JPH08237602A - Playback device and recording device - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To eliminate image quality deterioration due to repeated compression and expansion. An ECC decoder (30) corrects an error in reproduced data with an error correction code and sets an error flag (50) for an error that cannot be corrected.
Output to 0. The output of the decoder 30 is restored to image data by the expansion circuit 32 and the correction circuit 34. The output of the decoder 30 (compressed data without error correction parity) and the output of the retouching circuit 34 (decompressed image data) are output to the recording system for dubbing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reproducing device and a recording device.

[0002]

2. Description of the Related Art In recent years, digital VTRs of high image quality have been attracting attention so as to minimize the deterioration during dubbing. FIG. 3 shows a block diagram of its basic configuration. The video signal input to the input terminal 10 is digitized by the A / D converter 12 and supplied to the band compression encoding circuit 16 via the changeover switch 14. The ECC encoder 18 adds an error correction code, so-called parity, for correcting an error generated at the time of reproduction, to the signal band-compressed and encoded by the band compression encoding circuit 16. ECC encoder 18
Is modulated by a digital modulation circuit (not shown), amplified by the recording amplifier 20, and magnetically recorded on the magnetic tape 24 by the magnetic head 22.

A recording signal on the magnetic tape 24 is converted into an electric signal by a magnetic head 26 and amplified by a reproducing amplifier 28. In a normal recording / reproducing apparatus, the recording head and the reproducing head are also used, and the magnetic head 22 and the reproducing head 26 are the same.
Are the same head, and are shown as if they were different heads for ease of understanding.

The output of the reproduction amplifier 28 is demodulated by a digital demodulation circuit (not shown) and then the ECC decoder 30.
Is applied to The ECC decoder 30 includes an encoder 18
The reproduction error is corrected by using the error correction code added in. The decompression circuit 32 outputs the output of the ECC decoder 30,
The process opposite to the band compression encoding circuit 16, that is, band expansion and decoding, is performed, and the correction circuit 34 determines that the reproduction error is ECC.
This is a circuit for correcting an uncorrectable error by processing such as interpolation when the correction capability of the decoder 30 is exceeded. D /
The A converter 36 converts the output of the modifying circuit 34 into an analog signal and outputs it to the output terminal 38.

In case there are many uncorrectable errors during dubbing, the changeover switch 14 causes the A / D
The input digital signal from the converter 12 and the correction circuit 34
The output of can be switched.
That is, when a large number of uncorrectable errors exist such that the correction circuit 34 operates, the switch 14 is switched to the a contact side, the corrected data is applied to the compression encoding circuit 16, and the compression encoding is performed again. Magnetic tape 2
4 magnetically recorded.

In the case of a digital VTR, an analog VTR
As described above, there is no influence of distortion of the electromagnetic conversion system, and therefore, image quality deterioration is only due to band compression and error correction when many errors occur.
Further, regarding dubbing, it is considered to be advantageous over the analog VTR in that deterioration due to distortion of the electromagnetic conversion system does not accumulate.

[0007]

However, in the above-mentioned conventional example, the switch 14 is connected to the a-contact side during dubbing,
When the retouched data output from the retouching circuit 34 is recompressed and magnetically recorded, there is a problem that image quality deteriorates due to repeated compression and decompression.

[0008] Therefore, an object of the present invention is to provide a reproducing apparatus and a recording apparatus that solve such a problem.

[0009]

A reproducing device according to the present invention is a reproducing device for reproducing digital data in which information amount is compressed and parity data is added, and an error in the digital data using the parity data. Error correction means, a decompression means for decompressing the information amount of the digital data that has been subjected to the correction processing by the error correction means, and a digital data that has been subjected to the correction processing by the error correction means. A first output unit for removing the parity data and outputting the digital data in which the information amount has been compressed; and a second output unit for outputting the digital data in which the information amount has been expanded by the expansion unit. Is characterized by.

The recording apparatus according to the present invention includes a compression unit for compressing the information amount of digital data, an input unit for inputting the digital data with the compressed information amount, and an error by adding parity data to the digital data. Error correction coding means for correction coding, recording means for recording digital data error-correction coded by the error correction coding means, digital data compressed by the compression means, and input by the input means Supply means for selectively supplying digital data and the error correction encoding means.

[0011]

Since the digital data is output in a state where the information amount is compressed after the error correction process is performed and the digital data is output after the information amount is expanded, it is unnecessary when the information is recorded. Since the compression / decompression is not repeated, image quality deterioration can be prevented.

Further, when the compressed data is output, the parity data is removed and then output, so that the redundancy of the output data can be suppressed.

[0013]

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

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. The same components as those in FIG. 3 are designated by the same reference numerals. 40 is an error position storage circuit for storing the error position by the flag output 50 of the ECC decoder 30, 42 is a delay circuit having a predetermined delay time τ described later, 44 is a delay signal by the delay circuit 42, and the output of the compression encoding circuit 16. It is a selection switch for selectively applying to the ECC encoder 18.

Since a predetermined normal recording / reproducing operation is the same as that in FIG. 3, the operation during dubbing will be mainly described below. FIG. 2 shows the data format of the signal of each part. In FIG. 2, D _i (i = 1 to n) is data, P _i is parity, ED _i is data in which an error remains even after error correction by the ECC decoder 30, and F _i is error presence or absence of data after error correction. Is an error flag that indicates error·
The flag F _i is “1” when an error remains in the corrected data D _i and “0” when no error remains. Figure 2
Then, it is assumed that an uncorrectable error remains in the data D ₂ and the ECC decoder 30 completely corrects the error in other data.

FIG. 2A shows the data format of the input signal 46 of the ECC decoder 30 during the first dubbing. That is, a predetermined number of symbols of data D _i (i = 1 to n)
Is added with a predetermined number of symbols of parity P _i . For example, in the Reed-Solomon (36, 32) system, 3
Parity of 4 symbols is added to the data of 2 symbols, and an error of 2 symbols can be corrected.

FIG. 2B shows the data format of the output signal 48 of the ECC decoder 30. The error of the data D ₁ is corrected by the parity P ₁ , and the next data D ₂ is input to the ECC decoder 30 (simultaneously, an error correction decoding time is required, but this is not essential in the present embodiment, and is ignored Output the corrected data D ₁ ,
After that, the error flag F ₁ indicating whether or not there is an error is output. Since no error remains in the data D ₁ , the error flag F ₁ is “0” in this case.

For the data D ₂ , the ECC decoder 3
0 cannot correct all errors, outputs the data ED ₂ including the error, and the error flag F ₂ is “1”. The D ₃ to D _n, is corrected completely even if an error, an error flag F ₃ to F _n is "0".

FIG. 2C shows an output signal 54 of the compression / encoding circuit 14, and an output 48 of the ECC decoder 30 is expanded / modified and recompressed by the expansion circuit 32, the modification circuit 34 and the compression coding circuit 16. Signal is shown. Modification circuit 34
The subscript a is added to the data D ₂ in order to show the modification by the. That is, the error data ED ₂ is the modification data D _2a
Changed to. Output 54 of compression encoding circuit 16 at this time
Is the expansion circuit 3 for the output of the ECC decoder 30.
2. The delay time of the delay circuit 42 is set to this time τ, which is delayed by the time τ corresponding to the processing time in the modification circuit 34 and the compression encoding circuit 16. FIG. 2 (4) shows the output signal 58 of the delay circuit 42.

The error position storage circuit 40 stores an error flag F _i (F _{2 in} this embodiment) in which "1" is set, and the timing of data D _i (D _{2 in} this embodiment) corresponding thereto. Then, the switch 44 is switched to the b contact side. That is, the switch 44 selects the data which has not been error-corrected by the ECC decoder 30 and which is connected to the b contact side, which is modified by the modification circuit 34 and recompressed by the compression encoding circuit 16, For the data having no error at the output stage of the ECC decoder 30, the data having no error is connected to the a-contact side and time-adjusted by the delay circuit 42 is selected. FIG. 2 (5) shows the data thus selected (specifically, the output of the ECC encoder 18). E
The CC encoder 18 adds a parity P _2a different from the original parity P ₂ to the modified data D _2a . The same parity P ₁ , P _{3 to} P _n is naturally added to the other data D ₁ and D _{3 to} D _n .

Signal 58 (FIG. 2 (4)) and signal 56
The time difference T from ((5) in FIG. 2) is determined by the ECC encoder 18
Corresponds to the processing time of.

As described above, in this embodiment, if there is no error in the data to be dubbed, the band-compressed data is recorded as it is, and the decompression / decompression is performed only when the error remains.
Retouch and recompress and record. This makes it possible to minimize deterioration in image quality due to repeated band compression.

In the above description, a magnetic tape is taken as an example of a recording medium, but it goes without saying that it can also be applied to a recording / reproducing apparatus for various recording media such as an optical disc, a magneto-optical disc, a solid-state memory and the like.

[0024]

As described above, according to the present invention,
Since unnecessary compression / decompression processing is not repeated, image quality deterioration can be prevented, and the redundancy of input / output data can be suppressed.

[Brief description of drawings]

FIG. 1 is a configuration block diagram of an embodiment of the present invention.

FIG. 2 is a data format for explaining the operation.

FIG. 3 is a configuration block diagram of a conventional example.

[Explanation of Codes] 16: Band compression encoding circuit 18: ECC encoder 20: Recording amplifier 22: Magnetic head 24: Magnetic tape 26: Magnetic head 28: Reproducing amplifier 30: ECC decoder 32: Decompression circuit 34: Modifying circuit 40: Error position storage circuit 42: delay circuit

Claims (2)

[Claims] 1. A reproducing means for reproducing digital data in which information amount is compressed and parity data is added, an error correcting means for correcting an error in the digital data by using the parity data, and the error correcting means. The decompressing unit that decompresses the information amount of the digital data that has been subjected to the correction process by: First to output the digital data
And a second output unit for outputting the digital data whose information amount has been expanded by the expansion unit. 2. A compression means for compressing the information amount of digital data, an input means for inputting the digital data having the compressed information amount, and an error correction for adding parity data to the digital data and performing error correction coding. Encoding means, recording means for recording digital data error-correction encoded by the error-correction encoding means, digital data compressed by the compression means and digital data input by the input means are selectively And a supply means for supplying the error correction encoding means to the recording apparatus.