Note: Descriptions are shown in the official language in which they were submitted.
CA 02725177 2010-12-09
REPRODUCING APPARATUS AND METHOD, AND RECORDING MEDIUM
Technical Field
The present invention relates to a reproducing apparatus and method, and
more particularly, to a reproducing apparatus and method for reproducing still
image
data, such as a browsable slide show, to which sub audio data is separately
added,
and a recording medium therefor.
Background Art
io Because moving picture data is very large, the picture data needs to be
compressed using time-space compression to be encoded for easy transmission.
In general, to be recorded on an information storage medium, video data is
compressed and encoded under the Motion Picture Expert Groups (MPEG)
standards, prescribed by both the International Organization for
Standardization
(ISO) and the International Electrotechnical Commission (IEC), whereas audio
data
is compressed under the MPEG standards or is converted into digital data using
linear Pulse Code Modulation (PCM). Time information, necessary for
synchronizing the encoded video data and audio data with each other, is
incorporated into system multiplexed data. In this case, the MPEG2 standard is
also frequently used when encoding data.
The system multiplexing can be performed using packets. For example, as
shown in FIG. 1, when multiplexing of video data and audio data, the video
data and
- audio data are divided in bitstream packets of predetermined lengths,
additional
information such as a header is included in the bitstream packets, and video
packets
- and audio packets are mixed and-transmitied using time-sharing techniques.
Therefore, a start of a packet, i.e., a header, includes information
indicating whether
the packet is a video packet or an audio packet.
Meanwhile, time information called time stamp is used in synchronization
between audio and video packets according to the MPEG standards.
The time stamp is a type of time management tag that is provided in access
units for a decoding process required for data reproduction. That is, the time
stamp
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CA 02725177 2010-12-09
=
=
is information that specifies when audio or video data must be decoded and
reproduced in access units. There are two types of time stamps: Presentation
Time
Stamp (PTS) and Decoding Time Stamp (DTS).
The PTS is time management information of data reproduction selected
depending on an MPEG coding method adopted, when a System Time Clock (STC),
e.g., a reference synchronization signal, which is generated in a reference
decoder
of an MPEG system is equivalent to a PTS, related audio or video data is
reproduced
and output in access units.
The DTS is time management information of data decoding. The MPEG
standards require the DTS because a sequence of delivering encoded video
bitstreams is unique. For example, since an I frame picture and a P frame
picture
are delivered as encoded bitstreams before a B frame picture, sequences of
decoding and reproducing the 1 and P frame pictures are different from those
of
decoding and reproducing the B frame picture. If the PTS and the DTS are not
the
same, they are sequentially included in the packet data. If they are the same,
only
the PTS is included in the packet data.
Hereinafter, conventional MPEG encoding and decoding apparatuses will be
described with reference to FIGS. 2 through 6.
FIG. 2 illustrates a conventional hierarchical encoding apparatus 200 used in
MPEG encoding. Referring to FIG. 2, a video encoder 210 receives and encodes
digital video data, and an audio encoder 220 receives and encodes digital
audio = = == =
data.
A first packetizer 230 packetizes the encoded video data output from the video
encoder 210 by dividing it in predetermined units and generates Packetized
Elementary Streams (PESs). A second packetizer 240 packetizes the encoded
audio data output from the audio encoder 220 by dividing it in predetermined
units
and generates PESs.
Encoding time information such as the PTS and the DTS may be incorporated
into the PES. Such encoding time information is used to synchronize the PES
with
other data. In particular, the DTS indicates when an image is decoded and the
PTS
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CA 02725177 2010-12-09
indicates when an image is output. In general, only the PTS is included in the
audio
data. In this case, the DTS is regarded as being the same as the PTS. After
the
inclusion of the PTS and the DTS, the audio data or video data is packetized
in a
payload data format.
A program stream multiplexer 250 multiplexes the video PES packetized by
the first packetizer 230 into a program stream (PS). A transport stream
multiplexer
260 multiplexes the audio PES packetized by the second packetizer 240 into a
transport stream (TS). In multiplexing, each PES is divided into predetermined
units,
identification numbers are allocated to the predetermined units, and the PES
is then
multiplexed.
The program stream (PS) is made for information storage media and
multiplexed in PS packet units. In a DVD Video standard, a representative
application for moving image storage media, a PS packet unit of 2048 bytes is
used.
The TS is used in an application, such as digital broadcasting, where data
loss
is unavoidable. The TS is multiplexed into TS packet units. A TS packet unit
is
fixed to be 188 bytes long. Recently, the use of a TS when recording digital
broadcast data on a storage medium has been increased. In this disclosure, the
TS
is used in multiplexing but the. PS also can be used.
As described above, the TS is packetized data, such as video or audio data,
which is divided in predetermined units so that the data can be transmitted
via a
satellite, a cable, or a Local Area Network (LAN). Here, the predetermined
unit is '-
188 bytes long, when using the MPEG:-2 transmission stream according to the
ISO/IEC 13818-1 standard, and 53 bytes long, when using the Asynchronous
=
Transfer Mode (ATM).
In digital broadcasting, packet data is transmitted at variable time
intervals.
The transmitted packet data is input to a buffer of a receiving apparatus
having a
decoder, decoded by the decoder, and broadcasted so that a user can view
digital
broadcasting. The packet data can be temporarily stored on a recording medium
and reproduced at a desired time. In this case, the variable time intervals at
which
the packet data was transmitted is significant when the packet data is input
to a
decoder of a reproducing apparatus. This is because a transmitting side
transmits
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=
the packet data to a receiving side while adjusting time intervals between
transmissions of the packet data, in consideration of the state of the buffer
of the
receiving apparatus having the decoder. If the variable time intervals are not
adhered to, the buffer at the receiving apparatus overflows or underflows.
Therefore, information regarding arrival times of the respective packet data
transmitted to the recording apparatus is inserted in all packets, and the
packet data
is reproduced based on the information regarding the arrival times.
As described above, arrival time stamps (ATSs), which are the information
regarding the arrival times of data, are required for proper data reproduction
when
103 packet data transmitted in TS format is recorded on a recording medium
and
reproduced from the recording medium.
In other words, a recording apparatus receives packet data sent by a
transmitting side at particular time intervals and records it on a recording
medium.
To reproduce the.recorded packet data, a counter is required to transmit the
packet
data to a decoder of a reproducing apparatus at the same time intervals as the
particular time intervals used by the transmitting side. The counter operates
in
response to a system clock at 90 kHz or 27MHz, and includes a counter vakie
inserted into the packet data, the counter being en ATS obtained at an instant
of time
a packet is input to the counter. To reproduce the recorded packet data, the
time
intervals at which the packet data will be transmitted to the buffer of the
decoder are
determined by the counter value included in the packet data. Such a counter is
. called an an-ival time clock (ATC) counter. That is, an ATS is added.
into the input
packet data based on the counter value generated by the ATC counter, and the
packet data is output based on the ATS for data reproduction.
FIG. 3 illustrates a data structure of packet data including ATSs specifying
arrival times of the packet data to a receiving side, and a connection between
the
ATSs and data output time when the packet data is reproduced. Referring to
FIG. 3,
when packet data A, B, C, and D are received at arrival times 100, 110, 130,
and 150,
respectively, a recording apparatus makes ATSs indicating the arrival times
100, 110,
130, and 150 and inserts the ATSs into the packet data A, B, C, and D. For
data
reproduction, the packet data is output and reproduced based on the ATSs. That
is,
the packet data A is output at the output time 100, the packet data B is
output at the
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output time 110, the packet data C is output at the output time 130, and the
packet
data D is output at the output time 150.
FIG. 4 illustrates a data structure of packet data 400 including ATSs which is
recorded on a recording medium. For convenience, FIG. 4 illustrates the packet
data 400 to include information, such as an ATS 410, a decoding time stamp
(DTS)
420, a presentation' time stamp (PTS) 430, and audio/video (AV) data 440,
according
to the present invention.
FIG. 5 illustrates a part of a reproducing apparatus 500 that reproduces
packet
data including ATSs as shown in FIG. 4. The recording apparatus 500 includes a
disc driving unit 510, a buffer 520, a source depacketizer 530, and an ATC
counter
540.
The disc driving unit 510 reads the packet data including the ATSs and
transmits the packet data to the buffer 520.
The buffer 520 receives the packet data including the ATSs and transmits it to
the source depacketizer 530.
The ATC counter 540 is used when a data stream stored in a recording
medium is transmitted to a decoder (not shown) at intervals of time at which
the
packet data has first been transmitted from a receiving side. The ATC counter
540
operates in response to a system clock at 90 kHz or 27 MHz, resets an ATS
value,
which is obtained at an instant of time when a first packet in a TS format is
input to
the source depacketizer 530, as an initial value, and continues counting ATSs
of
input packets. When an ATS of an input packet is equivalent to a counting
value
generated by the ATC counter 540, the ATS i$ removed from the input packet and
the input packet is sent to the decoder.
, 25 In other words, the ATC counter 540 sets the ATS value of the
first input
packet transmitted to the source depacketizer 530 as the initial value and
begins
= counting. Next, the source depacketizer 530 checks ATS values of next
packet data
to itself, removes an ATS value from packet data whose ATS value is equivalent
to
the counting value generated by the ATC counter 540, and transmits the packet
data
to the decoder.
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For example, in the case of the packet data of FIG. 3, since a value of the
ATS
of a first packet data is 100, an initial value of the ATC counter 540 is set
as 100 and
the ATC counter 540 continues counting. The ATS is removed from the first
packet
data and the first packet data is transmitted to the decoder. Next, since a
value of
the ATS of second packet data is 110, the source depacketizer 530 removes the
ATS
from the second packet data and transmits the second packet data to the
decoder,
when a counting value of the ATC counter 540 is 110. The process is also
applied
to the other packet data in a similar manner.
FIG. 6 is a block diagram of a conventional= standard decoder 600 used for
to data synchronization based on encoded time information such as a PTS and
a DTS.
Referring to FIG. 6, the decoder 600 includes a demultiplexer 610, a video
decoder
620, a system time clock (STC) counter 630, an audio decoder 640, and a
graphics
processor 650.
The demultiplexer 610 demultiplexes multiplexed video packet data, audio
is packet data, and sub-picture packet data, and sends the demultiplexed
video packet
data and audio packet data to the video decoder 620 and the audio decoder.640,
respectively. The demultiplexed sub-picture may be subtitle data that is
displayed to
be overlapped with the video packet data. In FIG. 6, a decoder that decodes
the
sub-picture data is not illustrated.
20 The STC counter 630 operates at 90 KHz or 27 MHz and controls a value of
a
packet, which is obtained at an instant of time when the packet is input to a
buffer
(not shown) of the decoder, to be equivalent to a program clock reference
(PCR)
value of the packet. The- buffer temporarily s-tores packet data that is
output from
the demultiplexer 610 but has yet to be input to the video decoder 620. The
PCR
25 denotes a program clock reference that is information used to adjust a
value of an
STC counter, which is a reference time value, to a value set by an MPEG
decoding
apparatus with video and audio decoders.
A process of decoding packet data including DTSs and PTSs will be described
=
with reference to FIG. 6. First, the demultiplexer 610 demultiplexes an input
30 transport packet into the original video packet data and audio packet
data and sends
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CA 02725177 2010-12-09
the video packet data and the audio packet data to the video decoder 620 and
the
audio decoder 640, respectively.
Next, the STC counter 630 is set based on PCR information (not shown)
contained in the packet data. The video packet data is input to the video
decoder
620 by the set STC counter 630 at a DTS time and decoded by the video decoder
620. Because the audio packet data has only a PTS value, the audio packet data
is
input to the audio decoder 640 at a PTS time, decoded by the audio decoder
640,
and output.
Next, the decoded video packet data output from the video decoder 620 is
io input to the graphics processor 650 by the STC counter 630 based on the
PTS time,
processed by the graphics processor 650, and output as video data.
As described above, the audio and video packet data can be synchronized
with each other by controlling the decoding and outputting of the audio and
video
packet data at the PTS time and the DTS time, using a counting value generated
by
the STC counter 630. That is, the audio and video packet data are decoded and
synchronized with each other, in response to a clock generated by the STC
counter
630.
In general, there are two applications of still images. First, there is a
slide
show wherein still images are output at predetermined times. That is, a user
reproduces still images using a reverse play where a previous image is
reproduced
again or a forward play where reproduction of a current image is skipped and a
next
image is reproduced. When an STC value is updated with a new value, images can
be sequentially reproduced again. If audio data is included in a still image,
the
audio data is reproduced in synchronization with a newly updated still image.
Thus,
the reproduction of the audio data is discontinued, and the audio data is
reproduced
again starting from a portion of the audio data corresponding to a new still
image.
Second, there is a browsable slide show. In the browsable slide show,
= reproduction of audio data must not be discontinued even during the
reverse play or
the forward play. For instance, the slide show is reproduced as if leafing
through
the files of an album to view included photos. On the other hand, during
reproduction of the browsable slide show with background music, seamless
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reproduction of the background music is required for natural reproduction of
still
images even if a user selects and reproduces an image preceding or following a
current image.
Hereinafter, problems with the forward or reverse play of the browsable slide
s show will be described with reference to FIG. 7. Still images, such as
the browsable
slide show, are divided into mainstream data and sub audio data. In general,
the
mainstream data includes video data, audio data, and sub-picture data, but the
video
data in a browsable slide show application must be understood as still image
data
excluding audio data. The sub audio data indicates audio data that is
additionally
io made separately from the mainstream data and is reproduced as background
music
during reproduction of the still image data.
Referring to FIG. 7, each still image and sub audio data is synchronized using
PTS information, that is, encoding time information. As data reproduction
proceeds,
an STC counter value of a decoder (not shown) is increased and a normal play
is
15 performed in accordance with the increased STC counter value. However,
when a
user wants to perform the reverse or forward play, the STC counter value is
readjusted based on a target position of the reverse or forward play (e.g.,
3000 and
20000). If the STC counter value is updated, the STC counter is reset to 10000
to
restore both the original still image and the original sub audio, thereby
causing an
20 interruption in sub audio data, i.e., background music.
As described above, a conventional reproducing apparatus controls both a
_
.
video decoder and an audio decoder using an STC counte- r. Therefore, when the
conventional "reproducing apparatus is used to reproduce still images using an
-
application such as a browsable slide show, it is difficult to prevent an
Interruption in
25 reprodUction of background music when an STC value is readjusted during
a reverse
or forward play. In this case, the browsable slide show cannot be reproduced
smoothly and might cause a harsh grating noise.
=
Disclosure of the Invention
30 The present invention provides an apparatus and method for reproducing
still
image data, such as a browsable slide show, to which sub audio data is
additionally
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CA 02725177 2010-12-09
included, without interrupting reproduction of the sub audio data, i.e.,
background
music, even during a forward or reverse play, and a recording medium therefor.
According to an aspect of the present invention, there is provided a
reproducing apparatus comprising a reproducing unit to reproduce mainstream
data
s and sub audio data separately added in the mainstream data, wherein the
reproducing unit comprises a counter used in reproducing the sub audio data.
Additional aspects and/or advantages of the invention will be set forth in
part
in the description which follows and, in part, will be obvious from the
description, or
may be learned by practice of the invention.
In an aspect of the present invention, the counter includes a sub audio
arrival
time clock (ATC) counter that is used to depacketize the sub audio data.
In another aspect of the present invention, the counter comprises a sub
audio system time clock (STC) counter that is used to decode the depacketized
sub
audio data.
In an aspect of the present invention, the mainstream data includes still
image data.
According to another aspect of the present invention, there is provided a
reproducing apparatus including a mainstream reproducing unit to reproduce
mainstream data including still image data, using a clock for mainstream data;
and a
sub audio reproducing unit to reproduce sub audio data separately added into
the
- mainstream data, using a clock for sub audio data. -=
According to another aspect of the present invention, the mainstream
reproducing unit includes a mainstream depacketizer that depacketizes the
mainstream data; and a mainstream ATC counter that provides a clock used in
= 25 depacketizing the mainstream data with the mainstream depacketizer.
The sub
audio reproducing unit includes a sub audio depacketizer that depacketizes the
sub
audio data; and a sub audio ATC counter that provides a clock used in
depacketizing
the sub audio data with the sub audio depacketizer.
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"
According to another aspect of the present invention, the. mainstream
reproducing unit includes a mainstream decoder that decodes the mainstream
data
output from the mainstream depacketizer; and a mainstream STC counter that
,provides a clock used in decoding the mainstream data with the mainstream
decoder.
The sub audio reproducing unit includes a sub audio decoder that decodes the
sub
audio data output from the sub audio depacketizer; and a sub audio STC counter
that provides a clock used in decoding the sub audio data with the sub audio
decoder.
According to yet another aspect of the present invention, there is provided a
io reproducing method comprising reproducing sub audio data, separately
added into
mainstream data, using a clock for reproducing the sub audio data.
In an aspect of the present invention, the reproducing sub audio data
includes. depacketizing the sub audio data using a clock depacketizing the sub
audio
data.
In an aspect of the present invention, the reproducing sub audio data
includes decoding the sub audio data using a clock decoding the depacketized
sub
audio data.
According to still another aspect of the present invention, there is provided
a
reproducing method induding reproducing mainstream data including still image
data
using a clock reproducing the mainstream data; and reproducing sub audio data,
which is separately added in the mainstream data, using a clock reproducing
the sub = -
audio data..
In an aspect of the present invention reproducing mainstream data includes
depacketizing the mainstream data using a clock depacketizing the mainstream
data;
and decoding the mainstream data using a clock decoding the depacketized
mainstream data.
=
In an aspect of the present invention reproducing sub audio data includes
depacketizing the sub audio data using a clock depacketizing the sub audio
data;
decoding the sub audio data using a clock decoding the depacketized sub audio
data.
CA 02725177 2010-12-09
According to still another aspect of the present invention, there is provided
a
computer readable recording medium storing a program executing a reproducing
method, wherein the reproducing method comprises reproducing sub audio data
. separately added in mainstream data, using a clock reproducing the sub
audio data.
According to still another aspect of the present invention, there is provided
a
computer readable recording medium storing a program executing a reproducing
method, wherein the reproducing method comprises reproducing mainstream data
including still image data using a clock reproducing the mainstream data; and
reproducing sub audio data separately added into the mainstream data using a
clock
io reproducing the sub audio data.
Brief Description of the Drawings
These and/or other aspects and advantages of the invention will become
apparent and more readily appreciated from the following description of the
embodiments, taken in conjunction with the accompanying drawings of which:
FIG. 1 illustrates a conventional data structure of multiplexed packet data;
FIG. 2 illustrates a conventional hierarchical encoding apparatus for MPEG
encoding;
FIG. 3 illustrates a conventional data structure of packet data including
arrival
time stamps (ATSs) and a connection between the ATSs and data output time when
the packet data is reproduced;
FIG. 4 illustrates a conventional data structure of packet data including time
synchronization information;
FIG. 5 illustrates a part of a conventional reproducing apparatus that
reproduces packet data including ATSs; -
FIG. 6 is a block diagram of a part of a standard decoder included in a
conventional reproducing apparatus;
FIG. 7 illustrates a conventional method of resetting a system time clock
(STC)
when reproducing a browsable slide show;
FIG. 8 is a schematic block diagram of a reproducing apparatus according to
an embodiment of the present invention;
FIG. 9 is a detailed block diagram of the reproducing apparatus of FIG. 8;
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=
FIG. 10 is a detailed block diagram of a mainstream decoder shown in FIG. 9;
and
Fla 11 is a flowchart illustrating a method of reproducing still image data,
according to an embodiment of the present invention.
Best mode for carrying out the Invention
Reference will now be made in detail to the embodiments of the present
invention, examples of which are illustrated in the accompanying drawings,
wherein
like reference numerals refer to the like elements throughout. The embodiments
io are described below to explain the present invention by referring to the
figures.
FIG. 8 is a block diagram illustrating a reproducing apparatus 800 according
to
an embodiment of the present invention. The reproducing apparatus 800 includes
a
mainstream data reproducing unit 810 and a sub audio data reproducing unit
820.
The mainstream data reproducing unit 810 reproduces mainstream data using
15 a clock, and includes a mainstream arrival time clock (ATC) counter 905
and a
mainstream system time clock (STC) counter 910.
The sub audio data reproducing unit 820 reproduces sub audio data using a
dock, and includes a sub audio ATC counter 906 and a sub audio STC counter
911.
A structure of the reproducing apparatus 800 will be described in detail with
zo reference to FIG. 9. As described above, the reproducing apparatus 800
=
_ == :. = =
reproduces mainstream data using a clock for mainstream data and reproduces
sub
audio data using ä cloak for sub audio data. Therefore, even if fhe dock for
=
mainstream data is adjusted, the clock for sub audio data Is not affected by
the
adjustment, thus enabling seamless reproduction of sub audio data.
25
The structure of a reproducing apparatus 900 such as that shown in FIG. 8 will
now be described with reference to FIG. 9. The reproducing apparatus 900
includes
a disc driving unit 901, a mainstream buffer 902, a sub audio buffer 903, a
first
source depacketizer 904, a mainstream ATC counter 905, a sub audio ATC.
counter
906, a second source depacketizer 907, a demultiplexer 908, a mainstream
decoder
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909, a mainstream STC counter 910, a sub audio STC counter 9111 a sub audio
decoder 912, and a graphics processor 913.
The disc driving unit 901 reads packet data including arrival time stamps
(ATSs) from a recording medium 914, transmits mainstream packet data including
still image data from the packet data to the mainstream buffer 902, and
transmits sub
audio packet data to the sub audio buffer 903.
The first source depacketizer 904 receives the mainstream packet data from
the mainstream buffer 902, depacketizes the mainstream packet data, and sends
the
depacketized mainstream data to the demultiplexer 908. More specifically, the
first
io source depacketizer 904 transmits the depacketized mainstream data, from
which =
the ATSs are detached, to the demultiplexer 908 at predetermined time
intervals,
based on ATS information added to the mainstream packet data by the mainstream
ATC counter 905.
The mainstream ATC counter 905 controls the first source depacketizer 904 to
send the depacketized mainstream data to the demultiplexer 908 at the
predetermined time intervals. More specifically, the mainstream ATC counter
905 is
initialized based on an ATS value of the first mainstream packet data input to
the first
source depacketizer 904, and starts counting at the same time. When a counting
value of the mainstream ATC counter 905 is equivalent to a value of an ATS of
a
second mainstream packet data input to the first source depacketizer 904, the
first
source depacketizer 904 depacketizes the second mainstream packet data and
sends the depacketized mainstream data to the demultiplexer 908.
- -
The operations of the second source depacketizer 907 and the sub audio ATC
counter 906 are the same as those of the first source depacketizer 904 and the
mainstream ATC counter 905, respectively.
= The second source depacketizer 907 receives a sub audio packet data from
the sub audio buffer 903, depacketizes the sub audio packet data, and outputs
the
depacketized sub audio data to the sub audio decoder 912. More specifically,
the
second source depacketizer 907 outputs the depacketized sub audio data, from
which ATSs are detached, at predetermined time intervals, based on ATS
information
added to the sub audio packet data by the sub audio ATC counter 906.
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The sub audio ATC counter 906 controls the second source depacketizer 907
to output the sub audio packet data at the predetermined time intervals. More
specifically, the sub audio ATC counter 906 is initialized based on an ATS
value of a
first sub audio packet data input to the second source depacketizer 907, and
the sub
audio ATC counter 906 starts counting at the same time. When a counting value
of
the sub audio ATC counter 906 is equivalent to a value of an ATS added to a
second
sub audio packet data input to the second source depacketizer 907, the second
Source depacketizer 907 depacketizes the second sub audio packet data and
outputs the depacketized sub audio data. The depacketized sub audio data
output
from the second source depacketizer 907 may be sent to a buffer (not shown).
The demultiplexer 908 demultiplexes the depacketized mainstream data
containing a decoding time stamp (DTS) and presentation time stamp (PTS) and
sends the demultiplexed data to the mainstream decoder 909. The demultiplexed
mainstream data output from the demultiplexer 908 is buffered by a decoding
buffer
(not shown) before the demultiplexed mainstream data is input to the
mainstream
decoder 909.
The mainstream STC counter 910 operates at 90 kHz or 27 MHz. The
mainstream STC counter 910 is set based on program clock reference (PCR)
information (not shown) contained in the packet data, and controls a value of
the
packet data obtained at an instant of time when the packet data is input to
the
decoding buffer based on the PCR value contained in the packet data.
The set mainstream STC counter 910 controls the demultiplexed mainstream
data to be input to the mainstream decoder 909 at a DTS time specified in the
DTS.
information and decoded by the mainstream decoder 909.
The decoded mainstream data output from the mainstream decoder 909 is
input to the graphics processor 913 at a PTS time specified in the PTS
information.
The decoded mainstream data is processed by the graphics processor 913, and
output.
The operation of the mainstream STC counter 910 is similar to that.of the
mainstream ATC counter 905. That is, the mainstream STC counter 910 is
initialized based on the PCR information and starts counting at the same time.
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The mainstream decoder 909 decodes the demultiplexed mainstream data
and transmits the decoded result to the graphics processor 913. when a
counting
value of the mainstream STC counter 910 is equivalent to a value of a DTS of
packet
data. Also, the graphics processor 913 processes the received decoding result
and
outputs a processing result to a screen (not shown) when the counting value of
the
mainstream STC counter 910 is equivalent to a value of the PTS contained in
the
packet data.
The operations of the sub audio STC counter 911 and the sub audio decoder
912 are similar to those of the mainstream STC counter 910 and the mainstream
to decoder 909.
The sub audio STC counter 911 operates at 90 kHz or 27 MHz, and controls a
value of the depacketized sub audio data that is input to a decoding buffer,
which
temporarily stores data, based on a PCR value contained in the packet data.
The set sub audio STC counter 911 controls the depacketized sub audio data
to be input to the sub audio decoder 912 at a PTS time specified in the PTS
information and decoded by the sub audio decoder 912.
The operation of the sub audio STC counter 911 is similar to that of the
mainstream STC counter 910. That is, the sub audio STC counter 911 is
initialized
based on PCR information contained in the packet data and starts counting at
the
same time.
The sub audio decoder 912 decodes the depacketized sub audio data when a
- -
counting value of the sub audio STC counter 911 is equal to a PTS value
included in
the packet data. The sub audio data is decoded and output to the screen
without
performing additional processing on the sub audio data.
FIG. 10 illustrates in detail the mainstream decoder 909 of FIG. 9. The
mainstream decoder 909 includes an audio decoder 1 that decodes audio data, a
sub picture decoder 2 that decodes sub picture data, and a video decoder 3
that
decodes video data. Mainstream data of an application of still image data,
such as
a browsable slide show, may include video data, i.e., still image data, and
sub picture
CA 02725177 2010-12-09
data such as subtitles, but the mainstream data does not include audio data.
Accordingly, the audio decoder 1 is not used in the browsable slide show
application.
The audio decoder 1, the sub picture decoder 2, and the video decoder 3
decode audio data, sub picture data, and video data respectively, based on a
counting value of the mainstream STC counter 910 of FIG. 9.
FIG. 11 is a flowchart illustrating a method of reproducing still picture data
with
separately added sub-audio data, according to an embodiment of the present
invention. Referring to FIGS. 9 and 11, the disc driving unit 901. reads
packet data
from the recording medium 914 (operation 1100).
io Mainstream data of the read packet data, which includes still image
data, is
stored in the mainstream buffer 902 and sub audio data of the read packet data
is
stored in the sub audio buffer 903 (operation 1110).
Next, the first source depacketizer 904 depacketizes the mainstream data
based on a counting value of the mainstream ATC counter 905, and the second
source depacketizer 907 depacketizes the sub audio data based on a counting
value
of the sub audio ATC counter 906 (operation 1120).
Next, the demultiplexer 908 demultiplexes the mainstream data depacketized
by the first source depacketizer 904 (operation 1130).
Next, the mainstream decoder 909 decodes the demultiplexed mainstream
data based on a counting value of the mainstream STC counter 910, and the sub
-audio decoder 912 decodes the depacketized sub audio data based on a counting
value of the sub audio STC counter 911 (operation 1140).
Next, the decoded mainstream data and sub audio data are output (operation
'1150).
The method of FIG. 11 can be embodied as a computer readable code in a
computer readable medium. Here, the computer readable medium may be any
recording apparatus capable of storing data that is read by a computer system,
e.g.,
a read-only memory (ROM), a random access memory (RAM), a compact disc
(CD)-ROM, a magnetic tape, a floppy disk, an optical data =storage device, and
so on.
16
CA 02725177 2013-04-12
Also, the computer readable medium may be a carrier wave that transmits data
via
the Internet, for example. The computer readable recording medium can be
distributed among computer systems that are Interconnected through a network,
and
the present invention may be stored and implemented as a computer readable
code
in the distributed system.
As described above, according to the present invention, it is possible to more
naturally reproduce still image data, such as a browsable slide show, to which
sub
audio data Is separately added, using a dock for mainstream data and a dock
for
sub audio data, thereby preventing an interruption in reproducilon of sub
audio data
to such as background music even during a forward or reverse play.
Although a few embodiments of the present invention have been shown and
described, it would be appreciated by those skilled in the art that changes
may be
made in this embodiment without departing from the principles of the
invention, the scope of which is defined in the claims and their equivalents.
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