JPH10276452A - Recording and reproducing device for video signal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simply record color video information. SOLUTION: A 1st digital processing part 13 generates luminance data Y and color difference data U and V from video data D1, divides the data Y into two, outputs them as division luminance data Y1 and Y2, synthesizes the data U and V and outputs a composite color difference signal C. A modulator 15 modulates compression luminance data y1 and y2 and compression color difference data c which are undergone compression processing by a JPEG encoder 14 and outputs luminance modulation signals m1 and m2 and a color difference modulation signal mc. A clock synthesizing circuit 18 superimposes a reference clock CK on a sound signal S0 and outputs a hybrid sound signal S1. A recording/reproducing part 16 parallelly records the signals m1, m2 and mc together with the signal S1 on 1st to 4th recording tracks of a magnetic tape 30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal recording / reproducing apparatus which can compress a video signal for displaying a color screen and record it on a magnetic recording medium.

[0002]

2. Description of the Related Art In a solid-state imaging device such as a television camera using a CCD image sensor, timings of horizontal scanning and vertical scanning of an image sensor are set based on various synchronization signals according to a predetermined television system.
As a result, a video signal in which video information for one screen continues in a predetermined order is generated.

FIG. 10 is a block diagram showing a basic configuration of an image pickup apparatus using a CCD image sensor.
Is a timing chart for explaining the operation. The frame transfer type CCD image sensor 1 includes an imaging unit 1i, a storage unit 1s, a horizontal transfer unit 1h, and an output unit 1d. The imaging unit 1i is composed of a plurality of CCD shift registers that are continuous in a vertical direction and are parallel to each other. Each bit of the shift register constitutes a light receiving pixel, and stores information charges generated during an imaging period. The storage unit 1s
It consists of a plurality of CCD shift registers that are consecutive to the shift register of the imaging unit 1i and have the same number of bits, and each bit of these shift registers temporarily stores information charges transferred and output from each light receiving pixel of the imaging unit 1i. accumulate.
The horizontal transfer unit 1h is composed of a single CCD shift register in which the output of each shift register of the storage unit 1s is combined with each bit, and sequentially outputs information charges transferred and output from the storage unit 1s in units of one horizontal line. Transfer to 1d side. The output unit 1d includes a capacitor that receives information charges on the output side of the horizontal transfer unit 1h, receives information charges transferred and output from the horizontal transfer unit 1h, and outputs a voltage value corresponding to the charge amount. The change in the voltage value output here becomes the image signal I0.

The drive circuit 2 includes a frame clock generator 2
f, vertical clock generator 2v, horizontal clock generator 2h
And a reset clock generator 2r. The frame clock generation unit 2f generates a frame clock φf in response to the frame shift timing signal FT, and supplies the frame clock φf to the imaging unit 1i. As a result, information charges accumulated in each light receiving pixel of the imaging unit 1i are transferred at high speed to the accumulation unit 1s for each vertical scanning period. The vertical clock generation unit 2v generates a vertical clock φv in response to the vertical synchronization signal VT and the horizontal synchronization signal HT, and supplies the generated vertical clock φv to the storage unit 1s. As a result, in the storage unit 1s, the information charges transferred and output from the imaging unit 1i are taken in and temporarily stored, and the stored information charges are transferred to the horizontal transfer unit 1h in units of one horizontal line during each horizontal scanning period. Transferred to Horizontal clock generator 2h
Is the horizontal transfer clock φh in response to the horizontal synchronization signal HT.
Is generated and supplied to the horizontal transfer unit 1h. This gives 1
The information charges taken into the horizontal transfer unit 1h from the storage unit 1s for each horizontal line are sequentially transferred and output to the output unit 1d side. The reset clock generation unit 2r generates a reset clock φr for sequentially discharging the information charges of the output unit 1d in synchronization with the operation of the horizontal clock generation unit 2h, and supplies the reset clock φr to the output unit 1d. As a result, information charges output from the horizontal transfer unit 1h to the output unit 1d are accumulated in units of one pixel.

The timing control circuit 3 operates on the basis of a reference clock having a fixed period, generates a vertical synchronizing signal VT and a horizontal synchronizing signal HT for determining each timing of the vertical scanning and the horizontal scanning of the image sensor 1, and generates a driving circuit. Supply to 2. At the same time, a frame shift timing signal FT is generated with a period that matches the vertical synchronization signal VT, and is supplied to the drive circuit 2. The timing control circuit 3 discharges the information charges of the imaging unit 1i in the middle of the vertical scanning period according to the amount of the information charges generated in the imaging unit 1i in order to keep the exposure state of the image sensor 1 optimal. Shutter control is performed. That is, if the timing of the shutter operation is advanced, the period until the start of the frame transfer becomes longer, and the information charges are accumulated in the imaging unit 1i for a longer period. Conversely, if the timing of the shutter operation is delayed, the period until the start of frame transfer is shortened, and information charges are accumulated in the imaging unit 1i in a short period. Regarding the shutter operation of discharging the information charges of the imaging unit 1i,
This is executed by the action of a drive clock supplied from the drive circuit 2 to the image sensor 1.

The video signal I0 obtained as described above
Is for repeatedly displaying a subject image at a frame rate according to the vertical synchronization signal VT in units of one screen, and is supplied to a well-known television monitor or recording device.

[0007]

In computer equipment such as a personal computer, it has been considered to take in a video signal obtained from an image pickup device as digital video data and display it on a monitor screen. In general computer equipment, the image from the imaging device is rarely displayed on the entire monitor screen, and in most cases,
An image from the imaging device is reduced and displayed on a part of the monitor screen. As a video format corresponding to such a display method, VGA (Video Graphic Arr.
ay) The CIF (Common Intermediate Format) standard (35%) which is about 1/4 the size of the standard (640 × 480 pixels)
2 × 240 pixels) or the QCIF (Quarter CIF) standard (176 × 120
Pixel). These standards are becoming standard in the communication field of computer equipment.

[0008] In an image pickup apparatus corresponding to the CIF standard or the QCIF standard, the number of pixels of the image sensor is configured in accordance with each standard, and the image pickup apparatus corresponding to a general television system such as NTSC or PAL is used. In comparison, cost reduction in the imaging unit can be achieved. In an imaging device conforming to these CIF standards and QCIF standards,
Since a dedicated recording method such as the VHS method corresponding to the NTSC method has not been proposed, one problem is how to record a video signal. Generally, after a video signal is converted into a digital signal, it is taken into a computer device according to a predetermined format and recorded on a recording medium built in (or connected to) the computer device. However, when the video signal is taken into the computer device from the imaging device,
The imaging device and the computer device must be connected at all times, causing a problem that the usability of the imaging device is not good.

It is therefore an object of the present invention to enable a video signal having a small number of pixels per screen to be easily recorded using a magnetic tape.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and records a video signal indicating a continuous video in one screen unit on a magnetic recording medium having a plurality of recording tracks. Video signal recording and playback device,
A video supply source for continuously supplying video data individually representing a plurality of pixels each corresponding to a specific color component corresponding to the video signal, and a continuous supply of an audio signal corresponding to the video signal And a luminance data associated with each pixel based on the video data. The generated luminance data is divided into two, and a pair of divided luminance data is output in parallel. A processing unit that generates two types of color difference data associated with every four pixels based on the above, and alternately combines the generated two types of color difference data in a predetermined unit to output composite color difference data; A compression encoder that performs a compression process on the luminance data and the composite chrominance data according to a predetermined algorithm to generate a pair of compressed luminance data and compressed chrominance data; A modulation circuit that analog-modulates the pair of compressed luminance data and the compressed color difference data to generate a pair of luminance modulation signal and color difference modulation signal, and generates a mixed audio signal by superimposing a fixed period timing clock on the audio signal. And a recording circuit for writing the pair of the luminance modulation signal and the color difference modulation signal together with the hybrid audio signal into the first to fourth recording tracks of the magnetic recording medium in parallel. I have.

According to the present invention, two luminance modulation signals generated from a luminance signal and one color difference modulation signal generated by synthesizing two types of color difference signals together with an audio signal including a timing clock are combined with a magnetic signal. The data is recorded on the first to fourth recording tracks arranged in parallel on the recording medium. A luminance signal with a large amount of information is divided into two to reduce the frequency, and a color difference signal with a small amount of information is recorded on one recording track by combining two types. In addition, a timing clock in a high frequency band that matches the modulation cycle of the luminance modulation signal and the color difference modulation signal is superimposed on the audio signal having a small high frequency component, and is recorded on one recording track. As a result, a video signal for displaying a color video can be recorded using an audio cassette tape which usually has four recording tracks. At the same time, even if the playback speed of the cassette tape becomes unstable during playback, the luminance modulation signal and the color difference modulation signal can be correctly demodulated based on the timing clock superimposed on the audio signal.

Further, according to the present invention, there is provided a reproducing section for reading out a pair of a luminance modulation signal, a color difference modulation signal and a hybrid audio signal from the first to fourth recording tracks of the recording medium, respectively. A clock separation unit that independently extracts the timing clock, and performs demodulation processing on the pair of the luminance modulation signal and the color difference modulation signal at a timing according to the timing clock;
A demodulator that generates a pair of compressed luminance data and compressed chrominance data; and performs a decompression process on the pair of compressed luminance data and the compressed chrominance data according to the same algorithm as the compression encoder to generate a pair of divided luminance data and a composite. And a decompression decoder for reproducing color difference data.

According to the present invention, two luminance modulation signals read from the magnetic recording medium are combined to generate a luminance signal, and the color difference modulation signal is divided to generate two types of color difference signals. At the same time, a mixed audio signal

[0014]

FIG. 1 is a block diagram showing a configuration of a video signal recording / reproducing apparatus according to the present invention. The imaging unit 10 has the same configuration as the imaging device shown in FIG. 10, and includes a timing control circuit, a driving circuit, and an image sensor. In this imaging unit 10, the image sensor
For example, in compliance with the QCIF standard, 176 horizontal x 12 vertical
0 pixels are arranged. As a result, a video signal I0 in which one horizontal line includes 176 pixels and one screen includes 120 lines is output. In addition, a mosaic-type color filter is attached to the imaging unit of the image sensor of the imaging unit 10 so that each light receiving pixel is associated with a predetermined color component. In the mosaic type color filter, for example, as shown in FIG. 2, white (W) and green (G) are alternately assigned to segments in odd rows, and cyan (Cy) and yellow (Ye) are assigned to segments in even rows. Are assigned alternately.
Therefore, the video signal I0 includes a color component corresponding to the arrangement of each segment of the color filter.

The analog processing unit 11 includes an image pickup unit 10
In synchronization with the output operation, the video signal I0 input from the imaging unit 10 is subjected to analog signal processing such as sample hold and gamma correction to output a video signal I1 according to a predetermined format. For example, in the sample and hold process, only the signal level is extracted from the video signal I0 in which the reset level and the signal level are repeated in synchronization with the output operation of the image sensor of the imaging unit 10. In the gamma correction processing, nonlinear conversion is performed on a signal level sampled and held so as to correct a human visual deviation from the emission luminance of the reproduction screen.

The A / D converter 12 includes an analog processing unit 11
At the same time, in synchronization with the output operation of the imaging unit 10, the video signal I1 input from the analog processing unit 11 is converted into digital data to generate video data D1. The video data D1 generated by the A / D converter 12 is associated with each light receiving pixel of the image sensor of the imaging unit 10, and represents the amount of information charge accumulated in each light receiving pixel.

The first digital processing unit 13 performs predetermined arithmetic processing on the video data D1 input from the A / D converter 12, and outputs color data R representing each of red and blue components of the three primary colors. , B and luminance data Y in which each color component is synthesized at a predetermined ratio. Here, in the generation of the luminance data Y, the respective color components are combined such that the color components of the three primary colors are at a predetermined ratio, for example, red: green: blue is 1: 2: 1 in all the light receiving pixels. . Then, the color data R,
In generating B, a well-known color operation is performed for every four pixels. For example, when the color components of the video data D1 include yellow (Ye), cyan (Cy), green (G), and white (W) corresponding to the color filter shown in FIG.
Color data R representing a red component by subtracting + Cy
Is generated, and G + Ye is subtracted from W + Cy to generate color data B representing a blue component. As a result, the same number of luminance data Y as all the light receiving pixels of the image sensor of the imaging unit 10 and そ の of the color data R and B are generated. Then, by subtracting the luminance data Y from each of the color data R and B, two types of color difference data U and V are generated. At this time, since the number of each of the color data R and B is １ ／ of the number of the luminance data Y, every third luminance data Y is extracted and subtracted from each of the color data R and B, or The average value of every four is subtracted from each color data R, B.

Further, the first digital processing unit 13 temporarily buffers the luminance data Y, and
Processing unit (8 rows x 8) at the time of compression processing by the encoder 14
Column), and a pair of divided luminance data Y1, Y2
And output in parallel. At the same time, the chrominance data U and V are temporarily buffered, and are alternately taken out in the processing unit at the time of the compression processing by the JPEG encoder 14 and output as composite chrominance data C. Here, the output rates of the divided luminance data Y1, Y2 and the composite chrominance data C match each other because the data amounts of the chrominance data U, V are each 1/4 of the data amount of the luminance data Y. Become. The digital processing unit 13 uses JPEG
In order to cope with the compression processing by the encoder 14, one screen is divided into a plurality of blocks each having 8 rows × 8 columns of pixels, and each data is output in units of the blocks.

The JPEG encoder 14 applies JPEG (Joi) to the divided luminance data Y 1 and Y 2 and the composite chrominance signal C input from the first digital processing unit 13 in block units.
(nt Photographic Expert Group). This compression processing is performed on the divided luminance data Y1,
The processing is performed independently on the Y2 and the composite color difference signal C, and the processing is performed in parallel by three processing circuits, or the processing is performed by operating one processing circuit in a time-division manner. Thereby, the divided luminance data Y
Compressed luminance data y1, y2 and compressed chrominance data c corresponding to 1, Y2 and composite chrominance signal C, respectively, are output.

The modulator 15 performs analog modulation on the compressed luminance data y1, y2 and the compressed chrominance data c input from the JPEG encoder 14, and outputs luminance modulation signals m1, m2 and chrominance modulation signals recordable on a magnetic recording medium. The signal is supplied to the recording / reproducing unit 16 as a signal mc. In the modulator 15, since the array of digital data "1" and "0" is analog-modulated in association with the amplitude, one cycle of each modulation signal represents 2-bit data.

The transmitting unit 20 includes a microphone and an amplifier, and outputs a voice captured when capturing an image of a subject as a voice signal S0. Usually, this transmission unit 20
Are arranged in parallel with the imaging unit 10. As shown in FIG. 3A, the clock synthesizing unit 18 includes a low-pass filter 18a and an adder 18b, captures the audio signal S0 input from the transmission unit 20 through the low-pass filter 18a, and is shared by the adder 18b. Reference clock C
K is superimposed and output as a hybrid audio signal S1. Here, the reference clock CK is synchronized with the output operation of the compressed luminance data y1, y2 and the compressed color difference data c from the JPEG encoder 14, and is synchronized with the luminance modulation signals m1, m2 and the color difference modulation signal mc. In the case of a normal audio signal, a frequency component exceeding 10 KHz is difficult to be recognized by human hearing. Therefore, even if the cut-off frequency of the low-pass filter passed when capturing the audio signal S0 is set to 10 KHz, it is almost impossible for a human to hear. No change. On the other hand, the frequency of the reference clock CK is, as described later, the luminance modulation signal m.
Since the frequency is approximately 20 KHz, which is equivalent to 1, m2 and the color difference modulation signal mc, the frequency band can be separated between the audio signal S0 and the reference clock CK.

The recording / reproducing section 16 is connected to the magnetic head 17 and has a luminance modulation signal m 1 inputted from the modulator 15.
The m2, the color difference modulation signal mc, and the hybrid audio signal S1 input from the clock synthesizing section 18 are written in parallel on the four recording tracks of the magnetic tape 30 by the magnetic head 17 for recording. For example, as shown in FIG.
The luminance modulation signals m1 and m2 corresponding to 1 and y2 are successively recorded on the first and second recording tracks by one block (64 pixels), and the color difference modulation signal mc corresponding to the compressed color difference data c is converted to the third signal. Recorded on the recording track. At this time,
In the color difference modulation signal mc, a signal mc-U corresponding to the first color difference data U and a signal mc-V corresponding to the second color difference data V are alternately recorded for each block. Then, the mixed audio signal S1 including the reference clock CK is continuously recorded on the fourth recording track. The recording / reproducing unit 16
The modulation signals m1, m2, mc and the hybrid audio signal S1 are written, and the recorded modulation signals m1, m2, mc and the hybrid audio signal S1 are read out. That is, in the video reproduction operation, each modulation signal m recorded on the magnetic tape 30 is
1, m2, mc and the hybrid audio signal S1 are read out through the magnetic head 17, and the demodulator 1 and the clock separation unit 2 are read out, respectively.
5. This recording / reproducing unit 1
6 writes or reads out the modulation signals m1, m2, mc and the hybrid audio signal S1 to or from the magnetic tape 30 in response to an operation mode that can be arbitrarily switched.

The demodulator 21 demodulates the three-system reproduced signals input from the recording / reproducing unit 16 and reproduces compressed luminance data y1, y2 and compressed chrominance data c, which are digital data. In this modulator 21, a reference clock C supplied from a clock separation unit 25 described later is used.
The demodulation of the modulation signals m1, m2, and mc is performed based on K. Thereby, regardless of the fluctuation of the running speed of the magnetic tape 30, the processing opposite to the modulation processing in the modulator 15 is correctly performed.

The JPEG decoder 22 performs a decompression process on the compressed luminance data y1, y2 and the compressed chrominance data c input from the demodulator 21 by a process reverse to that of the JPEG encoder 14, thereby obtaining divided luminance data Y1, Y2. And the composite color difference data C is restored. The divided luminance data Y1, Y2 and the composite chrominance data C obtained here are basically the same as the divided luminance data Y1, Y2 and the composite chrominance data C generated by the digital processing unit 13.
When the compression ratio of the encoder 14 is set to a large value, the values may not completely match. In the JPEG decoder 22, similarly to the JPEG encoder 14,
The compressed luminance data y1, y2 and the compressed chrominance data c are independently processed, and are processed in parallel by three circuits or in a time-division manner by one circuit.

The second digital processing section 23 temporarily buffers the divided luminance data Y 1 and Y 2 inputted from the JPEG decoder 22 in block units, and
1, Y2 is synthesized and rearranged to generate continuous luminance data Y for each row. At the same time, the composite color difference data C input in units of blocks are sorted and rearranged, and color difference data U and V that are continuous in units of one line are generated. The second
The digital processing unit 23 supplies the luminance data Y and the chrominance data U and V to a computer device according to a predetermined format,
Is supplied to a display 24 for displaying an image. This makes it possible to display and monitor the image read from the magnetic tape 30 on the screen.

As shown in FIG. 3B, the clock separation unit 25 includes a low-pass filter 25a and a high-pass filter 25b, and converts the mixed audio signal S1 input from the recording / reproduction unit 16 into an audio signal through the low-pass filter 25a. S0 is extracted, and the reference clock CK is extracted through the high-pass filter 25b. Here, the cut-off frequency of the low-pass filter 25a is set to be the same as the cut-off frequency of the low-pass filter 18a of the clock synthesizing unit 18. The cut-off frequency of the high-pass filter 25b is determined by the low-pass filter 18 of the clock synthesizing unit 18.
The frequency is set higher than the cutoff frequency a and lower than the frequency of the reference clock CK. For example, the clock synthesizing unit 1
8 has a cutoff frequency of 10
Assuming that the frequency of the reference clock CK is 20 KHz at KHz, the cutoff frequency of the low-pass filter 25a is set to 10 KHz, and the cutoff frequency of the high-pass filter 25b is set to 15 KHz.

The audio reproducing section 26 includes an amplifier and a speaker, and reproduces audio from the speaker in response to the audio signal S0 (not including a frequency component of 10 kHz or more) from which the reference clock CK has been removed by the clock separating section 25. . Thereby, the sound can be reproduced in accordance with the display of the video by the display 24. By the way, when video information is sent to a computer device, a typical data format is a 411 format in which the composition ratio between luminance information and two pieces of color difference information is 4: 1, 1: 2, and the composition ratio is also 4: 2: 2.
422 format. In the case of the 411 format, as shown in FIG. 5, the 8-bit chrominance data U and V are also transmitted in two bits each in one transfer cycle, while the 8-bit luminance data Y is transmitted by one pixel in one transfer cycle. Configured to send. That is, by transmitting one set of color difference data U and V in four cycles of 2 × 2 bits at a time while transmitting one luminance data Y (8 bits) for each transfer cycle, a transfer line of 12 bits in total is obtained. Is used to transfer one set of color difference data U and V to four pieces of luminance data Y. Luminance data Y and color difference data U generated by the second digital processing unit 23,
Since the composition ratio of V is 4: 1: 1, it can be directly transferred to the computer device in the 411 format. In the case of the 422 format,
As shown in FIG. 5, luminance data Y consisting of 8 bits is 1
Two types of color difference data U and V, also composed of 8 bits, are alternately sent every other pixel every other transfer cycle, while being sent one pixel at a time in the transfer cycle. In the 422 format, the composition ratio of the luminance data Y and the color difference data U and V needs to be 4: 2: 2.
It is necessary to double the number of color difference data U and V by interpolating between adjacent pixels using the average value of both pixels.

Here, in the case of complying with the QCIF standard, the data transfer rate in each unit will be considered. QCIF
A screen corresponding to the standard is 176 pixels in the horizontal direction × 120 pixels in the vertical direction. When the video data D1 represents one pixel by 8 bits, the data amount per one screen is 176 × 120 × 8 = 168.96 Kb. Therefore, if the frame rate is 1/15 second, the transfer rate of the video D1 data at the input stage of the first digital processing unit 13 is 168.96K × 15 = 2534.4 Kbps. Since the luminance data Y has the same data amount as the video data D1, and the chrominance data U and V each have a data amount of ４ of the luminance data Y, the output stage of the first digital processing unit 13 The data amount becomes 1.5 times. Since this data is output to the JPEG encoder 14 via three transmission paths, the transfer rate of each transmission path is 2534.4K × 1.5 / 3 = 1267.2 Kbps. Here, if the compression ratio in the JPEG encoder 14 is set to 1/30, at the input stage of the modulator 15,
The transfer rate is 1267.2K / 30 = 42.24Kbps. In the case of an analog signal, two digital data can be represented in one cycle, so that 2 bps corresponds to 1 Hz. As a result, each of the modulation signals m1, m2, and mc input to the recording / reproducing unit 16 is converted. The frequencies are respectively 42.24 K / 2 = 21.12 KHz.

In the case of a general audio cassette tape, the frequency band is up to about 20 KHz, and it is possible to record each modulation signal m1, m2, mc. In the above calculation, all the pixels of 176 horizontal × 120 vertical are valid. However, in the actual imaging unit 10, it is rare to use all the pixels, and several pixels in the peripheral portion are outside the valid image area. Become. For this reason, the data amount per screen is reduced, and even if the frame rate of the imaging unit 10 and the compression rate of the JPEG encoder 14 are the same, the frequency of each of the modulation signals m1, m2, and mc is set to 20K.
Hz or less.

FIG. 6 is a block diagram showing an example of the configuration of the first digital processing unit 13. The first digital processing unit 13 includes a luminance calculation circuit 31, a contour correction circuit 32, a separation circuit 33, a color calculation circuit 34, a color difference calculation circuit 35, and a synthesis circuit 36. The luminance calculation circuit 31 adds the video data D1 corresponding to the adjacent pixel at a predetermined ratio to the video data D1 corresponding to the target pixel, and outputs the three primary colors (R, G,
The luminance data Y including the color component B) at a ratio of 1: 2: 1 is generated. For example, as shown in FIG.
Is obtained by adding そ れ ぞ れ each of video data D1 corresponding to four pixels (A2, B2, C1, C2) vertically and horizontally adjacent to video data D1 corresponding to a target pixel T, and adjoining diagonally. The video data D1 corresponding to the four pixels (A1, A3, B1, B3) are added to each other to generate 1/4. When such an operation is made to correspond to the color filter shown in FIG. 2, in all the pixels, W + G + Ye + Cy = 2R + 4G + 2B = Y, and red (R): green (G): blue (B) is 1: 2: 1. The synthesized luminance data Y can be obtained.

The contour correction circuit 32 generates luminance data Y 'with enhanced contrast by adding the difference between the luminance data Y corresponding to the target pixel and the luminance data Y between the target pixel and its adjacent pixels. For example, as shown in FIG. 7, the average of the difference between the luminance data Y of the target pixel T and the luminance data Y corresponding to the vertically adjacent pixels (A2, B2, C1, C2) is constant. The arithmetic processing is performed such that the values obtained by multiplying the coefficients are added.

The separation circuit 33 rearranges the arrangement order of the luminance data Y 'input from the contour correction circuit 32 from a raster unit that continues one row at a time to a block unit that continues eight rows by eight columns. 1st by alternately sorting every block
And the second divided luminance data Y1 and Y2. That is, the luminance data Y ′ input from the contour correction circuit 32
However, raster / block conversion is performed in units of 8 rows × 8 columns so as to be compatible with the compression processing performed by the JPEG encoder 14 because the data is continuous in units of one line according to the horizontal scanning of the image sensor. Is applied. Then, in order to reduce the data transfer rate, the luminance data Y ′, whose arrangement order has been converted in block units, is divided into odd-numbered blocks and even-numbered blocks so that the data can be output through two transmission lines. It is output as first and second divided luminance data Y1, Y2.

The color calculation circuit 34 takes in the video data D1 in units of four pixels so as to include different color components, performs a predetermined color calculation on each color component, and performs color data R and blue component data corresponding to the red component. Is generated. For example, in the case of a color filter as shown in FIG. 2, four adjacent pixels respectively correspond to W, G, Ye, and Cy. Therefore, the respective color data R and B are generated by the following arithmetic processing. From the sum (W + Ye) of the video data D1 corresponding to W and the video data D1 corresponding to Ye, the color data R is obtained by calculating the video data D1 and Cy corresponding to G.
Is generated by subtracting the sum (G + Cy) with the video data D1 corresponding to. The color data B is calculated from the sum (W + Cy) of the video data D1 corresponding to W and the video data D1 corresponding to Cy from the video data D1 and Y corresponding to G.
It is generated by subtracting the sum (G + Ye) with the video data D1 corresponding to e.

The color difference calculation circuit 35 generates color difference data U and V by subtracting the brightness data Y input from the brightness calculation circuit 31 from the color data R and B input from the color calculation circuit 34, respectively. Here, since the number of data of the color data R and B is ４ of that of the luminance data Y, in the subtraction processing in the color difference calculation circuit 35, every third luminance data Y is taken in, or The average value of the four luminance data Y is taken in.

The synthesizing circuit 36 rearranges the arrangement order of the color difference data U and V input from the color difference calculation circuit 35 from a raster unit which is continuous for each row to a block unit which is continuous for 8 rows × 8 columns. , And blocks corresponding to the two color difference data U and V are alternately extracted and output as composite color difference data C. That is, since the color difference data U and V input from the color operation circuit 35 are continuous in units of one line according to the horizontal scanning of the image sensor, eight lines of color difference data U and V are provided so that the JPEG encoder 14 can support the compression processing. Raster / block conversion is performed so as to be continuous in units of blocks consisting of × 8 columns. The color difference data U is output as an odd-numbered block and the color difference data V is output as an even-numbered block so that the transfer rates of the divided luminance data Y1 and Y2 are matched.

The first digital processing section 13 is connected to a RAM which can be commonly accessed by the circuits 31 to 36, and can hold an appropriate number of rows of data required by the circuits 31 to 36. I have to. FIG. 8 is a block diagram showing a configuration of the JPEG encoder 13 and the JPEG decoder 22. In this figure, a JPEG encoder 13 for processing the divided luminance data Y1 and a JPEG encoder 13 are shown.
Although the decoder 22 is shown, the same circuit configuration is used for the divided luminance data Y2 and the composite chrominance data C.

In the coding system according to the JPEG algorithm, as shown in FIG. 9, one screen is divided into a plurality of blocks in units of 8 × 8 pixels, and coding processing is performed for each block. That is, the data amount is compressed by encoding 64 data representing pixels P11 to P88 for 8 rows × 8 columns constituting each block as one unit. JP
The EG encoder 13 includes a DCT circuit 41, a quantization circuit 4
2 and an encoding circuit 43. And JPE
The G decoder 22 includes a decoding circuit 44, an inverse quantization circuit 45, and an IDCT circuit 46. For the JPEG encoder 13 and the JPEG decoder 22, a quantization table 47 for storing a threshold value for quantization / inverse quantization and a Huffman code for encoding / decoding are stored. The encoding table 48 is connected.

The DCT circuit 41 comprises one block (8 rows × 8
The divided luminance data Y1 corresponding to (column = 64 pixels) is fetched, and the two-dimensional discrete cosine transform (DCT:
Discrete Cosine Transform) is performed to generate 64 DCT coefficients. The quantization circuit 42 quantizes the DCT coefficients supplied from the DCT circuit 41 with reference to the threshold stored in the quantization table 47. The threshold value at the time of quantization determines the compression ratio of image data and the image quality of a reproduced image, and is arbitrarily set according to the purpose of use of the apparatus. The encoding circuit 43 performs variable length encoding on the quantized DCT coefficients based on the Huffman code stored in the encoding table 48, and generates compressed luminance data y1. The Huffman code is a variable-length code that is assigned to a quantized DCT coefficient in accordance with an appearance frequency that is predicted in advance, and is assigned a shorter code to a code with a higher appearance frequency. Therefore, according to the JPEG encoder, the data amount of the image data can be reduced to about 1/40.

The decoding circuit 44 comprises one block (8 rows × 8
The compressed luminance data y1 for the column (64 pixels) is fetched, and the compressed image data is subjected to variable-length decoding based on the Huffman code stored in the encoding table 48, contrary to the encoding circuit 3. The coefficient obtained by this variable length decoding process is
This corresponds to the DCT coefficient quantized by the JPEG encoder 13. The inverse quantization circuit 45 inversely quantizes the coefficient supplied from the decoding circuit 44 with reference to the threshold value stored in the quantization table 47, contrary to the quantization circuit 42,
Regenerate DCT coefficients. And the IDCT circuit 46
For the DCT coefficient supplied from the inverse quantization circuit 45,
Inverse Discrete Cosine Transform (IDCT)
Transform) to reproduce the expanded divided luminance data Y1. In the IDCT circuit 46, data for one block is converted at the same time, and is continuously output in a predetermined order for each pixel.

According to the above embodiment, the video signal is Q
Although the case corresponding to the CIF standard is exemplified, the standard of the video signal is not limited to this, and if the size is up to the CIF standard, it can be recorded on an audio cassette tape as a magnetic recording medium. It is. For the algorithm of the compression processing of each data, in addition to JPEG, MPEG and H.264 are used. 263 or the like can be used.

[0041]

According to the present invention, it is possible to record / reproduce a video signal for displaying a color video by a simple mechanism using an audio cassette tape. Therefore, it is possible to realize an image pickup apparatus capable of recording / reproducing a small-screen video signal suitable for being taken into a computer device at low cost.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a video signal recording / reproducing apparatus of the present invention.

FIG. 2 is a plan view illustrating a configuration example of a mosaic type color filter.

FIG. 3 is a block diagram illustrating a configuration of a clock synthesis unit and a clock separation unit.

FIG. 4 is a diagram showing a recording state of a recording track of a magnetic tape.

FIG. 5 is a diagram showing an output format of video information to a computer device.

FIG. 6 is a block diagram illustrating a configuration of a first digital processing unit.

FIG. 7 is a diagram showing a positional relationship between a target pixel and its adjacent pixels.

FIG. 8 is a block diagram illustrating a configuration of a JPEG encoder and a JPEG decoder.

FIG. 9 is a diagram showing a block configuration of a screen processed by a JPEG algorithm.

FIG. 10 is a block diagram illustrating a configuration of an imaging device.

FIG. 11 is a timing chart illustrating the operation of the imaging apparatus.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 image sensor 1 i imaging unit 1 s storage unit 1 h horizontal transfer unit 1 d output unit 2 driving circuit 2 f frame clock generation unit 2 v vertical clock generation unit 2 h horizontal clock generation unit 2 r reset clock generation unit 3 timing control circuit 10 imaging unit 11 analog processing unit Reference Signs List 12 A / D converter 13 First digital processing unit 14 JPEG encoder 15 Modulator 16 Recording / playback unit 17 Magnetic head 18 Clock synthesis unit 20 Transmission unit 21 Demodulator 22 JPEG decoder 23 Second digital processing unit 24 Display Device 25 Clock separation unit 26 Audio reproduction unit 30 Magnetic tape 31 Brightness calculation circuit 32 Contour correction circuit 33 Separation circuit 34 Color calculation circuit 35 Color difference calculation circuit 36 Synthesis circuit 41 DCT circuit 42 Quantization circuit 43 Encoding circuit 44 Decoding circuit 45 Reverse Coca circuit 46 IDCT circuit 47 quantization table 48 coding table

Claims (4)

[Claims] 1. A video signal recording / reproducing apparatus for recording a video signal indicating a video which is continuous in one screen unit on a magnetic recording medium having a plurality of recording tracks, wherein each of the video signals has a specific color A video source that continuously supplies video data individually representing a plurality of pixels associated with the components, an audio source that continuously supplies an audio signal corresponding to the video signal, And generates a pair of divided luminance data in parallel by dividing the generated luminance data into two parts, and associates the generated luminance data with every four pixels based on the video data. A processing unit that generates two types of color difference data, and alternately combines the two types of generated color difference data in predetermined units to output composite color difference data; and a pair of the divided luminance data and the composite color difference A compression encoder that performs compression processing on the data according to a predetermined algorithm to generate a pair of compressed luminance data and compressed chrominance data; and performs analog modulation on the pair of compressed luminance data and the compressed chrominance data, respectively. A modulation circuit that generates a modulation signal and a color difference modulation signal; a clock synthesis unit that generates a mixed audio signal by superimposing a timing clock having a fixed period on the audio signal; A recording circuit for recording and reproducing a video signal, comprising: a recording circuit for writing each of the first to fourth recording tracks of the magnetic recording medium in parallel with the audio signal. 2. The clock synthesizing section includes a low-pass filter circuit having a cut-off frequency higher than a highest frequency of the audio signal and lower than a frequency of the timing clock. 2. The video signal recording / reproducing apparatus according to claim 1, wherein the hybrid audio signal is generated by superimposing the timing clock. 3. A reproducing unit for reading a pair of a luminance modulation signal, a color difference modulation signal, and a hybrid audio signal from first to fourth recording tracks of the recording medium, respectively, and the audio signal and the timing clock from the hybrid audio signal. A clock separation unit that independently takes out, a demodulator that performs demodulation processing on the pair of luminance modulation signal and color difference modulation signal at a timing according to the timing clock to generate a pair of compressed luminance data and compressed color difference data, A decompression decoder that performs decompression processing on the pair of compressed luminance data and the compressed chrominance data according to the same algorithm as the compression encoder to reproduce a pair of divided luminance data and composite chrominance data. 2. The video signal recording / reproducing apparatus according to claim 1, wherein: 4. The clock synthesizing section includes a low-pass filter circuit having a cutoff frequency higher than a highest frequency of the audio signal and lower than a frequency of the timing clock. The hybrid clock signal is generated by superimposing the timing clock, and the clock separating unit sets a low-pass filter circuit having a cutoff frequency lower than the frequency of the timing clock and a cutoff frequency higher than the highest frequency of the audio signal. 4. The video signal according to claim 3, further comprising: extracting the audio signal from the hybrid audio signal through the low-pass filter, and extracting the timing clock from the hybrid audio signal through the high-pass filter. Recording and playback device.