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BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a recording arrangement for recording an
information signal in tracks on a record carrier, the recording
arrangement comprising
an input terminal for receiving the information signal,
channel encoding means for channel encoding the information signal so as to
obtain a channel signal suitable for recording in a track on said record
carrier,
writing means for writing the channel signal in the track, the channel
signal comprising subsequent signal blocks, each signal block comprising a
first block section which comprises a synchronisation signal and a second
block section which comprises a number of channel bytes, to a record
carrier obtained with the recording arrangement, and to a reproducing
arrangement for reproducing the video signal from the record carrier.
A recording arrangement as given in the opening paragraph is known from
EP-A492.704, document (1) in the list of references that can be found at
the end of this application.
2. Description of the Related Art
The known arrangement is a recording arrangement of the helical scan type
and records an information signal comprising a digital audio signal and a
digital video signal in audio signal recording sectors and video signal
recording sectors respectively in subsequent tracks, where, when recording
a track, the video signal recording sector in a track comes first and is
followed by the audio signal recording sector. The order in which the
sectors occur in a track can however also be in the reverse order.
Further, other sectors may be included in a track, such as a clock run-in
area located at the beginning of a track, so as to enable a locking-in of
the internal system clock on the signals read from the track, and preamble
and postamble areas that are located between the various sectors and
function as an edit gap. Reference is made in this respect to the earlier
filed European patent applications No.93.202.950, reference (2) in the
list of references and no. 93.201.263, reference (3) in the list of
documents.
The prior art documents relate to proposals for the realisation of a new
digital video cassette (DVC) recorder standard, which enables the
recording and reproduction of digital video and digital audio on/from a
longitudinal magnetic record carrier. This new digital video recorder
standard will lead to new digital videorecorders/reproducers of the
so-called DVC type.
SUMMARY OF THE INVENTION
The invention aims at providing a recording arrangement which is capable of
recording other type of information signals in the known tape format as
defined in the preamble. The recording arrangement in accordance with the
invention is characterized in that the information signal is an MPEG
information signal in accordance with an MPEG format, the MPEG information
signal comprising subsequent transport packets, that the channel encoding
means are adapted to store each time information included in x transport
packets of the MPEG information signal in the second block sections of a
group of y signal blocks of the channel signal, that the second block
section of at least the first signal block of the group of y signal blocks
comprise a third block section for storing identification information
identifying the signal block as being the first signal block of the group
of y signal blocks, and that x and y are integers such that x.gtoreq.1 and
y>1.
More specifically, the recording arrangement in accordance with the opening
paragraph is characterized in that the information signal is an MPEG
information signal in accordance with an MPEG format, the MPEG information
signal comprising subsequent transport packets, that the channel encoding
means are adapted to store each time information included in x transport
packets of the MPEG information signal in the second block sections of a
group of y signal blocks of the channel signal, that the second block
sections of the signal blocks comprise a third block section for storing
sequence number information relating to a sequence number of the signal
blocks, and that x and y are integers such that x.gtoreq.1 and y>1.
The invention is based on the following recognition. The draft Grand
Alliance HDTV System Specification dated Feb. 22, 1994, document (4) in
the list of references, more specifically the chapters V and VI of this
specification, comprises a description of a transport system for
transmitting an MPEG information signal, which includes a data compressed
digital video signal and a corresponding data compressed digital audio
signal, for broadcasting purposes or for transmission via a cable network.
The MPEG information signal is in the form of transport packets having
either an equal length or a variable length in time. In both cases
however, a transport packet comprises 188 bytes of information, the first
byte being a synchronization byte.
A transmission such an MPEG information signal in the form of a recording
on and a reproduction from a record carrier, such as a magnetic record
career, require special measures to be taken in order to realize such kind
of transmission via the known tape format. More specifically, the
invention relates to storing the transport packets in the signal blocks of
the known tape format.
Generally, it can be said that, when storing the information included in a
number of x transport packets of the MPEG information signal in a number
of y signal blocks, some unoccupied space remains available in the y
signal blocks for the storage of additional information, which additional
information relates to the specific application of recording and
reproducing the MPEG information signal on/from the record carrier. In a
specific example of the DVC format, the second-block sections can comprise
77 bytes of information. In that situation, two transport packets, from
each of which the sync byte has been deleted, can be stored in second
block sections of five signal blocks. Now, 11 bytes
(=5.times.77-2.times.187) remain available in the five signal blocks.
Those 11 bytes can be divided over the second block sections of the five
signal blocks in various ways so as to obtain the third block sections.
One such way is that the first two bytes of all second block sections are
available as third block sections and that the last byte available can be
considered as a third block section to indicate the boundary between the
information of the two transport packets as stored in the five signal
blocks.
In the above example, identification information identifying the signal
block as being the first signal block of the group of y signal blocks can
be stored in a third block section of the first signal block in a group of
y signal blocks. Or, sequence number information ( sequence numbers)
relating to the sequence of the signal blocks can be stored in the third
block sections. This sequence number can also be identified as a
continuity counter. The measures proposed result in a number of
advantages.
The advantage of using identification information identifying a signal
block as being the first signal block in a group of y signal blocks, is
that the beginning of a group can be detected, which simplifies the read
out of the data during reproduction.
One advantage using sequence numbers is that, when reproducing the signal
blocks, it can be decided upon retrieval of the sequence numbers, whether
a signal block has been missed because of reproduction errors or not, so
that an error correction or concealment can be carried out. Another
advantage is that one may shuffle the information to be stored in the
signal blocks upon recording. Upon retrieval of the sequence numbers it is
possible to realize a corresponding deshuffling in response to the
sequence numbers retrieved so as to obtain the original datastream.
Further, having sequence numbers included in the third block sections of
the signal blocks, makes it possible to repeat signal blocks in the case
that a transport packet of the MPEG data stream stored in those signal
blocks require a higher protection against errors that can occur during
the recording and a subsequent reproduction process.
The recording arrangement as given in the opening paragraph may be also
characterized in that the information signal is an MPEG information signal
in accordance with an MPEG format, the MPEG information signal comprising
subsequent transport packets, that the channel encoding means are adapted
to store each time information included in x transport packets of the MPEG
information signal in the second block sections of a first group of y
first signal blocks of said signal blocks of the channel signal so as to
enable a normal play mode using video information stored in said first
group of y first signal blocks during a normal play reproduction mode, the
channel encoding means further being adapted to retrieve a trick mode
video signal from the MPEG information signal and being adapted to store
said trick mode video signal in second block sections of a second group of
z second signal blocks of said signal blocks of the channel signal so as
to enable a trick play mode using the video information stored in said
second signal blocks, that the second block sections of at least one
signal block in each first and second group of first and second signal
blocks respectively comprise a third block section for storing
identification information indicating whether the group comprises first
signal blocks or second signal blocks, and that x, y and z are integers
such that x.gtoreq.1, y>1 and z>1.
More specifically, the information signal is an MPEG information signal in
accordance with an MPEG format, the MPEG information signal comprising
subsequent transport packets, that the channel encoding means are adapted
to store each time information included in x transport packets of the MPEG
information signal in the second block sections of a group of y signal
blocks of the channel signal, that the second block sections of at least
those signal blocks in a group of y signal blocks that comprises the start
portion of a transport packet comprise a third block section for storing
sequence number information relating to a transport packet sequence number
corresponding to the transport packet having its start portion stored in
the second block section of the signal block, and that x and y are
integers such that x.gtoreq.1 and y>1.
This enables a reproduction in the reproducing arrangement in a normal play
mode using the first signal blocks and a reproduction in a trick play mode
using the second signal blocks, in response to the detection of the
information indicating the groups comprising first signal blocks or second
signal blocks respectively.
The recording arrangement as given in the opening paragraph may also be
characterized in that the second block sections of all signal blocks in
each first and second group of first and second signal blocks respectively
comprise a third block section for storing identification information
indicating whether the group comprises first signal blocks or second
signal blocks.
More specifically, the second block sections of a group of y signal blocks
each comprise third block section for storing sequence number information
relating to a transport packet sequence number corresponding to the
transport packet of which information is stored in said signal block.
Storing a packet sequence number has its advantages if an MPEG datastream
is received having a constant bitrate, and comprising a number of
different video programs interleaved in the MPEG datastream. Generally,
such datastream has a too high bitrate for recording the total datastream
on the record carrier. The recording arrangement now comprises a program
selector for retrieving one video program and corresponding audio signal
from the MPEG datastream so as to obtain the MPEG information signal for
recording. As information corresponding to only one video program is
included in a MPEG transport packet, such program selector selects only
those transport packets from the MPEG datastream that comprise information
corresponding to said only one video program. That means that some packets
of the original MPEG datastream received are deleted. Upon reproduction
however, an MPEG video signal in accordance with the MPEG standard,
however now comprising only the one video program, should be regenerated.
Such regenerated datastream should have the transport packets that were
selected upon recording at the same location, that is in one or other way,
dummy packets corresponding to the packets deleted upon recording must be
inserted in the regenerated datastream. Upon recording a sequence number
is added to each transport packet received, that is: also for the packets
that will be deleted. The sequence numbers of the packets that are
selected and stored is stored in the third block section of the signal
blocks in which a transport packet is stored. Upon reproduction, a
sequence of numbers is retrieved, where subsequent numbers will not
necessarily be next higher numbers. In that situation one or more dummy
packets must be inserted so as to regenerate the replica of the original
MPEG datastream.
The recording arrangement as given in the opening paragraph can further be
characterized in that the information signal is an MPEG information signal
in accordance with an MPEG format, the MPEG information signal comprising
subsequent transport packets, the recording arrangement comprising
detection means for detecting the moment of receipt of the transport
packets and for generating timing information for each transport packet
received, the timing information for a transport packet corresponding to
said moment of receipt of said transport packet, that the channel encoding
means are adapted to each time store information included in x transport
packets of the MPEG information signal in the second block sections of a
group of y signal blocks of the channel signal, that the second block
sections of at least those signal blocks in a group of y signal blocks
that comprises the start portion of a transport packet comprise a third
block section for storing the timing information for said transport packet
having its start portion stored in the second block section of the signal
block, and that x and y are integers such that x.gtoreq.1 and y>1.
More specifically, the second block sections of a group of y signal blocks
each comprise a third block section for storing the timing information
corresponding to the transport packet which has information stored in the
second block section of said signal block. Storing timing information
corresponding to transport packet requires that the recording arrangement
is provided with detection means for detecting the time of receipt of a
transport packet. This measure has its advantages if an MPEG datastream is
received having a variable bitrate, and comprising a number of different
video programs interleaved in the MPEG datastream. As has been said above,
generally, such datastream has a too high bitrate for recording the total
datastream on the record carrier. The recording arrangement now comprises
a program selector for retrieving one video program with its corresponding
audio signal from the MPEG datastream so as to obtain the MPEG information
signal for recording. As information corresponding to only one video
program is included in a MPEG transport packet, such program selector
selects only those transport packets from the MPEG datastream that
comprise information corresponding to said only one video program. By
detecting and storing the timing information corresponding to a transport
packet, the reproducing arrangement will be capable of retrieving the
timing information and recreate the MPEG information signal using said
timing information.
It should be noted that the measures discussed above can be applied solely
or in combination with one another in the recording arrangement. As a
result, record carriers will be obtained having signal blocks stored in
tracks on the record carrier, the signal blocks having a first block
section which comprises a synchronisation signal and a second block
section which comprises a number of channel bytes, x transport packets of
the MPEG information signal being stored in the second block sections of a
group of y signal blocks of the channel signal. Further in accordance with
the invention,
the second block section of at least the first signal block of the group of
y signal blocks comprise a third block section for storing identification
information identifying the signal block as being the first signal block
of the group of y signal blocks, or
said identification information is sequence number information and the
second block sections of a group of y signal blocks all comprise a third
block section for storing sequence number information relating to the
sequence numbers of the signal blocks, or
the second block sections of the signal blocks each comprise a third block
section for storing identification information indicating whether the
signal block comprise ` normal play` data or ` trick mode` data, or
the second block sections of at least those signal blocks in a group of y
signal blocks that comprises the start portion of a transport packet
comprise a third block section for storing identification information
relating to a transport packet sequence number corresponding to the
transport packet having its start portion stored in the second block
section of the signal block, or
the second block sections of at least those signal blocks in a group of y
signal blocks that comprises the start portion of a transport packet
comprise a third block section for storing the timing information for said
transport packet having its start portion stored in the second block
section of the signal block, or
third block sections comprise information resulting from a combination of
one or more of the measures listed above.
It will be apparent that a reproducing arrangement will be needed which is
adapted to each specific embodiment of the recording arrangement, so as to
enable a reproduction of the MPEG information signal recorded on the
record carrier. Such reproducing arrangement is the subject of the claims
directed to the reproduction arrangement.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other aspects of the invention will be apparent from and
elucidated with reference to the embodiments described hereafter. In the
figure description shows
FIG. 1 the track format of a record carrier of the DVC-type,
FIG. 2 schematically the contents of the video signal recording sector in
the track of FIG. 1,
FIG. 3 schematically the serial MPEG datastream and the format of the
transport packets included in the serial MPEG datastream,
FIG. 4 an example of the storage of two transport packets in five signal
blocks,
FIG. 5 the contents of the track when having MPEG information recorded in
it,
FIG. 6 an embodiment of the recording arrangement,
FIG. 7 an embodiment of the reproducing arrangement,
FIG. 8a an example of an original serial MPEG datastream having a constant
bitrate and packet rate, FIG. 8b the MPEG datastream that is recorded and
FIG. 8c the regenerated replica of the original serial MPEG datastream,
FIG. 9 an embodiment of the `normal play` processing unit in the recording
arrangement of FIG. 6,
FIG. 10 an example of a sequence of three groups of five signal blocks
each,
FIG. 11 another example of a sequence of three groups of five signal blocks
each,
FIG. 12 an example of the `normal play` processing unit in the reproducing
arrangement of FIG. 7,
FIG. 13a an example of an original serial MPEG datastream having a variable
bitrate and packet rate, FIG. 13b the MPEG datastream that is recorded and
FIG. 13c the regenerated replica of the original serial MPEG datastream,
FIG. 14 another embodiment of the `normal play` processing unit in the
recording arrangement of FIG. 6,
FIG. 15 another embodiment of the `normal play` processing unit in the
reproducing arrangement of FIG. 7,
FIG. 16 the record carrier and the read head scanning the record carrier
during a trick play mode,
FIG. 17 the sequence of signal blocks in a track forming the trick play
area.
DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1 shows the format of the signals as they are recorded in a track on a
magnetic record carrier by means of a helical scan videorecorder of the
DVC type. The left end of the track 1 in FIG. 1 is the start of the track
and the right end of the track is the terminal pan of the track. The track
comprises a number of track parts. The track part denoted by G1 is the
pre-amble track pan. An example of the preamble track part G1 has been
described extensively in reference (1).
The track part G1 is followed by tracking tone recording part TP1, which is
denoted by ITI (insert timing information) track pan and which contains a
tracking tone, synchronisation information and identification (or timing)
information. Further explanation of the contents of the ITI track can be
found in reference (3).
The track part TP1 is followed by an edit gap G2. The edit gap G2 is
followed by the track part TP2, which is the audio signal recording sector
and comprises digital audio information. The edit gap G3 is followed by a
track part TP3 which is the video signal recording sector and comprises
digital video information. The edit gap G4 is followed by a track part
TP4, denoted by INDEX and which comprises amongst others subcode
information, such as absolute and/or relative time information and a table
of contents (TOC). The track is terminated by the track part G5. It can be
said that the sequence order in which the pans TP1, TP2 and TP3 occur in
the tracks may be different.
The contents of the video signal recording sector TP3 is given in FIG. 2.
FIG. 2 in fact shows schematically a number of 149 horizontal lines,
denoted by j=1 to j=149, having bytes of information stored in it. The 149
lines are in fact 149 signal blocks (or sync blocks) that are stored
sequentially in the video signal recording sector TP3.90 bytes of
information, denoted by i=1 to i=90, are stored in each signal block.
The first two bytes (i=1 and i=2) of each signal block form a
synchronisation pattern of 2 bytes long. The following three bytes in each
signal block form an ID code, comprising amongst others information which
indicates the sequence number of the signal block in the video signal
recording pan TP3. The last eight bytes in the signal blocks form
horizontal parity information. Vertical parity information is stored in
the storage locations i=6 to i=82 inclusive of the last 11 signal blocks.
Bytes of video signal information are stored in the storage locations i=6
to i=82 inclusive of the signal blocks having the sequence numbers j=3 to
j=137 inclusive. Bytes of auxiliary data are stored in the storage
locations i=6 to i=82 inclusive of the signal blocks having the sequence
numbers j=1, 2 and 138. The signal blocks are stored sequentially in the
video signal part TP3, starting with the signal block denoted y=1,
followed by the signal block denoted j=2, and so on until the signal block
denoted j=149.
The auxiliary data for storage in the signal blocks denoted j=1, 2 and 138
can be teletext data or control data.
It should be noted here that it can be specified that the auxiliary data
will be stored in a different location in the memory. Reference is made in
this respect to document (1), FIG. 13, where the auxiliary data is stored
in the memory part denoted by III.
FIG. 3 shows schematically the MPEG datastream applied to a recording
arrangement in accordance with the invention. The MPEG datastream
comprises subsequent transport packets, denoted by . . . , P.sub.k-1,
P.sub.k, P.sub.k+1, . . . . The packets each comprise a packet header
portion PH of 4 bytes long and a body portion of 184 bytes long. The
transport packets can be transmitted in a datastream having a constant
bitrate. This means that the packets are equally long, viewed in time, and
are received at a fixed packet rate. The transport packets may also be
transmitted in a datastream having a variable bitrate. In this situation,
the packets need not be of the same length, viewed in time, and may be
received with a variable packet rate. The first byte in the packet header
PH is a sync byte. The sync byte is identical for all the transport
packets. The other three bytes in the header comprise ID information, such
as a packet identifier. For a further explanation of the contents of the
ID information, reference is made to document (4) in the list of
references, more specifically chapter V, paragraph 5.1 on page 27.
The body portion of the transport packets comprise each 184 bytes for
storing the video and audio information that should be transmitted in
accordance with the MPEG format. The body portion of one transport packet
can store either audio information corresponding to a certain video
signal, or the video signal. Further, in the case that a number of video
programs are transmitted via the MPEG datastream, the body portion stores
a video signal corresponding to one of such video programs transmitted.
The invention now aims at recording the video signal, and the corresponding
audio signal as may be appreciated, corresponding to one of those video
programs transmitted via the MPEG data stream on the record carrier having
the track format disclosed in FIG. 1 and 2. Information stored in the
transport packets should be stored in the signal blocks, more
specifically, in the 135 signal blocks denoted j=3 to j=137 in the video
signal recording part TP3 of a track. The two sync bytes, denoted i=1 and
2, the ID information in the form of the three ID bytes denoted i=3, 4 and
5, as well as the 8 horizontal parity bytes, denoted by i=83 to 90, in
those signal blocks are required for a correct recording and reproduction.
As a consequence, only the 77 bytes, denoted by i=6 to 82, in the signal
blocks denoted by j=3 to 137, are available for the storage of the
transport packets of the MPEG information. The part of the signal blocks
formed by the 77 bytes i=6 to 82 is defined as being the second block
sections of the signal blocks.
As synchronization during recording and reproduction is assured by means of
the sync words in each of the signal blocks, there is no need for
transmitting the sync bytes of the transport packets via the record
carrier. So, before storing the information comprised in the transport
packets in the second block sections of the signal blocks denoted by j=3
to 135, the sync byte of all the transport packets is thrown away. As a
result only 187 bytes of information should be stored in the signal blocks
for each transport packet.
A simple calculation makes clear that two transport packets can be stored
in five signal blocks, and that 11 bytes remain available for the storage
of other information. FIG. 4 gives an example of how the two transport
packets can be stored in the second block sections of the group of five
signal blocks, denoted SB1 to SB5 in FIG. 4. FIG. 4 only shows the
contents of the second block sections of length of 77 bytes included in
the signal blocks. As can be seen in FIG. 4, the 11 bytes are divided over
the group of five signal blocks such that each second block section
comprises a third block section TB3.1 to TB3.5, of two bytes long at the
beginning of the second block sections of the five signal blocks SB1 to
SB5 respectively, and a third block section in the form of one byte,
denoted by FB, is available in the third signal block SB3. The 187 bytes
of the first transport packet are stored in the signal blocks SB1, SB2 and
SB3, where the three ID bytes of the packet header of the first transport
packet, indicated by TH1, are stored first in the signal block SB1,
directly after the third block section TB3.1, and next the first 72 first
bytes in the body of the first transport packet are stored thereafter in
the second block section of the signal block SB1. The next 75 bytes in the
body of the first transport packet are stored in the second block section
of the signal block SB2, after the third block section TB3.2, and the last
37 bytes in the body of the first transport packet are stored in the
second block section of the signal block SB3, after the third block
section TB3.3.
Next comes the byte FB, which indicates the boundary between the
information of the first and second transport packets stored in the group
of five signal blocks. The 187 bytes of the second transport packet are
stored in the signal blocks SB3, SB4 and SB5, where the three ID bytes of
the packet header of the second transport packet, indicated by TH2, are
stored first in the signal block SB3, directly after the byte FB. Next the
first 34 first bytes in the body of the second transport packet are stored
thereafter in the second block section of the signal block SB3. The next
75 bytes in the body of the second transport packet are stored in the
second block section of the signal block SB4, after the third block
section TB3.4, and the last 75 bytes in the body of the second transport
packet are stored in the second block section of the signal block SB5,
after the third block section TB3.5.
It should be noted that also another spreading of the 11 available bytes
over the five signal blocks is possible. As an example, the 11 bytes could
have been split into two third block sections, the one third block section
having as an example 6 bytes and being located at the beginning of the
first signal block SB 1, and the other third block section of 5 bytes long
being located in the third signal block and indicating the boundary
between the two transport packets stored in the five signal blocks.
Another example could have been to have a third block section located at
the beginning of the signal blocks SB1 and SB3 and another third block
section in the third signal block SB3, indicating the boundary between the
two transport packets stored in the five signal blocks, where the third
block section in the signal block SB1 can have eg. 4 bytes, the first
third block section in the signal block SB3 eg. 3 bytes and the third
block section in signal block SB3 indicating the said boundary being eg. 4
bytes long.
The third block sections TB3.1 to TB3.5 can be used for the storage of
additional information. As a first example, the third block section TB3.1
can include an indication identifying the signal block SB1 as being the
first signal block in a group of five signal blocks. This can be realized
by storing in one specific bit location in the third block section TB3.1 a
bit value of a certain polarity, such as `0` or `1` In the same bit
locations in the third block sections TB3.2 to TB3.5 a bit value of the
opposite polarity should be stored. In another example, sequence number
information, eg. sequence numbers running from 1 to 5 can be stored in the
third block sections TB3.1 to TB5 respectively, of the group of five
signal blocks, where the third block section TB3.1 has the sequence number
`1` and the third block section TB3.5 has the sequence number `5` stored
in them. Three specific bit locations in the third block sections TB3.1 to
TB3.5 are required to stored the sequence numbers. The sequence numbers
can however also run across the group boundaries so as to identify a
larger sequence of signal blocks, eg within one track, or even in more
than one track.
In another example, one specific bit location in the third block sections
TB3.1 to TB3.5 of a group of five signal blocks can be used to store
either a bit value of one polarity, such as `0` or `1`, so as to indicate
that the video dam included in the signal block is so-called `normal play`
data, or a bit value of the opposite polarity, so as to indicate that the
video dam included in the signal block is so-called `trick play` video
data. The use of the `normal play` video dam and `trick play` video dam
will be explained later.
In again another example, sequence numbers are generated in response to
transport packets in the MPEG datastream that is received. As has been
explained earlier, such MPEG datastream can include more than one video
programs. As the bitrate of the MPEG datastream is normally higher than
the bitrate of the signal that can be recorded, only one video program may
be selected from the serial MPEG datastream for recording. Selection of
one video program means selection of transport packets out of the
datastream of the MPEG datastream that comprise the information relating
to said video program, and deleting the other packets. Consequently the
serial array of transport packets that will be recorded have sequence
numbers that not necessarily are next higher numbers, as those sequence
numbers of the transport packets deleted are not present. When storing the
sequence numbers in the third block sections, those sequence numbers can
be retrieved upon reproduction. By checking the subsequent sequence
numbers retrieved, it can be established whether the original MPEG
datastream applied to the recording arrangement, originally included
deleted transport packets between two transport packets reproduced. If so,
a replica of the original MPEG datastream can be regenerated by inserting
one or more dummy packets between the two transport packets reproduced.
In a related example, timing information is stored in the third block
sections, for the same reason as given above, namely for regenerating a
replica of the original MPEG datastream, in the case that such datastream
is a datastream having a variable bitrate.
It will be clear that also a combination of the additional information
described above can be included in the 11 bytes available for the storage
of such information in a group of five signal blocks.
As an example, it has been made clear above that a 3-bit word is needed in
the third block sections to indicate the sequence numbers of the signal
blocks in the group of five signal blocks. More specifically, the 3-bit
words `000`, `001`, `010`, `011` and `100` could have been used to
identify the sequence. That means that the 3-bit words `101`, `110` and
`111` remain available for a further identification. As an example, the
3-bit words `101` and `110` could be used to identify either `normal play`
data or `trick mode` data.
FIG. 5 shows the track format of the track if the MPEG information has been
stored in the second block portions of the signal blocks of the track
portion TP3 of FIG. 1, now denoted by track portion TP3'. FIG. 5 shows the
first two signal blocks (j=1,2) in the track portion TP3' that still
includes the auxiliary data, followed by 135 signal blocks (j=3 to j=137)
now comprising the MPEG information and the additional information
described above. Next one signal block (j=138) also comprising the
auxiliary data, followed by 11 signal blocks comprising the parity
information. The storage of the MPEG information and the additional
information in the 135 signal blocks may require an additional error
encoding step to be carried out on the said information, resulting in
additional parity information that should also be stored in a track. As
the MPEG information, which includes video information and corresponding
audio information, is stored in the signal 135 blocks in the track portion
TP3', there is no need for storing audio information in the track portion
TP2 of FIG. 1. This portion, now denoted by TP2' in FIG. 5, can be used to
store the parity information resulting from the additional error encoding
step.
FIG. 6 shows schematically an embodiment of the recording arrangement. The
recording arrangement comprises an input terminal 11 for receiving the
MPEG serial datastream for recording transport packets included in the
datastream in the signal blocks of th | | |
