Note: Descriptions are shown in the official language in which they were submitted.
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Description
INFORMATION STORAGE MEDIUM STORING MULTI
ANGLE DATA, AND RECORDING METHOD AND RE
PRODUCING APPARATUS THEREOF
Technical Field
[1] The present invention relates to multi angle data used when encoding andbr
decoding video object data, and more particularly, to an information storage
medium
which stores the multi angle data, a method of recording andbr reproducing the
multi
angle data, and an apparatus for recording andbr reproducing the multi angle
data.
Background Art
[2] Multi angle data is obtained by photographing a scene with several cameras
at
different angles and encoding a result of the photographing. When a change of
viewing
angle of the photographed scene is desired during reproduction of contents
including
the multi angle data, a change of angle cc~m~and is sent to a reproducing
apparatus,
and the reproducing apparatus reproduces data of the scene photographed at the
desired angle in response to the command. For angle change, the multi angle
data are
divided into predetermined units and the units are alternately recorded using
in-
terleaving.
[3] Accordingly, a pickup of the reproducing apparatus must jump to other
positions so
as to detect and reproduce interleaved blocks at an angle or accomplish angle
change
while reading the multi angle data recorded using interleaving. However, an
increase
in sizes of the interleaved blocks results in an increase in the distance
between a
current position and a position to which a pickup of the reproducing apparatus
must
jump for angle change. In this case, seamless reproduction is not guaranteed.
On the
contrary, if a size of an interleaved block is small, jumping of the pickup of
the re-
producing apparatus is frequently required during data reproduction that does
not
require angle change. Accordingly, it is important to adjust a size of an
interleaved
block appropriately.
[4] Further, a jumping point allowing the reproducing apparatus to jump to
other in-
terleaved blocks at a different angle may be set within one interleaved block.
In this
case, a total number of jumping points must be appropriately determined so
that the
multi angle data is effectively reproducible.
Disclosure of Invention
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Technical Solution
[5] The present invention provides an information storage medium on which
multi
angle data is recorded to enable seamless reproduction, and a method of
recording and/
or reproducing the multi-angle data and an apparatus for recording and~r
reproducing
the multi angle data.
[6] The present invention also provides a method of determining a total number
of
angle points that allow a reproducing apparatus to jump to change reproduction
positions within an interleaved block.
Advantageous Effects
[7] As described above, according to the present invention, multi angle data
is ef-
fectively recordable so that the multi angle data is seamlessly without
excessive
jumping of a pickup for data reproduction.
Description of Drawings
[8] FIG. lA illustrates a first angle data file;
[9] FIG. 1B illustrates a second angle data file;
[10] FIG. 1C illustrates recording of the first and second angle data files
using in-
terleaving;
[11] FIG. 2 illustrates the multi angle data of FIG. 1 recorded on an
information storage
medium;
[12] FIG. 3 is a block diagram of a reproducing apparatus for seamlessly
reproducing
data, according to an embodiment of the present invention;
[13] FIG. 4 is a graph illustrating an amount of data stored in a read buffer
during
jumping of a pickup;
[14] FIG. 5 illustrates a structure of a clip file recorded using interleaving
to realize
multi angle data, according to an embodiment of the present invention ; and
[15] FIG. 6 is a flowchart illustrating a method of calculating the distance S
ANCLE_POINTS
between two angle points and a length S of an extent, according to an
EXTENT
embodiment of the present invention.
Best Mode
[16] According to an aspect of the present invention, there is provided an
information
storage medium on which multi angle data comprising at least one unit of angle
data is
recorded, wherein the multi angle data comprises interleaved blocks, each of
which
includes at least one predetermined sized packet, and the data of one angle
are in-
terleaved with the data of at least one other angle in units of the
interleaved blocks,
sizes of the interleaved blocks being integral multiples of sizes of integral
numbered
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aligned units that include packets.
[17] Each of the interleaved blocks may include at least one angle point that
allows a re-
producing apparatus to continue data reproduction while jumping to other
reproduction
positions during reproduction of the angle data, a number of angle points
includible in
each of the interleaved blocks being integral multiples of a number of the
aligned
units.
[18] According to another aspect of the present invention, there is provided a
method of
recording multi angle data that includes interleaved blocks, each of which
includes at
least one angle point that allows a reproducing apparatus to jump to other
reproduction
positions during data reproduction, using interleaving, the method comprising
computing a distance between angle points; compensating for an offset between
the
computed distance and a reproduction length of a packet comprising each of the
in-
terleaved blocks; computing a maximum number of angle points in one
interleaved
unit that is obtained when a possible longest jumping distance to which the re-
producing apparatus can jump during data reproduction is smaller than or equal
to a
maximum jumping distance given by the reproducing apparatus; and making in-
terleaved blocks based on the distance between angle points and a number of
angle
points, and recording the multi angle data on the interleaved blocks.
[19] According to yet another aspect of the present invention, there is
provided an
apparatus for reproducing multi angle data stored in interleaved blocks, each
of which
includes at least one angle point allowing the apparatus to jump to other
reproduction
positions during data reproduction, the apparatus comprising a reading unit
which
reads the multi angle data; and a buffer which stores the read multi angle
data, wherein
the multi angle data comprises interleaved blocks, each of which includes at
least one
predetermined sized packet, and the angle data of one angle are interleaved
with angle
data of at least one other angle in units of interleaved blocks, sizes of the
interleaved
blocks being integral multiples of sizes of integral numbered aligned units
that include
packets.
Mode for Invention
[20] 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 are
described below to explain the present invention by referring to the figures.
[21] FIGS. lA-1C illustrate multi angle data recorded using interleaving. The
multi
angle data comprises a first angle data file 110 as shown in FIG. lA and a
second angl
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a data file 120 as shown in FIG. 1B that contain audio/video (AV) data for
respective
angles. The first and second angle data files 110 and 120 are alternately and
con-
tinuously recorded in an area 130 of an information storage medium as shown in
FIG.
1C for fast change of angle views. In other words, the first and second angle
data files
110 and 120 are divided into predetermined units and the predetermined units
are
recorded using interleaving. Accordingly, a pickup of a reproducing apparatus
is not
required to move a large distance to read data at a changed angle when angle
views are
changed, thereby guaranteeing seamless reproduction.
[22] Each predetermined unit of angle data included in data recorded on the
information
storage medium using interleaving is referred to as an extent. In the case of
a digital
versatile disc - video (DVD-Video), an extent is equivalent to an interleaved
unit. That
is, the extent indicates data recorded in a file system without a pause.
Accordingly,
jumping of a pickup of the reproducing apparatus to other extents is required
to exactly
read data for data reproduction.
[23] FIG. 2 illustrates the interleaved data of FIGS. lA-1C recorded on an
information
storage medium 200. An AV stream indicates a bit stream comprising a plurality
of
source packets. A source packet is a 192-byte packet that includes a 188 byte
MPEG-2
transport stream (TS) and a 4-byte header. In general, data is stored in
sector units in
an information storage medium. A sector is a basic unit of recording a file.
In general,
a sector stored in a DVD is 2048 bytes long. Thus, a sector is comprised of
several
source packets.
[24] FIG. 3 is a simplified block diagram of a reproducing apparatus for
seamlessly re-
producing data. Referring to FIG. 3, data stored in an information storage
medium is
read by a reading unit 310 and the read data is transmitted to a read buffer
330 via a
demodulation unit 320. The read buffer 330 is used to buffer a bit stream that
is to be
transmitted to a decoder, and thus, use of the buffer guarantees seamless
reproduction
even during jumping of a pickup 305 in the reading unit 310. A source
depacketizer
340 converts the bit stream that includes a plurality of source packets into
an MPEG-2
TS packet and outputs the MPEG-2 TS packet.
[25] Parameters related to buffering are as follows:
[26] (a) R : A data rate of data transmitted from the reading unit 310 to the
read
UD
buffer 330 via the demodulation unit 320;
[27] (b) R : A maximum value of an encoding rate TS recording rate of an MPEG-
2
Ts
TSB i.e., a speed of outputting data to the decoder; and
[28] (c) R : A maximum bit rate of a source packet stream. An MPEG-2 TS packet
MAX
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is 188 byte long and inclusion of a 4-byte header into the MPEG-2 TS packet
forms a
source packet stream. Therefore, a maximum bit rate R equals (192/188) ' R
MAX TS
[29] Assuming that data B output from the read buffer 330 to the decoder at a
OCCUPIED
speed TS recording rate satisfies Equation (1), underflow of the read buffer
330 is not
caused even if data cannot further be stored in the read buffer 330 for a time
T
[30]
JUMP
$occcr~r~~ ~ ~''~~ ~~.~~ x 192 X ~,~, - recor~a~ag - ra ~~
1000 1~~
... (1)
[31] FIG. 4 is a graph illustrating an amount of data stored in the read
buffer 300 during
jumping of the pickup 305. In FIG. 4, T denotes a sum of a jumping time, i.e.,
JUMP
access time T , and a time T required to read two error correcting codes
ACCESS OVERHEAD
(ECCs). That is, T = T + T , and T (ms)
JUMP ACCESS OVERHEAD OVERHEAD
f 2 x ECC (bytes)/R (bps)}.
UD
[32] When reading data stored in an information storage medium, the read
buffer 330 is
[33]
filled with the read data. Before the pickup jumps to a new position, the read
buffer
330 must be filled with data as specified in Equation (1) so as to prevent
underflow of
the read buffer 330. That is, in order to prevent underflow of the read buffer
330, a
length S of data that must be read to the read buffer 330 before jumping of
the
READ
pickup must satisfy Equation (2).
S(ba~~ >_ Try' ('mss) x R~ X Z'S' -recor~dirag- r~ate(bps) x 192
1000 R~ (~~s) x 188- TS' -recardarag- rate(bps) x 192
... (2)
[34] FIG. 5 illustrates a structure of a clip file recorded using interleaving
to realize
multi angle data.
[35] As described above, respective angle data of one angle are interleaved
among angle
data of at least one other angle to reduce jumping time and response time for
angle
change, thereby seamlessly changing angles. As a result, jumping is required
not only
for angle change but also for normal playback at a same angle, in order to
detect and
reproduce desired angle data. An interleaved block is considered an extent of
a clip
file. An extent may include a plurality of angle points allowing a pickup to
jump to
other angle data. Accordingly, a length S of the extent in sectors and a
distance S
EXTENT
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between two angle points must satisfy Equation (3).
ANCLE POINTS
[36]
5,.(secL~ors)= I~l~'~ ( ~5~-~~~,~..~ + 6144- 192)16144}x 3
7T2 OPdF F~FJ72
... (3)
[37] The clip file of multi angle data, shown in FIG. 5, has the following
restrictions:
[38] (i) the clip file must be located on a layer;
[39] (ii) extents of multi angle streams must start with an angle point and be
aligned
with aligned units. If a last aligned unit of an extent is not completely
filled with input
transport streams, an unoccupied space of the last aligned unit is filled with
null
packets;
[40] (iii) each distance S is an integral multiple of a length of a source
packet
ANCLE POINTS
e.g., integral multiples of 192 byte s ; and
[41] (iv) the length S of the extent, a total number of angle points in the
extent, and
EXTENT
angle change time must meet the buffer occupancy rules defined in Equations
(1) and
(2). Examples of buffer parameters are shown in following Tables 1 and 2.
[42] The distance S between two angle points is shorter than the length S
ANCLE POINTS
of the extent, and a maximum value of the access time T for angle change is
EXTENT ACCESS
obtained when jumping to a farthest angle point in a next unit of angle data
from a
current angle point in a current unit of angle data. A unit of angle data may
be referred
to an a plurality of blocks of data corresponding to a same time, wherein each
block
corresponds to data at a respective angle. Referring to FIG. 5, the data Angle
1-1,
Angle 2-1 and Angle 3-1 may be considered the current unit of angle data and
the data
Angle 1-2, Angle 2-2 and Angle 3-2 may be considered a next unit of angle
data. If an
angle change command is received before arriving at the angle point 520 after
the
angle point 510, the maximum value of the access time T is obtained when
ACCESS
jumping to a first angle point 530 of angle 3-2 from a last angle point 520 of
angle 1-1
after reproducing remaining data of the angle 1-1.
[43] If several angle points are set within an extent, the length S of FIG. 4
is equal to
RE9D
the distance S . In this case, Equation (2) may be expressed as follows:
ANCLE POINTS
[44]
'Gras) x R~(6~s) T~' _ recarcda~ag- rate(bps) x 192
s~"~~-F°~xCb~~~ ~ 1000 x R~(bps) x 188- 7~' - recar~ang- rate (fps) x I
92
[45] FIG. 6 is a flowchart illustrating a method of calculating the distance S
ANCLE_POINTS
between two angle points and a length S of an extent, according to an
EXTENT
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embodiment of the present invention. Referring to FIG. 6, the distance S is
ANCLE POINTS
calculated with given access time T and data output speed TS recording rate,
ACCESS
using Equation (3) (5610). Next, lengths A and B of data that are reproduced
at the
data output speed TS recording rate for 500 ms and 1000 ms, respectively, are
calculated (5620). Since a distance between group-of-pictures (GOPs) is
between 500
ms and 1000 ms according to the MPEG-2 standards, a distance between angle
points
is preferably set between 500 ms and 1000 ms. Then, the distance S is
ANCLE_POINTS
compared with the lengths A and B (5630). If the distance S
ANCLE_POINTS
the length A, the distance S is determined to be equivalent to the length A,
ANCLE POINTS
and if the length A < the distance S
ANCLE POINTS
the length B, the distance S is determined to be equivalent to the length B
ANCLE_POINTS
(5630).
[46] Next, a maximum number M of angle points in an interleaved unit that
satisfies that
a longest jumping distance less than (<) a maximum jumping distance for the
given
access time T , is calculated (5640). Since the available maximum jumping
ACCESS
distance of a reproducing apparatus is set by the reproducing apparatus, the
longest
jumping distance is calculated by 2 ' (angle number - 1) ' M ' S . Thus, the
ANGLE POINTS
maximum number M can be computed using the computed longest jumping distance.
Then, the length S of the extent equals to INT ' 3 and has M angle points.
EXTENT
[47] Cbnsidering that jumping is made between two angle points, angle units,
each of
which corresponds to data between two angle points in an angle data unit, are
preferably aligned with sectors.
[48] Tables 1 and 2 show example values of the length S of an extent and the
EXTENT
distance S between two angle points computed using the above method. In
ANCLE POINTS
detail, Table 1 shows example values of the length S and the distance S
EXTENT
when a scene is photographed at three angles. Table 2 shows example
ANCLE POINTS
values of the length S and the distance S when the scene is pho-
EXTENT ANCLE_POINTS
tographed at nine angles.
Table 1
[49]
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Maximum Jump
Distance
10000 sectors 20000 sectors 40000 sectors
T5 recording
rate
[TACCESS~ 210 [TACCESS~ 270 [TACCESS.
mS~ mS~ 330 ms)
S~xrENr~ and
Angle Point
Number and
Length in
SExrEn~r
20Mbps 2496, 4, 500 4989, 8, 500 9975, 8, 1
ms ms sec
24Mbps 2247, 3, 500 4491, 3, 1 8979, 6, 1
ms sec sec
30Mbps 1872, 1, 1 3741, 2, 1 9351, 5, 1
sec sec sec
Table 2
~50~
Maximum Jump
Distance
10000 sectors 20000 sectors 40000 sectors
T5 recording
rate
[TACCESS: 210 [TACCESS: 270 [TACCESS:
ms) ms) 330 ms)
5~~~~rr, and
Angle Point
Number and
Length in
S~~~Nr
20Mbps 624, 1, 500 1248, 2, 500 2496, 2,
ms ms 1 sec
24Mbps N.A. N.A. 1497, 1,
1 sec
30Mbps N.A. N.A. 1872, 1,
1 sec
[51] In general, extents of a file are aligned with sectors. According to the
present
invention, a source packet is 192 bytes long and thus cannot be aligned with a
sector of
2048 bytes. Therefore, three continuous sectors are grouped into an access
unit. An
access unit of three sectors is a minimum unit where an integral multiple of a
length of
a source packet is equal to a length of the access unit. In other words, where
a sector
has a length of 2048 bytes, a length of 32 source packets equals a length of
three
sectors, i.e., one access unit.
[52] The present invention may be realized as a computer program. In this
case, codes
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and code se~nents that are the members of the present invention can be easily
inferred
by computer programmers in the art to which the present invention belongs.
Also, the
computer program may be stored in a computer readable medium. When the
computer
program is read and executed by a computer, a method of recording a multi
angle data
is accomplished. The computer readable medium may be any medium, such as a
magnetic recording medium, an optical recording medium, and a carrier waver
medium.
[53] 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 and spirit of the
invention,
the scope of which is defined in the claims and their equivalents.
