JPH11213577A - Error rate checking device for digital video tape recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable checking (or measuring) an error rate of a reproduction system at the time of a recording mode such as insert edition. SOLUTION: This device is a digital VTR performing insert recording by a recording head 13 at the time of insert edition and simultaneously reproducing a recorded signal from a tape 16 by an advance reproduction head 1, and provided with at least an advance reproducing head 1 reproducing a recorded signal on a tape 16 preceding to recording by a recording head 13, has an error rate detector 5 detecting error rate information of a reproduced signal reproduced from the tape 16 by the advance reproducing head 1 preceding to recording a signal by the recording head 13 at the time of insert edition a microcomputer 9 discriminating whether the error rate is good or not based on error rate information detected by the error rate detector 5, and a display device 11 displaying the judged result of quality.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an error rate check apparatus for checking an error rate in a recording state of a digital video tape recorder, and more particularly to an error rate check at the time of splicing recording in insert editing.

[0002]

2. Description of the Related Art In recent years, since video and audio signals handled by broadcasting stations and video studios are of high quality and can be easily subjected to various signal processing processes, digital video and audio signals are converted from conventional analog video and audio signals. Replaced by a traffic light. Therefore, a video tape recorder (hereinafter, referred to as a VTR) for recording and reproducing video and audio signals has been replaced with a digital VTR from a conventional analog VTR.

[0003] By the way, editing work is frequently performed in a broadcasting station, a video studio, and the like, and even when the digital VTR is used, the same editing operation as that of a conventional analog VTR is realized.

There are various kinds of work contents in the editing work using the digital VTR. Among them, the editing work at the time of insert editing will be described below.

A digital video and audio signal format handled by a digital VTR is a so-called MPEG (Movi).
ng Picture Image Coding Experts Group). Therefore, insert editing of video signals is performed in units of frames, but recording on tape is GOP (Group Of Pic
ture) unit.

For this reason, in the process of insert editing, for example, at the IN point, the GOP data immediately before the GOP including the IN point is reproduced from the tape by the pre-read head (advanced reproducing head), and the video signal (insert) at the IN point is inserted. (Encoded video signal). The insert on the tape is recorded by encoding from the GOP including the in point. Therefore, when the IN point is an I picture (because insert editing is performed on a frame basis, a picture is hereinafter referred to as a frame), the B
The frame will be encoded and recorded again.

If the in-point is a B frame,
Since the frame has no correlation with the I frame of the immediately preceding GOP, a forced backward process is performed at the time of encoding.

When the IN point is an I frame, GOP
Since there is no correlation with the I frame, the B frame immediately before the pair becomes a re-encoding by forced forward processing at the time of encoding.

On the other hand, in the process at the out point of the insert editing, the video signal to be inserted and the pre-read and decoded signal are switched at the out point as in the process at the in point.

If the B frame is immediately after the OUT point, the B frame of the GOP recorded on the tape cannot be decoded because the I frame at the time of encoding is lost. Therefore, since the B frame (including GOP) needs to be re-encoded, the GOP to be recorded is 1 GO.
A process of extending P is performed. Viewing on the foot point of the tape results in recording from the GOP including the in point to the next GOP after the out point.

[0011] The B frame to be re-encoded in the extended GOP has no correlation with the I frame in the immediately preceding GOP to be inserted. Therefore, re-encoding is performed by forced backward processing.

If the I frame is immediately after the OUT point, GO
The B frame to be inserted immediately before the pair of P has no correlation with the I frame. Therefore, as encoding for the B frame, encoding is performed by forced forward processing.

[0013]

As described above, in insert editing in a digital VTR, data (base data) previously recorded on a tape is read while recording, and processing for splicing is performed. It is made as follows. Therefore, the quality of the error rate of the reproduced data read from the tape prior to the recording has a very important meaning as reference data for the splicing process.

However, the check (or measurement) of the error rate in the conventional digital VTR is performed only in the reproduction only mode in which the recording mode is released.
It is not performed in the recording mode such as the insert editing described above. That is, the conventional digital VTR cannot check the error rate in the recording mode.

In the recording mode in the digital VTR, the related ICs including the microcomputer operate the recording process in full operation. Therefore, it can be said that this is the most disadvantageous mode with respect to the interface for extracting / transmitting the reproduced data.

In particular, regarding the reproduction signal system in the rotating drum, since a recording signal of a large amplitude is generated in the vicinity,
It can be said that the error rate degradation is most likely to occur.

However, regarding such a system, as described above, the conventional digital VTR does not include an error rate check system in the recording mode.
For example, at present, it is not known exactly how much margin the error rate of the reproducing system has in the recording mode in the manufacturing process or the actual use state.

Accordingly, the present invention has been proposed in view of the above-mentioned circumstances, and has an error rate checking device for a digital VTR capable of checking (or measuring) an error rate of a reproducing system in a recording mode such as insert editing. The purpose is to propose.

[0019]

SUMMARY OF THE INVENTION The present invention comprises at least a preceding reproducing head for reproducing a recording signal on a magnetic tape prior to signal recording by a recording head. An error rate checker of a digital video tape recorder that reproduces a recording signal from a magnetic tape by a reproducing head. The error rate of the reproduced signal reproduced from the magnetic tape by the preceding reproducing head at the time of insert editing, or information proportional to the error rate. The above-described problem is solved by detecting the error rate and outputting an error rate pass / fail determination result or an error rate value based on the error rate detected at the time of insert editing or information proportional to the error rate.

That is, according to the present invention, the error rate of the preceding reproducing head can be detected at the time of insert editing, so that the error rate of the reproducing system at the time of recording of insert editing can be reduced, for example, in a manufacturing process or an actual use state. It is possible to know exactly how much room there is.

[0021]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a configuration of a main part of a rotary drum type recordable / reproducible digital VTR system capable of detecting an error rate or information proportional thereto. In the configuration shown in FIG. 1, an example is described in which the error rate check device of the present invention is built in a digital VTR. However, it is needless to say that the error rate check device can be formed as a single configuration separated from the digital VTR. It is. Further, in the present embodiment, description of other operations is omitted, and particularly, only operations during insert editing are described.

The digital VTR according to the present embodiment has the configuration shown in FIG.
As shown in the figure, a rotating drum D on which a plurality of heads are arranged
And a signal processing system corresponding to each head. In FIG. 1, for simplification, only the advanced reproduction head 1, the simultaneous reproduction-only head 7, the recording head 13, and their signal processing systems for one system are shown as representatives.

More specifically, on the rotating drum D, as shown in FIG. 2, two systems of digital recording heads RA and RB, which are recording heads, and these recording heads R
Two digital reproduction heads (simultaneous reproduction-only heads) PCA and PCB for tracing tracks immediately after recording by A and RB and taking in data immediately after the recording.
And two digital reproducing heads PA1 and PB1 used in the normal reproducing mode, and two digital reproducing heads (advanced reproducing heads) PA2 and PB2 for tracing the tape ahead of the recording heads RA and RB. Are provided as heads for digital signals.
On the rotating drum D, four analog reproducing heads PCA, PYA, PCB, P
In addition to the YB, an erasing head FE and two dummy heads DM for rotation adjustment are also provided.

In the head arrangement shown in FIG. 2, the advanced reproducing heads PA2 and B2 for reproducing data on the tape prior to the recording are located at positions closer to the recording heads RA and RB. Accordingly, for example, when reading data (base data) recorded on a tape while performing recording and performing processing for continuous shooting as in the above-described insert editing, the recording system is easily affected by the error and the error rate Is likely to deteriorate. For this reason, it is necessary to confirm that a sufficient error rate can be obtained even at the time of the insert editing, and the digital VTR of this embodiment can check (or measure) the error rate at the time of insert editing.

The operation of the digital VTR according to the present embodiment when checking (or measuring) the error rate during insert editing will be described below.

In FIG. 1, a key panel 10 is a man-machine interface to which various kinds of operation information are inputted by a user. From this key panel 10, for example, a command of an error rate check (or measurement) in an insert mode is inputted. If so, the command is sent to the microcomputer 9.

The microcomputer 9 is a processor that controls various parts of the digital VTR and performs various arithmetic processing. For example, a command for error rate check (or measurement) in the insert mode is input from the key panel 10. In this case, each part is set and controlled to operate in the insert mode.

Here, a flow when the digital VTR shifts to the error rate check mode in the insert mode in response to an input from the key panel 10 will be described. Each menu described below is an example.

First, when, for example, a “menu” button is pressed (ON) among various buttons provided on the key panel 10, a plurality of menu items are displayed on the display device 11. The display device 11 used in the present embodiment is for displaying information supplied from the microcomputer 9, and is connected to a television monitor connected via a video output terminal of the digital VTR. Digital VTR
It may be a display panel provided on the main body or a display panel provided on a remote controller.

Among the plurality of menu items displayed on the display device 11, there is, for example, a menu item of "maintenance mode", and when performing an error rate check, the menu item of "maintenance mode" is displayed. select.

When the "maintenance mode" menu item is selected, the menu items displayed on the display device 11 are changed to a plurality of "maintenance mode" menu items. This "maintenance mode"
Among a plurality of menu items for use, there is a menu item of “RF check” as a menu item for checking a reproduced RF signal, and when performing an error rate check, the “RF check” is selected. Select a menu item.

When the "RF check" menu item is selected, the menu items displayed on the display device 11 are changed to a plurality of menu items for the "RF check". Among the plurality of menu items for “RF check”, there is a menu item of “recording channel condition” as a menu item for checking an error rate of reproduction at the same time as recording, and the error rate check is performed. In this case, the menu item "recording channel condition" is selected.

When the menu item "recording channel condition" is selected, the menu items displayed on the display device 11 are changed to a plurality of menu items for the "recording channel condition". Among the plurality of menu items for “recording channel condition”, there are a menu item for designating a check for each channel, an “all” menu item for sequentially checking all channels, and the like. The menu item “all” exists and is selected in the present embodiment.

As described above, the digital VTR shifts to the error rate check mode in the insert mode.

When the insert mode is set as described above and insert recording is performed in the digital VTR, the video and audio signals already recorded on the tape 16 precede the recording head 13 and the tape 16 Is reproduced by an advanced reproducing head 1 for tracing, amplified by a reproducing amplifier 2 and equalized by an equalizer 3. The reproduced RF signal that is an analog signal output from the equalizer 3 is converted into a digital signal by the A / D converter 4 and sent to the error rate detector 5.

The error rate detector 5 detects the error rate of the input reproduced digital signal or detects information proportional to the error rate. In the following description, the error rate or information proportional thereto will be collectively referred to as error rate information. The error rate information detected by the error rate detector 5 is sent to the microcomputer 9. The digital video and audio signals are sent from the error rate detector 5 to the terminal 6. A decoding processing system for video and audio is connected to a stage subsequent to the terminal 6.

The microcomputer 9 can grasp the error rate of the digital signal extracted by a specific head among the plurality of advance reproduction heads 1 based on the error rate information detected by the error rate detector 5. It has been done. The microcomputer 9
When the above error rate is grasped, the result, that is, the result of checking the error rate is displayed on the display device 11.
To be displayed. As the error rate in insert mode, for example, it is required about 10 ^-5, and therefore, the microcomputer 9, and the 10 ^-5 degrees and the threshold value, the error rate satisfies the extent the ^10-5 At this time, for example, [OK] is displayed on the display device 11 as the check result, and conversely, if the value does not satisfy about 10 ^-5, for example, [NG] is displayed on the display device 11 as the check result. Further, the check result from the microcomputer 9 can be output to the outside via the terminal 12.

On the other hand, recording digital data obtained by encoding video and audio data for insert recording is input to the terminal 15. The recording digital data input to the terminal 15 includes data re-encoded using digital data reproduced by the advanced reproduction head 1 prior to recording at the in-point or out-point of insert editing. The re-encoding is not limited to the re-encoding at the time of insert editing when the above-mentioned MPEG signal format is applied, but may be another signal format. It is not bound by format.

The recording digital data input from the terminal 15 is supplied to the recording driver 14. The operation of the recording driver 14 is controlled by the microcomputer 9, generates a recording signal from the recording digital data, and sends the recording signal to the recording head 13. Thus, insert recording is performed.

FIG. 3 is a flowchart showing the operation in the error check mode in the insert mode described above.

In FIG. 3, in step S1, an error check mode is set from the key panel 10 by a user operation. In the next step S2, the recording driver 14 drives the recording head 13 with the set current value,
Thus, the recording head 13 records the recording data on the tape 16 as in step S3.

On the other hand, in step S4, the information previously recorded on the tape 16 is fetched by the advanced reproduction head 1 simultaneously with the above-mentioned recording. In the next step S5, the reproduction RF signal from the advance reproduction head 1 is amplified by the reproduction amplifier 2 and further equalized by the equalizer 3.
Next, in step S6, the signal equalized by the equalizer 3 is converted into a digital signal by the A / D converter 4.

This digital signal is sent to the error rate detector 5 in step S7, where the error rate is detected.

In the next step S 8, the error rate information from the error rate detector 5 is
The microcomputer 9 determines whether or not the error rate is optimal based on the error rate information.

In the next step S9, the result of the judgment, that is, the check result is displayed on the display device 11.

Thereafter, in step S10, a determination is made as to whether or not to perform an error rate check on the next channel (reproducing head system). When the error rate check on the next channel is performed, the processing from step S1 is performed. If not, the error rate check process is terminated.

Returning to FIG. 1, in the digital VTR of the present embodiment, the simultaneous reproduction-only head 7 traces the track immediately after the recording by the recording head 13 and takes in the data immediately after the recording. The block 8 includes a reproduction amplifier 2, an equalizer 3, and an A / D converter 4 similar to the above, and amplifies, equalizes, and A / D converts a reproduction RF signal from the simultaneous reproduction-only head 7. The output data from the block 8 is also sent to the error rate detector 5. As a result, the error rate detector 5 evaluates the error rate of the recording data in the same manner as the data obtained from the advanced reproducing head 1.

That is, in the error check mode of the insert mode in the present embodiment, the error rate check of the reproduction RF signal processing system of the advance reproduction head 1 and the reproduction RF from the simultaneous reproduction only head 7 are performed.
An error rate check of the signal processing system is also performed. Therefore, the error rate detector 5 and the microcomputer 9 distinguish between the error rate check of the reproduction RF signal processing system of the advance reproduction head 1 and the error rate check of the reproduction RF signal processing system from the simultaneous reproduction-only head 7. The error rate check results are displayed on the display device 11 separately. In the microcomputer 9,
The threshold value (error rate pass / fail threshold) of the error rate check of the reproduction RF signal of the advance reproduction head 1 and the error rate check of the reproduction RF signal from the simultaneous reproduction dedicated head 7 may be the same value or a different value. it can.

In the digital VTR of this embodiment, the result of checking the error rate in the insert mode as described above can be individually displayed for each system of a plurality of reproducing heads. Thereby, the advanced reproduction head 1 in the digital VTR of the present embodiment,
Regenerative amplifier 2, equalizer 3, A / D converter 4, and
The reproducing system error rate measuring system in the insert mode, which is the most disadvantageous for the characteristics of the reproducing system constituted by the simultaneous reproduction-only head 7 and the block 8 and which is frequently used, can be constructed.

That is, the digital VTR of the present embodiment
In, the error rate of all the reproducing heads can be checked in the insert mode in which the error rate degradation is most likely to occur for the reproducing signal system in the rotary drum D, so that the digital VT of high reliability and high quality can be checked.
R can be manufactured and the user can, for example,
To help you use it correctly and optimally.

Further, the digital VTR of the present embodiment
In, when performing insert editing, it is possible to grasp whether the error rate characteristic of the advanced reproducing head 1 system that prefetches data at a joint shooting point satisfies a desired characteristic in the insert mode (recording state). While the data is being recorded by the recording head 13, the data is immediately reproduced by the subsequent simultaneous reproduction exclusive head 7, and it is checked whether the error rate for confirming the characteristics and quality of the recorded data satisfies the desired characteristics. Can also be grasped.

In the above description, an example has been described in which the error rate of channels corresponding to all reproduction heads is checked in a digital VTR having a plurality of reproduction heads. However, the check result of each channel corresponding to each head is checked. Can be displayed without displaying all the worst channels. In addition, the check result is not only displayed on the display device 11, but also displayed.
It is also possible to display on a display panel provided on a digital VTR main body or a display panel provided on a remote controller. Further, in the present embodiment,
Although an example in which “OK” or “NG” is displayed as the check result has been described, a numerical value of the error rate itself may be displayed.

[0054]

As described in detail above, in the error rate checking apparatus of the digital video tape recorder according to the present invention, the error rate or error rate of the reproduced signal reproduced from the magnetic tape by the preceding reproducing head during insert editing is reduced. Recording mode such as insert editing by detecting proportional information and outputting an error rate pass / fail judgment result or an error rate value based on the detected error rate or information proportional to the error rate. It is possible to check (or measure) the error rate of the reproduction system at the time, and thus, for example, in the manufacturing process or the actual use state, accurately determine how much margin the error rate of the reproduction system has when recording insert edits. It becomes possible to grasp.

[Brief description of the drawings]

FIG. 1 is a block circuit diagram showing a schematic configuration of only one system in a digital VTR incorporating an error check device according to an embodiment of the present invention.

FIG. 2 is a diagram showing an arrangement of heads on a rotating drum of the digital VTR according to the embodiment.

FIG. 3 is a flowchart showing a flow of an error rate check in an insert mode in the digital VTR according to the embodiment.

[Explanation of symbols]

1 advanced reproduction head, 2 reproduction amplifier, 3
Equalizer, 4 A / D converter, 5 Error rate detector, 7 Simultaneous playback dedicated head, 8 blocks,
9 microcomputer, 10 key panel,
11 display device, 13 recording head, 14
Recording driver

Claims (6)

[Claims] At least a preceding reproduction head for reproducing a recording signal on a magnetic tape prior to signal recording by a recording head is provided, and at the time of insert editing, the insert recording by the recording head is simultaneously performed from the magnetic tape by the preceding reproduction head. An error rate check device of a digital video tape recorder that performs recording signal reproduction of an error rate of a reproduction signal reproduced from a magnetic tape by the preceding reproduction head prior to signal recording by a recording head during the insert editing, or Detecting means for detecting information proportional to the error rate, based on the error rate detected by the detecting means at the time of the insert editing or information proportional to the error rate, output a pass / fail determination result of the error rate, or Check result to output error rate value Error rate checking apparatus in a digital video tape recorder, characterized in that it comprises a power means. 2. The digital video tape recorder error rate checking device according to claim 1, further comprising display means for displaying the error rate check result from said check result output means. 3. The digital video tape according to claim 1, further comprising operation setting input means for setting a detection operation of said detection means and a check result output operation of said check result output means at the time of insert editing. Error rate checker for recorder. 4. The check result output means compares the error rate detected by the detection means or information proportional to the error rate at the time of the insert editing with a predetermined threshold value, and determines whether the error rate is good or bad. 2. The error rate check device for a digital video tape recorder according to claim 1, wherein the error rate is checked. 5. The digital video tape recorder according to claim 1, further comprising a succeeding reproducing head for reproducing a recording signal immediately after recording by the recording head, wherein the detecting means converts the signal immediately after recording by the recording head during insert editing. The error rate of the reproduced signal reproduced by the row reproducing head, or information proportional to the error rate is also detected. In the check result output means, the following reproducing head detected by the detecting means at the time of the insert editing is used. 2. The digital video tape according to claim 1, wherein an error rate good or bad judgment result or an error rate value is output based on an error rate of a reproduced signal reproduced or information proportional to the error rate. Error rate checker for recorder. 6. The error rate check device for a digital video tape recorder according to claim 2, wherein said digital video tape recorder has a display panel, and said display panel is used as said display means.