JPH07254237A - Reproducing apparatus - Google Patents

Abstract

PURPOSE:To reproduce recorded data without making an error remaining in a reproduced signal stand out by a method wherein the status of the error is reflected on a flag set on a packet to be recorded. CONSTITUTION:A signal which is reproduced from a tape 11 through a head 12 is subjected to predetermined signal processing such as demodulation by a reproduced signal processor 13 and inputted to an error correction decoder 14. The error correction decoder 14 corrects the error in the reproduced signal and sets a flag which shows the existence of the error which can not be corrected. A packet detector 15 divides the signals whose errors are corrected and the flags into the respective packets as the units. In accordance with the fact that whether a part which has the remaining error shown by the flag exists or not and in accordance with the status of the error flag set on the packet, an error packet processor 16 processes the status of the flag set on the packet into a required status.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reproducing device suitable for use in a digital video tape recorder or the like.

[0002]

2. Description of the Related Art In recent years, digital TV broadcasting and CAT
The business of supplying highly efficient coded signals by digital transmission, such as V and video services using telephone lines, is under consideration. Transmission methods currently being considered (for example,
In the US Grand Alliance ATV system, etc.), a variable-length packet is first constructed from a high-efficiency coded signal, the variable-length packet is repacked into a fixed-length packet, and then an error correction code is added to each fixed-length packet. The mainstream of this is to convert the data to a modulated signal for transmission. Each user has a receiver and demodulates / error-corrects / decodes / receives the received data.
The original signal can be obtained by performing predetermined signal processing such as high-efficiency decoding.

It is expected that it will be necessary to record and reproduce the digitally transmitted signal accordingly. A conventional recording / reproducing apparatus records / reproduces a signal input from a transmission signal receiving apparatus in a variable length packet state.

[0004]

However, in the above-mentioned configuration, when an error remains even after error correction is performed on the reproduced signal, the signal in which the error remains remains as it is from the reproducing device. There is a problem in that the original signal cannot be obtained at all because it is output to the receiving device and the receiving device does not know that there is an error.

The present invention solves the problems of the conventional reproducing apparatus and prevents the reproduction error from adversely affecting the transmission decoding when recording and reproducing the signal during the transmission decoding process. It is an object of the present invention to provide a reproducing device that operates.

[0006]

In order to solve the above-mentioned problems, the reproducing apparatus of the present invention reproduces a recording medium in which a packet provided with an error flag indicating whether or not an error exists in the packet is recorded. In the reproducing apparatus, at least an error correcting unit that performs error correction of the reproduced signal and outputs a flag that indicates the result, a packet detection unit that detects the delimiter between the error-corrected reproduced signal and the packet in the flag, If the flag indicates that there is an error in the packet, and the error flag provided in the packet indicates that there is an error, the error flag is set to indicate that the packet is in error. Output, the flag indicates that the packet is in error, and the error flag provided in the packet is in error. If it is in the state indicating that the error flag is output, the packet is output in a state indicating that there is an error, the flag indicates that the packet has no error, and the error flag provided in the packet. Is in a state indicating that there is an error, the error flag is output in a state indicating that the packet is in error, the flag indicates that the packet has no error, and When the error flag is in a state indicating that there is no error, the error flag processing means that outputs the packet with the error flag indicating that there is no error is provided.

[0007]

According to the present invention, in the above structure, the error state remaining in the reproduced signal is reflected in the error flag set in the packet to be recorded, so that the recorded data is erroneous as compared with the conventional one. A playback device that can play back inconspicuously is configured.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the reproducing apparatus of the present invention will be described below with reference to the drawings.

FIG. 1 shows a block diagram of the reproducing apparatus in the first embodiment of the present invention. Reference numeral 11 is a tape, 12 is a head, 13 is a reproduced signal processor, 14 is an error correction decoder, 15 is a packet detector, and 16 is an error flag processor. Less than,
The operation of this reproducing apparatus will be described based on (FIG. 1).

First, it is assumed that a packet provided with an error flag is recorded on the tape 11 after being subjected to predetermined signal processing. The signal reproduced from the tape 11 through the head 12 is subjected to predetermined signal processing such as demodulation in the reproduction signal processor 13 and input to the error correction decoder 14.
The error correction decoder 14 performs error correction on the reproduced signal and generates a flag indicating whether or not there is an uncorrectable error. The packet detector 15 divides the error-corrected signal into packets. Further, the packet detector 15 also divides the packet into units by associating the flag with the signal. Error flag processor 16
Indicates whether or not there is a portion of the data that constitutes each packet that is flagged as having an error, and the state of the error flag provided in the packet. The provided error flag is processed as shown in (Table 1).

[0011]

[Table 1]

With the above arrangement, by using the error flag provided in the packet in advance, it is possible to construct a system in which the receiving device can correct the error even if the error remains during reproduction.

Further, it is expected that the error which cannot be corrected and remains will be in a wide range and the packet cannot be recovered at all or a part of the packet will be lost. The packet detector 15 makes it possible to generate pseudo correct packets by predicting from the relationship between the preceding and succeeding packets, and further indicates with a flag that there is an error in the data forming these packets. . Alternatively, the error flag to be set may be set in an incorrect state. With the above configuration, it is possible to construct a system in which even if an error remains during reproduction, the receiver can correct the error.

A pseudo-correct packet means a synchronization pattern indicating the beginning of the packet, a packet header for explaining the contents of the data of the packet, a packet length satisfying the format, and the contents of the data do not matter. A fixed pattern is generally determined as the synchronization pattern. The packet header shall be reconstructed with a value that is inferred from the packet headers of the preceding and succeeding packets and a default value.

Here, as the packet, for example, a transport packet in the ATV system (1994. 2.22, announced by The Grand Alliance in the US) can be used. As shown in FIG. 2, this transport packet has a fixed length of 188 bytes, and the first 1 byte is a sync byte of a fixed pattern, and the error correction code is after decoding (even before being coded. It is). The following bit is a transport packet error indicator, where 0 indicates that this packet is “no error” and 1 indicates that this packet is “in error”.

Therefore, for example, the flag indicating an error remaining in the packet is set to 0 for "no error" for each packet.
If "Error" is set to 1, it is possible to generate a transport packet error indicator output by an OR operation of an input transport packet error indicator and a flag indicating an error remaining in the packet.

When an attempt is made to record a signal transmitted using the ATV system, transport packets are input from the receiving device and are recorded.
The transport packet error indicator has already reflected the result of error correction in the transmission system. Therefore, if these transport packets are directly input to the high-efficiency code decoder of the receiving device, the high-efficiency code decoder will
The high-efficiency code of the input data is decoded, and the transport packet whose transport packet error indicator shows that there is an error is subjected to a predetermined modification process to obtain the original data.

With respect to the recorded transport packet, since error correction decoding of the transmission system has already been performed,
When the error caused by the reproduction cannot be corrected by the error correction decoding of the recording / reproduction system, the reproduction device inputs the error to the receiving device with the added error. Therefore, by using the transport packet error indicator for errors that remain in the recording / playback system,
The high-efficiency code decoder of the receiving device can operate properly.

The error correction code used in the recording / reproducing system is arbitrary. Further, an appropriate recording / reproducing device can be used instead of a dedicated recording / reproducing device for such a packet. When it is determined that the correction capability of the error correction code of the recording / reproducing apparatus itself is not sufficient, the unique error correction code can be added to the input transport packet. For example, as a device capable of recording data of 25 Mbps, there is a device announced by HD-DIGITAL VCR CONFERNCE, but the transport packet of ATV system is
It is 18 Mbps, and it is possible to record and reproduce by adding extra information such as parity of error correction code and data for special reproduction.

The flag generated by the error correction decoder 14 is
The present invention can be applied even if it is generated in a symbol unit, a codeword unit, or any other unit.

In this embodiment, the structure of the reproducing apparatus has been described as an example, but it may be the reproducing portion of the recording / reproducing apparatus. Further, although the receiving device and the reproducing device are separated, it may be a receiving and recording / reproducing device or a reproducing and high efficiency encoding / decoding device.

Further, in the present embodiment, the device which receives the transmitted signal and reproduces the recorded one is used, but the same applies to a device which reproduces the recorded one as the stock of the signal to be transmitted. Configurable.

[0023]

As described above, according to the reproducing apparatus of the present invention, the error state remaining in the reproduced signal is reflected in the error flag set in the packet to be recorded. The recorded data can be reproduced without making an error conspicuous, and the practical effect thereof is larger than that of the reproduction device described in (1).

[Brief description of drawings]

FIG. 1 is a block diagram of a playback device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of an example of a packet that can be recorded and reproduced according to the present invention.

[Explanation of symbols]

 11 Tape 12 Head 13 Playback signal processor 14 Error correction decoder 15 Packet detector 16 Error flag processor

Claims (3)

[Claims] 1. A reproducing apparatus for reproducing a recording medium recorded with a packet having an error flag indicating whether or not an error exists in the packet, at least performing error correction of a reproduced signal, and Error correction means for outputting a flag representing an error correction result, packet detection means for detecting a boundary between the packets in the error-corrected reproduction signal and the flag, and the flag indicating that the packet has an error, When the error flag provided in the packet is in a state indicating that there is an error, the packet is output in a state in which the error flag indicates that there is an error, and the flag indicates that the packet has an error. , And the error flag provided in the packet indicates that there is no error, the error flag The packet is output in a state indicating that the packet has an error, the flag indicates that the packet has no error, and the error flag provided in the packet indicates that there is an error. Output the packet with the error flag indicating that there is an error, the flag indicates that the packet has no error, and the error flag provided in the packet indicates that there is no error. And an error flag processing means for outputting the packet in a state in which the error flag indicates that there is no error. 2. The reproducing apparatus according to claim 1, wherein the packet detecting means artificially generates a packet that cannot be reconstructed due to an error. 3. The error flag processing means outputs an error flag provided in a pseudo-generated packet that cannot be reconstructed due to an error in a state indicating that there is an error. The playback device described.