Note: Descriptions are shown in the official language in which they were submitted.
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Description
BROADCASTING SERVICE TRANSMITTING APPARATUS
AND METHOD AND BROADCASTING SERVICE RECEIVING
APPARATUS AND METHOD FOR EFFECTIVELY ACCESSING
BROADCASTING SERVICE
Technical Field
[1] The present invention relates to an apparatus and method for providing a
broadcasting service composed of various types of data, and more particularly,
to a
broadcasting service transmitting apparatus and method and a broadcasting
service
receiving apparatus and method for enabling fast and direct access to desired
services.
Background Art
[2] In digital broadcasting, when several service channel signals are
multiplexed and
transmitted via a single transmission path, the service channel signals are
first indi-
vidually compressed and transformed into packets, and the packets are then mul-
tiplexed into a transport stream. An identical packet identifier (PID) is
allocated to
packets corresponding to a single channel so that the packets can be
distinguished from
packets corresponding to other channels. As such, when packets having
different
specific IDs allocated according to the types of channels are transmitted in
the form of
a transport stream, a receiver selects only packets of a desired channel from
the
transport stream by referring to the IDs of the packets in the desired channel
and de-
multiplexes the selected packets.
[3] FIG. 1 is a flowchart illustrating a related art method of processing a
transport stream
generated using packet identifiers (PIDs).
[4] A related art receiver processes a transport stream according to the
method illustrated
in FIG. 1. In operation S 110, an encoded transport stream including packets
is
received. In operation S120, Reed-Solomon (RS) decoding is performed on the
packets
of the transport stream. In operation S 130, the packets of the transport
stream are
filtered according to the PIDs. In operation S 140, the packets of the
transport stream
are depacketized in each of layers, namely, a transport layer, a packetizing
layer, and a
stream layer. In operation S 150, data obtained by the depacketizing is
decoded.
[5] In the related art method, the packets of the transport stream can be
clearly dis-
tinguished from one another by using the PIDs. However, the packets of the
transport
stream should have PIDs, and the related art receiver should perform RS
decoding with
respect to each of the packets of the transport stream and perform filtering
by indi-
vidually checking the PIDs.
[6] FIG. 2 illustrates a related art transport stream generated using PIDs.
Referring to
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FIG. 2, a transport stream packet transporting audio/video (A/V) data, a
transport
stream packet transporting Internet protocol (IP) data, and a transport stream
packet
transporting object data are transported via a single channel. When the
related art
transport stream is processed, even if users want to receive only an A/V
service, all of
the transport stream packets should undergo Router/RS decoding and filtering
by the
individual check of the PIDs. Therefore, when a related art receiver processes
data,
temporal and spatial resources are wasted.
Disclosure of Invention
Technical Solution
[7] The present invention provides a broadcasting service transmitting
apparatus and
method and a broadcasting service receiving apparatus and method for enabling
efficient data processing due to fast and direct access to desired services.
Advantageous Effects
[8] According to the present invention, in contrast with a method of providing
a service
constructed by filtering packets by using packet identifiers (PIDs), direct
access to
each of the service components included in a service is possible.
[9] In addition, according to the present invention, an operation of
performing RS
decoding on all RS-encoded transport packets and checking all of the PIDs of
the
transport packets is not needed when selecting service components that
constitute a
service. Thus, the waste of system resources due to accesses to unnecessary
transport
packets can be prevented.
[10] Furthermore, according to the present invention, when locations of a LMT
and a LIT
within a transport frame are fixed, services and service components can be
quickly
accessed.
[11] Furthermore, according to the present invention, by including information
about next
LMT in current LMT, services and service components can be quickly accessed
even
when the locations of a LMT and a LIT within a transport frame are variable.
[12] Furthermore, according to the present invention, by including information
about the
number of LMTs having an identical version in a current LMT, the current LMT
can
be restored using previous LMT even when an error is generated in the current
LMT.
[13] Moreover, according to the present invention, an error packet can be
detected without
needing to use an error flag, by changing the header of the error packet.
Description of Drawings
[14] The above and other features and advantages of the present invention will
become
more apparent by describing in detail exemplary embodiments thereof with
reference
to the attached drawings in which:
[15] FIG. 1 is a flowchart illustrating a related art method of processing a
transport stream
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generated using packet identifiers (PIDs);
[16] FIG. 2 illustrates a related art transport stream generated using PIDs;
[17] FIG. 3 illustrates a structure of a transport frame according to an
embodiment of the
present invention;
[18] FIG. 4 illustrates the structure of the transport frame illustrated in
FIG. 3, in greater
detail, according to an embodiment of the present invention;
[19] FIGS. 5A and 5B illustrate a structure of a location map table (LMT)
field according
to an embodiment of the present invention;
[20] FIG. 5C illustrates a structure of a LMT field according to another
embodiment of
the present invention;
[21] FIG. 6A illustrates a structure of a linkage information table (LIT)
field according to
an embodiment of the present invention;
[22] FIG. 6B illustrates a structure of a LIT field according to another
embodiment of the
present invention;
[23] FIG. 7A is a flowchart illustrating a method of interpreting a LMT field
and a LIT
field, according to an embodiment of the present invention;
[24] FIG. 7B is a flowchart illustrating a method of interpreting a LMT field
and a LIT
field, according to another embodiment of the present invention;
[25] FIG. 8 is a block diagram illustrating a structure of a broadcasting
service
transmitting apparatus according to an embodiment of the present invention;
[26] FIG. 9 is a flowchart illustrating a broadcasting service transmitting
method
according to an embodiment of the present invention;
[27] FIG. 10 is a block diagram illustrating a structure of a broadcasting
service receiving
apparatus according to an embodiment of the present invention; and
[28] FIG. 11 is a flowchart illustrating a broadcasting service receiving
method according
to an embodiment of the present invention.
Best Mode
[29] According to an aspect of the present invention, there is provided a
broadcasting
service transmitting apparatus comprising: a broadcasting data packetization
unit
packetizing at least one type of broadcasting data so as to generate at least
one
broadcasting data packet; a transport packet generation unit generating at
least one
transport packet for transporting the at least one broadcasting data packet; a
transport
frame generation unit generating a transport frame having a predetermined size
for
transporting at least one broadcasting service that is constructed with the at
least one
transport packet; and a transmission unit transmitting the transport frame,
wherein the
transport frame generation unit generates the transport frame so that service
access in-
formation for accessing the at least one broadcasting service transported via
the
transport frame is included in the transport frame.
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[30] The service access information may be located in a predetermined area of
the
transport frame.
[31] The service access information may comprise location information about
next service
access information.
[32] The transport frame may comprise at least one virtual data channel that
is dis-
tinguished according to the types of data. Each of the at least one virtual
data channel
may comprise at least one sub-data channel that comprises the at least one
transport
packet.
[33] The service access information may comprise a location map table (LMT)
comprising information indicating a physical location of sub-data channels cor-
responding to service components that constitute the at least one broadcasting
service
included in the transport frame, and a linkage information table (LIT)
comprising in-
formation about the configuration of the at least one broadcasting service
included in
the transport frame.
[34] The LMT may comprise type information indicating types of data
transmitted via the
transport frame, version information indicating the version of the LMT, sub-
data
channel number information indicating the number of sub-data channels
corresponding
to each data type, and channel pointer information indicating the locations of
the sub-
data channels.
[35] The LMT may further comprise at least one piece of identical version LMT
number
information indicating the number of LMTs having the same version as the LMT,
LMT pointer information indicating a location of a next LMT, additional data
number
information indicating the number of pieces of additional data associated with
the at
least one broadcasting service, and additional data pointer information
indicating the
locations of the additional data.
[36] The LIT may comprise service number information indicating the number of
broadcasting services that are transmitted via the transport frame, version
information
indicating the version of the LIT, and service information indicating a
configuration of
the broadcasting services.
[37] The service information may comprise LMT index numbers which are
allocated to
the channel pointer information indicating the locations of the sub-data
channels.
[38] The transmission unit may generate and transmit an ATSC frame into which
at least
one transport frame described above is inserted.
[39] According to another aspect of the present invention, there is provided a
broadcasting
service transmitting method comprising the operations of: packetizing at least
one type
of broadcasting data so as to generate at least one broadcasting data packet;
generating
at least one transport packet for transporting the at least one broadcasting
data packet;
generating a transport frame having a predetermined size for transporting at
least one
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broadcasting service that is constructed with the at least one transport
packet; and
transmitting the transport frame, wherein the transport frame is generated so
as to
include service access information for accessing the at least one broadcasting
service
transported via the transport frame.
[40] According to another aspect of the present invention, there is provided a
broadcasting
service receiving apparatus comprising: a receiving unit receiving a transport
frame
having a predetermined size; a transport frame processing unit acquiring from
the
transport frame service access information for accessing at least one
broadcasting
service and also acquiring from the transport frame at least one transport
packet for
transporting at least one broadcasting data packet, by using the service
access in-
formation; a transport packet processing unit processing the at least one
transport
packet so as to acquire the at least one broadcasting data packet from the at
least one
transport packet; and a broadcasting data processing unit processing the at
least one
broadcasting data packet.
[41] According to another aspect of the present invention, there is provided a
broadcasting
service receiving method comprising the operations of: receiving a transport
frame
having a predetermined size; acquiring from the transport frame service access
in-
formation for accessing at least one broadcasting service and also acquiring
from the
transport frame at least one transport packet for transporting at least one
broadcasting
data packet, by using the service access information; processing the at least
one
transport packet so as to acquire at least one broadcasting data packet from
the at least
one transport packet; and processing the at least one broadcasting data
packet.
Mode for Invention
[42] This application claims the benefits of U.S. Provisional Patent
Application No.
60/917,776, filed on May 14, 2007, and U.S. Provisional Patent Application No.
60/974,321, filed on September 21, 2007, in the U.S. Patent and Trademark
Office, and
the benefits of Korean Patent Application No. 10-2007-0077165, filed on July
31,
2007, and Korean Patent Application No. 10-2007-0012437 1, filed on December
03,
2007, in the Korean Intellectual Property Office, the disclosures of which are
in-
corporated herein in their entirety by reference.
[43] The present invention will now be described more fully with reference to
the ac-
companying drawings, in which exemplary embodiments of the invention are
shown.
[44] The present invention is used in deterministic environments where
broadcasting
services are provided by transmitting frames having a constant size, that is,
a fixed
size, at regular intervals. In the specification, frames of constant size are
referred to as
transport frames.
[45] FIG. 3 illustrates a structure of a transport frame 300 according to an
embodiment of
the present invention.
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[46] Referring to FIG. 3, the transport frame 300 according to the current
embodiment of
the present invention includes a service information area 310 and a data area
320. As
illustrated in FIG. 3, the transport frame 300 according to the current
embodiment of
the present invention may be inserted into and transported as a part of a
transport frame
of a broadcasting system other than a broadcasting system for the transport
frame 300,
for example, as a part of an ATSC frame of an ATSC broadcasting system. Al-
ternatively, the transport frame 300 may be independently transported, or
mapped with
a transport stream of a broadcasting system other than a broadcasting system
for the
transport frame 300 in a one-to-one correspondence to be transported.
[47] The data area 320 of the transport frame 300 is divided into virtual data
channels that
are distinguished according to the type of data. The virtual data channels
denote
channels into which channels for transmitting a data stream are physically
classified
according to the type of data. Each of the virtual data channels may be
divided into in-
dependent sub-data channels. Each of the sub-data channels is composed of at
least one
transport packet, which is a minimum unit of a data stream packetized in a
transport
layer.
[48] The service information area 310 includes service access information for
accessing
data that constitutes a broadcasting service, where the data is transported
via the
transport frame 300. The service access information may be implemented so as
to be
periodically located in a predetermined area of a frame as illustrated in FIG.
3. In
addition, current service access information may include information about the
location of next service access information so as to control a cycle in which
service
access information is inserted into a frame or to change a location in the
frame into
which service access information is inserted.
[49] FIG. 4 illustrates the structure of the transport frame 300 in greater
detail, according
to an embodiment of the present invention. FIG. 4 illustrates the structure of
a transport
frame 400 according to an embodiment of the present invention. Referring to
FIG. 4,
each of the virtual data channels of the data area 320 illustrated in FIG. 3
is divided
into sub-data channels, and the sub-data channels establish services.
Referring to FIG.
4, the transport frame 400 according to the current embodiment includes a
signaling
packet 410 (or a signaling virtual data channel), a real-time media virtual
data channel
420, an IP virtual data channe1430, and an object virtual data channe1440.
[50] Each of the virtual data channels in FIG. 4 is divided into sub-data
channels. The
structure of the transport frame 400 illustrated in FIG. 4 is based on an
assumption that
real-time media data, IP data, and object data are illustrated as three data
types.
[51] Referring to FIG. 4, the real-time media virtual data channe1420 includes
a first sub-
data channel R-1 and a second sub-data channel R-2 both for transporting real-
time
media data such as an A/V stream. The IP virtual data channe1430 includes a
sub-data
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channel IP-1 for transporting IP data. The object virtual data channe1440
includes a
first sub-data channel 0-1, a second sub-data channel 0-2, a third sub-data
channel 0-
3, and a fourth sub-data channel 0-4, which are used to transport object data
that is
used in real time or after being received and stored by a broadcasting service
receiving
apparatus.
[52] A single service includes at least one service component. Accordingly, in
order to
provide a service to a user, the broadcasting service receiving apparatus
should receive
service components that constitute the service. A sub-data channel is a path
through
which a single service component is transported. Thus, in order to access a
certain
service, the broadcasting service receiving apparatus needs to know the
locations of
sub-data channels through which the service components that constitute the
service are
transported.
[53] Service access information for accessing service components that
constitute a service
is included in the signaling packet 410 of FIG. 4 corresponding to the service
in-
formation area 310 of FIG. 3. The signaling packet 410 includes the service
access in-
formation described above with reference to FIG. 3. As illustrated in FIG. 4,
the
signaling packet 410 includes a header field, a location map table (LMT)
field, a
linkage information table (LIT) field, and a payload.
[54] The LMT field provides information about the configuration and physical
locations
of sub-data channels within a transport frame.
[55] The LIT field provides service configuration information, namely, how
many
services are transported via a transport frame and which sub-data channels
each service
is to be transported by. In other words, a LIT denotes information indicating
which
sub-data channels, the number of which is at least one, are used to constitute
each
service.
[56] Referring to FIG. 4, the LIT field of the signaling packet 410 indicates
that service 1,
service 2, and service 3 are transported via the transport frame 400. In
addition, the
LIT field indicates that service 1 includes the first and second sub-data
channels R-1
and R-2 of the real-time media virtual data channe1420 and the third sub-data
channel
0-3 of the object virtual data channe1440.
[57] FIGS. 5A and 5B illustrate a structure of a LMT field according to an
embodiment of
the present invention. Referring to FIGS. 5A and 513, the LMT field according
to the
current embodiment includes a type bitmap field, a version number field, and
at least
one sub-data channel number field.
[58] The type bitmap field indicates which data is included in a transport
frame which is
transported in a predetermined cycle. It is assumed that the transport frame
transports
object data, audio and video (A/V) data, and IP data.
[59] The type bitmap field is composed of 3 bits, which may indicate whether
A/V data,
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IP data, and object data exist. For example, a bit `1' for the type bitmap
field indicates
existence of data corresponding to the bit, and a bit `0' for the type bitmap
field
indicates absence of data corresponding to the bit. Accordingly, when the type
bitmap
field is 111, A/V data, IP data, and object data are all included in the
transport stream.
Meanwhile, when the type bitmap field is 011, A/V data is not included in the
transport
stream, and IP data and object data are both included in the transport stream.
[60] The version number field indicates the version number of the LMT field.
[61] A sub-data channel number in the sub-data channel number field denotes
the number
of sub-data channels that belong to each type of virtual data channel. The sub-
data
channel number corresponds to the number of channel pointers that indicate the
physical addresses of the sub-data channels that belong to each virtual data
channel.
Referring to FIG. 5A, channel pointer fields for real-time media data are
first through
f-th channel pointer fields, channel pointers for IP data are (f+1)th through
m-th
channel pointer fields, and channel pointers for object data are (m+1)th
through n-th
channel pointer fields. Here, f, m, and n denote integers equal to or greater
than 0. For
example, if no real-time media data is transported via a transport stream, no
sub-data
channel number fields for real-time media data and no channel pointer fields
for real-
time media data may exist.
[62] For example, if the type bitmap field value is 100 and the at least one
sub-data
channel number field value is 2, two channel pointer fields that respectively
indicate
two channel pointers of two sub-data channels through which real-time media
data is
transported are included next to the sub-data channel number field.
[63] In the LMT field, each channel pointer field includes information
indicating the
physical location of each sub-data channel. Index numbers may be sequentially
allocated to the channel pointer fields. The index numbers sequentially
allocated to the
channel pointer fields of the LMT field are referred to as LMT index numbers.
The
LMT index numbers are not included in the channel pointer fields when the cor-
responding transport stream is generated, and instead a broadcasting service
receiving
apparatus may sequentially allocate the LMT index numbers to the channel
pointer
fields while interpreting the LMT field. In this case, the LMT index numbers
are se-
quentially allocated without distinguishing the types of sub-data channels.
[64] When the type bitmap field value is 011, the sub-data channel number
field value for
IP data is 2, and the sub-data channel number field value for object data is
3, the LMT
field may be constructed as illustrated in FIG. 5B. In FIG. 5B, first and
second channel
pointer fields indicate the locations of sub-data channels for IP data, and
third through
fifth channel pointer fields indicate the locations of sub-data channels for
object data.
Here, the first through fifth channel pointers are sequentially numbered with
LMT
index numbers 1 through 5, respectively.
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[65] However, alternatively, LMT index numbers may be sequentially allocated
to the
channel point fields according to types of the virtual data channels indicated
by the
channel point fields. In other words, the sub-data channels may be separately
numbered according to the types of sub-data channels.
[66] In this case, the first and second channel pointer fields are
respectively numbered
with index number 1 and index number 2, and the third, fourth, and fifth
channel
pointer fields are respectively numbered with index numbers 1, 2, and 3. Thus,
it is not
clear whether index number 1 corresponds to either the first channel pointer
field or the
third channel pointer field. This problem may be addressed by further
including in-
formation for use in determining whether the corresponding index number is
allocated
for either an IP virtual data channel or an object virtual data channel.
Information in-
dicating which type of virtual data channel an index number corresponds to
will be
described later with reference to FIG. 6B.
[67] FIG. 5C illustrates a structure of a LMT field 500 according to another
embodiment
of the present invention. Referring to FIG. 5C, the LMT field 500 according to
the
current embodiment is divided into a LMT coverage field 501, a version number
field
502, a signaling encapsulation packet (SEP) flag field 503, a LMT boundary
field 504,
an SEP pointer field 505, a first indicator field 506, an A/V data channel
pointer field
507, a second indicator field 508, an IP data channel pointer field 509, a
third indicator
field 510, and an object data channel pointer field 511.
[68] The LMT coverage field 501 indicates the number of LMT fields having the
same
version as that of the LMT field 500. For example, if the version of the LMT
field 500
is 1 and a bit value of the LMT coverage field 501 is `00001', the number of
LMT
fields having the version `1' to be transmitted after the LMT 500 is 1.
[69] The version number field 502 indicates the version of the LMT field 500.
[70] The SEP flag field 503 indicates whether the LMT field 500 includes a
signaling
packet. The signaling packet may be additional data for use in transport frame
processing, such as LMT or LIT, or may be additional data associated with
services
loaded in a transport stream, such as an electronic program guide (EPG) or an
electronic service guide (ESG). When the bit value of the SEP flag field 503
is `1', the
SEP pointer field 505, indicating the location of the signaling packet, exists
next to the
SEP flag field 503. The LMT boundary field 504 indicates the range of packets
that the
LMT field 500 affects. For example, the LMT boundary field 504 may indicate
the
address of the last packet that affects the LMT field 500, or the number of
packets that
affect the LMT field 500. When the LMT boundary field 504 indicates the
address of
the last packet that affects the LMT field 500, packets located at addresses
prior to the
address of the last packet are determined to be the packets that affect the
LMT field
500. This means that a new LMT field exists at the address next to the address
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indicated by the LMT boundary field 504. Accordingly, the use of the LMT
boundary
field 504 enables the location of the next LMT field to be easily predicted.
[71] The SEP pointer field 505 indicates the location of the signaling packet.
[72] The first indicator field 506 indicates whether a sub-data channel
exists. When the
value of the first indicator field 506 is `1', a channel pointer exists next
to the first
indicator field 506. Referring to FIG. 5C, the first indicator field 506
indicates
existence of an A/V sub-data channel.
[73] The A/V data channel pointer field 507 indicates the location of the A/V
sub-data
channel.
[74] The second indicator field 508 indicates whether an additional sub-data
channel
exists. When the value of the second indicator field 508 is `1', a channel
pointer exists
next to the second indicator field 508. Referring to FIG. 5C, the second
indicator field
508 indicates existence of an IP sub-data channel.
[75] The IP data channel pointer field 509 indicates the location of the IP
sub-data
channel.
[76] The third indicator field 510 indicates whether an additional sub-data
channel exists,
similar to the second indicator 508. When the value of the third indicator
field 510 is
`1', a channel pointer exists next to the third indicator field 510. Referring
to FIG. 5C,
the third indicator field 510 indicates existence of an object sub-data
channel.
[77] The object data channel pointer field 511 indicates the location of the
object sub-data
channel.
[78] The broadcasting service receiving apparatus can know the number of sub-
data
channels by using the first, second, and third indicators 506, 508, and 510,
and know
the locations of the sub-data channels by using the channel pointers 507, 509,
and 511.
[79] FIG. 6A illustrates a structure of a LIT field according to an embodiment
of the
present invention. Referring to FIG. 6A, the LIT field according to the
current em-
bodiment includes a service number field, a version number field, and at least
one
service field indicating at least one service.
[80] The service number field indicates the number of services included in a
single
transport frame according to the present invention.
[81] The version number field indicates the version of the LIT field.
[82] Each of the service fields includes a service identifier field (SID) and
at least one
LMT index number field. As in the above-described structure of the LIT field,
the at
least one LMT index number field indicates at least one number allocated to at
least
one channel pointer. Accordingly, the broadcasting service receiving apparatus
can
know the physical addresses of sub-data channels corresponding to a desired
service
from a transport frame, by interpreting the LIT field.
[83] For example, suppose that the broadcasting service receiving apparatus
interprets a
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signaling packet of a received transport stream, in which a LMT field is as
illustrated
in FIG. 5B, an n-th service field shown in FIG. 6A includes a first LMT index
number
field and a second LMT index number field, and the values of the first and
second
LMT index number fields are 2 and 5, respectively. In this case, the
broadcasting
service receiving apparatus interprets the n-th service as a service, the
service
including data included in a sub-data channel having the physical location
indicated by
the second channel pointer field shown in FIG. 5B and data included in a sub-
data
channel having the physical location indicated by the fifth channel pointer
field shown
in FIG. 5B. Accordingly, when the n-th service is desired, the broadcasting
service
receiving apparatus does not process all of the transport packets included in
the
transport stream, and instead processes only the data transported via
transport packets
included in sub-data channels at the physical locations indicated by the
second and
fifth channel pointer fields, thereby rapidly and efficiently processing
broadcasting
data.
[84] FIG. 6B illustrates a structure of a LIT field according to another
embodiment of the
present invention. Referring to FIG. 6B, the LIT field according to the
current em-
bodiment includes a service number field, a version number field, and at least
one
service field indicating at least one service.
[85] Each of the service fields includes an SID and at least one channel
information field.
[86] For example, suppose that the LMT field of a transport stream is as
illustrated in FIG.
5B and sequential LMT index numbers are independently allocated to the channel
pointer fields according to types of sub-data channels indicated by the
channel pointer
fields. In other words, the sub-data channels are independently numbered with
index
numbers according to the types of data. In addition, suppose that an n-th
service shown
in FIG. 6B includes two sub-data channels. Accordingly, the n-th service field
of FIG.
6B includes a first channel information field and a second channel information
field.
[87] In this case, the first and second channel pointer fields, corresponding
to sub-data
channels for IP data, shown in FIG. 5B are respectively numbered with index
number 1
and index number 2, and the third, fourth, and fifth channel pointer fields,
cor-
responding to sub-data channels for object data, shown in FIG. 5B are
respectively
numbered with index numbers 1, 2, and 3.
[88] Each of the channel information fields includes a type information field
and a LMT
index number field.
[89] The type information field is composed of 2 bits and indicates the type
of sub-data
channel corresponding to a LMT index number. A data value `01' of the type in-
formation field may indicate that the sub-data channel corresponding to a LMT
index
number is a sub-data channel for IP data. On the other hand, a data value `10'
of the
type information field may indicate that the sub-data channel corresponding to
a LMT
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index number is a sub-data channel for object data.
[90] The LMT index number field is composed of 5 bits.
[91] When the value of the first channel information field is '0100010', 2
upper bits
indicate an IP virtual sub-data channel and 5 lower bits indicate a channel
pointer
having an LMT index number 2. Accordingly, it can be known that the n-th
service
includes the data included in the sub-data channel at the physical location
indicated by
the second channel pointer field.
[92] When the value of the second channel information field is '1000011', 2
upper bits
indicate an object virtual sub-data channel and 5 lower bits indicate a
channel pointer
having an LMT index number 3. Accordingly, it can be known that the n-th
service
also includes the data included in the sub-data channel at the physical
location
indicated by the fifth channel pointer field.
[93] Consequently, when the n-th service is desired, the broadcasting service
receiving
apparatus does not process all of the transport packets included in the
transport stream,
and instead processes only the data transported via transport packets included
in sub-
data channels at the physical locations indicated by the second and fifth
channel
pointer fields, thereby rapidly and efficiently processing broadcasting data.
[94] FIG. 7A is a flowchart illustrating a method of interpreting a LMT field
and a LIT
field in a broadcasting service receiving apparatus, according to an
embodiment of the
present invention. The LMT field is transmitted at regular intervals and
located in a
predetermined area of a transport frame.
[95] Referring to FIG. 7A, in operation S701, when the broadcasting service
receiving
apparatus receives a transport frame, it acquires and interprets a signaling
packet
including service access information, which is located in a predetermined area
of the
transport frame.
[96] In operation S703, the broadcasting service receiving apparatus
determines whether a
LMT field exists in the signaling packet. If it is determined in operation
S703 that no
LMT fields exist in the signaling packet, it is determined whether a previous
LMT
field has been stored in the broadcasting service receiving apparatus, in
operation
S705. If it is determined in operation S705 that a previous LMT field exists
in the
broadcasting service receiving apparatus, the method proceeds to operation
S711.
[97] If it is determined in operation S703 that a LMT field exists in the
signaling packet,
the broadcasting service receiving apparatus determines according to version
in-
formation included in the LMT field whether the version of the LMT field has
been
updated, in operation S707. If it is determined in operation S707 that the
version of the
LMT field has been updated, the LMT field is interpreted in operation S709. By
in-
terpreting the LMT field in operation S709, information about the locations of
sub-data
channels is obtained.
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[98] In operation S711, the broadcasting service receiving apparatus
determines whether a
LIT field exists in the signaling packet. If it is determined in operation
S711 that no
LIT fields exist in the signaling packet, it is determined whether a previous
LIT field
exists in the broadcasting service receiving apparatus, in operation S713. If
it is de-
termined in operation S713 that a previous LIT field exists in the
broadcasting service
receiving apparatus, the method proceeds to operation S719.
[99] If it is determined in operation S711 that the LIT field exists in the
signaling packet,
the broadcasting service receiving apparatus determines according to version
in-
formation included in the LIT field whether the version of the LIT field has
been
updated, in operation S715. If it is determined in operation S715 that the
version of the
LIT field has been updated, the LIT field is interpreted in operation S717. By
in-
terpreting the LIT field in operation S717, linkage information about each
service, that
is, service configuration information, is obtained.
[100] In operation S719, services are obtained from the results of the
interpretations of the
LMT field and LIT field, and then processed.
[101] FIG. 7B is a flowchart illustrating a method of interpreting a LMT field
and a LIT
field, according to another embodiment of the present invention. In FIG. 7B,
the
location of the LMT field and a cycle in which the LMT field is inserted into
a
transport frame vary. Operations in FIG. 7B indicated by the same reference
numbers
as those in FIG. 7A are the same operations as those in FIG. 7A, and thus
detailed de-
scriptions thereof will be omitted.
[102] Referring to FIG. 7B, in operation S720, a LMT field is extracted from a
transport
frame according to LMT pointer information extracted from a previous LMT
field. The
LMT pointer information points out the location of the next LMT field.
Accordingly,
even when the LMT field fails to be inserted into a predetermined area of the
transport
frame, the LMT field can be easily extracted from the transport frame.
[103] In operation S703, the broadcasting service receiving apparatus
determines whether a
LMT field exists at a location indicated by the LMT pointer information. If it
is de-
termined in operation 703 that a LMT field exists in the location indicated by
the LMT
pointer information, the method proceeds to operation S707. On the other hand,
if it is
determined in operation 703 that a LMT field does not exist in the location
indicated
by the LMT pointer information, the method proceeds to operation S730. Where
no
LMT field exists in the location indicated by the LMT pointer information
implies a
case where the LMT field is omitted and a case where an error is generated in
the LMT
field.
[104] In operation S730, it is determined according to identical version LMT
number in-
formation included in a previous LMT field whether the previous LMT field is
valid.
The fact that the previous LMT field is valid means that the previous LMT
field can be
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continuously used. If it is determined in operation S730 that the previous LMT
field is
valid, the method proceeds to operation S711.
[105] In the specification, the identical version LMT number information
denotes the
number of LMT fields having an identical version. For example, suppose that
the
previous LMT field is referred to as a first LMT field. Identical version LMT
number
information included in the first LMT field denotes the number of LMTs that
have the
same version as that of the first LMT field and are to be transported (or
received) after
the first LMT field. If the identical version LMT number information included
in the
first LMT field is `3', there are three LMTs that have the same version as
that of the
first LMT field. Accordingly, when the identical version LMT number
information
included in the first LMT field is equal to or greater than `1', the version
of the LMT
field included in a current frame is the same as that of the first LMT field,
and thus
packets included in the current frame can be processed using the first LMT
field.
[106] FIG. 8 is a block diagram illustrating a structure of a broadcasting
service
transmitting apparatus 800 according to an embodiment of the present
invention.
Referring to FIG. 8, the broadcasting service transmitting apparatus 800
according to
the current embodiment includes a broadcasting data packetization unit 810, a
transport
packet generation unit 820, a transport frame generation unit 830, and a
transmission
unit 840.
[107] The broadcasting data packetization unit 810 packetizes at least one
type of
broadcasting data to thereby generate at least one broadcasting data packet.
The
broadcasting data includes application data such as real-time media data
(e.g., an A/V
stream), IP data, object data, etc., and signaling data such as program
specific in-
formation (PSI), service information (SI), and metadata. For example, the
application
data can be packetized according to an MPEG-4 system standard.
[108] The transport packet generation unit 820 generates at least one
transport packet for
transporting the at least one broadcasting data packet. The transport packet
may have
the same size as an MPEG-2 transport stream packet. However, according to an
em-
bodiment of the present invention in which service access information is
included in a
predetermined area of a transport frame, inclusion of a packet identifier in a
transport
packet like the inclusion of a PID in an MPEG-2 transport stream packet is not
needed.
Similarly, according to another embodiment of the present invention in which
service
access information is not included in a predetermined area of a transport
frame,
inclusion of a packet identifier in a transport packet is not needed because
the service
access information includes information about the location of next service
access in-
formation.
[109] The transport frame generation unit 830 generates a transport frame
having a prede-
termined size for transmitting the at least one broadcasting service which is
constructed
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using the generated at least one transport packet. As illustrated in FIG. 4,
the transport
frame generation unit 830 forms at least one transport packet into at least
one sub-data
channel and generates a transport frame including the at least one sub-data
channel.
[110] The transport frame generation unit 830 generates the transport frame so
that service
access information for accessing the at least one broadcasting service that is
transmitted via the transport frame is included in the transport frame. In
order to
achieve this function, the transport frame generation unit 830 may include a
service
access information generation unit 832 for generating the service access
information.
[111] As described above, the service access information may be transported by
being
included in a predetermined area of the transport frame, for example, in a
first packet
of the transport frame. By fixing the location of the service access
information, a
broadcasting service receiving apparatus can easily access the service access
in-
formation included in a transport frame. However, the service access
information is not
necessarily included in the predetermined area of the transport frame. This is
because
next service access information can be easily accessed by utilizing location
in-
formation about the next service access information included in current
service access
information.
[112] The transport frame includes at least one virtual channel which is
distinguished
according to the type of data. Each of the at least one virtual channel
includes at least
one sub-data channel. A sub-data channel corresponds to each of at least one
service
component that constitutes a broadcasting service within a transport frame.
[113] The service access information includes a LMT which indicates the
location of each
sub-data channel included in the transport frame, and a LIT which indicates in-
formation about the configuration of at least one broadcasting service which
is
transported via the transport frame.
[114] The LMT includes type information indicating the type of data
transported via the
transport frame, version information indicating the version of the LMT, sub-
data
channel number information indicating the number of sub-data channels
corresponding
to each data type, and channel pointer information indicating the location of
each of
the sub-data channels. The LMT may further include at least one piece of
identical
version LMT number information indicating the number of LMTs having an
identical
version, LMT pointer information indicating the location of a next LMT,
additional
data number information indicating the number of pieces of additional data
associated
with at least one broadcasting service, and additional data pointer
information in-
dicating the location of each piece of additional data.
[115] The LIT includes service number information indicating the number of
broadcasting
services transported via the transport frame, version information indicating
the version
of the LIT, and service information indicating the configuration of each of
the services.
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The service information includes an index number allocated to the channel
pointer in-
formation included in the LMT. If index numbers are sequentially allocated to
the
channel pointer information but independently according to the types of sub-
data
channels indicated by the channel pointer, the service information may include
type in-
formation and index numbers, as described above. In this case, the type
information
indicates which type of sub-data channel a corresponding index number is
associated
with.
[116] The transmission unit 840 sequentially transmits a series of transport
frames which
are generated by the transport frame generation unit 830, at intervals of a
prede-
termined period. The transmission unit 840 may generate an ATSC frame in which
at
least one transport frame is inserted, and transmit the ATSC frame according
to an
ATSC system standard.
[117] FIG. 9 is a flowchart illustrating a broadcasting service transmitting
method
performed in the broadcasting service transmitting apparatus 800 of FIG. 8,
according
to an embodiment of the present invention.
[118] Referring to FIGS. 8 and 9, in operation S910, the broadcasting data
packetization
unit 810 of the broadcasting service transmitting apparatus 800 packetizes at
least one
type of broadcasting data to thereby generate at least one broadcasting data
packet.
[119] In operation S920, the transport packet generation unit 820 generates at
least one
transport packet for transporting the at least one broadcasting data packet.
[120] In operation S930, the transport frame generation unit 830 generates a
transport
frame having a predetermined size for transmitting at least one broadcasting
service
which is constructed using the generated at least one transport packet. In
operation
S930, the transport frame is generated so that service access information for
accessing
the at least one broadcasting service that is transmitted via the transport
frame is
included in the transport frame.
[121] In operation S940, the transmission unit 840 transmits a series of
transport frames
which are generated by the transport frame generation unit 830. The transport
frames
may be sequentially transmitted at intervals of a predetermined period.
[122] FIG. 10 is a block diagram illustrating a structure of a broadcasting
service receiving
apparatus 1000 according to an embodiment of the present invention. Referring
to FIG.
10, the broadcasting service receiving apparatus 1000 according to the current
em-
bodiment includes a receiving unit 1010, a transport frame processing unit
1020, a
transport packet processing unit 1030, a broadcasting data processing unit
1040, and a
user input unit 1050.
[123] The receiving unit 1010 receives at least one transport frame having a
predetermined
size. The receiving unit 1010 may be constructed so as to receive an ATSC
frame and
acquire the at least one transport frame from the ATSC frame.
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[124] The transport frame processing unit 1020 acquires from the transport
frame service
access information for accessing at least one broadcasting service.
Thereafter, the
transport frame processing unit 1020 also acquires from the transport frame at
least one
transport packet for transporting at least one broadcasting data packet, by
using the
service access information. If the service access information is located in a
prede-
termined area of the received transport frame, the transport frame processing
unit 1020
acquires the service access information from the predetermined area of the
received
transport frame. On the other hand, if the service access information is not
located in
the predetermined area of the received transport frame, the transport frame
processing
unit 1020 acquires the service access information from the received transport
frame on
the basis of location information included in previous service access
information. The
location information included in current service access information denotes in-
formation about the location of next service access information.
[125] More specifically, the transport frame processing unit 1020 interprets a
LMT field
and a LIT field which are the service access information, thereby accessing
sub-data
channels for each service. When one of several services transmitted via the
transport
frame is selected, the transport frame processing unit 1020 transmits to the
transport
packet processing unit 1030 transport packets included in sub-data channels
that
constitute the selected service.
[126] The operation of selecting a service from the several services
transmitted via the
transport frame may be performed according to a user input signal received via
the user
input unit 1050. When a user selects a service, only the transport packets
included in
the sub-data channels that constitute the selected service may be transmitted
to the
transport packet processing unit 1030 and processed thereby. Accordingly,
there is no
need to perform a conventional operation of interpreting all of the PIDs
included in
transport packets and filtering out only transport packets having a
predetermined PID.
[127] The transport packet processing unit 1030 processes the at least one
transport packet
received from the transport frame processing unit 1020, thereby acquiring at
least one
broadcasting data packet from the at least one transport packet. The transport
packet
processing unit 1030 may further include a header changing unit (not shown).
When an
error exists in the acquired broadcasting data packet, the header changing
unit changes
the header value of the erroneous broadcasting data packet to a predetermined
value.
At this time, the header changing unit may change the header value of the
erroneous
broadcasting data packet to a header value that the headers of general packets
cannot
have. For example, the header of the erroneous broadcasting data packet may
include
both information indicating that the erroneous broadcasting data packet is not
the first
packet and information indicating that decoding information is included in the
erroneous broadcasting data packet. The above-described header of the
erroneous
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broadcasting data packet is incorrect because decoding information is supposed
to be
transmitted via the first packet. According to the present invention, an
erroneous
packet can be detected without using bits, in contrast with the conventional
art in
which bits are used to indicate an erroneous packet. Thus, the amount of data
transmitted can be reduced.
[128] The broadcasting data processing unit 1040 processes the at least one
broadcasting
data packet. The broadcasting data processing unit 1040 can be implemented as
a
decoder for processing broadcasting data encoded according to the MPEG-4
system
standard.
[129] FIG. 11 is a flowchart illustrating a broadcasting service receiving
method according
to an embodiment of the present invention.
[130] Referring to FIG. 11, in operation S1110, at least one transport frame
having a prede-
termined size is received.
[131] In operation S 1120, service access information for accessing at least
one
broadcasting service is acquired from the transport frame, and at least one
transport
packet for transporting at least one broadcasting data packet is also acquired
from the
transport frame by using the service access information.
[132] In operation S 1130, the at least one transport packet is processed so
that at least one
broadcasting data packet is acquired from the at least one transport packet.
[133] In operation S 1140, the at least one broadcasting data packet is
processed.
[134] The invention can also be embodied as computer readable codes on a
computer
readable recording medium. Functional programs, codes, and code segments for
ac-
complishing the present invention can be easily construed by programmers of
ordinary
skill in the art to which the present invention pertains. The computer
readable
recording medium is any data storage device that can store data which can be
thereafter
read by a computer system. Examples of the computer readable recording medium
include read-only memory (ROM), random-access memory (RAM), CD-ROMs,
magnetic tapes, floppy disks, optical discs, flash memory, and so on. The
computer
readable recording medium can also be distributed over network coupled
computer
systems so that the computer readable code is stored and executed in a
distributed
fashion.
[135] While the present invention has been particularly shown and described
with reference
to exemplary embodiments thereof, it will be understood by those of ordinary
skill in
the art that various changes in form and details may be made therein without
departing
from the spirit and scope of the present invention as defined by the following
claims.
