JP3235268B2 - Rotating head type digital video signal recording / reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary head type digital video signal recording and reproducing apparatus for recording and reproducing digital video signals on a magnetic tape using a rotary head.

[0002]

2. Description of the Related Art Digital video signals generally have a large amount of data.
For example, it is necessary to compress the data by DCT and record the compressed data as a plurality of tracks on a magnetic tape. In a digital VTR, it is preferable that the amount of data recorded on one track is constant in consideration of editing processing.

The applicant of the present application has proposed a digital VTR that uses a DCT to perform a process for equalizing the recording data amount (hereinafter, referred to as a buffering process). Furthermore, when errors occurring during recording / reproduction are dispersed to make them inconspicuous or when performing equal length processing,
Shuffling processing is performed to prevent large variations in distortion between buffering units. The shuffling process is a process of rearranging the spatial position from the original one in a certain unit. More specifically, the buffering unit includes data obtained by collecting areas from various positions of one image.

In a digital VTR, one frame of data is generally recorded as a plurality of tracks. Therefore, when shuffling is used, data of one frame apart from the screen is recorded on each track. Will be.

[0005]

SUMMARY OF THE INVENTION Such a digital VT
With R, there was a problem that the quality of the image during high-speed reproduction was not good. At the time of normal reproduction, one frame image is composed of a series of reproduction data of, for example, ten consecutive tracks, while at the time of high-speed reproduction, one frame image is reproduced data fragmentally from discrete tracks. Composed of FIG. 18 shows a state in which a tape on which one frame of recording data is recorded on ten continuous tracks is reproduced at a tape speed three times as fast as that for recording. FIG.
, 0 to 9 are track numbers, and A and B represent two channels corresponding to two rotating heads.
Channels A and B are recorded using tilt azimuth recording in order to suppress crosstalk between adjacent tracks.

In FIG. 18, a hatched area is an area where recorded data can be reproduced from the tape. At the time of variable-speed reproduction, data that can be reproduced as a sync block in the reproduction data is treated as valid data. Then, the reproduced data is stored in the image memory, and when new image data at the same position is obtained, the data at that position is updated. As a result of this processing, an image of one frame is restored using data of a plurality of frames. Therefore, the reproduced image is a mixture of images of a plurality of frames, resulting in poor quality. Moreover, since the above-described shuffling process is performed, the image of the same frame reproduced from the hatched area of each track in FIG. 18 is also an image at a spatially distant position, and has a certain area There is a problem that the reproduced image is not good as compared with the reproduction.

Accordingly, an object of the present invention is to provide a rotary head type digital video signal recording / reproducing apparatus capable of improving the quality of reproduced images at the time of high-speed reproduction.

[0008]

SUMMARY OF THE INVENTION According to the present invention, an input digital video signal is encoded with high efficiency, the encoded output is recorded as a plurality of tracks on a recording medium, and the recording medium is transmitted at the same speed as that at the time of recording. In a rotary head type digital video signal recording / reproducing apparatus capable of selectively performing a normal reproducing operation performed by a recording medium and a high-speed reproducing operation in which a recording medium is sent faster than that at the time of recording, a second reproducing apparatus for recording and normal reproducing is used. One pair of rotary heads and at least one second
Rotating head and the first rotating head during high-speed playback .
Ck signal and reproduced signal from the second rotary head from one
Switch for switching between at the stage of the reproduced RF signal
Switching means, an output signal of the switching means and the first
Playback at the time of high-speed playback from the playback signal from the other head
A rotary head type digital video signal recording / reproducing apparatus comprising: means for generating an image .

[0009]

A second rotary head is added to the first rotary head used for normal reproduction operation, and during high-speed reproduction, reproduction is performed using the reproduction output of the first and second rotary heads. Since the image is formed, the proportion of the image of the same frame in the reproduced image is increased, and a certain area can be reproduced. Therefore, an image at the time of high-speed reproduction becomes good.

[0010]

An embodiment of the present invention will be described below. First, a recording circuit of a digital VTR basically similar to the previously proposed one will be described.

FIG. 1 shows a configuration of a video data processing circuit provided on the recording side of a digital VTR. In FIG. 1, digitized video data is supplied to an input terminal 1. This video data is supplied to the blocking circuit 2. In the blocking circuit 2, video data in the order of interlaced scanning is, for example, a (8 × 8) D data.
It is converted into data of the structure of the CT block. That is,
A (8 × 8) block is formed by combining two (4 × 8) blocks at the same spatial position in the first and second fields that are temporally continuous. In the (8 × 8) block, pixel data on odd-numbered lines is included in the second field.

The output of the blocking circuit 2 is supplied to a shuffling circuit 3. In the shuffling circuit 3, errors are concentrated due to dropouts, tape scratches, head clogs, and the like, so that deterioration of pixels is prevented from being noticeable.
Within one frame, a plurality of macroblocks are used as a unit.
The process of making the spatial position different from the original one,
Shuffling is performed. The shuffling averages the data amount of the image included in the buffering unit. In this example, as will be described later, the shuffling unit and the buffering unit are equal, that is, 5 macroblocks.

The output of the shuffling circuit 3 is supplied to a DCT (cosine transform) circuit 4 and a motion detection circuit 5.
The DCT circuit 4 generates (8 × 8) coefficient data (that is, coefficient data of DC component DC and AC component AC). The DCT circuit 4 is switched in response to the detection result of the motion detection circuit 5 so as to perform the intra-field DCT on the (4 × 8) blocks included in the (8 × 8) blocks. .

The DC component DC of the (8 × 8) coefficient data generated by the DCT circuit 4 is transmitted to the subsequent circuit without being compressed, and 63 AC components thereof are quantized via the buffer 6 through the buffer 6. Is supplied to the conversion circuit 7. The coefficient data of the AC component is transmitted in order from the AC component having the lower order to the component having the higher order in the zigzag scanning order. Further, the coefficient data for the AC is also supplied to the activity detection circuit 8 and the data amount estimator 9. The buffer 6 delays the coefficient data for a time necessary for the estimator 9 to determine an appropriate quantization number QNo, and outputs the coefficient data of each of the still block and the motion block in a predetermined order. Is provided. The quantization number QNo from the estimator 9 is supplied to the quantization circuit 7 and transmitted to the subsequent stage.

The generation of the coefficient data from the DCT circuit 4 is the case of the DCT transform in the frame.
When the motion detection circuit 5 detects that there is motion,
The processing of the DCT in the field is selected. That is,
The intra-field DCT performs DCT for every two (4 × 8) blocks at the same position in the first and second fields that are temporally continuous. If the motion detection circuit 5 detects that there is a motion between fields with respect to the block, the intra-frame DCT is changed to the intra-field DCT in response to this detection. The motion detection circuit 5 (8
The still / movement determination is performed for each block based on the coefficient data in the vertical direction when the image data of the × 8) block is subjected to Hadamard transform. Alternatively, the motion detection may be performed based on the absolute value of the field difference.

In the case of intra-field DCT, (4 × 8) coefficient data for the first field and (4 × 8) coefficient data for the second field are generated.
These are treated as an (8 × 8) array located above and below. The DC data DC1 is included in the coefficient data of the first field. The DC component DC2 is similarly included in the second field. When the coefficient data of each of these fields is handled separately, the DCT in the frame and the D
The subsequent processing must be performed separately from the CT. As a result, problems such as an increase in hardware scale occur. Therefore, in this embodiment, the DC component DC2 of the second field
Instead of the differential DC component ΔDC2 (= DC1−DC2)
Is transmitted. The detection signal (motion flag) M from the motion detection circuit 5 is supplied to the data amount estimator 9 and transmitted to the subsequent stage.

The quantizing circuit 7 quantizes the AC component in the coefficient data. That is, the coefficient data for the AC is divided by an appropriate quantization step, and the quotient is converted to an integer.
This quantization step corresponds to the quantization number QN from the estimator 9.
o. In the case of a digital VTR,
Since processing such as editing is performed in units of one field or one frame, the amount of generated data per one field or one frame must be equal to or less than a target value. Since the amount of data generated by DCT and variable-length coding varies depending on the pattern to be coded, one field or one field is used.
A buffering process is performed to reduce the amount of data generated in a buffering unit shorter than the frame period to a target value or less. The reason for shortening the buffering unit is to simplify the buffering circuit, for example, by reducing the memory capacity for buffering. In this example, five macroblocks (= 30 DCT blocks) are set as buffering units.

Further, the activity detection circuit 8 has a D
Check the fineness of the pattern in the unit of CT block, and check its DC
The activity of the T block is divided into four classes, and a 2-bit activity code AT indicating the class is generated. The detection result is supplied to the estimator 9,
The activity code AT is transmitted to the subsequent stage.

The output of the quantization circuit 7 is the variable length coding circuit 1
1 for run-length coding, Huffman coding and the like. For example, a two-dimensional Huffman coding that generates a variable-length code (encoded output) by giving a run length, which is a continuous number of coefficient data “0”, and a value of the coefficient data to a Huffman table stored in a ROM is adopted. Is done. The code signal from the variable length encoding circuit 11 is supplied to the subsequent stage.

In connection with the estimator 9, the same Huffman table 12 as that referred to by the variable length coding circuit 11 is provided. The Huffman table 12 generates bit number data of an output code when variable length coding is performed.
The estimator 9 determines an optimal set of quantization steps, and the determination output is supplied to the selector 10. Selector 10
Controls the quantization circuit 7 to quantize the coefficient data in this set of quantization steps. At the same time, a quantization number QNo for identifying a set of quantization steps is transmitted to the subsequent stage.

The data (DC component data, variable-length coded output, quantization number QNo, motion flag M, activity code AT) generated in the above-described processing are processed by the subsequent framing circuit for error correction coding processing. A process of converting the recording data into a frame structure is performed. From the framing circuit, data of a sync block configuration appears. The recording data is supplied to a rotary head via a channel encoding circuit and a recording amplifier.

Here, the format of the video signal processed by the above configuration will be described. FIG.
It concerns the signal of the 5/60 system. The format of this system is shown below. 525/60 system Sampling frequency: 13.5 MHz Sampling number / line: 858 Frame rate: 29.97 Hz Line frequency: 15.734 kHz Effective image: Y 720 (H) × 480 (V) U, V 180 (H) × 480 (V)

As shown in FIG. 2A, the effective area of the Y signal is divided into 8 × 8 DCT blocks,
Blocks are formed. As for the color difference signals U and V, as shown in FIG. 2B, the effective area is divided into DCT blocks, and 22.5 × 60 DCT blocks are formed. The 23rd block 1-23, 2 in FIG.
-23,..., 60-23 have a size of 4 × 8.

The component system (Y: U:
In order to process the luminance signal Y and the color difference signals U and V of V = 4: 1: 1), a macro block (MB) is defined. The macro block is (8 ×
This is a collection of a plurality of blocks of the coefficient data of 8). As shown in FIG. 2C, a total of six blocks, four Y blocks, one U block, and one V block, at the same position in one frame constitute one macro block. For the Y signal, the total number of DCT blocks in one frame is (90 ×
60 = 5400), and for the color difference signal, this is (22.5 × 60 = 1350), which is 810 in total.
There are 0 DCT blocks / one frame. Therefore, 8
100 ÷ 6 = 1350 is the number of macroblocks in one frame.

FIG. 3 shows the relationship between the screen of one frame and the shuffling pattern in this embodiment. In the division of FIG. 3, one frame indicates (22.5 × 60) MB. Then, as indicated by the arrows in FIG. 3, 18 macro blocks are selected. As a result, 5 patterns in the horizontal direction and 15 patterns in the vertical direction are selected.

FIG. 4 shows the relationship between the shuffling pattern on the screen and the shuffling pattern on the track in this embodiment. To form a shuffle pattern on the track from a shuffle pattern on the screen,
For example, three patterns in the upper left corner of FIG. 3 are extracted, and for 54 macro blocks included therein,
As shown in FIG. 4A, A0 to B26 are numbered.
Next, the 54 macroblocks are rearranged in a 9 × 6 array as shown in FIG. 4B. This rearranged 5
The four macroblocks correspond to the region of number 0 in the upper left corner of FIG. 4c.

By repeating the above processing, FIG.
A 5 × 5 array is created, numbered as shown in FIG. Each area is called a sub-area, and the number is called a sub-area number. The presence of five horizontal sub-regions corresponds to a buffering unit of five macroblocks. There are five sub-regions in the vertical direction
This is related to the number of tracks (= 10) required to record one frame of data.

FIG. 5 shows a shuffling pattern on a track in this embodiment. In FIG. 5, the rotating head traces the tape from right to left, and the tape runs diagonally to the lower left, so that tracks are sequentially formed from bottom to top. The recording data of each frame is recorded as ten tracks. When each track is divided into five macroblock buffering units, 27 buffering units are formed. Therefore, one track records 27 × 5 = 135 MB.

When five macroblocks of the buffering unit to be recorded are collected, they are collected from five positions of (sub area number-macroblock number). For example, the first number of the first track of an odd frame (0-A0)
Indicates that the sub area number is 0 and the macroblock is A0. As shown in FIG. 8C, since there are five sub-regions having the sub-region number 0, from the central sub-region to the surrounding sub-regions, a total of one each for right, left, right, and left. Five macroblocks are collected.

As shown in FIG. 5, the order of the macroblock numbers A and B is exchanged between the odd frame and the even frame. As a result, even if clogging occurs in the rotating head of one channel, interpolation processing during reproduction is facilitated.

Next, the format of the video signal of the 625/50 system will be described. FIG. 6 relates to the signals of this system. The format of this system is shown below. 625/50 system Sampling frequency: 13.5 MHz Sampling number / line: 864 Frame rate: 25 Hz Line frequency: 15.625 kHz Effective image: Y 720 (H) × 576 (V) U, V 360 (H) × 288 ( V)

As shown in FIG. 6A, the effective area of the Y signal is divided into 8 × 8 DCT blocks, and 90 × 72 DCT blocks are formed.
Blocks are formed. As for the color difference signals U and V, as shown in FIG. 6B, the effective area is divided into DCT blocks to form 45 × 36 DCT blocks.

Then, as shown in FIG. 6C, a total of six blocks of four Y blocks, one U block and one V block at the same position in one frame constitute one macro block. As for the Y signal, all DC in one frame
The number of T blocks is (90 × 72 = 6480), and for the color difference signal, it is (45 × 36 = 1620), and there are 9720 DCT blocks / one frame in total. Therefore, 9720 ÷ 6 = 1620 is the number of macroblocks in one frame.

FIG. 7a shows the shuffling pattern of a 625/50 system. As shown by the arrow in FIG.
Nine macroblocks in the horizontal direction and two macroblocks in the vertical direction, that is, a total of 18 macroblocks are selected. As a result, 5 patterns in the horizontal direction and 18 patterns in the vertical direction are selected.

In order to form a shuffle pattern on the track from a shuffle pattern on the screen, for example, three patterns at the upper left corner of FIG.
For the 54 macroblocks contained therein, A0
To B26. Next, the 54 macroblocks are rearranged in a 9 × 6 array as shown in FIG. 7B. The rearranged 54 macro blocks are
This corresponds to the area of number 0 in the upper left corner of FIG. 7c.

By repeating the above processing, FIG.
A 5 × 6 array is formed, numbered as shown in FIG. Each area is called a sub-area, and the number is called a sub-area number. The presence of five horizontal sub-regions corresponds to a buffering unit of five macroblocks. There are five sub-regions in the vertical direction because the number of tracks required to record one frame of data (= 12)
Is related to

FIG. 8 shows a shuffling pattern on a track in the 625/50 system. The recording data of each frame is recorded as 12 tracks. Each track includes 27 buffering units of 5 macroblocks. Therefore, one track contains 27 × 5
= 135 MB is recorded. Compared with the above-described 525/60 system, the number of tracks per frame is increased by two.
(Macro block number) is (10-A0) to (10-A2)
Except for (6), shuffling is performed in the same manner as in the 525/60 system described above.

In a digital VTR for performing the above-described recording processing, the present invention provides a recording / reproducing apparatus which employs two recording /
One rotating head is newly added to the reproducing head, thereby improving the image quality during high-speed reproducing operation.

FIG. 9 shows the state of the tape trace at the time of high-speed reproduction, for example, at the quadruple-speed reproduction when one rotary head is added to two rotary heads which perform normal recording and reproduction. In FIG. 9, Ach and Bch are each 1
The channel corresponding to a pair of rotating heads at an interval of 80 ° is shown. An additional rotating head is provided so as to trace adjacent to the trace locus of Ach. The channel of the added head is B'ch. Then, the reproduction signal of Ach and the reproduction signal of B'ch are selectively synthesized, and the synthesized output and the reproduction signal of Bch are used as the reproduction signal at the time of high-speed reproduction.

As shown in FIG. 10A, a pair of rotary heads Ha (Ach) and Hb (Bch) are mounted so as to face the rotary drum 180 °. The direction in which the gap of these heads extends forms a predetermined angle, and tilt azimuth recording is performed. The magnetic tape is wound around the drum at a winding angle slightly larger than 180 °. Head Ha
And Hb are used for recording and normal playback operations.

An additional head Hb '(B'ch) for tracing the tape in the vicinity of the head Ha and later than the head Ha
Is provided. The azimuth of this head Hb ′ is
Is consistent with that of The step DA between the heads Ha and Hb '(see FIG. 10b) is selected such that the head Hb' traces a trajectory next to the trajectory traced by the head Ha. The set value of the level difference DA is an example, but it is necessary to appropriately select the value in order to improve the image quality at the time of high-speed reproduction. That is, the data to be reproduced by the head Ha is selected so that the positions on the reproduction screen do not overlap as much as possible. Further, when the above-described shuffling is adopted, it is preferable to trace the adjacent image because the neighboring images can be collectively reproduced. As a result of the provision of the additional head Hb ', data that can be reproduced from the tape during high-speed reproduction increases, and the image quality of the reproduced image can be improved.

FIG. 11 shows a circuit configuration for combining RF signals reproduced from a tape by the heads Ha, Hb ', and Ha into one channel. The output signal of the head Ha is supplied to a reproduction amplifier 21a and a reproduction equalizer 22.
The signal is supplied to one input terminal of the switching circuit 23 and the select signal generation circuit 24 through the line a. Similarly, the output signal of the additional head Hb 'is supplied to the other input terminal of the switching circuit 23 and the select signal generation circuit 24 via the reproduction amplifier 21a and the reproduction equalizer 22a. The select signal generating circuit 24 monitors the envelope levels of the reproduced RF signal RFa of the head Ha and the reproduced RF signal RFb 'of the head Hb', and generates a select signal for selecting a higher level. The switching circuit 23 is controlled by the select signal. This switching circuit 23 is used for the head Ha in the normal reproducing operation.
Is fixed so that the signal RFa is always selected.

The RFc from the switching circuit 23 is supplied to one input terminal of the switching circuit 25. The other input terminal of the switching circuit 25 has a recording amplifier 2
1b, RFb is supplied via the reproduction equalizer 22b. The switching circuit 25 is controlled by a switching pulse Ps synchronized with the rotation of the head. That is, the reproducing signal of the heads Ha and Hb opposed by 180 ° is selected by the switching circuit 25 in each period of tracing the tape. The output terminal 27
The reproduced RF signal is extracted.

FIG. 12 shows waveforms of the respective parts in FIG. 11 during high-speed reproduction. The level of the switching pulse Ps is synchronized with the rotation of the drum, and the level of the switching pulse Ps corresponds to each trace period of the heads Ha and Hb. Is inverted. A reproduction RF signal RFa from the head Ha is generated during the high level period of the switching pulse Ps, and an RFb from the head Hb is generated during the low level period. The signal RFa and the signal RFb 'from the additional head Hb' are combined by the switching circuit 23 to generate a signal RFc. The reproduction R at the time of high-speed reproduction is determined by these RFc and RFb.
An F signal is formed.

FIG. 13 shows a modification of the configuration shown in FIG.
In FIG. 13, TBCs 28a and 28b are provided. The TBC 28a is provided additionally to the additional head Hb '. TBC28a and 2
8b is composed of a digital memory and removes a time-axis variation included in the reproduced signal. In addition, these TBC digital memories are used to store data that can be fragmentarily reproduced during high-speed reproduction and to restore images. Therefore, by supplying the reproduction data stored in both the TBCs 28a and 28b to the error correction circuit 29 at the next stage, the reproduction data of the additional head Hb 'can be effectively used.

As can be seen from FIG. 12, the additional head H
Since b ′ is provided, the proportion of the image of the same frame in the reproduced image at the time of high-speed reproduction increases, and an image of an area having a certain area in the same frame can be reproduced. As a result, the quality of the reproduced image can be improved.
One of the methods for evaluating the improvement in image quality during high-speed reproduction is an image data update rate. This is the ratio of the number of macroblocks that can be picked up by 10 traces based on 1350 MB of 10 tracks on which data of one frame is recorded.

The vertical axis in FIG. 14 indicates the update rate, and the horizontal axis indicates the double speed number. 14 in FIG. 14 has no additional head, that is, indicates a change in the update rate of the digital VTR proposed earlier. Reference numeral 32 indicates a change in the update rate according to the present invention. Comparing these changes 31 and 32, it will be apparent that the invention has improved the update rate. Since the update rate can be greatly improved, the image at the time of high-speed reproduction is updated quickly and smoothly, and the visual improvement effect is large.

Here, as can be seen from the waveform diagram of FIG. 12, when combining by switching, the phase of the envelope change of the reproduced RF signal of the head Ha and the additional head Hb '
Is preferably in antiphase. As a result, the higher level of the two signals can be selected. To accomplish this with a delay circuit, digital memory, or the like, the amount of hardware increases. Therefore, in this embodiment, the above-described rotary heads Ha and Hb
By appropriately setting the gap distance GL in the arrangement of ', the opposite phase relationship between the level changes of the two signals is realized.

Hereinafter, the appropriate setting of the gap distance GL and the head level difference DA will be described. FIG. 15 is a schematic diagram for explaining this, and it is assumed that at time T = 0, the head Ha is at the position of P _A0 and starts tracing on the tape. Note that θ _r is, as shown in FIG.
The angle of the track inclination (recording angle), and θ _r ′ is the trace angle. Θ _S is a still angle, and T _P is a track pitch. The head Hb 'is located at a distance of GL in the tape running direction. When the head Ha is at P _At when the head Hb ′ starts tracing on the tape at T = t, RFa from the head Ha and the head Hb
As shown in FIG. 16, RFb 'from''overlaps for a time corresponding to 1 (lowercase letter L).

When the overlap 1 becomes 0, the overlap between RFa and RFb 'becomes 0. Thereby, by switching these signals as described above, R
Fa and RFb 'can be appropriately synthesized. Therefore, 1 is set to 0, and a condition for preventing the RF signals from overlapping is obtained. This is the geometric relationship shown in FIG. Figures _{17 r l = T P / sin} (θ r '-θ r) = (sinθ S / sin
θ _r ') · GL _{Therefore, GL = (T P · sinθ} r') / {sinθ S · sin (θ r '-θ r)}

Here, the trace angle θ _r ′ is represented by an equation. θ _r ′ = tan ⁻¹ {(D × π × _RS sin θ _S ) / (D × π × _RS cos θ _S −N T _S )} In the above equation, (D: drum diameter, R _S : drum rotation speed) ,
T _S : tape speed during normal reproduction, N: double speed number).
As an example of specific values, θ _S = 9.957 (deg), D = 21 (m
m), R _s = 149.8501 (rps), and T _s = 15.591 (mm / sec). In this case, specific examples of the double speed number N and the gap distance (mm) are as follows.

[0052]

[Table 1]

Furthermore, in order for the trace locus of the additional head Hb 'to be adjacent to that of the head Ha, the step Da must satisfy the following condition. DA = GL · tan (θ _r −θ _S )

The arrangement of the rotary head is 180
° The double azimuth head in which the two gaps are integrally formed may be used instead of the opposed one. Further, two heads can be added to make a total of four heads.

[0055]

According to the present invention, in a digital VTR, the quality of a reproduced image at the time of high-speed reproduction can be improved by adding a head different from a normal recording / reproducing rotary head. Further, according to the present invention, by setting the mounting position of the additional head in a predetermined relationship with respect to the normal recording / reproducing head, the reproduction signal of the additional head can be effectively used, and the circuit can be simplified. .

[Brief description of the drawings]

FIG. 1 is a block diagram of an example of a recording circuit of a digital VTR to which the present invention can be applied.

FIG. 2 is a schematic diagram for explaining block division of a video signal of a 525/60 system.

FIG. 3 is a schematic diagram illustrating a shuffling process of the 525/60 system.

FIG. 4 is a schematic diagram illustrating shuffling processing of the 525/60 system.

FIG. 5 is a schematic diagram illustrating a recording pattern on a tape of the 525/60 system.

FIG. 6 is a schematic diagram for explaining block division of a 625/50 system video signal.

FIG. 7 is a schematic diagram illustrating shuffling processing of the 625/50 system.

FIG. 8 is a schematic diagram illustrating a recording pattern on a tape of the 625/50 system.

FIG. 9 is a schematic diagram showing an operation of reproducing data from a tape during variable speed reproduction.

FIG. 10 is a schematic diagram illustrating an arrangement of a rotary head according to the embodiment.

FIG. 11 is a block diagram showing an example of a circuit configuration for synthesizing a reproduction signal from a rotary head.

12 is a waveform chart of each part in FIG. 11;

FIG. 13 is a block diagram showing an example of a circuit configuration for synthesizing a reproduction signal from a rotary head.

FIG. 14 is a graph showing an update rate of reproduction data during high-speed reproduction.

FIG. 15 is a schematic diagram for explaining selection of a gap distance.

FIG. 16 is a schematic diagram for explaining selection of a gap distance.

FIG. 17 is a schematic diagram for explaining selection of a gap distance.

FIG. 18 is a schematic diagram showing traces of a rotating head during high-speed reproduction.

[Explanation of symbols]

 Reference Signs List 3 Shuffling circuit 4 DCT circuit 7 Quantization circuit Ha, Hb Rotating head for recording and normal reproduction Hb 'Additional head for high-speed reproduction 23, 25 Switching circuit

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-2-202186 (JP, A) JP-A-2-154303 (JP, A) JP-A-60-167584 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) G11B 5/09 H04N 5 / 92,5 / 93

Claims (4)

(57) [Claims] 1. A normal reproducing operation in which an input digital video signal is encoded with high efficiency, an encoded output is recorded as a plurality of tracks on a recording medium, and the recording medium is sent at a speed equal to that at the time of recording. In a rotary head type digital video signal recording / reproducing apparatus capable of selectively performing a high-speed reproducing operation in which a recording medium is sent faster than a recording medium, a pair of first rotary heads for recording and normal reproduction are provided. At least one second rotary head; and at the time of the high-speed reproduction, switching between a reproduction signal from one of the first rotary heads and a reproduction signal from the second rotary head at the stage of a reproduction RF signal. generates a switching means, the reproduced image at the time of the high-speed reproduction from the reproduction signal from the other output signal and the first rotary head of the switching means for Rotary head and means type digital video signal recording and reproducing apparatus. The apparatus according to the claim 1, as spatial positions on the playback screen is not Awa becomes heavy, first
A rotary head-type digital video signal recording / reproducing apparatus, wherein a step between one of the rotary heads and the second rotary head is selected. 3. The rotary head type digital device according to claim 1 , wherein the distance between the gaps is selected so that portions of the reproduced RF signal having relatively large amplitudes can be alternately selected. Video signal recording and playback device. 4. A rotary head type digital video signal recording / reproducing apparatus according to claim 3 , wherein the gap distance GL is selected according to the following equation. GL = (TP · sinθr ′) / {sinθS · sin (θr′−θr)} TP: track pitch, θr: recording angle, θr ′: trace angle, θS: still angle, θr ′ = tan-1 ｛(D × π × RS sin θS) / (D × π × RS cos θS −N TS)｝ D: Drum diameter, RS: Drum rotation speed, TS: Tape speed during normal playback, N: Double speed