JP2751421B2 - Video signal playback device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a digital video tape recorder (digital VT) using, for example, a D-1 format video tape.
R) The present invention relates to a video signal reproducing device suitable for use in R).

[Summary of the Invention]

The present invention relates to a video signal reproducing apparatus suitable for use in a digital VTR using, for example, a D-1 format video tape, and has a boundary of identification information for identifying a recording area in a center portion of a track, and has a recording area. In a video signal reproducing apparatus that reproduces the identification information and the video signal from a recording medium in which the video signal is recorded together with the identification information of the recording area in the area, the order of the reproduced identification information and the video signal is changed in units of the recording area. By providing the order conversion means and operating the order conversion means at the time of reverse reproduction, the subsequent data processing becomes easy and the capacity of the memory for the reproduced video signal can be reduced.

[Conventional technology]

When recording a large amount of information such as a digital VTR, it is difficult to record a video signal of one field on one track, so the method of recording the video signal of one field on a plurality of tracks Has been adopted. In this case, if the tracks are alternately traced by a pair of recording or reproducing heads provided on the rotating head, the load on the processing speed of the obtained data is too large. Scanning. Also, in order to perform noiseless reproduction in a wide speed range in a digital VTR, a dynamic tracking technology developed for an analog VTR is being applied.

FIG. 7 shows a rotary head for a conventional dynamic tracking digital VTR. In FIG.
(1) is a rotary head, (2) is a video tape transported in the forward direction (V ₊ direction), R (A) to R (D) are recording heads, and P (A) to P (D) are each. The reproducing heads (3) and (4) are bimorph elements each supporting a pair of reproducing heads. Hereinafter, reproduction heads are indicated by symbols A to D, respectively. When the rotary head (1) rotates at the rotation speed ω, the bimorph elements (3) and (4) cause
The pair of reproducing heads A and B and the pair of reproducing heads C and D are θ _{1 respectively.}
It is freely displaceable within a predetermined range in the direction and theta ₂ directions.

As a format of a video tape for a digital VTR, the D-1 format, which is an international standard, has become widespread. In this D-1 format, FIG.
As shown in the figure, video and audio signals for one field of the NTSC system (525/60 system) are recorded in a curved manner in ten tracks, and each track includes a time code located at the center. It is composed of an audio sector part (2b) and two video signal video sectors (2a) and (2c) sandwiching the audio sector part (2b). The reason why the audio sector part (2b) is arranged at the center is that the error rate of audio data needs to be lower than that of video data. Further, the ten tracks are divided into five segments (segment numbers 0 to 4) by two tracks, and each of the segments 0 to 4 has a screen (5a), (5b) of one field as shown in FIG. ) And (5c) are divided into five equal parts, and video signals of 50 horizontal scanning lines are recorded. Each of the sections 0 to 4 is composed of four sexual units (sector numbers 0 to 3), and each of these sectors is identified by an ID address (identification address) defined as follows.

ID address = (sector number, segment number (field number)) Sector number = 0 to 3 Segment number = 0 to 4 Field number = 0 to 3 (2 bits) However, the least significant bit number is used as the field number 0 indicates an even field, 1 indicates an odd field, and the second bit of the normal field number is used as a frame number.

As shown in FIG. 8B, each video sector is composed of a preamble including a synchronization pattern and an ID pattern, 160 synchronization blocks, and a postamble not shown.
A synchronization pattern and an ID pattern are added to each of the synchronization blocks, and the ID pattern has an ID as shown in FIG. 8C.
Contains address information. In addition, for example, the PAL method (6
In the 25/50 system), the video signal for one field is recorded in a distributed manner over 12 tracks, so the segment number is 0 to 5
Becomes

Referring to FIG. 10, the operation in the case where reproduction is performed at +1 times speed in the forward direction using the rotary head of FIG. 7 will be described. In this case, the video tape (2) is transported in the V ₊ direction. In the drawing, the tape (2) is displayed stationary so that one set of reproducing heads A and B and one set of reproducing heads C and D move in the direction opposite to the V ₊ direction while tracing the tape. In the initial state, it is assumed that the reproducing heads A and B are on tracks 1 and 2 of field 0, respectively, and thereafter, the reproducing head moves to tracks 3, 4, 5, 6 and so on. At this time, the field numbers in the ID address are extracted from the reproduced data output from the respective reproducing heads, and the field numbers arranged along the time axis are shown in FIG. This second
As is clear from FIG. 11, in the case of forward reproduction, the field number of reproduced data monotonously increases, and there is no inconvenience in subsequent data processing.

Next, using the rotating head of FIG.
With reference to FIG. 12, the operation in the case of reproducing at double speed will be described. In FIG. 12, the reproducing heads A and B start tracing from the tracks 17 and 18 of the field 2 in the initial state, respectively. The head will now track 16,15,14,13
Assume that you move with ‥‥. Such a method of reproducing one field of data from the end track to the start track during reverse reproduction is disclosed in Japanese Patent Application Laid-Open No. 61-150476 by the present applicant. Further, a part of the trajectory of the reproducing head when the dynamic tracking operation is not performed is indicated by a broken line, and the actual trajectory of the reproducing head by the dynamic tracking operation is indicated by a solid line. The reproducing heads A and B are given a deflection in the direction of the arrow (6a), and the reproducing heads C and D are given a deflection in the direction of the arrow (6b). At this time, FIG. 13 shows the field numbers extracted from the reproduction data output from the respective reproduction heads arranged along the time axis. From FIG. 13, the field numbers of the reproduction data are monotonous during the reverse reproduction. It can be seen that the inversion does not occur at the boundary of each field. In addition, as the initial phase of the reproducing heads A and B in FIG. 12 is displaced in the
The pattern in the figure varies in various ways.

Similarly, when reproduction is performed at -0.75 times speed using the rotary head of FIG. 7, the pattern in which the field numbers of the reproduction data obtained from the respective reproduction heads are arranged along the time axis is the 14th. There are various patterns as shown in FIGS.

The present applicant has proposed a digital VTR having a rotating head (1) as shown in FIG. 16 in Japanese Patent Application No. 63-261860 as an improved digital VTR of the example shown in FIG. In FIG. 16, the recording head is the same as the conventional one, but the number of reproducing heads supported by the bimorph elements (3) and (4) is four (P (A ₁ ), P (B ₁ ), P (C ₂ ), P (D ₂ ) and P
(C ₁ ), P (D ₁ ), P (A ₂ ), P (B ₂ )). When indicating these reproducing heads merely _{A 1 ~D 2, C 1 ~B} 2, with four playback heads _{A 1, B 1, C 2} , D 2 traces the tape in synchronization with the parallel therewith 180 (4) With the phase delayed, the four reproducing heads C ₁ , D ₁ , A ₂ , and B ₂ trace the tape synchronously in parallel.

Referring to FIGS. 17 to 19, the state of the reproduced data in the case of performing reproduction at, for example, -1 × speed using the rotary head of FIG. 16 will be described. As shown in FIG. It is assumed that data is reproduced in the reverse order from field 10 (= 2) to field 01, field 00, and field 11 (= 3). Note that the field number is a 2-bit number, and strictly speaking, the fields 00 to 11 (0 to 0)
Up to 3) can be identified, but in this example, it is assumed that only the lower one bit is used to identify whether the field is an even field or an odd field. The video tape is transported in the reverse direction (V _- direction). FIG. 17 shows that the reproducing head is gradually transported in the reverse direction of the V _- direction using a tape stationary system. Each sector is assigned an ID address consisting of a segment number of 0 to 4 and a field number of 0 or 1. Further, the data reproduced from the sector having the ID address is
Identify by adding an address.

In this case, as shown in FIG. 17, the reproducing heads A ₁ , B ₁ , C ₂ , D
₂ respectively Sector 4 (1), 4 (1), 0 (0) 0 (0) Assuming that start tracing from the next reproducing head
Tracing is performed from a position where C ₁ , D ₁ , A ₂ , and B ₂ are shifted by two tracks, and then the reproducing heads A ₁ , B ₁ , C ₂ , and D ₂ are again moved by 2
Since the trace is performed from the position shifted by the track, if the data reproduced from each reproducing head is arranged on the time axis,
As shown in Figure 18. The data reproduced from the fields 10, 01, and 00 are recorded in three field memories for each segment.

As is clear from FIGS. 17 and 18, in the case of this multi-head system, not only the field numbers but also the segment numbers are always reversed.

Similarly, FIG. 19 shows a state of the change of the ID address when the reproduction is performed at -0.75 times speed using the rotary head of the example of FIG. As described above, at −0.75 × speed, the ID address changes extremely complicatedly.

[Problems to be solved by the invention]

When the reverse reproduction is performed using the video tape of the D-1 format as described above, a reverse phenomenon occurs in the field number and the segment number of the reproduction data output from each reproduction head, and the data processing after the reproduction is performed. Is complicated.

Specifically, in a digital VTR, the data itself is subjected to complicated shuffling for error countermeasures, and when a reverse phenomenon such as the field number of the reproduced data occurs on this, an error has occurred in the reproduced data. In some cases, a complicated processing program is required to suppress the occurrence of this error.

In reverse slow reproduction, a frame-forward image without noise is required. To realize this, a plurality of (for example, three) field memories are usually provided, and some of these field memories are provided. When image data is sufficiently written in the field memory, a method of switching to the next field memory is adopted.

However, in the prior art, the above-described reversal of the reproduced field number occurs, which adversely affects the determination of the switching of the field memory. That is, after detecting a new field number, judging that the image data of the previous field has been completely reproduced, and specifying the number of the field memory to be written next, the image data of the previous field comes in. In this case, image data of different fields is mixed into one field memory, and an error such as an erroneous correction occurs.

For example, if the field number pattern of the data reproduced from each reproducing head is as shown in FIG. 15A assuming that reproduction is performed at -0.75 times speed, the image is reproduced using three field memories A, B and C. Consider the case of inputting and outputting data. In this case, as shown in FIG. 15B, the reproduced image data respectively corresponding to the field numbers 2, 1, and 0 are sequentially written in the field memories A, B, and C. Then, image data is sequentially read from the field memories A, B, and C in which no writing is performed in the cycle of one field period V, and the read image data is digital / analog (D / A). Supply it to the monitor via the converter.

For example, when image data is read out in the order of field memory C → field memory A → field memory B at the timing shown in FIG. 15C, data is erroneously written to the read field memory. There is no particular inconvenience. However, during variable speed playback by operating a search dial or the like,
If the speed becomes 0.75 times faster, the field memories A, B,
While reading from C is performed periodically in one field period V, the phase of the reproduced image data is not constant and can take various cases. Therefore, when the field memory for writing (FIG. 15B) is used as a reference, the phase of the field memory for reading is 15
There can be various cases as shown in FIGS.

In this case, the reversal phenomenon occurs on both sides of the image data of the field number 1, and the period V1 during which the field number is stable at ₁ is smaller than V between one field. Therefore, for example, the period (9) in FIG. 15D and the period in FIG.
As shown in the period (10), a so-called address overtaking in which data is written in the field memory during reading may occur. This indicates that in the related art, three field memories are not enough to accurately process the reproduction data, and four field memories are required.

In view of the above, the present invention facilitates subsequent data processing and reproduces a video signal even when a reverse phenomenon of identification information such as an ID address occurs during reverse reproduction in a D-1 format digital VTR or the like. The purpose of the present invention is to reduce the capacity of a memory for use.

[Means for solving the problem]

As shown in FIG. 1, for example, the video signal reproducing apparatus according to the present invention has a boundary of identification information (for example, a segment number, a field number, a frame number, etc.) for identifying a storage area in a center portion of a track. In a video signal reproducing apparatus for reproducing a video signal from a recording medium (for example, a video tape (2) of D-1 format) in which a video signal is recorded together with the identification information of the recording area in the area, And an order conversion means (23) for changing the order of the video signals in units of recording areas, so that the order conversion means (23) is operated during reverse reproduction.

[Action]

According to the present invention, at the time of reverse reproduction, the order of the reproduced identification information and the video signal is the same as at the time of forward reproduction. Therefore, the reproduced data can be processed in the same manner as in the forward reproduction, and the subsequent data processing becomes easy.

Further, since the reversal phenomenon of the identification information is eliminated in the data processing stage, the capacity of the memory for the reproduced video signal can be reduced.

〔Example〕

Hereinafter, an embodiment of a video signal reproducing apparatus according to the present invention will be described with reference to FIGS. This example is D-1
The present invention is applied to a digital VTR using a video tape of a format. Further, as the rotary head of this example, the multi-head and dynamic tracking type rotary head of FIG. 16 is used as it is.

FIG. 1 shows a playback device for one channel of a digital VTR of this embodiment. In FIG. 1, playback is performed by one playback head (20) among eight playback heads mounted on a rotary head. PLL for bit clock reproduction of reproduced data
(21) is converted into input data DX, and this input data
Write DX to a predetermined address in the memory (22). As shown in FIG. 2A, the pattern of the input data DX is a series of tracks in the D-1 format (for example, tracks 18 and 1 in FIG. 12).
7, 16, 15}), the data of the audio sector portion is inserted between the data a1, b1, etc. of the pair of video sectors. The memory (22) may be a memory that also serves as a memory for a time base collector, in addition to the working memory.

(23) indicates an address conversion circuit. This address conversion circuit (23) generates a read address in the same order as the write address during forward reproduction and supplies the read address to the memory (22).
At the time of reverse reproduction, for each of the data corresponding to one track, an address formed by exchanging the data write address of a pair of video sectors is supplied to the memory (22) as a read address. The output data DY read from the memory (22) is supplied to an extraction circuit (24), and the extraction circuit (24) extracts a synchronization signal (SYNC) and an ID address. The image data and the ID address obtained by removing the synchronization signal and the ID address from the output data DY are written into a predetermined area of the field memory (26) via the inner code correction circuit (25).

The image data read from the field memory (26) is subjected to predetermined processing in an outer code correction circuit (27) and an error correction circuit (28), and the output data of the error correction circuit (28) is converted into a D / A converter ( Feed to monitor (30) via 29). In this example, the field memory (26) has a storage capacity for three fields for all eight reproducing heads, and these logically identified field memories are referred to as field memories A, B, and C, respectively.

The operation in the case of performing the reverse reproduction in the example of FIG.
As will be described with reference to FIG. 4 to FIG. 4, at the time of reverse reproduction, the address conversion circuit (23) performs an address conversion operation. Therefore, the input data DX written in the memory (22) in the pattern shown in FIG. 2A is converted into the pattern shown in FIG. 2B and read as output data DY at the time of reading.

For example, focusing on the field number in the reproduction data output from each reproduction head when the reproduction is performed at -0.75 times speed, in the conventional example, the field number is reversed at the boundary between the fields as shown in FIGS. 14A to 14E. A phenomenon has occurred. However, in this example, since the reproduction data is rearranged with the audio sector portion as the center, the field numbers in the reproduction data output from the respective reproduction heads are as shown in FIGS. 3A to 3E, and no inversion phenomenon occurs. . Therefore, according to this example, there is an advantage that the subsequent data processing is extremely easy.

When the pattern of the field number in the reproduction data is the pattern shown in FIG. 4A, for example, the image data of the field numbers 2, 1, 0 are sequentially stored in the field memories A, B, Write in C. In this case, during variable speed playback using the search dial,
For example, when the speed becomes 0.75 times, the writing timing changes variously, whereas the reading of data from the field memories A, B, and C is performed periodically at a cycle of one field period V. Therefore, based on the write timing (FIG. 4B), various cases may occur in the timing of reading data from the field memories A, B, and C as shown in FIGS.

However, in this example, since the reversal phenomenon of the field numbers does not occur, the reproduced field numbers of FIG. 4A are stable for at least one field period V at least in the range of -1 × to 0 × speed. Therefore, unlike the conventional example, it is possible to avoid erroneous writing in the field memory during reading, and there is an advantage that noiseless reproduction can be performed up to about -1 times speed with only three field memories.

Next, another embodiment of the present invention will be described with reference to FIGS. 5 and 6. Also in this embodiment, a multi-head rotating head of a dynamic tracking system shown in FIG. 16 is used.

In this example, during reverse playback, as shown in FIG.
Each reproducing head has D-1 along a curved path along the solid line (32).
The dynamic tracking operation is performed so as to trace the track of the video tape of the format. For example, at the time of -0.75 times speed, when the dynamic tracking is not acting, each reproducing head is displaced along the path along the broken line (33). is there.

In this case, assuming that the initial phases of the reproducing heads A ₁ , B ₁ , C ₁ , and D ₁ are 1 (1), 1 (1), 2 (1), and 2 (1), respectively, The pattern in which the ID addresses in the output reproduced data are arranged along the time axis is as shown in FIG. As is apparent from FIGS. 5 and 6, no inversion phenomenon occurs in the field numbers output from the respective reproducing heads. Therefore, in the case of the example of FIG. 5, the order conversion means for changing the order of the reproduced signals is the dynamic tracking mechanism itself, but the operation and effect are the same as in the example of FIG.

In the example of FIG. 1, the memory (22) may be provided at any position in the range X in FIG. Further, the present invention can be applied to a digital VTR or the like using a rotary head having a small number of reproducing heads as shown in FIG. As described above, the present invention is not limited to the above-described embodiment, and it is needless to say that various configurations can be adopted without departing from the gist of the present invention.

〔The invention's effect〕

According to the present invention, the video signal is reproduced in the same order as in the case of reproduction in the forward direction even in the case of reproduction in the reverse direction, so that there is an advantage that subsequent data processing becomes easy.

Furthermore, since the reversal phenomenon of the identification information in the data processing unit is eliminated and the period for reproducing the video signal in each recording area is made uniform, there is an advantage that the video signal can be sequentially stored in a memory having a small storage capacity.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIGS.
5 is a diagram for explaining the operation of the example shown in FIG. 1, FIGS. 5 and 6 are diagrams for explaining another embodiment of the present invention, and FIG. 7 is a plan view showing a conventional rotary head. 8 and 9 are diagrams for explaining the D-1 format, FIGS. 10 to 15 are diagrams for explaining the example of FIG. 7, and FIG. 16 is a rotation diagram of the prior application. Plan view showing the head, Fig. 17-
FIG. 19 is a diagram for explaining the example of FIG. 16; (2) is a video tape of D-1 format, (3) and (4) are bimorph elements, (20) is a reproducing head,
(22) is a memory, (23) is an address conversion circuit, and (26) is a field memory.

Claims (1)

(57) [Claims] 1. A recording medium having an identification information boundary for identifying a recording area at the center of a track and recording a video signal in each recording area together with the identification information of the recording area. In the video signal reproducing apparatus for reproducing, a sequence conversion means for changing the order of the reproduced identification information and the video signal in units of the recording area is provided, and the sequence conversion means is operated at the time of reverse reproduction. Video signal playback device.