KR100294168B1 - Error correction device and its method in magnetic recording and playback equipment - Google Patents

Abstract

The error correcting apparatus and method thereof of the disclosed magnetic recording and reproducing apparatus detect the sink block in which the error occurs without miscorrection even when there is a large dropout or channel error and it is out of the ECC correction range. In this case, high-quality image quality can be obtained even if the media recorded on the magnetic tape or the disk is bad.

The apparatus of the present invention comprises a reproduction amplifier section for amplifying a signal reproduced by the reproduction head to a predetermined level, a data detector for detecting digital data from the signal amplified by the reproduction amplifier section, and digital data detected by the data detector section. A synchronizing signal detector for detecting a synchronizing signal as a reference signal from the apparatus; an area detecting unit detecting data for audio data, video data, and additional information in one track based on the synchronizing signal detected by the synchronizing signal detecting unit; A dropout detector for outputting a dropout pulse when the signal output from the reproduction amplifier unit is smaller than a predetermined reference level after comparing the signal output from the predetermined reference level with each data input from the area detector; The dropout detection after performing error correction according to an internal code on the data ECC unit that performs error correction according to external code or compares with data of previous screen when error correction is difficult compared to the maximum number of error correction sync blocks for audio and video data according to dropout pulse input from do.

Accordingly, the present invention can secure the best image quality even when the number of sink blocks in which an error occurs exceeds the error correction range according to an external code or when the number of sink blocks is wrong due to a burst error. Can be replaced with the data of the same sync block of the previous screen, thereby providing a cleaner image quality.

Description

Error correction device and its method in magnetic recording and playback equipment

The present invention relates to an error correction apparatus and method thereof of a magnetic recording and reproducing apparatus, and more particularly, a sink block in which an error occurs without miscorrection even when a dropout or a channel error is out of the ECC correction range. The present invention relates to an error correction device and a method of a magnetic recording / reproducing apparatus which replaces data of the same sync block on a previous screen so that a high quality image can be obtained even if a medium recorded on a magnetic tape or a disk is bad.

Ideally, if there is no error in storing or transmitting a bit stream encoded by MPEG, the possibility of bit error due to external factors such as noise cannot be avoided. In particular, the MPEG2 system defines a program stream PS assuming an error-free environment and a transport stream TS corresponding to an error-free environment.

In digital broadcasting, a transport stream packet is used, in which error detection and correction are performed by an outer code that adds an error correction code outside the TS packet and an inner code that uses convolutional coding in the previous step of modulation. Inner), and Reed Solomon (Outed) code is used in particular, and is adopted in many digital broadcasting systems including Grand Alliance (GA) and Digital Video Broadcasting (DVB).

1 is a schematic block diagram for explaining the configuration of an error correction apparatus of a magnetic recording / playback apparatus according to the prior art.

As shown, a reproduction amplifier 10 for amplifying the signal reproduced by the reproduction head to a predetermined level, a data detector 20 for detecting digital data from the signal amplified by the reproduction amplifier 10; And a synchronization signal detection unit 30 for detecting a synchronization signal as a reference signal from the digital data detected by the data detection unit 20, and a synchronization signal input from the synchronization signal detection unit 30 with respect to the internal code. After correcting the error, separate the audio data and the video data, perform the error correction according to the external code, determine whether the error flag exists, and if the error correction is difficult, replace it with the data of the previous screen and output it. It consists of an ECC unit 40.

If error correction is difficult in the above-described ECC unit 40, it is replaced in units of one frame to replace the data of the previous screen. One frame consists of 10 tracks.

The operation of the error correction apparatus of the magnetic recording / playback apparatus having the above-described configuration will be described with reference to FIG.

FIG. 2 is a flowchart illustrating an operation of performing error correction on audio data and video data input in an ECC block applied to FIG. 1.

As shown, first, the reproduction amplifier 10 amplifies a signal reproduced through a reproduction head (not shown) to a predetermined level, and the amplified reproduction signal is digital data through the data detector 20. Is detected.

The detected data is input to the synchronization signal detector 30, and the synchronization signal detector 30 detects the synchronization signal from the detected data and transmits the data to the ECC unit 40 together with the data. Then, the ECC unit 40 receives the output of the synchronization signal detector 30 and performs error correction based on the internal signal based on the synchronization signal (S21).

As described above, the ECC unit 40 performing error correction according to the internal code separates the audio data and the video data on the basis of the synchronization signal input from the synchronization signal detection unit 30, which is the audio data and the video data. This is because the outer code blocks have different sizes. The ECC unit 40 performs the error correction according to the external call on the audio data and the video data thus detected (S22).

In addition, the ECC unit 40 that has performed error correction on the audio data and the video data according to the external code determines whether or not an error flag exists in each of them (S23). The generated frame is replaced with the frame data of the previous screen (S24).

If the determination result of the determination step (S23), if the error flag does not exist, the data is decompressed (S24) and output to the signal processing block provided at the rear end. On the other hand, since the damaged data is replaced frame by frame for the previous screen data to which the damaged data cannot be corrected as described above, no problem occurs on the slow screen, but the screen is displayed at a slow speed on the fast screen. do.

However, as described above, when the ECC performs the error correction process, the error occurrence range exceeds the error correction range according to the external code or when the sync block number is incorrect due to a burst error. Rather, an error occurs for more sync blocks, which may cause more sync blocks to be broken on the screen than before ECC correction, and when an error occurs, there is a problem in that data must be replaced in units of frames.

Accordingly, an object of the present invention is to detect the sink block where an error occurs without miscorrection even when the dropout or channel error is out of the ECC correction range due to a large number of dropout or channel errors so as to solve the above problem. The present invention provides an error correcting apparatus and a method of a magnetic recording / reproducing apparatus which can obtain high quality image quality even when a medium recorded on a magnetic tape or a disk is replaced with data.

1 is a schematic block diagram for explaining the configuration of an error correction apparatus of a magnetic recording / playback apparatus according to the prior art;

2 is a flowchart illustrating an operation of performing error correction on audio data and video data input in an ECC block applied to FIG. 1;

3 is a schematic block diagram for explaining the configuration of an error correction apparatus of the magnetic recording / playback apparatus according to the present invention;

4 is a detailed circuit diagram of a dropout detection block applied to FIG. 3;

5 is a waveform diagram output by a circuit provided in a dropout detection block;

6 is a waveform diagram illustrating a process of detecting a sink block in which dropout occurs in the present invention;

FIG. 7 is an operation flowchart for explaining error correction on audio data and video data input in an ECC block applied to FIG. 2;

8 is an operation flowchart for explaining another embodiment of performing error correction on audio data and video data input in an ECC block applied to FIG. 2;

FIG. 9 is a view showing audio data and video data in which a sink block capable of performing maximum error correction to be compared with a sink block in which dropout has been generated for error correction in the present invention; FIG.

FIG. 10 is a diagram for explaining output of a sink block in which a dropout occurs, by replacing data with the same sink block in a previous screen according to the present invention.

* Description of Signs of Main Parts of Drawings *

100: reproduction amplifier 200: data detector

300: sync signal detector 400: region detector

500: dropout detection unit 600: ECC unit

In the error correcting apparatus of the magnetic recording and reproducing apparatus according to the present invention for achieving the above object, the apparatus of the present invention comprises: a reproducing amplifier section for amplifying a signal reproduced by the reproducing head to a predetermined level; A data detector for detecting digital data from the signal amplified by the signal, a sync signal detector for detecting a sync signal as a reference signal from the digital data detected by the data detector, and a track based on the sync signal detected by the sync signal detector. An area detector for detecting data of audio data, video data, and additional information therein; and a signal output from the reproduction amplification unit after comparing the signal output from the reproduction amplifier with a predetermined reference level is smaller than the predetermined reference level. A dropout detector for outputting a dropout pulse, and each input input from the area detector; After receiving the data, the data is corrected according to the internal code, and then the maximum number of error correction sync blocks for the audio and video data is compared to the external code according to the dropout pulse input from the dropout detector. If the error correction or error correction is difficult to perform according to the data of the previous screen is characterized in that it consists of an ECC unit for outputting.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 is a schematic block diagram for explaining the configuration of an error correction apparatus of the magnetic recording / playback apparatus according to the present invention.

As shown, a reproduction amplifier section 100 for amplifying the signal reproduced by the reproduction head to a predetermined level, a data detection section 200 for detecting digital data from the signal amplified by the reproduction amplifier section 100; A synchronization signal detection unit 300 for detecting a synchronization signal as a reference signal from the digital data detected by the data detection unit 200, audio data in a track based on the synchronization signal detected by the synchronization signal detection unit 300, The region detector 400 which detects data for the video data and the additional information, and the signal output from the reproduction amplifier 100 after comparing the signal output from the reproduction amplifier 100 with a predetermined reference level If it is smaller than the reference level, the dropout detection unit 500 outputs a dropout pulse and each data input from the area detection unit 400 is input. After performing the routine correction, it may be difficult to perform error correction or error correction according to an external code in comparison with the maximum number of error correction sync blocks for audio and video data according to the dropout pulse input from the dropout detection unit 500. In this case, it is composed of the ECC unit 600 to replace the data of the previous screen and output.

When the dropout result detected by the dropout detection unit 500 is larger than the maximum number of error correction syncblocks for the audio data and the video data, the ECC unit 600 displays the data for the damaged sync block as shown in the previous screen. Replace with the data for the sync block.

As another embodiment of the ECC 600 described above, the function receives each data input from the area detector 400 and performs error correction according to an internal code on each data, and then the dropout detector 500. If error plug is present by determining whether there is an error flag after performing error correction according to external code by comparing with the set number of error correction sync blocks for audio and video data according to the dropout pulse input from If the dropout result detected by the dropout detection unit 500 is larger than the set number of error correction sinkblocks for the audio data and the video data, or if an error flag exists, the damaged syncblock is outputted. The data for is replaced with the data of the same sync block of the previous screen.

4 is a detailed circuit diagram of the dropout detection block applied to FIG. 3.

As shown, the envelope is detected by comparing the envelope detection circuit unit 510 for detecting an envelope from the reproduced signal amplified by the reproduction amplifier unit 100 and the envelope output from the envelope detection circuit unit 510 with a predetermined reference level. When the reference level is less than the comparator 520 outputs a low level signal, and the output signal of the comparator 520 and the inverter outputs the dropout pulse generated by inverting the output to the ECC unit 600.

5 is a waveform diagram output by a circuit provided in the dropout detection block.

FIG. 6 is a waveform diagram illustrating a process of detecting a sink block in which dropout occurs in the present invention. First, the terms shown in the drawings will be briefly described as follows.

The SSA is an Insertion reference signal from the digital video camcorder into the Start Sync Block Area and has 61 sync blocks of 30 bits. In the present invention, the SSA flag is described as an example of generating one by one after detecting 30 bits.

D _A is the number of clocks in the audio drop zone, D _V is the number of clocks in the video drop zone, C _A is the number of clocks from the start of the audio zone to the point where the dropout occurred, and D _A is the number of dropouts from the start of the video zone. The number of clocks to the point of occurrence, D _AS is the number of _{sinkblocks that} have dropped out in the audio domain, D _AE is the number of _{sinkblocks that} have been dropped out in the audio domain, and D _VS is the number of dropouts in the video domain. The number of sync blocks, D _VE is the number of sink blocks that have been dropped out in the video area.

6, the waveform of the digital video camcorder according to the present invention, which is a kind of magnetic recording and reproducing apparatus, detects and counts 61 syncs in the SSA region and counts it based on the reference. Recognizes each region as 995 clock after audio data region, 13,245 clock after video data region, and 128,020 clock after sub code data region, and transmits the detection result to ECC unit 600. ) Is provided.

As described above, when a predetermined signal is recorded on the magnetic recording medium through the recording head by detecting 61 sinks of the SSA area and then detecting each data area, the first portion of the signal recording may occur for each channel. If it depends on the error, it can prevent the error that can occur during playback.

The operation of the error correction apparatus of the magnetic recording / playback apparatus according to the present invention configured as described above will be described in more detail with reference to the accompanying drawings.

FIG. 7 is a flowchart illustrating an operation of performing error correction on audio data and video data input in an ECC block applied to FIG. 2.

As shown, the signal reproduced by the reproduction head (not shown) is amplified to a predetermined level by the reproduction amplifier 100 and then digital data is detected by the data detector 200.

The detected digital data is input to the synchronization signal detector 300, and the synchronization signal detector 300 detects the synchronization signal, which is a reference signal, from the detected data and outputs the synchronization signal to the ECC unit 600.

In this case, the area detector 400 detects data existing in the same track, that is, data about audio data, video data, and additional information, based on the sync signal input from the sync signal detector 300.

Meanwhile, the dropout detection process of the dropout detection unit 500 will be described with reference to FIG. 5. The envelope detected through the envelope detection unit 510 at the output of the reproduction amplifier 100 is non-inverted by the comparator 520. Compared with the reference voltage Vref inputted to the terminal (+) and inputted to the inverting terminal (−), a high signal is outputted when the reference voltage is higher than the reference voltage, and a low signal is outputted by the inverter 530. Since the output is inverted, a high level dropout pulse is output when the envelope detected by the envelope detector 510 is smaller than the reference voltage.

Data detected by the area detector 400 is input to the ECC unit 600 through the above-described process, and a dropout pulse indicating the dropout area detected by the dropout detector 500 is input.

Then, the ECC unit 600 performs error correction according to the internal code on the inputted reproduction data (S71), and then the audio / video is detected based on the detection result of the area detection unit 400 and the detection result of the dropout detection unit 500. It is determined whether the number of error sync blocks generated in the data area is smaller than the number of audio / video ECC maximum error correction sync blocks (Amax / Vmax) (S72).

As a result of the determination, when the number of audio / video sync blocks where an error occurs is smaller than the maximum number of error correction sync blocks (Amax / Vmax), error correction according to an external code is performed (S73). Without performing the correction, the sink block in which the error occurs is replaced with data of the same sink block of the previous screen (S74).

By performing the ECC process as described above, the sink block number or burst error in which an error due to the dropout occurs is detected in advance, and error correction is performed according to the internal code, and then the damaged sync block without the error correction according to the external code. Is replaced with data of the same sink block of the previous screen, and miscorrection can be prevented. At this time, the sink block number where the dropout occurred by the area detector 400 and the dropout detector 500 can be known. The generated sync block can be easily replaced with the data of the same sync block in the previous screen, so that a cleaner picture quality can be obtained.

Meanwhile, when an error occurs in an area where ECC is impossible, there may be various methods for correcting the error. That is, there is a method of replacing an error-prone frame with a previous frame, a method of replacing an error-prone track with a previous track, and a method of replacing an error-prone sync block with an old sync block.

That is, in the related art, only a method of replacing an error-prone frame with a previous frame was possible, but in the present invention, the number of sync blocks of damaged data can be known using the data detection and dropout detection results, and thus, the frame can be replaced by a frame unit. In addition, it is possible to replace track units and sync block units.

That is, in the present invention, when the error area is replaced by the previous screen, the sync block number is calculated by calculating from the start point of the audio data area or the video data area to the start point of the dropout area from the detection result of the area detector 400. The dropout width can be used to accurately determine the range of sink blocks in which the dropout occurred.

As described above, the number of sink blocks in which the dropout has occurred can be accurately obtained by the following equation.

D _AS = INT {(C _A -500) / 720}

D _AE = D _AS + INT (D _A / 720) + 1

D _VS = INT {(C _V -500) / 720}

D _VE = D _VS + INT (D _A / 720) + 1

The sync block may be replaced with data of the same sync block of the previous screen by using the result value obtained by the above-described equation. As shown in FIG. 10, the sync block may be replaced with the Nth frame and track number = 3. If a dropout is detected between 103 (= D _VS ) and sync block 115 (= D _VE ), then when N-th frame is displayed on the screen, sync blocks 103-115 are the same as previous frame data, that is, N-1th frame data. By displaying the data of the sync blocks 103 to 115 as they are, the error of the Nth sync block can be hidden.

FIG. 8 is an operation flowchart for explaining another embodiment of performing an error correction process on audio data and video data input from an ECC block applied to FIG. 2, and as shown in FIG. 8. The description of the operation will be omitted, and only the ECC unit 600 that performs another operation will be described below.

The ECC unit 600 performs error correction according to an internal code on the audio data and the video data detected based on the synchronization signal detected by the synchronization signal detector 300 (S81), and then the area detector 400. The error correction for the audio data and the video data in which the number of sink blocks D _A (D _V ) in which the dropout occurs for audio data and video data is set according to the detection result of the dropout detection unit 500 and the detection result of the dropout detection unit 500. It is determined whether or not the number of sink blocks A _X (V _X ) that can be made (S82).

As a result of the above-described determination in step S82, when the number of sink blocks D _A (D _V ) where the dropout has occurred is smaller than the number of sink blocks A _X (V _X ) for the set error correction, According to the error correction (S83), and as a result of the determination in step S82, the number of sink blocks (A _X ) (V _X ) for error correction in which the number of sink blocks (D _A ) (D _V ) where dropout has occurred is set. If larger than), the sink block in which the dropout occurs is replaced with data of the same sink block of the previous screen (S84).

After performing the error correction according to the external code in the above-described step (S83), it is determined whether an error flag exists (S85), and if the error flag exists as a result of the determination, the data on the area where the error occurred is displayed on the previous screen. The audio data and the video data, which are replaced with the data of the same sync block (S86) and there is no error flag or the error correction process is completed, are stretched (S87) through the data stretcher (not shown in the drawing), and the rear end is made. Is output to the signal processing block.

At this time, as described above, the number of sink blocks that can be set for error correction that is compared with the number of sink blocks in which an error is compared to the sink blocks for which dropout is detected is replaced with data of the same sink block of the previous screen. It is set to be smaller than the number of sync blocks because the ECC can be performed in a stable state.

FIG. 9 is a diagram illustrating audio data and video data in which a sync block capable of performing maximum error correction to be compared with a sync block in which dropout is generated for error correction is shown. FIG. As shown, in the case of a digital video camcorder, the maximum correctable burst error value Amax of the audio region is as follows.

Amax = 4 + 90 × 5 + 9 = 463 bytes = 3,704 bits ≒ 143 μm (width direction) 902 μm (track length direction),

The maximum correctable burst error value Vmax of the video region is as follows.

Vmax = 4 + 90 x 11 + 9 = 1,003 bytes = 8,024 bits # 311 m (width direction) # 1.95 mm (track length direction).

FIG. 10 is a diagram illustrating that a sink block in which a dropout has occurred is replaced with the same sink block of a previous screen according to the present invention.

Therefore, as described above, in the conventional ECC, when the number of sync blocks is wrong due to an error number exceeding an error code or due to a burst error, an error occurs in more sync blocks. Due to this, more sync blocks are broken in the displayed screen than before ECC correction.This prevents the sync blocks from exceeding the error correction range according to the external code or prevents the sync blocks from bursting. Even if the number is wrong, the best image quality can be secured, and the damaged data can be replaced with the data of the previous screen in sync block unit, thereby providing a cleaner image quality.

Claims (9)

A reproduction amplifier for amplifying the signal reproduced by the reproduction head to a predetermined level; A data detector for detecting digital data from the signal amplified by the reproduction amplifier; A synchronization signal detector for detecting a synchronization signal as a reference signal from the digital data detected by the data detector; An area detector for detecting data of audio data, video data, and additional information in one track based on the sync signal detected by the sync signal detector; A dropout detector for comparing a signal output from the reproduction amplifier with a predetermined reference level and outputting a dropout pulse when the signal output from the reproduction amplifier is smaller than a predetermined reference level; And After receiving the data inputted from the area detector and performing error correction for each data according to the internal code, the number of sink blocks in which dropout occurred and the maximum error correction according to the dropout pulse input from the dropout detector. An error correction apparatus of a magnetic recording and reproducing apparatus, comprising: an ECC unit configured to compare the number of sync blocks to perform error correction according to an external call, or to replace data with the same sync block data on a previous screen when error correction is difficult. The error correcting apparatus of claim 1, wherein the start number of the sink block in which the dropout occurs and the end number of the sink block in which the dropout occurs are recognized by the dropout pulse. The method of claim 1, wherein the ECC unit; If the number of sink blocks in which the dropout is detected by the dropout detection unit is larger than the maximum number of error correction sinkblocks for the audio data and the video data, the data for the sync block in which the dropout is detected is converted into the data of the same sync block of the previous screen. Error correction apparatus of the magnetic recording and reproducing apparatus, characterized in that the replacement. A first step of performing error correction according to an internal code on the detected audio data and video data based on the synchronization signal; After performing the error correction according to the internal code in the first step, the number of sink blocks in which dropout occurs for the audio data and the video data is smaller than the number of sink blocks for the maximum error correction for the audio data and the video data. A second step of determining whether or not; As a result of the determination in the second step, if the number of sink blocks in which the dropout occurs is smaller than the number of sink blocks for the maximum error correction, error correction is performed according to an external call, and as a result, the number of sink blocks in which the dropout occurs is the maximum error. A third step of replacing an error-producing sync block with data of the same sync block of the previous screen when it is larger than the number of sync blocks for correction; And And a fourth step of decompressing the audio data and the video data after performing error correction on the audio data and the video data in the third step. A reproduction amplifier for amplifying the signal reproduced by the reproduction head to a predetermined level; A data detector for detecting digital data from the signal amplified by the reproduction amplifier; A synchronization signal detector for detecting a synchronization signal as a reference signal from the digital data detected by the data detector; An area detector for detecting data of audio data, video data, and additional information in one track based on the sync signal detected by the sync signal detector; A dropout detector for comparing a signal output from the reproduction amplifier with a predetermined reference level and outputting a dropout pulse when the signal output from the reproduction amplifier is smaller than a predetermined reference level; And After receiving the data inputted from the area detector and performing error correction for each data according to the internal code, the maximum error correction sync block for the audio and video data according to the dropout pulse inputted from the dropout detector. Magnetic recording and reproducing apparatus, characterized in that the ECC unit performs error correction according to an external code and compares the number with an error flag to determine the presence or absence of an error flag. Error correction device. The apparatus of claim 1 or 5, wherein the dropout detection unit; An envelope detection circuit section for detecting an envelope from the playback signal amplified by the playback amplifier; A comparator for comparing the envelope output from the envelope detecting circuit unit with a predetermined reference level and outputting a low level signal when the envelope is below the reference level; And And an inverter for outputting a dropout pulse generated by inverting the output signal of the comparator to the ECC unit. The method of claim 5, wherein the ECC unit; If the number of sync blocks dropped out by the dropout detection unit is greater than the maximum number of error correction sync blocks for audio data and video data, or if an error flag is present, the damaged sync block is replaced with data of the same sync block of the previous screen. And an error correcting apparatus of the magnetic recording and reproducing apparatus. A first step of performing error correction according to an internal code on the detected audio data and video data based on the synchronization signal; After performing error correction according to the internal code in the first step, the number of sink blocks in which dropout occurs for audio data and video data is smaller than the number of sync blocks for error correction for audio data and video data. A second step of determining whether or not; As a result of the determination in the second step, if the number of sink blocks in which dropout has occurred is smaller than the number of sink blocks for set error correction, error correction is performed according to an external call. A third step of replacing an error generated sink block with data of the same sink block of a previous screen when the number of sink blocks for error correction is larger than the number of sync blocks; A fourth step of determining whether an error flag exists after performing error correction according to the external code in the third step; A fifth step of replacing a sink block in which an error occurs with data of the same sink block of a previous screen when an error flag is present as a result of the determination of the fourth step; And a sixth step of decompressing the audio data and the video data after performing the error correction according to the external code as a result of the determination in the fifth step. 9. The method of claim 8, wherein the number of sync blocks capable of error correction of the set audio data and video data is smaller than the maximum number of error correction sync blocks.