U.S. patent application number 09/022021 was filed with the patent office on 2001-10-11 for method of and apparatus for data recording, method of and apparatus for data reproduction, recording medium, and method of and apparatus for data transmission.
Invention is credited to UCHIDE, KOUICHI.
Application Number | 20010028789 09/022021 |
Document ID | / |
Family ID | 26447954 |
Filed Date | 2001-10-11 |
United States Patent
Application |
20010028789 |
Kind Code |
A1 |
UCHIDE, KOUICHI |
October 11, 2001 |
METHOD OF AND APPARATUS FOR DATA RECORDING, METHOD OF AND APPARATUS
FOR DATA REPRODUCTION, RECORDING MEDIUM, AND METHOD OF AND
APPARATUS FOR DATA TRANSMISSION
Abstract
Disclosed are a method of and apparatus for data recording, a
method of and apparatus for data reproduction, a recording medium,
and a method of and apparatus for data transmission in which
compression-coded moving picture signals can be continuously
reproduced irrespective of the amount of information generated.
When recording data obtained by compression-coding a moving picture
signal of a fixed period of time on a recording medium, only
writing to an FIFO buffer memory is effected and reading to the
recording medium is inhibited for a fixed period of time from the
output start of the data and, after the fixed period of time has
elapsed, the writing of the compression-coded data to the FIFO
buffer memory is continued and, at the same time, the data written
to the FIFO buffer memory is read out at a data rate which is riot
lower than the data rate for the writing to packetize the data, the
data thus packetized being recorded on the recording medium.
Inventors: |
UCHIDE, KOUICHI; (KANAGAWA,
JP) |
Correspondence
Address: |
FROMMER LAWRENCE & HAUG
745 FIFTH AVENUE- 10TH FL.
NEW YORK
NY
10151
US
|
Family ID: |
26447954 |
Appl. No.: |
09/022021 |
Filed: |
February 11, 1998 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09022021 |
Feb 11, 1998 |
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08628507 |
Apr 5, 1996 |
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5974223 |
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Current U.S.
Class: |
386/328 ;
386/E9.013 |
Current CPC
Class: |
H04N 9/8042 20130101;
H04N 21/812 20130101 |
Class at
Publication: |
386/111 ;
386/125 |
International
Class: |
H04N 005/92; H04N
005/781 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 8, 1995 |
JP |
07-107975 |
Apr 8, 1995 |
JP |
07-107976 |
Claims
What is claimed is:
1. A data recording method in which a moving picture signal of a
fixed period of time T is compression-coded and recorded on a
recording medium, comprising the steps of: writing the
compression-coded data to a first buffer memory and inhibiting
recording the same on the recording medium for a fixed period of
time Tw from the input start of compression-coded data; after the
fixed period of time Tw has elapsed, continuing the writing of the
compression-coded data to the first buffer memory and reading out
the compression-coded data written to the first buffer memory at a
data rate Rw which is not lower than the data rate Re of the
writing to the first buffer memory; packetizing the read
compression-coded data of a fixed size; and, recording the
packetized data on the recording medium.
2. A data recording method according to claim 1, wherein the fixed
period of time Tw is set to be a value (Be/Re) which is not smaller
than the value of the minimum requisite time for reading an amount
of data corresponding to the total capacity (Be) of a second buffer
memory, which is provided in an encoding section for encoding the
moving picture signal into compression-coded data and outputting
it, from this second buffer memory.
3. A data recording method according to claim 1, wherein the data
rate at which the compression-coded data is read from the first
buffer memory after the fixed period of time Tw has elapsed is a
data rate sufficient for making it possible for compression-coded
data corresponding to the moving picture signal of the fixed period
of time T and data corresponding to the total capacity Be of a
second buffer memory, which is provided in an encoding section for
encoding the moving picture signal into compression-coded data and
outputting it, to be read within the fixed period of time T.
4. A data recording method according to claim 1, wherein, when the
first memory has become empty during the reading of
compression-coded data from the first memory, meaningless stuffing
data is added to thereby generate the packet data of a fixed
size.
5. A data recording apparatus comprising: an encoding section for
compression-coding a moving picture signal of a fixed period of
time T and outputting it; a first buffer memory to which
compression-coded data is input from the encoding section and
which, for a fixed period of time Tw from the input start of the
compression-coded data, only allows the writing of the
compression-coded data and inhibits reading and, after the fixed
period of time Tw has elapsed, reads the compression-coded data
that has been written at a data rate which is not lower than the
data rate for the writing while continuing the writing of the
compression-coded data; and a packetizing section for packetizing
the compression-coded data read from the first buffer memory and
recording it on a recording medium always as packet data of a fixed
size.
6. A data recording apparatus according to claim 5, wherein the
fixed period of time Tw is set to be a value which is not smaller
than the value of the minimum requisite time for reading an amount
of data corresponding to the total capacity Be of a second buffer
memory, which is provided in the encoding section, from this second
buffer memory.
7. A data recording apparatus according to claim 5, wherein the
data rate at which the compression-coded data is read from the
first buffer memory after the fixed period of time Tw has elapsed
is a data rate sufficient for making it possible for
compression-coded data corresponding to the moving picture signal
of the fixed period of time T and data corresponding to the total
capacity of a second buffer memory, which is provided in the
encoding section, within the fixed period of time T.
8. A data recording apparatus according to claim 5, further
comprising means for generating stuffing data, wherein, when the
first memory has become empty during the reading of
compression-coded data from the first memory, the packetizing
section adds the stuffing data to generate the packet data
9. A data reproducing method in which compression-coded data
obtained by compression-coding a moving picture signal of a fixed
period of time T is accumulated in a first buffer memory for a
fixed period of time Tw from the input start and, after that, while
the writing to the first buffer memory is being continued, data is
read at a rate higher than the writing rate to packetize the data
to thereby obtain packet data, which is recorded on a recording
medium and reproduced therefrom, the reproducing method comprising
the steps of: reading out the packet data at a data rate not lower
than the data rate at which the packet data was written to the
recording medium; writing the read out packet data to a second
buffer memory; reading out the data written to the second buffer
memory at a data rate which is substantially the same as the data
rate of writing the compression-coded data to the first buffer
memory; and decoding the data.
10. A data reproducing apparatus comprising: a data extracting
section in which compression-coded data obtained by
compression-coding a moving picture signal of a fixed period of
time T is accumulated in a first buffer memory for a fixed period
of time Tw from the output start and, after that, while the writing
to the first buffer memory is being continued, data is read at a
rate higher than the writing rate to packetize the data to thereby
obtain packet data, which is recorded on a recording medium and
read therefrom, the compression-coded data being extracted from
this packet data; a second buffer memory to which the
compression-coded data is sequentially input and written from the
data extracting section, wherein, after the writing, the
compression-coded data is read out at a data rate which is lower
than the rate at which the compression-coded data is read from the
data extracting section and which is substantially the same as the
data rate at which the compression coding is effected; and a
decoding section for decoding the compression-coded data read from
the second buffer memory to obtain the moving picture signal.
11. A recording medium on which compression-coded data obtained by
compression-coding a moving picture signal of a fixed period of
time T is recorded as packet data of a fixed size regardless of the
amount of compression-coded data generated, wherein said packet
data is of the following two kinds: first packet data consisting of
header data and the compression-coded data; and second packet data
consisting of header data, the compression-coded data and dummy
data.
12. A data transmission method in which data obtained by
compression-coding a moving picture signal of a fixed period of
time T is transmitted through a transmission line, comprising the
steps of: writing the compression-coded data to a first buffer
memory and inhibiting data output to the transmission line for a
fixed period of time Tw from the input start of the
compression-coded data; after the fixed period of time Tw has
elapsed, continuing the writing of the compression-coded data to
the first buffer memory and reading out the compression-coded data
that has been written to the first buffer memory at a data rate Rw
which is not lower than the data writing rate; packetizing the read
compression-coded data of a fixed size; and outputting the
packetized data to the transmission line.
13. A data transmission apparatus comprising: an encoding section
for compression-coding a moving picture signal of a fixed period of
time T and outputting it; a first buffer memory to which
compression-coded data is input from the encoding section and
which, for a fixed period of time Tw from the input start of the
compression-coded data, only allows the writing of the
compression-coded data and inhibits outputting and, after the fixed
period of time Tw has elapsed, reads the compression-coded data
that has been written at a data rate which is not lower than the
data rate for the writing while continuing the writing of the
compression-coded data; and a packetizing section for packetizing
the compression-coded data read from the first buffer memory and
outputting it to a transmission line always as packet data of a
fixed size.
14. A data transmission method in which compression-coded data
obtained by compression-coding a moving picture signal of a fixed
period of time T is accumulated in a first buffer memory for a
fixed period of time Tw from the input start and, after that, while
the writing to the first buffer memory is being continued, data is
read at a rate higher than the writing rate to packetize the data,
which is received through a transmission line, the data
transmission method comprising the steps of: reading out the packet
data at a data rate not lower than the data rate at which the
packet data was output to the transmission line; writing the read
out packet data to a second buffer memory; reading out the data
written to the second buffer memory at a data rate which is
substantially the same as the data rate of writing the
compression-coded data to the first buffer memory; and transmitting
the data.
15. A data transmission apparatus comprising: a data extracting
section in which compression-coded data obtained by
compression-coding a moving picture signal of a fixed period of
time T is accumulated in a first buffer memory for a fixed period
of time Tw from the output start and, after that, while the writing
to the first buffer memory is being continued, data is read at a
rate higher than the writing rate to packetize the data to thereby
obtain packet data, which is received through a transmission line,
the compression-coded data corresponding to the moving picture
signal being extracted from this packet data; a second buffer
memory to which the compression-coded data read from the data
extracting section is sequentially input and written from the data
extracting section, wherein, after the writing, the
compression-coded data is read out at a data rate which is lower
than the data rate at which the compression-coded data is read from
the data extracting section and which is substantially the same as
the data rate at which the compression coding is effected; and a
decoding section for decoding the compression-coded data read from
the second buffer memory to obtain the moving picture signal.
16. A data recording method in which a moving picture signal of a
fixed period of time T is compression-coded and recorded on a
recording medium, comprising the steps of: packetizing
compression-coded data output from an encoding section into packet
data of a fixed size; writing the packet data to a first buffer
memory and inhibiting recording thereof on the recording medium for
a fixed period of time Tw from the output start of the packet data;
after the fixed period of time Tw has elapsed, continuing writing
of the packet data to the first buffer memory; and, reading out the
packet data that has been written to the first buffer memory at a
data rate which is not lower than the data rate of the writing to
the first buffer memory to record the data on the recording
medium.
17. A data recording method according to claim 16, wherein the
fixed period of time Tw is set to be a value which is not smaller
than the value of the minimum requisite time for reading an amount
of data corresponding to the total capacity of a second buffer
memory, which is provided in an encoding section for encoding the
moving picture signal into compression-coded data and outputting
it, from this second buffer memory.
18. A data recording method according to claim 16, wherein the data
rate at which the packet data is read from the first buffer memory
after the fixed period of time Tw has elapsed is a data rate
sufficient for making it possible for compression-coded data
corresponding to the moving picture signal of the fixed period of
time T and data corresponding to the total capacity of a second
buffer memory, which is provided in an encoding section for
encoding the moving picture signal into compression-coded data and
outputting it, to be read within the fixed period of time T.
19. A data recording method according to claim 16, wherein, when
the first memory has become empty during the reading of the packet
data from the first memory, a meaningless padding packet is
generated and recorded on the recording medium.
20. A data recording apparatus comprising: an encoding section for
compression-coding a moving picture signal of a fixed period of
time T and outputting it; a packetizing section to which
compression-coded data is input from the encoding section and in
which the compression-coded data is packetized; and a first buffer
memory to which packet data is input from the encoding section and
which, for a fixed period of time Tw from the input start of the
packet data, only allows the writing of the packet data and
inhibits the reading thereof and, after the fixed period of time Tw
has elapsed, reads the packet data that has been written at a data
rate which is not lower than the data rate for the writing while
continuing the writing of the packet data and writes it to a
recording medium.
21. A data recording apparatus according to claim 20, wherein the
fixed period of time Tw is set to be a value which is not smaller
than the value of the minimum requisite time for reading an amount
of data corresponding to the total capacity of a second buffer
memory, which is provided in the encoding section, from this second
buffer memory.
22. A data recording apparatus according to claim 20, wherein the
data rate at which the packet data is read from the first buffer
memory after the fixed period of time Tw has elapsed is a data rate
sufficient for making it possible for compression-coded data
corresponding to the moving picture signal of the fixed period of
time T and data corresponding to the total capacity of a second
buffer memory, which is provided in the encoding section, within
the fixed period of time T.
23. A data recording apparatus according to claim 20, further
comprising means for generating a meaningless padding packet,
wherein, when the first memory has become empty during the reading
of the packet data from the first memory, the padding packet is
recorded on the recording medium.
24. A data reproducing method in which packet data that is obtained
by packetizing compression-coded data obtained by
compression-coding a moving picture signal of a fixed period of
time T is accumulated in a first buffer memory for a fixed period
of time Tw from the output start and, after that, while the writing
to the first buffer memory is being continued, the packet data is
read at a rate higher than the writing rate and recorded on a
recording medium and reproduced therefrom, the reproducing method
comprising the steps of: reading out the packet data at a data rate
not lower than the data rate at which it was written to the
recording medium; writing the read out packet data to a second
buffer memory; reading out the packet data written to the second
buffer memory at a data rate which is substantially the same as the
data rate for the packetizing; and decoding the packet data read
out of the second buffer memory.
25. A data reproducing apparatus comprising: a data extracting
section in which packet data that is obtained by packetizing
compression-coded data obtained by compression-coding a moving
picture signal of a fixed period of time T is accumulated in a
first buffer memory for a fixed period of time Tw from the output
start and, after that, while the writing to the first buffer memory
is being continued, the packet data is read from a recording medium
at a rate higher than the writing rate to extract the
compression-coded data from the packet data; a second buffer memory
to which the packet data is sequentially input and written from the
data extracting section, wherein, after the writing, the packet
data is read out at a data rate which is lower than the rate at
which the packet data is read from the data extracting section and
which is substantially the same as the data rate at which the
packetizing of the compression-coded data is effected; and a
decoding section for decoding the packet data read from the second
buffer memory to obtain the moving picture signal.
26. A recording medium on which compression-coded data obtained by
compression-coding a moving picture signal of a fixed period of
time T is recorded always as packet data of a fixed size regardless
of the amount of compression-coded data generated, wherein said
packet data is of the following two kinds: first packet data
consisting of header data and the compression-coded data; and
second packet data consisting of header data and dummy data.
27. A data transmission method in which data obtained by
compression-coding a moving picture signal of a fixed period of
time T is transmitted through a transmission line, comprising the
steps of: packetizing the compression-coded data output from the
encoding section into packet data of a fixed size; writing the
packet data to a first buffer memory and inhibiting data output to
the transmission line for a fixed period of time Tw from the output
start of the packet data; after the fixed period of time Tw has
elapsed, continuing the writing of the packet data to the first
buffer memory; and reading out the packet data that has been
written to the first buffer memory at a data rate which is not
lower than the data writing rate to transmit the packet data to the
transmission line.
28. A data transmission apparatus comprising: an encoding section
for compression-coding a moving picture signal of a fixed period of
time T and outputting it; a packetizing section for packetizing the
compression-coded data read from the first buffer memory and
outputting it as packet data; and a first buffer memory to which
the packet data is input and which, for a fixed period of time Tw
from the input start of the packet data, only allows the writing of
the packet data and inhibits the outputting thereof and, after the
fixed period of time Tw has elapsed, reads the packet data that has
been written at a data rate which is not lower than the data rate
for the writing while continuing the input of the packet data.
29. A data transmission method in which packet data that is
obtained by packetizing compression-coded data obtained by
compression-coding a moving picture signal of a fixed period of
time T is accumulated in a first buffer memory for a fixed period
of time Tw from the output start and, after that, while the writing
to the first buffer memory is being continued, the packet data is
read at a rate higher than the writing rate and recorded on a
recording medium and read therefrom, the data transmission method
comprising the steps of: reading out the packet data at a data rate
not lower than the data rate at which it was written to the
recording medium; writing the read out packet data to a second
buffer memory; reading out the packet data written to the second
buffer memory at a data rate which is substantially the same as the
data rate for the packetizing; and decoding the packet data read
out of the second buffer memory.
30. A data transmission apparatus comprising: a data extracting
section in which packet data that is obtained by packetizing
compression-coded data obtained by compression-coding a moving
picture signal of a fixed period of time T is accumulated in a
first buffer memory for a fixed period of time Tw from the output
start and, after that, while the writing to the first buffer memory
is being continued, the packet data is read at a rate higher than
the writing rate and received form a transmission line for data
transmission, the compression-coded data corresponding to the
moving picture signal being extracted from this packet data; a
second buffer memory to which the packet data read from the data
extracting section is sequentially input and written, wherein,
after the writing, the packet data is read out at a data rate which
is lower than the data rate at which the compression-coded data is
read from the data extracting section and which is substantially
the same as the data rate for the packetizing of the data; and a
decoding section for decoding the packet data read from the second
buffer memory to obtain the moving picture signal.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a data recording apparatus,
a data reproducing apparatus, etc. in which moving picture signals
are compression-coded for recording or reproduction.
[0003] The present invention further relates to a data transmission
apparatus in which moving picture signals are compression-coded for
transmission to remote sites.
[0004] 2. Description of the Related Art
[0005] Generally speaking, in systems for recording and reproducing
digital moving picture signals and systems for transmitting them to
remote sites, an image signal compression-coding method is adopted
in order to efficiently utilize the capacity of the recording
medium, the transmission line, etc. In such a method, it is general
practice to perform the compression coding of moving picture
signals by utilizing in-frame correlation or inter-frame
correlation. Examples of the compression coding formats include
MPEG1 and MPEG2. Further, coding methods in conformity with the H.
261 recommendation, etc. are available.
[0006] In compression coding apparatuses, etc. operating in
accordance with such coding formats, coding is to be effected such
that the amount of moving picture signal data generated during a
fixed period of time is kept constant.
[0007] However, the amount of data generated by compression coding
is usually not constant. Further, the amount of data thus generated
differs from frame to frame.
[0008] If the amount of data generated per unit time is not
constant, it is very difficult to directly record the generated
data on a recording medium or directly transmit it.
[0009] This is generally due to the fact that the data recording
rate or the data transmission rate is constant.
[0010] In view of this, a buffer memory is usually provided between
the moving picture image compression coding section and the medium
recording section or between the moving picture image compression
coding section and the transmission section so that the data rate
of the variable amount of coded data output to the recording
apparatus, the transmission line, etc. may be kept constant. In the
moving picture image compression coding section, the amount of
coded data generated is adjusted such that the buffer memory will
not suffer failure.
[0011] Thus, the average rate of data amount generated per unit
time in the moving picture image compression coding section when
performing moving picture image compression coding is the same as
the data rate of the coded data output from the buffer memory.
[0012] The device for performing these operations is generally
called an encoder, which includes the buffer memory.
[0013] In the device for decoding the compression-coded data to the
original moving picture signals, a buffer memory similar to the one
mentioned above is provided between the recording apparatus or the
output end of the transmission line and the expansion decoding
section. The device for performing these operations is generally
called a decoder, which includes the buffer memory.
[0014] In this way, in the conventional encoder and decoder,
compression coding processing is effected so that the amount of
moving picture signal data per unit time may approach a constant
value or it may approach a target generation amount of coded
data.
[0015] Here, a case will be considered in which coded data obtained
by compression-coding a moving picture signal of a time length T is
recorded on a recording medium at a writing rate R, the recorded
data then being read out at reading rate R and decoded to thereby
reproduce the moving picture signal. In this case, the target
generation amount of coded data Ei is given by the following
equation:
Ei=R.times.T (1)
[0016] However, as shown by the following inequality, the actual
amount of data generated Er is not the constant value R.times.T but
varies as follows:
R.times.T-B.ltoreq.Er.ltoreq.R.times.T+B (2)
[0017] where B represents the capacity of the buffer memory
provided in the encoder. That is, it is possible for the amount of
coded data Er to vary by the capacity B of the buffer memory in the
encoder.
[0018] Assuming that this data is recorded on the recording medium
as it is and then read out, the reading time t is as shown by the
following inequality: 1 T - B R t T + B R ( 3 )
[0019] The reproduction time for the moving picture signal which is
obtained by decoding the data read out is also T. This shows that
image reproduction time and the requisite time for reading out the
data is not the same.
[0020] When, as in the case of an AV server, an arbitrary number of
items of data obtained by compression-coding moving picture signals
of a fixed period of time (they will be hereinafter referred to as
"clips") are written to a medium, and an arbitrary number of clips
are read out from the medium to continuously reproduce the image
signals, the following problem is involved:
[0021] When an arbitrary number of clips obtained by
compression-coding moving picture signals of a fixed period of time
are written to a medium and an arbitrary number of clip image
signals are continuously reproduced therefrom, the requisite time
for reading out data differs for each item of data, so that, when
the time for reading out data is longer than the time for
reproduction, it is impossible to continuously reproduce the actual
clip image signals without interruption.
SUMMARY OF THE INVENTION
[0022] It is an object of the present invention to provide a method
of and apparatus for data recording, a method of and apparatus for
data reproduction, a recording medium, and a method of and
apparatus for data transmission which enable a clip image of an
arbitrary length of time to be reproduced without interruption.
[0023] To achieve the above object, in accordance with the present
invention, when recording compression-coded moving picture signals
of a fixed period of time or outputting them to the transmission
line, the compression-coded data is only written to an FIFO buffer
memory for a period of time from the output start of the
compression-coded data, and the reading thereof to the recording
medium or to the transmission line is inhibited.
[0024] When a fixed period of time has elapsed from the output
start of the compression-coded data, the compression-coded data is
written to the FIFO buffer memory, and, at the same time, the
compression-coded data which has been written to the FIFO buffer
memory is read out at a data rate exceeding that at the time of
data writing and packetized. This packetized data is recorded on
the recording medium, or output to the transmission line.
[0025] When packet data is read from a recording medium on which
compression-coded data, obtained by compression-coding moving
picture signals of a fixed period of time, is recorded after being
converted to packet data whose size is constant independently of
the amount of data generated, or when it is received from a
transmission line, the packet data is read at a data rate not lower
than the rate at which it was written to the recording medium or
the rate at which it was output to the transmission line and is
then written to an FIFO buffer memory. After that, the written
compression-coded data is read from the FIFO buffer memory at a
rate that is the same at which it was compression-coded and is then
decoded.
[0026] Generally speaking, when compression-coding a moving picture
signal, the amount of data generated fluctuates. However,
regardless of this fluctuation, the compression-coded data when it
is recorded on a recording medium or output to a transmission line
is converted to packet data of a fixed size. Thus, it is possible
for the moving picture signal to be recorded or transmitted within
a fixed period of time regardless of the amount of data
generated.
[0027] Further, it is possible for the moving picture signal to be
reproduced or received, whether on the reproduction or reception
side, within a fixed period of time regardless of the amount of
data generated.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] FIG. 1 is a block diagram showing the basic construction of
a data recording apparatus and of a data reproducing apparatus
according to the present invention;
[0029] FIG. 2 is a flowchart illustrating a recording operation by
the data recording apparatus;
[0030] FIG. 3 is a flowchart illustrating a reproducing operation
by the data reproducing apparatus;
[0031] FIG. 4 is a schematic diagram showing the relationship
between data generation amount and processing time in
recording;
[0032] FIG. 5 is a schematic diagram showing the relationship
between data generation amount and processing time in
reproduction;
[0033] FIG. 6 a block diagram showing the basic construction of a
data recording apparatus and of a data reproducing apparatus
according to another embodiment of the present invention;
[0034] FIG. 7 is a flowchart illustrating a recording operation by
the data recording apparatus;
[0035] FIG. 8 is a schematic diagram showing the relationship
between data generation amount and processing time in
recording;
[0036] FIG. 9 is a schematic diagram showing the relationship
between data generation amount and processing time in
reproduction;
[0037] FIG. 10 is a block diagram showing an example of the
construction of an AV server system; and
[0038] FIG. 11 is a block diagram showing another example of the
construction of an AV server system.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE
INVENTION
[0039] (1) The Principle on Which Recording and Reproduction are
Performed
[0040] To write an arbitrary number of items of data obtained by
compression-coding a moving picture image of a fixed period time,
that is, an arbitrary number of clips, to a recording medium and to
continuously reproduce an arbitrary number of image signals from
this recording medium without interruption, the recording apparatus
of this embodiment adopts an arrangement in which, after writing
compression-coded data to an FIFO buffer memory for a fixed period
of time, the data is read out at a data rate higher than the rate
of writing to record packetized data on the recording medium.
[0041] Further, in the reproducing apparatus of this embodiment,
data is extracted from a packet read from a recording medium at a
rate that is the same or higher than the recording rate, and this
data is written to an FIFO buffer memory having a capacity not
smaller than that for the recording. Then, the data is read out at
a rate that is the same as the coding rate to effect expansion
decoding.
[0042] (2) Basic System Configuration
[0043] (2-1) Construction of Recording Apparatus and Reproducing
Apparatus
[0044] FIG. 1 shows a hardware construction example of a recording
apparatus 1 for executing this recording method and a reproducing
apparatus 2 for executing this reading method.
[0045] First, the construction of the recording apparatus 1 will be
described. The recording apparatus 1 is composed of an encoder 1A,
an FIFO buffer memory 1B, a packetizing section 1C and a stuffing
section 1D.
[0046] The encoder 1A is composed of a compression coding section
1A1 and an encoding buffer memory 1A2. The compression coding
section 1A1 effects variable-amount compression coding of a moving
picture signal S1 at an average rate of Re, and successively
outputs coded data S2 to the encoding buffer memory 1A2 having a
capacity Be.
[0047] Further, when a fixed amount of coded data S2 has been
accumulated in the memory, the encoding buffer memory 1A2 outputs
coded data S3 (S2) at the rate Re. Data indicating the buffer
remainder Be' of the encoding buffer memory 1A2 is fed back to the
compression coding section 1A1 and the processing of the
compression coding section 1A1 is controlled so that the buffer may
not suffer failure.
[0048] The FIFO buffer memory 1B is a buffer memory with a capacity
Bw provided for data rate conversion. The FIFO buffer memory 1B
accumulates the coded data S3 written at the rate Re for a
predetermined period of time Tw. After that, it outputs the data to
the packetizing section 1C at a reading rate Rw higher than the
writing rate Re. Here, the accumulation time Tw, the reading rate
Rw and the buffer capacity Bw are set as follows:
Tw.gtoreq.(Re.times.T+Be)/Re-T=Be/Re (4)
Rw.gtoreq.(Re.times.T+Be)/T=Re+Be/T (5)
[0049] In the packetizing section 1C, coded data S4 time-compressed
by the FIFO buffer memory 1B is successively input and stored in
one or a plurality packets before being output. In this process,
the packetizing section 1C writes the requisite information, such
as the packet size, the kind of data, and time information, to a
packet header, and records it on a recording medium 3 at the fixed
rate Rw. Strictly speaking, the rate at which the recording on the
recording medium is effected must be somewhat higher than Rw
because of the increase in data amount due to the packet header.
However, this is negligible since it is a small amount as compared
with the coded data.
[0050] As a result, packet data S5 can be written without fail to
the recording medium 3 within a period of time corresponding to the
clip reproduction time T regardless of the amount of information
generated.
[0051] Due to the relation ship: Rw>Re, when the FIFO buffer
memory 1B runs out of data during the packet processing, the
packetizing section 1C inserts meaningless data that is not
directly related to the data supplied from the stuffing section 1D
(i.e., stuffing data) in the packet for the purpose of filling,
whereby failure in data transmission form is prevented. The encoder
1A, the packetizing section 1C, the FIFO buffer 1B and the stuffing
section 1D are controlled by a control section 1F.
[0052] Next, the construction of the reproducing apparatus 2 will
be described. The reproducing apparatus 2 is composed of a data
extracting section 2A, an FIFO buffer memory 2B and a decoder
2C.
[0053] The reproducing apparatus 2 reads out recording data
recorded on the recording medium 3 at a fixed rate Rw, and reads it
in the data extracting section 2A as reproduction data S6.
[0054] The data extracting section 2A extracts coded data S7
corresponding to the moving picture signal from the packet on the
basis of header information, etc., and transmits it to the FIFO
buffer memory 2B for reading out. In this process, when stuffing
data is extracted from the packet, the data extracting section 2A
scraps it so that it may not be decoded.
[0055] Assuming that the reading rate at which the data extracting
section 2A reads the recording data S6 from the recording medium 3
is the same as the writing rate, i.e., Rw, the requisite time for
reading Td can always be kept within the clip display time as shown
by the following formula:
Td=(Re.times.T+Be)/Rw.ltoreq.T (7)
[0056] In this way, the coded data S7 extracted by the data
extracting section 2A is written to the FIFO buffer memory 2B for
reading, and the data rate is restored to the original value. The
capacity Br of the FIFO buffer memory 2B satisfies the following
condition:
[0057] Generally speaking, the capacity of the decoding buffer
memory 2C1 contained in the decoder 2C is not smaller than that of
the encoding buffer memory 1A2, so that, in this embodiment, the
capacity Br of the FIFO buffer memory 2B is the same or larger than
the capacity Bw of the FIFO buffer memory 1B for writing, as shown
by the following inequality:
Br.gtoreq.Bw (8)
[0058] Finally, the decoder 2C will be described. The decoder 2C is
composed of a decoding buffer memory 2C1 and an expansion decoding
section 2C2.
[0059] The decoding buffer memory 2C1 reads coded data S8 from an
FIFO buffer memory 2B at a fixed rate Re and supplies it to the
expansion decoding section 2C2. The expansion decoding section 2C2
decodes the coded data S8 at the average decoding rate Re, and
outputs the decoding result as a moving picture signal S10.
[0060] The extracting section 2A, the FIFO buffer 2B and the
decoder 2C are controlled by a control section 2F.
[0061] (2-2) Procedures for Recording and Reproduction
[0062] Recording and reproducing operations executed in the
recording apparatus 1 and the reproducing apparatus 2 of the above
construction at the time of recording and reproduction will be
described one by one.
[0063] First, the recording operation when a plurality of clips are
to be continuously reproduced without interruption, that is, the
control operation of the control section 1F, will be described with
reference to FIG. 2.
[0064] When the recording operation is started, the procedure for
the recording apparatus 1 advances from step SP 1 to step SP 2, and
designates the position for the recording of the moving picture
signal on the recording medium 3 by means of a pointer. This
pointer is used as the reading pointer for reading out the
recording data of the moving picture signal at the time of
reproduction.
[0065] When the designation with the writing pointer has been
completed, the procedure for the recording apparatus 1 advances to
step SP 3, in which the moving picture signal S1 is input to the
encoder 1A, and variable amount encoding is started.
[0066] When the encoding is started, the recording apparatus 1
encodes the moving picture signal S1 by the encoder 1A at the
average rate Re and, as shown in step SP 4, writes the coded data
S3 obtained by the encoding from the encoding buffer memory 1A2 to
the FIFO buffer memory 1B.
[0067] As shown in the next step SP 5, the recording apparatus 1
checks the period of time elapsed from the writing start time and
makes a judgment as to whether the period of time elapsed is larger
than the accumulation time Tw as given by formula (4).
[0068] When the result of the judgment is in the affirmative, the
reading of the coded data S4 from the FIFO buffer memory 1B to the
packetizing section 1C is started in the recording apparatus 1, as
shown in step SP 6. The data rate Rw in this reading is, as
described above, a value larger than the data rate Re when the data
is written to the FIFO buffer memory 1B.
[0069] After this, as shown in steps SP 7 through SP 9, the
recording apparatus 1 packetizes the coded data S4 in the
packetizing section 1C and records it on the recording medium 3 as
packet data S5 until it is made certain that the buffer remainder
B'w of the FIFO buffer memory has become empty result of step SP 9
is in the affirmative and it is made sure that the FIFO buffer
memory 1B has become empty, the procedure for the recording
apparatus 1 advances to step SP 10, in which a judgment is made as
to whether the writing to the FIFO buffer memory 1B by the encoder
1A has been completed.
[0070] When the result of the judgment is in the negative, it is
determined that the FIFO buffer memory 1B has become temporarily
empty due to the fact that the rate Rw at which reading from the
FIFO buffer memory is effected is higher than the writing rate Re
and, in steps SP11-SP7-SP8-SP9, operation is effected such that the
shortage in packet data is compensated for by filling with stuffing
data. This processing routine is continued until the reading from
the FIFO buffer memory 1B is started again.
[0071] When the reading from the FIFO buffer memory 1B is started
again, the processing routines of steps SP9-SP7-SP8-SP9 are
repeatedly executed.
[0072] When the result obtained in steps SP 9 and SP 10 is in the
affirmative, the completion of the recording of a series of moving
picture signals S1 is confirmed in step SP 12, and in the next step
SP 13, a judgment is made as to whether the moving picture signal
S1 of the next clip is to be recorded or not.
[0073] As long as the result of the judgment is in the affirmative,
the recording apparatus 1 repeatedly executes the procedures of
steps SP 2 through SP 13. When the result obtained is in the
negative, the recording of a plurality of clips is completed.
[0074] Next, the reproducing operation effected when reproducing
the thus recorded recording data from the recording medium 3, that
is, the control operation of the control section 25, will be
described with reference to FIG. 3.
[0075] When the reproducing operation is started, the procedure for
the reproducing apparatus 2 advances from step SP 21 to step SP 22
and the position on the recording medium 3 for the reading of the
recording data is designated with the reading pointer.
[0076] When the designation with the reading pointer has been
completed, the reading of data from the recording medium 3 is
started as shown in step SP 23.
[0077] When reproduction data S6 has been read to the data
extracting section 2A, the reproducing apparatus 2 extracts, as
shown in step SP 24, stuffing data from the reproduction data S6
read out at the fixed rate Rw, and, in step SP 25, operates such
that only the portion of the coded data S7 corresponding to the
moving picture signal is supplied to the FIFO buffer memory 2B.
[0078] In the next step SP 26, the reproducing apparatus 2 supplies
coded data S8 rate-converted by the FIFO buffer memory 2B to the
decoder 2C, and the reproduction of the moving picture signal S10
is started again by the decoder 2C.
[0079] Then, in the next step SP 28, the reproducing apparatus 2
makes a judgment as to whether the data reading has been entirely
completed or not. As long as the result of the judgment is in the
negative, the procedures of the steps:
SP29-SP24-SP25-SP26-SP27-SP28 are repeated.
[0080] When data reading corresponding to one clip has been
completed by repeating this processing loop, the procedure for the
reproducing apparatus 2 advances from step SP 28 to SP 29, and a
judgment is made as to whether there is a next clip to be
continuously reproduced.
[0081] As long as the result of the judgment is in the affirmative,
the reproducing apparatus 2 repeats the procedures of steps SP 22
through SP 28. When the result of the judgment obtained is in the
negative, the procedure advances to step SP 30.
[0082] When, in step SP 30, it is made sure that the buffer
remainder of the decoding buffer memory 2C1 has been reduced to
zero, the procedure advances to step SP 31, in which the
reproducing operation is completed.
[0083] FIGS. 4 and 5 show the relationship between data amount and
processing time in an example of recording/reproducing operation in
which two clips, clip 1 and clip 2, are continuously recorded.
[0084] It will be assumed that the image periods of the clip 1 and
clip 2, which are to be recorded continuously, are T and T', as
shown in FIG. 4(A). Generally speaking, it is possible for the
amount of coded data generated in the encoder 1A to fluctuate by an
amount corresponding to the capacity Be of the encoding buffer
memory 1A2 of the encoder 1A. For example, assuming that the amount
of coded data is large, it takes T+.DELTA.T and T'+.DELTA.T' to
read the coded data S3 of clip 1 and clip 2 from the FIFO buffer
memory 1B, as shown in FIG. 4(B).
[0085] If this coded data S3 were recorded as it is on the
recording medium 3 as in the prior art, it would take T+.DELTA.T
and T'+.DELTA.T' to reproduce clip 1 and clip 2 from the recording
medium 3, which would be longer than the display time. Thus, in
conventional reproducing apparatus, there is a fear of a blank time
.DELTA.T being generated if two clips, clip 1 and clip 2, are
continuously reproduced
[0086] In the recording apparatus 1 of this embodiment, in
contrast, data is read from the FIFO buffer memory 1B at a data
rate higher than the average encoding rate Re and in a condition
satisfying formula (5), so that the data portions including clip 1
and clip 2 can be completely written to the recording medium 3
within the image periods T and T' regardless of the buffer
remainder Be'. This is shown in FIG. 4(C). The shaded portions in
the drawing represent the stuffing data filling periods.
[0087] At the time of completion of the recording on the recording
medium, data is recorded on the recording medium 3 in a data
construction as shown in FIG. 4(C).
[0088] In reproduction, the reproducing apparatus 2 can read the
recording data of the moving picture signals corresponding to clip
1 and clip 2 within the periods T and T', respectively, as shown in
FIG. 5(A).
[0089] Furthermore, stuffing data is extracted from the
reproduction data S6 read out, so that, as shown in FIG. 5(B), only
the data really corresponding to the moving picture signals are
read to the FIFO buffer memory 2B.
[0090] After this, coded data S8 is read out, as shown in FIG.
5(C), from the FIFO buffer memory 2B to the decoder 2C at the
original data rate Re and decoded. At this time, in FIG. 5(C), the
apparent data reading periods are longer than the display periods
of clip 1 and clip 2 by an amount corresponding to the buffer
remainder. However, since the decoding operation for each item of
coded data is completed in periods T and T', respectively, it is
possible to continuously reproduce two clips, clip 1 and clip 2, as
shown in FIG. 5(D).
[0091] In the above-described construction, it is possible to read
moving picture signals of two clips to be continuously reproduced
from the recording medium 3 within the respective display periods T
and T', whereby delay in clip display due to delay in decoding
operation can be avoided. This makes it possible to realize a
recording apparatus 1 and a reproducing apparatus 2 which can
continuously reproduce a plurality of clips without involving any
blank periods. Further, it is also possible to realize a recording
medium which allows continuous reproduction.
[0092] (3) Another Embodiment
[0093] (3-1) Construction of Recording Apparatus and Reproducing
Apparatus
[0094] In a recording apparatus according to another embodiment,
packetized data is written to an FIFO buffer memory for a fixed
period of time after the compression coding, and then read out at a
data rate not lower than the writing data rate and recorded on a
recording medium.
[0095] FIG. 6 shows a hardware construction example of a recording
apparatus 1' for executing the recording method and a reproducing
apparatus 2' for executing the reading method. In the following
description, the components which are the same as those in the
above-described embodiment will be indicated by the same reference
numerals.
[0096] First, the construction of the recording apparatus 1' will
be described. The recording apparatus 1' is composed of an encoder
1A, a packetizing section 1G, an FIFO buffer memory 1H, and a
padding packet processing section 1I.
[0097] The encoder 1A is composed of a compression coding section
1A1 and an encoding buffer memory 1A2. The compression coding
section 1A1 effects variable-amount compression coding of a moving
picture signal S1 at an average rate of Re, and successively
outputs coded data S2 to the encoding buffer memory 1A2 having a
capacity Be.
[0098] Further, when a fixed amount of coded data S2 has been
accumulated in the memory, the encoding buffer memory 1A2 outputs
coded data S2 at the rate Re. The buffer remainder Be' of the
encoding buffer memory 1A2 is fed back to the compression coding
section 1A1 so that the buffer may not suffer failure.
[0099] The packetizing section 1G successively inputs items of
coded data S3 output from the encoder 1A and stores them in one or
a plurality of packets before outputting them. In this process, the
packetizing section 1G writes the requisite information, such as
the packet size, the kind of data and the time information, to the
packet header, and outputs it to the FIFO buffer memory 1H at a
fixed rate Re which is the same as the encoding rate.
[0100] The FIFO buffer memory 1H is a buffer memory with a capacity
Bw provided for data rate conversion. The FIFO buffer memory 1H
accumulates the coded data S4' written at the rate Re for a
predetermined period of time Tw. After that, it reads the data at a
reading rate Rw higher than the writing rate Re and records it on
the recording medium 3.
[0101] As a result, packet data S5' can be written without fail to
the recording medium 3 within a period of time corresponding to the
clip reproduction time T regardless of the amount of information
generated at the time of encoding.
[0102] Here, the accumulation time Tw, the reading rate Rw and the
buffer capacity Bw of the FIFO buffer memory 1H at the time of this
reading operation are calculated as follows:
Tw.gtoreq.(Re.times.T+Be)/Re.times.T=Be/Re (9)
Rw.gtoreq.(Re.times.T+Be)/T=Re+Be/T (10)
Bw.gtoreq.Tw.times.Re+total number of bytes of packet header
(11)
[0103] Due to the relation ship: Rw>Re, it is possible for the
FIFO buffer memory 1H to run out of data during the data writing to
the recording medium 3. In view of this, the padding packet
processing section 1I is provided.
[0104] The padding packet processing section 1I or the control
section 1F constantly detects the buffer remainder B'w of the FIFO
buffer memory 1H. When the buffer remainder B'w has become zero,
the padding packet processing section 1I outputs a meaningless
packet that is not directly related to the data (i.e., padding
packet) for the purpose of filling the blank period, whereby
failure in data transmission form is prevented. The encoder 1A, the
packetizing section 1G, the FIFO buffer 1H, and the padding packet
processing section 1I are controlled by the control section 1F.
[0105] Next, the construction of the reproducing apparatus 2' will
be described. The reproducing apparatus 2' is composed of a data
extracting section 2A, an FIFO buffer memory 2B and a decoder
2C.
[0106] The reproducing apparatus 2' reads out recording data
recorded on the recording medium 3 at a fixed rate Rw, and reads it
to the data extracting section 2A as reproduction data S'6.
[0107] The data extracting section 2A removes the padding packet
from the reproduction data S'6 read out and scraps it, and extracts
only the encoding data S'7 corresponding to the moving picture
signal and transmits it to the FIFO buffer memory 2B for
reading.
[0108] Assuming that the reading rate at which the data extracting
section 2A reads the recording data S'6 from the recording medium 3
is the same as the writing rate, i.e., Rw, the requisite time for
reading Td can always be kept within the clip display time as shown
by the following formula:
Td=(Re.times.T+Be)/Rw.ltoreq.T (12)
[0109] In this way, the coded data S'7 extracted by the data
extracting section 2A is written to the FIFO buffer memory 2B for
reading, and the data rate is restored to the original value. The
capacity Br of the FIFO buffer memory 2B satisfies the following
condition:
[0110] Generally speaking, the capacity of the decoding buffer
memory 2C1 contained in the decoder 2C is not smaller than that of
the encoding buffer memory 1A2, so that, in this embodiment, the
capacity Br of the FIFO buffer memory 2B is the same or larger than
the capacity Bw of the FIFO buffer memory 1H for writing, as shown
by the following inequality:
Br.gtoreq.Bw (13)
[0111] (3-2) Procedures for Recording and Reproduction
[0112] Recording and reproducing operations executed in the
recording apparatus 1' and the reproducing apparatus 2' of the
above construction at the time of recording and reproduction will
be described one by one.
[0113] First, the recording operation when a plurality of clips are
to be continuously reproduced without interruption, that is, the
control operation of the control section 1F, will be described with
reference to FIG. 7.
[0114] When the recording operation is started, the procedure for
the recording apparatus 1' advances from step SP 41 to step SP 42,
and designates the position for the recording of the moving picture
signal on the recording medium 3 by means of a writing pointer.
This pointer also is used as the reading pointer for reading out
the recording data of the moving picture signal at the time of
reproduction.
[0115] When the designation with the writing pointer has been
completed, the procedure for the recording apparatus 11 advances to
step SP 43, in which the moving picture signal S1 is input to the
encoder 1A, and variable amount encoding is started.
[0116] When the encoding is started, the recording apparatus 1'
encodes the moving picture signal S1 by the encoder 1A at the
average rate Re and, as shown in step SP 44, successively
packetizes the coded data S3 obtained by the encoding. At the same
time, the recording apparatus 1' starts to write the packetized
packet data S4 to the FIFO buffer memory 1H.
[0117] As shown in the next step SP 45, the recording apparatus 1'
checks the period of time elapsed from the writing start time and
makes a judgment as to whether the period of time elapsed is larger
than the accumulation time Tw as given by formula (4).
[0118] When the result of the judgment is in the affirmative, the
recording apparatus 1' starts the reading of the packet data S'5
from the FIFO buffer memory 1H, as shown in step SP 46. The data
rate Rw in this reading is, as described above, a value larger than
the data rate Re when the data is written to the FIFO buffer memory
1H.
[0119] After this, as shown in step SP 47, the recording apparatus
1' returns from step SP 47 to step SP 46 until it is made sure that
the remainder B' of the FIFO buffer memory 1H has become zero, and
continues to write the packet data S'5 read from the FIFO buffer
memory 1H to the recording medium 3.
[0120] When the result of step SP 47 is in the affirmative and it
is made sure that the FIFO buffer memory 1H has become empty, the
procedure for the recording apparatus 1' advances to step SP 48, in
which a judgment is made as to whether the writing of the packet
data S4 to the FIFO buffer memory 1H has been completed or not.
[0121] When the result of the judgment is in the negative, it is
determined in the recording apparatus 1' that the FIFO buffer
memory 1H has become temporarily empty due to the fact that the
reading rate Rw is higher than the writing rate Re and the
procedure advances to step SP 48, where the shortage in packet data
is compensated for by filling with padding packet.
[0122] After this, the procedure for the recording apparatus 1'
returns to step SP 47, in which a judgment is made again as to
whether the buffer remainder B' is zero or not. If it is not zero,
the writing to the recording medium 3 is started again. When it is
zero, a judgment is made in step SP 48 as to whether the writing to
the FIFO buffer memory 1H has been completed or not.
[0123] When the result obtained in step SP 48 is in the
affirmative, the completion of the recording of a series of moving
picture signals S1 is confirmed in step SP 50, and in the next step
SP 51, a judgment is made as to whether the moving picture signal
S1 of the next clip is to be recorded or not.
[0124] As long as the result of the judgment is in the affirmative,
the recording apparatus 1' repeatedly executes the procedures of
steps SP 42 through SP 51. When the result obtained is in the
negative, the recording of a plurality of clips is completed.
[0125] The reproducing operation effected when reproducing the thus
recorded recording data from the recording medium 3 is basically
the same as that in the above-described embodiment. In this
embodiment, the padding packet is removed from the reproduction
data S'6 in step SP 24.
[0126] FIGS. 8 and 9 show the relationship between data amount and
processing time in an example of recording/reproducing operation in
which two clips, clip 1 and clip 2, are continuously recorded.
[0127] It will be assumed that the image periods of the clip 1 and
clip 2, which are to be recorded continuously, are T and T', as
shown in FIG. 8(A). Generally speaking, it is possible for the
amount of coded data generated in the encoder 1A to fluctuate by an
amount corresponding to the capacity Be of the encoding buffer
memory 1A2 of the encoder 1A. For example, assuming that the amount
of coded data is large, it takes T+.DELTA.T and T'+.DELTA.T' to
read the coded data S3 of clip 1 and clip 2 from the FIFO buffer
memory 1H, as shown in FIG. 8(B).
[0128] If this coded data S3 were recorded as it is on the
recording medium 3 as in the prior art, it would take T+.DELTA.T
and T'+.DELTA.T' to reproduce clip 1 and clip 2 from the recording
medium 3, which would be longer than the display time. Thus, in
conventional reproducing apparatus, there is a fear of a blank time
.DELTA.T being generated if two clips, clip 1 and clip 2, are
continuously reproduced.
[0129] In the recording apparatus 1' of this embodiment, in
contrast, data is read from the FIFO buffer memory 1H at a data
rate higher than the average encoding rate Re and in a condition
satisfying formula (5), so that the data portions including clip 1
and clip 2 can be completely written to the recording medium 3
within the image periods T and T' regardless of the buffer
remainder Be'. This is shown in FIG. 8(C). The shaded portions in
the drawing represent the padding packet filling periods.
[0130] At the time of completion of the recording on the recording
medium, data is recorded on the recording medium 3 in a data
construction as shown in FIG. 8(C).
[0131] In reproduction, the reproducing apparatus 2' can read the
recording data of the moving picture signals corresponding to clip
1 and clip 2 within the periods T and T', respectively, as shown in
FIG. 9(A).
[0132] Furthermore, data unrelated to the coded data, such as
padding packet, is extracted from the reproduction data S6 read
out, so that, as shown in FIG. 9(B), only the data really
corresponding to the moving picture signals is read to the FIFO
buffer memory 2B.
[0133] After this, coded data S8 is read out, as shown in FIG.
9(C), from the FIFO buffer memory 2B to the decoder 2C at the
original data rate Re and decoded. At this time, in FIG. 9(C), the
apparent data reading periods are longer than the display periods
of clip 1 and clip 2 by an amount corresponding to the buffer
remainder. However, since the decoding operation for each item of
coded data is completed in periods T and T', respectively, it is
possible to continuously reproduce two clips, clip 1 and clip 2, as
shown in FIG. 9(D).
[0134] (4) Application System
[0135] Next, a system construction example to which this basic
system is applied will be described. Here, the recording apparatus
1 will be described with reference to an integral-type system in
which the recording medium 3 and the reproducing apparatus 2 are
connected through a communication channel and to with reference to
a separation type system in which there is a connection through
cable between the recording apparatus 1 and the recording medium 3
or between the recording medium 3 and the reproducing apparatus
2.
[0136] (4-1) Integral-Type System
[0137] Here, as an example of the integral-type system, a server
system in which AV signals (audio and video signals) are
distributed to a number of terminal devices through a communication
circuit (hereinafter referred to as an "AV server system") will be
described. FIG. 10 shows the overall construction of an AV server
system 11.
[0138] This AV server system 11 is composed of a data supply source
12, an encoding section 13 and a server section 14. The system is
used to distribute AV signals from the server section 14 to a
number of terminals 15A1 through 15AN. Each section is constructed
as described below.
[0139] The data supply source 12 consists of reproducing
apparatuses 12A, such as video tape recorders (VTR) or
magneto-optical disks. Each reproducing apparatus 12A supplies AV
data signals SD1, SD2 . . . to the encoding section 13 through a
transmission line or a signal line. In this example, a plurality of
data supply sources 12 are provided.
[0140] The encoding section 13 is a section corresponding to the
recording apparatus 1 of the basic system, and is composed of an
encoder 13A, an FIFO-buffer/packet-processing section 13B and a
control section 13C.
[0141] Of these, the encoder 13A encodes the AV data signals SD1,
SD2 . . . input from the data supply sources 12 into signals of a
data format in conformity with the MPEG 2 standards, converting
them to data streams D1, D2, . . . .
[0142] The FIFO-buffer/packet-processing section 13B stores these
data streams D1, D2 . . . temporarily in the FIFO buffer memory for
rate conversion, and the rate-converted coded data is converted to
packet data Dw in the packet processing section.
[0143] The control section 13C controls the data supply source 12,
the encoder 13A and the server section 14 by a control signal
S.sub.CTL, and manages the operating condition of each section.
[0144] The server 14 is composed of a recording/reproducing section
14A and a decoding section 14B. The recording/reproducing section
14A records coded data obtained by further compressing
compression-coded data supplied from the encoding section 13 in
time-axis direction on the recording medium, and, when there is an
instruction from the user, reads corresponding coded data to output
it to the decoding section 14B. The instruction from the user is
input as a request signal S.sub.request.
[0145] The recording/reproducing section 14A is composed of a media
control section 14A1 and a plurality of media units 14A2 through
14A8. Here, the media control section 14A1 is a unit for
controlling the recording/reproducing operations of the plurality
of media units 14A2 through 14A8. Further, each of plurality of
media units 14A2 through 14A8 contains a plurality of hard disks so
that they can record and reproduce a plurality of signals
simultaneously and in parallel, whereby multi-access from a number
of terminals 15A1 through 15AN can be realized. Further, coded data
supplied from the encoding section 13 are recorded on these hard
disks as clips.
[0146] The decoding section 14B is composed of a
data-extracting-section/F- IFO-buffer-memory 14B0 and a plurality
of decoders 14B1 through 14BM. Here, the number of the decoders
14B1 through 14BM provided in the decoding section 14 is determined
by the number of terminals 15A1 through 15AN finally connected and
the number of items of coded data that can be simultaneously
reproduced by the recording/reproducing section 14A.
[0147] The decoding section 14B decodes coded data read out by the
decoders 14B1 through 14BM through the media units 14A2 through
14A8 and outputs it to the terminals 15A1 through 15AN.
[0148] It is not always necessary for this AV server system 11 to
be provided in one room; it also allows connection through LAN
(local area network) or the like.
[0149] (4-2) Separation-Type System
[0150] Next, as an example of the separation-type system, an AV
server system, which distributes AV signals (audio and video
signals) to a number of terminal devices through physical delivery
of a recording medium, will be described. FIG. 11 shows the
construction of an AV server system 21.
[0151] This AV server system 21 is a system composed of a
production station 22, a key station 23, an artificial satellite
24, a cable station 25, a branch station 26, a home 27, etc., which
are geographically spaced apart from each other.
[0152] In this example, the recording apparatus 1 described with
reference to the basic system corresponds to an encoder 22A
provided in the production station 22, and the reproducing
apparatus 2 corresponds to a decoder 26A provided in the branch
station 26.
[0153] The production station 22 is a producing company or a
producing office which edits image source to produce commercials
(CM), programs, etc. The moving picture of a program or a CM is
compression-coded here and recorded on the recording medium 3. The
recording medium 3 is physically delivered to the key station 23,
the cable station 25, etc.
[0154] The key station 23 is used when image data reproduced from
the recording medium 3 is transmitted to the artificial satellite
24 in the form of compression-coded data and transferred to the
branch station 26, which is at a remote site. This data transfer
may be regarded as a radio transfer between the recording medium 3
and the reproducing apparatus 2 in the basic system.
[0155] The cable station 25 is used when image data reproduced from
the recording medium 3 is transmitted in the form of
compression-coded data to the branch station 26, which is at a
remote site, through a cable. Apart from this, data transmission
between the cable station 25 and the branch station 26 can also be
effected through physical delivery of the recording medium 3.
[0156] The branch station 26 is provided with a decoder 26A and a
file server 26B and is used when decoding received coded data at
the original data rate and transmitting it to the home 27 as a
moving picture signal.
[0157] The basic system allows such an application, too. Further,
while in this example the encoder 22 is provided in the production
station 22, it is also possible for the encoder to be provided in
the key station 23.
[0158] Further, while in this example the decoder 26A is provided
in the branch station 26, it is also possible to realize an example
in which the decoder is provided in each home 27.
[0159] (5) Still Another Embodiment
[0160] While in the above-described embodiment the encoder 1A, the
FIFO buffer memory 1B, the packetizing section 1C and the stuffing
section 1D (or the padding packet processing section 1I) are united
as the recording apparatus 1, the present invention is not
restricted to this construction. It is also possible for these
components to be contained in separate casings.
[0161] Similarly, while in the above-described embodiment the data
extracting section 2A, the FIFO buffer memory 2B, and the decoder
2C are united as the reproducing apparatus 2, the present invention
is not restricted to this construction. It is also possible for
these components to be contained in separate casings.
[0162] Further, while in the above-described embodiment a hard
disk, a video tape or the like is used as the recording medium 3,
this should not be construed restrictively. The present invention
is also applicable to other recording media. For example, it is
also applicable to an optical disk or a so-called optical card,
such as a video disk, a magneto-optical disk or a phase change type
disk. Further, it is also applicable to a magnetic recording
medium, such as a floppy disk.
[0163] Further, while in the above-described embodiment the reading
of data from the recording medium 3 is effected at the rate Rw
which is the same as the rate at which the writing of data to the
recording medium is effected, the reading rate may be higher than
this.
[0164] When compression-coding a moving picture signal, the amount
of data generated usually fluctuates. However, as described above,
in accordance with the present invention, conversion of data to
packet data of a fixed size has been effected when the data is
recorded on a recording medium or when it is output to a
transmission line, so that, in spite of this fluctuation, it is
possible to complete the recording or transmission of a moving
picture signal within a fixed period of time regardless of the
amount of data generated, whereby it is always possible, in
reproduction or reception, to reproduce or receive a moving picture
signal within a fixed period of time regardless of the amount of
data generated, making it possible to continuously reproduce
expansion-decoded moving picture signals.
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