JP2000030210A - Magnetic recording and reproducing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic recording and reproducing apparatus capable of recording and reproducing an HD signal transmitted at high bit rate. SOLUTION: A packet distributing part 10 distributes each inputted packet data into a channel A and a channel B to output it, and the packet data of each channel are simultaneously recorded in different tracks on a magnetic tape. At reproduction, it adjusts packet spacing, based on the time-stamp information on a packet data reproduced from each truck and sums them in a channel mixing part 24.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing apparatus for recording / reproducing packet data, and more particularly to a magnetic recording / reproducing apparatus suitable for recording a high-quality HD signal.

[0002]

2. Description of the Related Art With the advancement of digital technology and integrated circuit technology, not only analog television broadcasting but also digital television broadcasting has recently been put to practical use. A typical example of digital television broadcasting is D.
SS (Digital Satellite System) or DVB (Digital Video Broadcasting) practically used in Europe
Etc.

[0003] In these digital television broadcasts, signals are transmitted in predetermined transport packet units,
It is also possible to transmit an SD signal substantially equivalent to an SC signal by time division multiplexing for a plurality of programs (programs).
It is also possible to transmit a high-definition HD signal as compared with a signal for one program (program).

[0004] As a magnetic recording / reproducing apparatus for recording digital television broadcasts transmitted in this manner, D-D
Although VHS is standardized, this D-VHS makes it possible to record a received digital television broadcast in a bit stream on a magnetic tape at a recording rate of about 14 Mbps.

[0005] Therefore, even if the bit rate of a plurality of programs transmitted by time-division multiplexing using an SD signal is 30 Mbps, only one program is selected from the plurality of transmitted programs, and the actual bit rate of the selected program is selected. When the rate is 10 Mbps, the selected program can be recorded by performing the bit rate conversion from 30 Mbps to 10 Mbps using the bit rate conversion buffer.

[0006]

At present, as one of signal transmission systems for transmitting high-quality HD signals, one screen has one screen.
The so-called 1080i digital television broadcasting system composed of 080 interlaced scanning signals has been standardized. In the 1080i digital television broadcast, a transport stream of the MPEG2 system (hereinafter, referred to as MPEG2-TS) is about 20 Mbp.
transmitted at bit rates as high as s.

[0007] Therefore, a high-quality HD signal transmitted at such a high bit rate exceeds the recording rate of the magnetic recording / reproducing apparatus, and it is impossible to record the signal as it is.

In order to solve the above-mentioned problems, a magnetic recording and reproducing apparatus according to the present invention provides a magnetic recording / reproducing apparatus by adding time management information of a time at which data arrives to transmitted packet data. A magnetic recording / reproducing apparatus that records on a medium and reproduces data recorded based on the time management information during reproduction, and a channel distribution unit that distributes the transmitted packet data to a plurality of channels.
Recording means for converting the allocated packet data into 1 / N times the bit rate for each channel and recording the data on different tracks on the magnetic recording medium; A reproducing means for reproducing the packet data; a packet interval restoring means for converting a bit rate of the reproduced packet data for each channel to N times and restoring a packet interval based on the time management information; And an adder for adding the packet data whose packet interval has been restored.

[0008]

FIG. 1 is a block diagram showing a main part of a magnetic recording / reproducing apparatus according to an embodiment of the present invention. FIG. 2 is a diagram for explaining how packets are distributed by a channel distribution unit. FIG. 4 is a diagram for explaining bit rate conversion, FIG. 4 is a diagram showing the arrangement of the first to fourth heads on a cylinder, and FIG. 5 is a diagram showing the arrangement of recording tracks and packets recorded on a magnetic tape. FIG. 6 and FIG. 6 are block diagrams for explaining the channel assignment unit, and FIG. 7 is a timing chart for explaining the operation of the channel assignment unit.

Hereinafter, a magnetic recording / reproducing apparatus according to an embodiment of the present invention will be described with reference to the drawings. In FIG. 1, a channel distribution unit 10 in a recording system of a magnetic recording / reproducing apparatus is shown.
When the MPEG2-TS is input to the MPEG-2 TS, the channel distribution unit 10 outputs the input MPEG2-T as shown in FIG.
S is distributed to the A channel and the B channel for each packet, and each input packet is output alternately with the A channel and the B channel, respectively.

[0010] Then, the packet data of the A channel and the B channel are input to the time stamp adding unit 11, and the time stamp adding unit 11 inputs time information (ts1, ts2,
..) Is added to each packet, and the packet data of the A channel and the B channel are output respectively.

A buffer memory is provided inside each of the bit rate converters 12a and 12b provided for each channel, and the read clock is set to a lower clock than the write clock to the buffer memory. As a result, as shown in FIG.
Can be converted into packet data having a 倍 times bit rate (10 Mbps) and output.

Also, buffer memories are provided inside the correction code adding sections 13a and 13b, respectively, and output from the bit rate conversion sections 12a and 12b so that the recording area of the magnetic tape T can be effectively used. After adjusting the time interval for each of the A-channel and B-channel packet data, an error correction code called an outer code or an inner code is added, and the correction code adding unit 13a sends the first head (H1)
Alternatively, a recording signal to which the error correction code in the A channel is added is output to the second head (H2), and the correction code adding unit 13b outputs the recording signal to the third head (H3) or the fourth head (H4). Then, a recording signal to which an error correction code in the B channel is added is output.

FIG. 4 is a diagram showing the arrangement of the first to fourth heads on a cylinder. Here, the first head (H1) and the second head (H2) are
The third head (H3) and the fourth head (H4) are similarly mounted at an angle of 180 degrees on the cylinder, and are mounted at an angle of 80 degrees.

Further, the first head (H1) and the second head (H2) are at different height positions in the direction of the rotation axis of the cylinder than the third head (H3) and the fourth head (H4). Further, the first head (H1) and the third head (H3) are heads having different azimuths of the gap, and the second head (H2) and the fourth head (H4). Similarly, the heads have different azimuths in the gap.

[0015] During the period when the first head (H1) and the third head (H3) are in contact with the magnetic tape T, two first and second heads (H1) and (H3) are used. The signals are recorded by simultaneously forming the inclined tracks, and during the period when the second head (H2) and the fourth head (H4) are in contact with the magnetic tape T, the second head (H
Signals are recorded by simultaneously forming two inclined tracks using 2) and the fourth head (H4).

FIG. 5 is a diagram showing the arrangement of recording tracks and packets recorded on the magnetic tape T in this manner.
The track tr1 on the magnetic tape T corresponds to the first head (H
1), track tr2 indicates a track formed by the third head (H3), track tr3 indicates a track formed by the second head (H2), and track tr4 indicates a track formed by the fourth head (H4). The numbers on the tracks tr1 and tr2 indicate the packet numbers shown in FIG. 2, and as shown in FIG. 5, the packet data of the A channel and the B channel are recorded on separate tracks.

As described above, the input MPEG2-TS is divided into the A channel and the B channel for each packet, and the packet data of the A channel and the B channel are simultaneously recorded on different tracks, respectively.
Even when the PEG2-TS is transmitted at a high bit rate of about 20 Mbps, signal recording can be performed.

Next, a reproducing system of the magnetic recording / reproducing apparatus will be described. Each packet data recorded in this way is
The error correction units 21a and 21b reproduced by the first to fourth heads and shown in FIG.
The error correction unit 21a obtains the A-channel packet data and the error correction unit 21b obtains the B-channel packet data by performing the reverse process to the processes performed in 3a and 13b.

Further, the bit rate converters 23a and 23b perform processing opposite to the bit rate conversion performed by the recording bit rate converters 12a and 12b to restore the packet signals of the bit rate shown in FIG. . Further, when recording packet data as described above, the time interval of each packet data is adjusted and recorded so that the recording area of the magnetic tape can be effectively used. It is necessary to return the time interval of the packet data for each channel as shown in FIG. At this time, the packet interval adjusters 23a and 23b output the input time information (ts1, ts
2,...), The time interval of each packet is restored.

Then, in the interval adjusting units 23a and 23b, FIG.
The packet data restored to the same packet intervals as shown in the A channel and the B channel are added by the channel mixing unit 24, and the MPEG-2 data before the packet distribution is performed by the channel distribution unit 10 during recording. TS can be obtained.

Next, the configuration and operation of the channel distribution unit 10 will be described with reference to FIGS. When the MPEG2-TS is input to the channel distribution unit 10, Syn
The c detector 1 detects a Sync signal inserted at the head of each packet data and outputs this.

The MPEG2-TS input to the channel allocating unit 10 is previously clear that one packet of data is composed of 188 bytes of data. Val that counts the period of 188 bytes
Outputs an id signal. Therefore, the Valid signal can extract only the portion where the input MPEG2-TS packet data exists, and masking even if there is invalid data such as noise during the period when the packet data does not exist. Can be.

On the other hand, the Sync signal from the Sync detecting unit 1 is also input to the toggle output unit 3, and the toggle output unit 3
A toggle signal whose phase is inverted every time the Sync signal rises is output. The toggle signal output from the toggle output unit 3 is further input to an inversion circuit, and an inverted signal obtained by inverting the phase of the toggle signal is output.

For the A-channel changeover switch, the signal is switched by a changeover signal obtained by ANDing the Valid signal and the toggle signal, and for the B-channel changeover switch, the Valid signal is changed. The signal is switched by a switching signal obtained by a logical product of the AND signal and the inverted signal.

[0025] By the switching operation of the changeover switch in the A channel and the B channel, the input M is
Each packet data in the PEG2-TS can be alternately distributed to the A channel and the B channel for each packet.

[0026]

As described above, according to the magnetic recording / reproducing apparatus of the present invention, an input transport stream is distributed to a plurality of channels and recorded. The bit rate for each channel can be suppressed, and signal recording becomes possible.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a main part of a magnetic recording and reproducing apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining how packets are distributed by a channel distribution unit.

FIG. 3 is a diagram for explaining bit rate conversion.

FIG. 4 is a diagram showing a head arrangement of first to fourth heads on a cylinder.

FIG. 5 is a diagram showing the arrangement of recording tracks and packets recorded on a magnetic tape.

FIG. 6 is a block diagram illustrating a channel distribution unit.

FIG. 7 is a timing chart for explaining an operation of a channel distribution unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Sync detection part 2 ... 188 byte counter 3 ... Toggle output part 10 ... Channel distribution part 11 ... Time stamp addition part 12a, 12b, 22a, 22b ... Bit rate conversion part 13a, 13b ... Correction code addition part 21a, 21b ... Error correction units 23a, 23b Packet interval adjustment unit 24 Channel mixing units H1 to H4 First to fourth heads tr1 to tr4 First to fourth tracks T Magnetic tape

Claims (1)

[Claims] 1. A magnetic recording apparatus which adds time management information of a time at which data arrives to packet data to be transmitted, records the data on a magnetic recording medium, and reproduces the recorded data based on the time management information during reproduction. A channel allocation means for allocating the transmitted packet data to a plurality of channels; a bit rate of 1 / N times for each of the allocated packet data for each channel; Recording means for recording on different tracks; reproducing means for reproducing the packet data for each channel from different tracks on the magnetic recording medium; converting the bit rate of the reproduced packet data for each channel to N times Packet interval restoring means for restoring the packet interval based on the time management information, Magnetic recording and reproducing apparatus characterized by packet intervals of Le has an adding means for adding said packet data recovered.