer uncomfortable and giving the viewer discomfort. In the case of such pause reproduction, even if a moving object becomes a multiplex image, no motion is detected, and it is preferable that the moving object is always processed as a still image.

How an object moving during a pause is reproduced will be described with reference to FIG. FIG. 8 shows a case where the temporary stop occurs at the timing of the signals S0 to S3 in FIG. At this time, 8
The signals S0 to S7 for the fields (four frames) simply repeat the signals for four fields in a state where the object is located at X0 to X3.

Next, the conventional motion detection circuit 2 in this state
Explain the behavior of Since the positions of the objects match between the two frames, the difference between the two frames is not output, and the two-frame detection signal Δ04 and the signals Δ15, Δ26, and Δ37 obtained by delaying them are all “0”. However, since the position of the object is different between one frame, a one-frame detection signal Δ02 is obtained. Since both the one-frame detection signal Δ02 and the delayed signal Δ13 have a value, the final motion detection signal k is as shown in the figure. That is, the object is processed as a moving image, and the positions of X0 to X3 are repeatedly reproduced. As described above, in the MUSE decoder provided with the conventional motion detection circuit 2, no special consideration was given to the special reproduction of the recording medium such as the laser disk, and thus the flicker occurred at a four-field cycle during the pause reproduction. There is a problem that an unsightly image is given.

The present invention has been made in view of the above problems, and provides a motion detection circuit capable of obtaining a good pause reproduction image when a recording medium such as a laser disk is paused and reproduced. The purpose is to:

[0019]

According to the present invention, in order to solve the above-mentioned problems of the prior art, sub-sampling is performed between two frames , and a multiplex period of an audio signal is set as an audio data period.
A motion detection circuit used in a device that decodes a predetermined television signal. The motion detection circuit calculates a difference between the input television signal and a signal obtained by delaying the television signal by two frames, and calculates a difference between the two signals by using a motion detection component between two frames. A two-frame detecting means for obtaining a certain two-frame detection signal, and obtaining a one-frame detection signal which is a motion detection component between one frame by calculating a difference between the input television signal and a signal obtained by delaying the one-frame signal. A signal obtained by reproducing the television signal in a motion detection circuit having frame detection means;
Audio signal detection means for detecting whether or not an audio signal that should be included in the audio data period is included in the audio data period;
The case where it contains no speech signal is detected in,
The present invention provides a motion detection circuit characterized by comprising a blocking means for blocking a one-frame detection signal by the one-frame detection means.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a motion detection circuit according to the present invention will be described with reference to the accompanying drawings. FIG. 1 is a block diagram showing an embodiment of a motion detection circuit according to the present invention, FIG. 2 is a block diagram showing a first configuration example of an audio signal detection circuit 31 in FIG. 1, and FIG. 3 is an audio signal detection in FIG. FIG. 4 is a block diagram showing a second configuration example of the circuit 31, and FIG. 4 is a waveform diagram for explaining the operation of the motion detection circuit of the present invention. In FIG. 1, the same parts as those in FIG. 6 are denoted by the same reference numerals.

In FIG. 1, a MUSE signal S0 input from an input terminal 10 is sequentially input to frame memories 11 and 12, and a signal S2 delayed by one frame and a signal S4 delayed by two frames are obtained. The signal S0 of the current frame and the signal S4 of two frames before are input to the subtractor 13, and the difference between them is obtained. The output of the subtractor 13 is input to an absolute value (ABS) circuit 14 and converted into an absolute value.
A two-frame detection signal Δ04, which is a motion detection component between two frames, is obtained. The two-frame detection signal Δ04 is sequentially input to the field memories 21, 22, and 23, and signals Δ15, Δ26, and Δ37 delayed by one field are obtained.

On the other hand, the subtractor 15 receives the signal S0 of the current frame and the signal S2 of the previous frame, and calculates the difference between them. The output of the subtractor 15 is input to a low-pass filter (LPF) 16 to extract only low-frequency components. The output of the LPF 16 is input to an absolute value (ABS) circuit 17 and converted into an absolute value, thereby obtaining a one-frame detection signal Δ02 which is a motion detection component between one frame. This one-frame detection signal Δ02 is input to the field memory 24, and a signal Δ13 delayed by one field is obtained. One-frame detection signal Δ02 output from absolute value circuit 17
Is input to the terminal a of the switch 321 in the switching circuit 32 newly provided according to the present invention. The signal Δ13 output from the field memory 24 is
Is input to the terminal a of the switch 322 in FIG. The terminals b of the switches 321 and 322 in the switching circuit 32 are grounded. The switching circuit 32 is switched by the audio signal detection circuit 31 as described later.

The two-frame detection signal Δ04 obtained as described above and the delayed signals Δ15, Δ26, Δ
37 is input to the arithmetic circuit 25. The switching circuit 32
Are the signals δ02 and δ13, respectively, these signals δ02 and δ13 are also input to the arithmetic circuit 25. The signals δ02, δ13 are either the one-frame detection signal Δ02, the signal Δ13, or no signal. The arithmetic circuit 25 includes, for example, the input signal groups Δ04, Δ15, Δ26, Δ37, δ02, δ13.
By outputting the maximum value at each time point, a final motion detection signal k is generated.

Further, the MU input from the input terminal 30
The SE signal (same as the signal S0 input from the input terminal 10) is input to the audio signal detection circuit 31, and it is detected whether the MUSE signal includes MUSE audio data. When the audio signal detection circuit 31 detects that the audio data is included in the MUSE signal, the audio signal detection circuit 31 controls the switching circuit 32 so that the switches 321 and 322 are connected to the terminal a. When detecting that no audio data is included, the audio signal detection circuit 31 controls the switching circuit 32 so that the switches 321 and 322 are connected to the terminal b.

This utilizes the fact that audio data is not included during special reproduction on a laser disc,
The E decoder side is based on the fact that the special reproduction state can be identified by the presence or absence of audio data.

Here, the operation of the motion detection circuit of the present invention while the laser disk is temporarily stopped will be described with reference to FIG. FIG. 4 shows a temporary stop signal S0 in FIG.
The case where it occurs at the timing of S3 is shown.
At this time, 8 fields (4 frames) related to motion detection
The minute signals S0 to S7 only periodically repeat signals for four fields in a state where the object is located at X0 to X3. Since the position of the object matches between the two frames, the difference between the two frames is not output, and the two-frame detection signal Δ04 and the signal Δ15,
Δ26 and Δ37 are all “0”. Since the position of the object is different between one frame, one frame detection signal Δ0
2 (and a delayed signal Δ13) is obtained.

However, during the pause, the audio signal detection circuit 31 detects that no audio data is included in the MUSE signal as described above, and thereby the switching circuit 32
Control the switching circuit 32 so that the switches 321 and 322 are connected to the terminal b, δ02 and δ13 output from the switching circuit 32 become “0”. As a result, the final motion detection signal k becomes "0" as shown in FIG.

The reason why the two-frame detection signal Δ04 is not interrupted is as follows. That is, special reproduction of a laser disk includes not only pause but also search reproduction such as slow reproduction, fast forward and rewind. In these special reproductions, it is preferable that motion is detected. However, in the detection by the audio signal detection circuit 31, the pause and the other special reproduction cannot be distinguished, so that the two-frame detection signal Δ04 is not interrupted. In this way, no motion is detected in pause reproduction, and motion is detected in slow reproduction and search reproduction.

Next, a specific configuration of the audio signal detection circuit 31 will be described. The audio signal detection circuit 31 is configured as shown in FIG. 2 as an example. In FIG. 2, a MUSE signal input from an input terminal 30 is a comparator 311, 31.
2 is input. The comparator 311 compares the input MUSE signal with the threshold TL, and outputs 1 when the MUSE signal is equal to or smaller than the threshold TL. The comparator 312 receives the input MUS
The E signal is compared with the threshold value TH, and the MUSE signal is compared with the threshold value TH.
In this case, 1 is output. These comparators 311 and 312
Is input to an OR gate 313 and is ORed. The output of the OR gate 313 is input to one terminal of the AND gate 315. The audio period gate pulse output from the audio period gate pulse generation circuit 314 is input to the other terminal of the AND gate 315, and the logical product of these input signals is obtained. Thereby, the OR gate 3
13 is limited to only the audio data period.

The output of the AND gate 315 is the counter 31
7 is input to the enable terminal (EN). Counter 3
The field pulse output from the field pulse generation circuit 316 is input to the clear terminal (CLR) 17 and is reset for each field by the line number 2 and the line number 564 before the start of the audio data period. The counter 317 increments (+1) the count value (Q) in units of 16.2 MHz clock only when 1 is input to the enable terminal. The output of the counter 317 operating in this way is input to the comparator 318,
This is compared with the set value Tc. If the input count value is equal to or greater than the set value Tc, the comparator 318 determines that audio data is included and outputs 1. Note that the comparator 318
The reason for comparing the output of the counter 317 with the set value Tc is to prevent erroneous determination due to noise, and the set value Tc may be set to about 1/10 of the total number of samples in the audio data period.

By the way, in the current MUSE type laser disk player, the line numbers 3 to 46 and the line numbers 565 to 60 in the MUSE signal are set so that the sound decoded at the time of the special reproduction does not erroneously generate noise.
The audio data portion assigned to 8 is replaced with a fixed level (128 out of 256 tones). On the other hand, when the audio signal is included in the normal reproduction, based on the encoded audio data, the ternary level (21 + ／, 128,234+
2/3) are moderately distributed.

Therefore, the threshold value TL input to the comparator 311
Is set to a value between 21 + ／ and 128 (for example, 75), and the threshold values TH 128 and 234+
If the value is between 2/3 (for example, 181), if audio data is present, data below the threshold value TL or data above the threshold value TH is detected. Data exceeding the threshold value TH will not be detected. Threshold values TL and TH of comparators 311 and 312
Is set in this way, if audio data is present, the counter 317 is incremented and the comparator 318 is incremented.
When the audio data is set to a fixed level during special reproduction, the counter 317 is not incremented, and the comparator 318 obtains a determination value 0.

As described above, the audio signal detection circuit 31
By detecting whether or not data equal to or less than the threshold value TL or equal to or greater than the threshold value TH exists in the audio data period, the presence or absence of an audio signal can be detected. When the output of the audio signal detection circuit 31 (comparator 318) is 1, the arithmetic circuit 25 sends the one-frame detection signal Δ02
In addition, the switches 321 and 322 in the switching circuit 32 are controlled so as to be connected to the terminal a so as to supply the signal Δ13 delayed therefrom. The audio signal detection circuit 31 (comparator 3
When the output of 18) is 0, the switches 321 and 3 in the switching circuit 32 are controlled so as not to supply the one-frame detection signal Δ02 and the signal Δ13 obtained by delaying the one-frame detection signal Δ02 to the arithmetic circuit 25.
22 is connected to the terminal b.

Further, another example of the configuration of the audio signal detection circuit 31 will be described with reference to FIG. Audio signal detection circuit 3
The first configuration example uses an existing audio decoding processing circuit 6 (shown in FIG. 5). In FIG. 3, the MUSE signal of 16.2 MHz rate input to the input terminal 30 is input to the frequency conversion circuit 61 and is output at 12.15 MHz.
The sampling frequency is converted to a rate. This is because the MUSE audio signal is actually multiplexed at a rate of 12.15 MHz. The output of the frequency conversion circuit 61 is input to a ternary-binary conversion circuit 62, which converts data from a binary sample having a ternary level into binary 3-bit data. The output of the ternary-to-binary conversion circuit 62 is the time expansion circuit 6
3 and time-division-compressed data is expanded into a signal having a uniform bit rate (1.35 Mbps).
The output of the time decompression circuit 63 is input to the block deinterleave circuit 64, and the signal that has been block-interleaved on the transmission side is restored to prevent continuation of bit errors. The signal obtained by this is an audio bit stream signal (bit rate is 1.35 Mbps)
It is.

This audio bit stream signal is a DPC
DPCM decoding circuit 65 for restoring an M-encoded signal, control signal extracting circuit 6 for extracting various control signals
6. Synchronization detection circuit 67 for synchronizing audio frames
Is input to Various control signals are input from the control signal extraction circuit 66 to the DPCM decoding circuit 65, and an audio synchronization signal is input from the synchronization detection circuit 67 to decode the DPCM encoded signal. The output of the DPCM decoding circuit 65 is input to a D / A converter 68 and converted into an analog audio signal.

As can be seen from the format of the audio bit stream signal in the MUSE system shown in FIG.
In this bit stream, a frame synchronization signal (16-bit pattern,
0001001101011110)
Is inserted. The synchronization detection circuit 67 detects whether or not this frame synchronization signal (voice synchronization signal) exists in one frame cycle. The synchronization signal is detected in one frame period when the audio signal exists, but is not detected when the audio signal does not exist. Even if a coincident pattern is detected,
The probability of appearing in the frame period is almost zero. Therefore, it is possible to recognize whether or not it is the special reproduction by detecting the synchronization of the audio bit stream signal.

Since the synchronization detection circuit 67 is used for the timing of extracting the control signal and the DPCM data and for muting processing for preventing unnecessary noise from being generated when there is no audio signal, the MUSE audio decoder is used in the MUSE audio decoder. The synchronization detection circuit 67 always exists, and the signal detected here can be used as it is for controlling the switching circuit 32. That is, the synchronization detection circuit 67 included in the audio decoding processing circuit 6 can be used as the audio signal detection circuit 31.

The two configuration examples of the audio signal detection circuit 31 described above can detect the presence or absence of an audio signal with a very simple configuration. However, the gist of the present invention is to judge whether or not special reproduction is performed based on the presence or absence of an audio signal and to control the detection for one frame based on the presence or absence of the audio signal. May be detected.

[0039]

As described in detail above, the motion detection circuit according to the present invention is capable of reproducing the sound of a television signal.
In the data period, audio signal detection means for detecting whether or not an audio signal that should be included is included, and it is detected by the audio signal detection means that the television signal contains no audio signal. In such a case, since a blocking means for blocking the one-frame detection signal by the one-frame detection means is provided, when the recording medium such as a laser disk is paused and reproduced, a good paused reproduction image without flicker is obtained. It has the feature of being able to.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is a block diagram illustrating a first configuration example of an audio signal detection circuit 31 in FIG. 1;

FIG. 3 is a block diagram illustrating a second configuration example of the audio signal detection circuit 31 in FIG. 1;

FIG. 4 is a waveform chart for explaining the operation of the present invention.

FIG. 5 is a block diagram illustrating a schematic configuration of a MUSE decoder.

FIG. 6 is a block diagram showing a conventional example.

FIG. 7 is a waveform chart for explaining the operation of the conventional example.

FIG. 8 is a waveform chart for explaining a problem of the conventional example.

FIG. 9 is a diagram showing a configuration of a MUSE signal.

FIG. 10 is a diagram illustrating a configuration of an audio bit stream of a MUSE signal.

[Explanation of symbols]

 11, 12 Frame memory 13, 15 Subtractor 14, 17 Absolute value circuit 16 Low-pass filter 21, 22, 23, 24 Field memory 25 Operation circuit 31 Audio signal detection circuit 32 Switching circuit (cutoff means)

Claims (3)

(57) [Claims] 1. An audio signal subsampled between two frames.
The multiplex period of the signal is predetermined as the audio data period.
That a motion detection circuit for use in apparatus for decoding a television signal, the inputted television signal and which is a motion detection component between 2 frames obtains the difference between the two-frame delayed signal 2 frame detection A two-frame detecting means for obtaining a signal, a one-frame detecting means for obtaining a one-frame detection signal which is a motion detection component between one frame by calculating a difference between the input television signal and a signal obtained by delaying the one-frame signal. in the motion detection circuit wherein the audio data signal obtained by reproducing the television signal
An audio signal detecting means for detecting whether or not an audio signal that should be included in the period is included; and an audio signal is not included in the audio data period by the audio signal detecting means. A motion detecting circuit for detecting a one-frame detection signal by the one-frame detecting means. Wherein said audio signal detecting means includes means for signal before Kion voice data period to detect whether or not a fixed level, means for determining that the information does not include an audio signal when a fixed level 2. The motion detection circuit according to claim 1, comprising: Wherein the speech signal detecting means, means for determining and means for detecting a signal audio synchronization from the signal before Kion voice data period, and contains no speech signal when not detecting audio synchronization signal 2. The motion detection circuit according to claim 1, comprising: