JPH10173607A - Digital information processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the repetition of compression/expansion. SOLUTION: A band compression circuit 14 band-compresses a digital video signal, and an error correction code addition circuit 16 adds an error code to output data of the circuit 14. The output of the circuit 16 is digitally modulated by a modulation circuit 18 and is recorded in a magnetic tape 22 by a magnetic head 20. The recording signal of the magnetic tape 22 is reproduced by the magnetic head 24 and is demodulated by a demodulation circuit 26. An error correction circuit 28 corrects the error, in accordance with the error correction code added in the error correction code adding circuit 16. An interpolation circuit 32 interpolates data, which cannot be corrected in the error correction circuit 28 into a compression state as it is. A switch 62 selects the output of the compression circuit 14 or the interpolation circuit 32. An error correction code addition circuit 36 adds the error correction code for transmission to the output of the interpolation circuit 32, and a modulation circuit 38 executes modulation for transmission and transmits the signal to a transmission line 40.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a digital information processing apparatus.

[0002]

2. Description of the Related Art In recent years, digital tape recorders for digitizing and recording various signals such as video and audio have been actively developed and put into practical use, and digital media such as optical fibers and communication satellites have been digitized. Has been actively researched, and some have been put into practical use. However, when a video signal such as a standard television signal is digitized and recorded or transmitted, the amount of data becomes enormous. In general, the statistical information and visual characteristics of image information are used. A band compression technique for reducing the data amount to about a fraction is used. In addition, since data errors occur due to noise in a recording / reproducing system or a communication line, an error correction code is used to detect and correct the errors.
Furthermore, when a large amount of noise is mixed in, it may occur that the error correction code cannot completely correct the error, but in the case of an image, a spatial or temporal correlation such as a vertical correlation is used. The missing data can be compensated. This process is called interpolation.

Although these techniques are common to the recording / reproducing system and the communication system, actually, different systems are often used. This is because the quality of the recording / reproducing system is significantly different from that of the communication line, for example, the number of continuous burst errors is much larger. More specifically, the recording / reproducing system and the communication system employ their own compression systems and error correction codes, respectively. At the time when the signal is passed from the recording / reproducing system to (the transmission circuit of) the digital or digital system, It was returning to an analog video signal. In addition, when the encoding sampling rate differs between the recording / reproducing system and the communication system, it is necessary to return to an analog signal or to interpose an interface circuit.

[0004]

As described above, in the conventional example, the recording / reproducing system and the communication system independently perform compression / expansion processing. When the digital recording / reproducing system is incorporated in the digital transmission system, the system is not used. In addition to the increase in size and cost, repetition of compression / decompression processing may cause deterioration in image quality. That is, when the recording band compression method is different from the transmission band compression method, there is a high possibility that the image quality is deteriorated. For example, the sub-sampling may be based on the field offset method on the one hand and the line offset method on the other hand, or when the setting values of the quantizers for differential quantization are different.

Accordingly, an object of the present invention is to provide a digital information processing apparatus which does not cause the above-described signal deterioration.

[0006]

A digital signal transmission apparatus according to the present invention comprises a compression means for compressing input digital information, and an additional means for adding an error correction detection code to the compressed digital information compressed by the compression means. Means,
Recording means for recording, on a recording medium, compressed digital information to which an error correction detection code has been added by the addition means; reproducing means for reproducing compressed digital information to which the error correction detection code has been added, recorded on the recording medium; An error correction unit that corrects an error code of the compressed digital information reproduced by the reproduction unit using the error correction detection code; and a correction process performed by the compressed digital information output from the compression unit and the error correction unit. Output means for selectively outputting the compressed digital information to a transmission path.

[0007] By the above means, even the same compressed digital information can be transmitted to the transmission path by selecting one that has passed through the recording and reproducing system and one that has not passed through the recording and reproducing system. Since the compressed information is not expanded at the time of reproduction, the configuration of the apparatus is simplified, and signal deterioration due to repeated compression and expansion can be prevented.

[0008]

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. In FIG. 1, an analog video signal is input to an input terminal 10, and the signal is digitized by an A / D converter 12. The band compression circuit 14 includes the A / D converter 1
The output data (digital video signal) of No. 2 is band-compressed by sub-sampling, differential encoding, etc. to reduce the data amount to a fraction. The error correction code adding circuit 16 adds an error correction code to the output data of the band compression circuit 14,
The modulation circuit 18 performs digital modulation by, for example, a scramble NRZ method, and the output is recorded on a magnetic tape 22 by a magnetic head 20.

The recording signal of the magnetic tape 22 is transmitted to the magnetic head 2
4 and demodulated by the demodulation circuit 26. The error correction circuit 28 performs error correction according to the error correction code added by the error correction code addition circuit 16. The output of the error correction circuit 28 is a compressed video signal. In the conventional example, the output of the error correction circuit 28 is expanded by the expansion circuit.
In this embodiment, the output of the error correction circuit 28 is
, And interpolates the data that could not be corrected by the error correction circuit 28. The interpolation circuit 32 supplements necessary data by, for example, intra-frame or inter-frame interpolation. When performing interpolation on a compressed signal, it may not be easy depending on the compression method.However, for example, line interpolation may be performed on a differential quantized signal, etc. What is necessary is just to select the combination of methods.

Next, the output of the interpolation circuit 32 is applied to a processing system for transmission. That is, the error correction code addition circuit 36 adds an error correction code for transmission, and the modulation circuit 38 performs modulation for transmission. The output of the modulation circuit 38 is sent to the transmission line 40. The transmission path 40 is, for example, an optical fiber or a communication satellite. The signal passing through the transmission path 40 is demodulated by a demodulation circuit 42 of the receiving device, an error correction circuit 44 performs error correction using the error correction code added by the error correction code addition circuit 36, and a decompression circuit 46 A decompression process corresponding to the band compression circuit 14 is performed to return to a digital video signal. The interpolation circuit 48 interpolates a portion that cannot be corrected by the error correction code by the error correction code adding circuit 36. D /
The A converter 50 converts the output data of the interpolation circuit 48 into an analog signal and outputs it to an output terminal 52.

In the embodiment shown in FIG. 1, a signal reproduced from a magnetic tape 22 as a recording medium is interpolated by an interpolation circuit 32 without performing a decompression process, and an error correction code for transmission is added to transmit the signal. Since the signal is transmitted to the path 40, the signal is passed from the recording / reproducing system to the transmitting circuit of the communication system in the form of a compressed signal. Therefore, the deterioration of the image quality due to the repetition of the compression / expansion processing is eliminated.

FIG. 2 is a block diagram showing the configuration of another embodiment of the present invention. The same components as those in FIG. 1 are denoted by the same reference numerals. In the present embodiment, the recording / reproducing system (that is, the circuits 16 to 32) of the magnetic tape 22 can be bypassed by the bypass circuit 60 and the changeover switch 62 on the transmission side. On the receiving side, the output of the error correction circuit 44 is applied to the interpolation circuit 64, and interpolation of the error-correctable data is performed first, and the output of the interpolation circuit 64 is sent to the recording / reproducing system 65 and its bypass circuit 66. Applied, and the recording / reproducing system 6
5 and the detour 66 are selected. The output of the switch 68 is applied to a decompression circuit 69, which performs a decompression process corresponding to the band compression in the band compression circuit 14. In the recording / reproducing system 65, 70 is an error correction code adding circuit, 72 is a modulation circuit,
74 is a recording head, 76 is a magnetic tape, 78 is a reproducing head, 80 is a demodulation circuit, 82 is an error correction circuit, 84 is an interpolation circuit, and has the same action as the circuits 16 to 32. That is, when a transmitting / receiving circuit having both functions of the transmitting side and the receiving side shown in the drawing is configured, the functions of the circuits 16 to 32 and the recording / reproducing system 65 can be shared by one recording / reproducing system.

In the embodiment of FIG. 2, when the switch 62 is connected to the contact a, the operation is the same as that of the transmitting side of the embodiment of FIG. When the switch 62 is connected to the contact b,
The signal at the input terminal 10 is transmitted to the transmission line 40 in real time.

On the other hand, on the receiving side, first, the interpolation circuit 64 interpolates data that cannot be corrected by the error correction circuit 44. When the switch 68 is connected to the contact b, the output of the interpolation circuit 64 is expanded by the expansion circuit 69,
The signal is returned to an analog signal by the / A converter 50. When the switch 68 is connected to the contact a, the output of the interpolation circuit 64 is temporarily recorded on the magnetic tape 76. As described above, by performing the interpolation process on the compressed video signal, it is not necessary to repeat the compression and decompression even when the received signal is once recorded on the recording medium.

In the embodiment shown in FIG.
, Four types of usage are possible.

In FIGS. 1 and 2, the magnetic head 20,
24; 74 and 78 are shown, but of course there may be more than one, and they may be used for both recording and reproduction. Further, a rotary head system such as a VTR may be used. Instead of the magnetic tapes 22 and 76, a magnetic disk or an optical disk may be used.

In the above embodiment, a system for transmitting a digital video signal as a digital signal has been described. However, the present invention is naturally applicable to a system for transmitting another digital signal such as an audio signal. is there.

[0019]

As can be easily understood from the above description, according to the present invention, compression and decompression are not repeated during recording / reproduction processing and transmission processing, so that the configuration of the apparatus can be simplified, and the cost, size, and cost can be reduced. Power consumption can be reduced, and signal quality is not impaired.

[Brief description of the drawings]

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

FIG. 2 is a configuration block diagram of another embodiment of the present invention.

[Explanation of symbols]

 10: input terminal 14: band compression circuit 16, 36, 70: error correction code adding circuit 18, 38, 72: modulation circuit 20, 24, 74, 78: magnetic head 22, 76: magnetic tape 26, 42, 80: Demodulation circuits 28, 44, 82: Error correction circuits 32, 48, 64, 84: Interpolation circuits 46: Decompression circuits 52: Output terminals

Claims (1)

[Claims] A compression means for compressing the input digital information; an addition means for adding an error correction detection code to the compressed digital information compressed by the compression means; and an error correction detection code added by the addition means. Recording means for recording the compressed digital information on the recording medium, reproducing means for reproducing the compressed digital information recorded with the error correction detection code recorded on the recording medium, and reproducing the compressed digital information reproduced by the reproducing means. Error correction means for correcting an error code using the error correction detection code; and selectively transmitting the compressed digital information output from the compression means and the compressed digital information corrected by the error correction means to a transmission path. A digital information processing device comprising: an output unit that outputs the digital information.