U.S. patent application number 12/071940 was filed with the patent office on 2008-07-03 for method and device for ensuring storage time for digital broadcast.
This patent application is currently assigned to MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD.. Invention is credited to Eiji Miyagoshi, Akihiro Watabe.
Application Number | 20080163327 12/071940 |
Document ID | / |
Family ID | 32652812 |
Filed Date | 2008-07-03 |
United States Patent
Application |
20080163327 |
Kind Code |
A1 |
Miyagoshi; Eiji ; et
al. |
July 3, 2008 |
Method and device for ensuring storage time for digital
broadcast
Abstract
When a digitized broadcast is recorded in a storage medium, a
required capacity of the storage medium is firstly calculated on
the basis of a bit-rate of digitized broadcast data and a recording
time which is known in advance. If the remaining capacity of the
storage medium is smaller than the required capacity of the storage
medium, for example, a frame rate decimation and pixel reduction
are performed upon a broadcast to be newly stored, a re-encoding
processing is performed for the broadcast and then the resultant
broadcast is stored in the storage medium. If the remaining storage
capacity of the storage medium is larger than the required capacity
of the storage medium and thus remains, a frame interpolation and
pixel interpolation are performed for the broadcast to be stored
and then a re-encoding processing is performed for the resultant
broadcast in order to improve its image quality. As a result,
recording of the broadcast data in the storage medium can be
ensured.
Inventors: |
Miyagoshi; Eiji; (Osaka,
JP) ; Watabe; Akihiro; (Nara, JP) |
Correspondence
Address: |
MCDERMOTT WILL & EMERY LLP
600 13TH STREET, NW
WASHINGTON
DC
20005-3096
US
|
Assignee: |
MATSUSHITA ELECTRIC INDUSTRIAL CO.,
LTD.
Osaka
JP
|
Family ID: |
32652812 |
Appl. No.: |
12/071940 |
Filed: |
February 28, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10692804 |
Oct 27, 2003 |
7359615 |
|
|
12071940 |
|
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Current U.S.
Class: |
725/134 ;
348/E5.108; 375/E7.129; 375/E7.154; 375/E7.16; 375/E7.211;
375/E7.252; 375/E7.254; 386/E5.001; G9B/20.001; G9B/20.009;
G9B/27.012; G9B/27.052 |
Current CPC
Class: |
G11B 20/00007 20130101;
H04N 5/4401 20130101; G11B 27/034 20130101; H04N 19/46 20141101;
H04N 21/4424 20130101; G11B 2020/00079 20130101; G11B 2220/2541
20130101; H04N 19/59 20141101; H04N 21/426 20130101; G11B 2220/216
20130101; H04N 19/15 20141101; H04N 19/587 20141101; G11B 2220/218
20130101; H04N 9/8042 20130101; H04N 5/76 20130101; H04N 5/85
20130101; H04N 19/146 20141101; H04N 19/61 20141101; G11B 2220/2562
20130101; H04N 21/234363 20130101; H04N 19/132 20141101; G11B 27/36
20130101; G11B 2220/2575 20130101; H04N 5/781 20130101; G11B 20/10
20130101 |
Class at
Publication: |
725/134 |
International
Class: |
H04N 7/173 20060101
H04N007/173 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 22, 2003 |
JP |
2003-013181 |
Claims
1. A method for ensuring a storage time for digital broadcast at
the time of storing broadcast data transmitted in a state of being
digitized and compressed, comprising the steps of: monitoring a
predetermined recording time for the broadcast and a bit-rate of
the broadcast in the compressed state and calculating a required
capacity of a storage medium; determining whether or not said
calculated required capacity of the storage medium can be contained
within an empty area or a freely limited area of the storage
medium; if said calculated required capacity of the storage medium
cannot be contained as the result of said determination,
converting, in real time, said bit-rate of the broadcast into a
smaller one by decoding and then re-compressing the broadcast data
in the compressed state; and storing said converted broadcast in
said storage medium.
2. The method for ensuring a storage time for digital broadcast of
claim 1 further comprising the steps of: if said calculated
required capacity of the storage medium can be contained as the
result of said determination, determining whether or not said empty
area or freely limited area of the storage medium remains; if said
empty area or freely limited area remains, converting, in real
time, said bit-rate of the broadcast into a larger one; and storing
said converted broadcast into said storage medium.
3. The method for ensuring a storage time for digital broadcast of
claim 1 further comprising the step of: if said calculated required
capacity of the storage medium can be contained as the result of
said determination, storing said broadcast in said storage medium
without converting the bit-rate.
4. The method for ensuring a storage time for digital broadcast of
claim 1, wherein said step of converting said bit-rate of the
digitized broadcast into a smaller one is an operation of missing a
part of said broadcast data.
5. The method for ensuring a storage time for digital broadcast of
claim 1, wherein said step of converting said bit-rate of the
digitized broadcast into a smaller one is an operation of returning
said broadcast in a baseband and performing a compression
processing again for the broadcast.
6. The method for ensuring a storage time for digital broadcast of
claim 5, wherein said operation of returning said broadcast in a
baseband and performing a compression processing again for the
broadcast is performed by utilizing a system for compressing an
analog broadcast, decoding the compressed digital data and then
playing back the resultant data.
7. The method for ensuring a storage time for digital broadcast of
claim 5, wherein said step of converting said bit-rate of the
digitized broadcast into a smaller one is an operation of returning
said broadcast in a baseband, then performing image resolution
conversion or image frame rate conversion upon the broadcast and
performing the compression processing again upon the resultant
broadcast.
8. The method for ensuring a storage time for digital broadcast of
claim 1, wherein said step of converting said bit-rate of the
digitized broadcast into a smaller one is performed by selecting
one from three kinds of operations, i.e., the operation of missing
a part of the broadcast data, the operation of returning the
broadcast in a baseband and performing a compression processing
again upon the broadcast and the operation of returning the
broadcast in a baseband, then performing image resolution
conversion or image frame rate conversion upon the broadcast and
performing the compression processing again upon the resultant
broadcast.
9. The method for ensuring a storage time for digital broadcast of
claim 1 further comprising the step of: if said calculated required
capacity of the storage medium cannot be contained, deleting a
broadcast which has been already stored in said storage medium to
ensure the required capacity of the storage medium.
10. The method for ensuring a storage time for digital broadcast of
claim 1 further comprising the step of: if said calculated required
capacity of the storage medium cannot be contained, re-compressing
said broadcast which has been already stored in the storage medium
to ensure the required capacity of the storage medium.
11. The method for ensuring a storage time for digital broadcast of
claim 10, wherein said step of re-compressing said broadcast which
has been already stored in the storage medium is performed by the
operation of missing a part of the stored broadcast data, the
operation of returning the stored broadcast in a baseband and
performing a compression processing again upon the broadcast or the
operation of returning said stored broadcast in a baseband, then
performing image resolution conversion or image frame rate
conversion and performing a compression processing again upon the
broadcast.
12. The method for ensuring a storage time for digital broadcast of
claim 9, wherein when a plurality of already stored broadcasts
exist in the storage medium, a broadcast that a set period of time
or longer has passed since its storage will be deleted.
13. The method for ensuring a storage time for digital broadcast of
claim 9, wherein when a plurality of already stored broadcasts
exist in the storage medium, a broadcast which has been decoded at
least once since its storage will be deleted.
14. The method for ensuring a storage time for digital broadcast of
claim 9, wherein when a plurality of already stored broadcasts
exist in the storage medium, a broadcast which is stored in the
storage medium and then copied in other storage medium will be
deleted.
15. The method for ensuring a storage time for digital broadcast of
claim 9, wherein when a plurality of already stored broadcasts
exist in the storage medium, a broadcast which was stored at the
earliest date will be deleted.
16. The method for ensuring a storage time for digital broadcast of
claim 9, wherein when a plurality of already stored broadcasts
exist in the storage medium, a broadcast that a set period of time
or longer has passed since its storage, a broadcast which has been
decoded at least once since its storage, a broadcast which is
stored in the storage medium and then copied in other storage
medium or a broadcast which was stored at the earliest date will be
deleted, and these broadcasts are selected in accordance with a
predetermined priority.
17. The method for ensuring a storage time for digital broadcast of
claim 10, wherein when a plurality of already stored broadcasts
exist in the storage medium, a broadcast that a set period of time
or longer has passed since its storage will be re-compressed.
18. The method for ensuring a storage time for digital broadcast of
claim 10, wherein when a plurality of already stored broadcasts
exist in the storage medium, a broadcast which has been decoded at
least once since its storage will be re-compressed.
19. The method for ensuring a storage time for digital broadcast of
claim 10, wherein when a plurality of already stored broadcasts
exist in the storage medium, a broadcast which is stored in the
storage medium and then copied in other storage medium will be
re-compressed.
20. The method for ensuring a storage time for digital broadcast of
claim 10, wherein when a plurality of already stored broadcasts
exist in the storage medium, a broadcast which was stored at the
earliest date will be re-compressed.
21. The method for ensuring a storage time for digital broadcast of
claim 10, wherein when a plurality of already stored broadcasts
exist in the storage medium, a broadcast that a set period of time
or longer has passed since its storage, a broadcast which has been
decoded at least once since its storage, a broadcast which is
stored in the storage medium and then copied in other storage
medium or a broadcast which was stored at the earliest date will be
re-compressed, and these broadcasts are selected in accordance with
a predetermined priority.
22. A device for ensuring a storage time for digital broadcast at
the time of storing a digitized and then transmitted broadcast
comprising: a required capacity calculation circuit for monitoring
a predetermined recording time of the broadcast and a bit-rate of
the broadcast and calculating, in real time, a required capacity of
the storage medium; a determination circuit for determining whether
or not the required capacity of the storage medium calculated in
said required capacity calculation circuit can be contained within
an empty or freely limited area in the storage medium; and a
bit-rate conversion circuit for, if said calculated required
capacity of the storage medium cannot be contained as the result of
said determination by said determination circuit, converting, in
real time, said bit-rate of the broadcast into a smaller one and
storing the converted broadcast in said storage medium.
23. The device for ensuring a storage time for digital broadcast of
claim 22, wherein said determination circuit further determines, if
said calculated required capacity of the storage medium can be
contained, whether or not said empty or freely limited area of the
storage medium remains, and said device further comprising: a
second bit-rate changing circuit for, if the empty or freely
limited area remains as the result of said determination by said
determination circuit, converting, in real time, said bit-rate of
the broadcast into a larger one and storing the converted broadcast
in said storage medium.
24. The device for ensuring a storage time for digital broadcast of
claim 22, wherein said required capacity calculation circuit
comprising: a determination circuit for writing an inputted
broadcast stream in a storage memory and determining said bit-rate
of the broadcast on the basis of its storage time and storage
amount.
25. The device for ensuring a storage time for digital broadcast of
claim 22 further comprising: a deletion circuit for, if said
calculated required capacity of the storage medium cannot, be
contained as the result of determination by said determination
circuit, deleting a broadcast which has been already stored in the
storage medium.
26. The device for ensuring a storage time for digital broadcast of
claim 22 further comprising: a re-compression circuit for, if said
calculated required capacity of the storage medium cannot be
contained as the result of determination by said determination
circuit, re-compressing a broadcast which has been already stored
in the storage medium.
27. The device for ensuring a storage time for digital broadcast of
claim 22, wherein said required capacity calculation circuit, said
determination circuit and said bit-rate conversion circuit are
integrated onto a chip.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a method and a device for
ensuring storage time for digital broadcast that can ensure
recording time required when a digital broadcast compressed by MPEG
or the like is stored and recorded in a recording medium such as an
optical disk, an optomagnetic disk or a hard disk.
[0002] Recently, in accordance with improvement of image signal
processing techniques, a record-and-playback device for recording
in a disk-shaped storage medium that is capable of freely
recording/playing back a video or voice digital signal, such as a
DVD-RAM or a hard disk has been developed.
[0003] As a method for storing and recording analog broadcast data
in such a storage medium, for example, as disclosed in Japanese
Patent Application Laid-Open (JP-A) No. 8-17137, there has been
known a method that a target bit-rate is calculated on the basis of
the storage capacity of the storage medium and a predetermined
recording time and then the data is encoded so as to be contained
in the storage medium. Namely, because the recording capacity for
the storage medium and the recording time for an analog broadcast
to be stored are known, a bit-rate can be determined by the
expression, recording capacity/recording time. Then, control is
performed so that the analog broadcast is compressed and recorded
at this resultant bit-rate.
[0004] In the case of storing and recording not analog broadcast
data but digital broadcast data, however, sources for the digital
broadcast are for a standard television in current CS broadcasting
performed in Japan. In BS digital broadcasting, a standard
television and high-definition television are supported. Further,
even in the same standard television or high-definition television,
a bit-rate of broadcast is different for each program. In ground
wave digital broadcasting that will be started in 2003 or later, a
standard television, a high-definition television and a level lower
than MPEG4 Simple Profile Level 3 will be provided. In accordance
with MPEG4 Simple Profile Level 3, an image size is CIF (1/4 of
current vertical and horizontal sizes, respectively) and a bit-rate
is equal to or less than 384 kbit/s. Thus, when these three kinds
of broadcasts are stored and recorded in a digital form, a storage
time may be varied for each of the bit-rates for these broadcasts
even in the case of storing the same broadcast program, unlike a
conventional analog VHS VTR which can simply define the storage
time in a 120 min tape as two hours in a standard mode and six
hours in a triple-mode. Accordingly, a problem exists in the method
for ensuring a storing and recording time.
SUMMARY OF THE INVENTION
[0005] An object of the present invention is to provide a method
and a device for ensuring the time for digital broadcasts
transmitted at various bit-rates to be recorded in a storage
medium.
[0006] In order to accomplish the aforementioned object, in
accordance with the present invention, when a digitized and then
transmitted broadcast is stored and recorded, the capacity of a
storage medium required for storing the broadcast is calculated.
Then, the required capacity is compared to an actual empty area in
the storage medium, a bit-rate of the broadcast to be stored is
appropriately converted, and the resultant broadcast is stored.
[0007] According to the present invention, a method for ensuring a
storage time for digital broadcast at the time of storing data for
a digitized and then transmitted broadcast comprises the steps of:
monitoring a predetermined recording time for the broadcast and a
bit-rate of the broadcast and calculating, in real time, a required
capacity of a storage medium; determining whether or not the
calculated required capacity of the storage medium can be contained
within an empty area or a freely limited area of the storage
medium; if the calculated required capacity of the storage medium
cannot be contained as the result of the determination, converting,
in real time, the bit-rate of the broadcast into a smaller one; and
storing the converted broadcast in the storage medium.
[0008] In accordance with the present invention, the method for
ensuring a storage time for digital broadcast further comprises the
steps of: if the calculated required capacity of the storage medium
can be contained as the result of the determination, determining
whether or not the empty area or freely limited area of the storage
medium remains; if the empty area or freely limited area remains,
converting, in real time, the bit-rate of the broadcast into a
larger one; and storing the converted broadcast into the storage
medium.
[0009] According to the present invention, the method for ensuring
a storage time for digital broadcast further comprises the step of:
if the calculated required capacity of the storage medium can be
contained as the result of the determination, storing the broadcast
in the storage medium without converting the bit-rate.
[0010] According to the present invention, in the method for
ensuring a storage time for digital broadcast, the step of
converting the bit-rate of the digitized broadcast into a smaller
one is an operation of missing a part of the broadcast data.
[0011] In accordance with the method for ensuring a storage time
for digital broadcast of the present invention, the step of
converting the bit-rate of the digitized broadcast into a smaller
one is an operation of returning the broadcast in a baseband and
performing a compression processing again for the broadcast.
[0012] In accordance with the method for ensuring a storage time
for digital broadcast of the present invention, the operation of
returning the broadcast in a baseband and performing a compression
processing again for the broadcast is performed by utilizing a
system for compressing an analog broadcast, decoding the compressed
digital data and then playing back the resultant data.
[0013] According to the present invention, in the method for
ensuring a storage time for digital broadcast, the step of
converting the bit-rate of the digitized broadcast into a smaller
one is an operation of returning the broadcast in a baseband, then
performing image resolution conversion or image frame rate
conversion upon the broadcast and performing the compression
processing again upon the resultant broadcast.
[0014] According to the present invention, in the method for
ensuring a storage time for digital broadcast, the step of
converting the bit-rate of the digitized broadcast into a smaller
one is performed by selecting one from three kinds of operations,
i.e., the operation of missing a part of the broadcast data, the
operation of returning the broadcast in a baseband and performing a
compression processing again upon the broadcast and the operation
of returning the broadcast in a baseband, then performing image
resolution conversion or image frame rate conversion upon the
broadcast and performing the compression processing again upon the
resultant broadcast.
[0015] The method for ensuring a storage time for digital broadcast
of the present invention further comprises the step of: if the
calculated required capacity of the storage medium cannot be
contained, deleting a broadcast which has been already stored in
the storage medium to ensure the required capacity of the storage
medium.
[0016] The method for ensuring a storage time for digital broadcast
of the present invention further comprises the step of: if the
calculated required capacity of the storage medium cannot be
contained, re-compressing the broadcast which has been already
stored in the storage medium to ensure the required capacity of the
storage medium.
[0017] In accordance with the present invention, in the method for
ensuring a storage time for digital broadcast, the step of
re-compressing the broadcast which has been already stored in the
storage medium is performed by the operation of missing a part of
the stored broadcast data, the operation of returning the stored
broadcast in a baseband and performing a compression processing
again upon the broadcast or the operation of returning the stored
broadcast in a baseband, then performing image resolution
conversion or image frame rate conversion and performing a
compression processing again upon the broadcast.
[0018] In accordance with the present invention, in the method for
ensuring a storage time for digital broadcast, when a plurality of
already stored broadcasts exist in the storage medium, a broadcast
that a set period of time or longer has passed since its storage
will be deleted.
[0019] In accordance with the present invention, in the method for
ensuring a storage time for digital broadcast, when a plurality of
already stored broadcasts exist in the storage medium, a broadcast
which has been decoded at least once since its storage will be
deleted.
[0020] In accordance with the present invention, in the method for
ensuring a storage time for digital broadcast, when a plurality of
already stored broadcasts exist in the storage medium, a broadcast
which is stored in the storage medium and then copied in other
storage medium will be deleted.
[0021] In accordance with the present invention, in the method for
ensuring a storage time for digital broadcast, when a plurality of
already stored broadcasts exist in the storage medium, a broadcast
which was stored at the earliest date will be deleted.
[0022] In accordance with the present invention, in the method for
ensuring a storage time for digital broadcast, when a plurality of
already stored broadcasts exist in the storage medium, a broadcast
that a set period of time or longer has passed since its storage, a
broadcast which has been decoded at least once since its storage, a
broadcast which is stored in the storage medium and then copied in
other storage medium or a broadcast which was stored at the
earliest date will be deleted, and these broadcasts are selected in
accordance with a predetermined priority.
[0023] According to the present invention, a device for ensuring a
storage time for digital broadcast at the time of storing a
digitized and then transmitted broadcast comprises a required
capacity calculation circuit for monitoring a predetermined
recording time of the broadcast and a bit-rate of the broadcast and
calculating, in real time, a required capacity of the storage
medium; a determination circuit for determining whether or not the
required capacity of the storage medium calculated in the required
capacity calculation circuit can be contained within an empty or
freely limited area in the storage medium; and a bit-rate
conversion circuit for, if the calculated required capacity of the
storage medium cannot be contained as the result of the
determination by the determination circuit, converting, in real
time, the bit-rate of the broadcast into a smaller one and storing
the converted broadcast in the storage medium.
[0024] According to the present invention, in the device for
ensuring a storage time for digital broadcast, the determination
circuit further determines, if the calculated required capacity of
the storage medium can be contained, whether or not the empty or
freely limited area of the storage medium remains. The device
further comprises a second bit-rate changing circuit for, if the
empty or freely limited area remains as the result of the
determination by the determination circuit, converting, in real
time, the bit-rate of the broadcast into a larger one and storing
the converted broadcast in the storage medium.
[0025] In the device for ensuring a storage time for digital
broadcast of the present invention, the required capacity
calculation circuit comprises a determination circuit for writing
an inputted broadcast stream in a storage memory and determining
the bit-rate of the broadcast on the basis of its storage time and
storage amount.
[0026] The device for ensuring a storage time for digital broadcast
of the present invention further comprises a deletion circuit for,
if the calculated required capacity of the storage medium cannot be
contained as the result of determination by the determination
circuit, deleting a broadcast which has been already stored in the
storage medium.
[0027] The device for ensuring a storage time for digital broadcast
of the present invention further comprises a re-compression circuit
for, if the calculated required capacity of the storage medium
cannot be contained as the result of determination by the
determination circuit, re-compressing a broadcast which has been
already stored in the storage medium.
[0028] In the device for ensuring a storage time for digital
broadcast of the present invention, the required capacity
calculation circuit, the determination circuit and the bit-rate
conversion circuit are integrated onto a chip.
[0029] As described above, in accordance with the present
invention, even if the bit-rate of a digitized broadcast is varied,
a required capacity of a storage medium at an original bit-rate of
the broadcast is successively calculated. If the required capacity
of the storage medium cannot be contained within an empty or freely
limited area in the storage medium, the bit-rate of the broadcast
is converted into a smaller one. Thus, the capacity of the storage
medium required for the broadcast can be contained within the
remaining storage capacity and the broadcast can be reliably stored
and recorded in the storage medium.
[0030] Especially in the present invention, if the required
capacity of the storage medium can be successfully contained within
the remaining storage capacity, the transmission bit-rate of the
broadcast is converted into a larger one and the resultant
broadcast is stored in the storage medium. Thus, the broadcast can
be stored and recorded with high image quality.
[0031] The present invention can be provided inexpensively because
a re-compression processing is performed for a broadcast to be
newly stored by utilizing existing devices in a
storage-and-playback system.
[0032] Further, in accordance with the present invention, the
required capacity of the storage medium is ensured in an empty area
therein by deleting or re-compressing a broadcast which has been
already stored in the storage medium. Thus, while maintaining at a
bit-rate required for successfully maintaining a played back image,
the broadcast to be newly stored can be reliably stored and
recorded in the storage medium. In accordance with the present
invention, among a plurality of already stored broadcasts, a
broadcast that a set period of time has passed since its storage or
a broadcast that is at least decoded or copied is preferentially
deleted or re-compressed. As a result, the already stored broadcast
can be deleted or re-compressed depending on a degree of
necessity.
BRIEF DESCRIPTION OF THE DRAWINGS
[0033] FIG. 1 is a block diagram illustrating a device for ensuring
a storage time for digital broadcast relating to embodiments of the
present invention.
[0034] FIG. 2 is a flowchart illustrating the detail of a method
for ensuring the storage time performed by the device for ensuring
storage time for digital broadcast.
[0035] FIG. 3 is a view illustrating the algorithm for establishing
the priority of a broadcast to be deleted or re-compressed.
DETAILED DESCRIPTION OF THE INVENTION
[0036] Preferred embodiments of the present invention will be
described hereinafter with reference to the attached drawings.
[0037] FIG. 1 is a block diagram illustrating the specific
structure of a device for ensuring storage time for digital
broadcast relating to the embodiments of the present invention.
[0038] The device for ensuring storage time for digital broadcast
illustrated in FIG. 1 is mainly configured by an input section 1,
an MPEG transport decoder 17, a stream controller 6, an MPEG
decoder 10, an image resolution/frame rate converter 9, an MPEG
encoder 11, a drive section 16 and a microcomputer 14 for entirely
controlling these elements.
[0039] Inputted to the input section 1 is a broadcast signal
MPEG-TS 2 obtained by multiplexing at least one broadcast program
inputted from a tuner section of a satellite, cable television or
ground wave digital broadcasting, such as an MPEG-TS signal. The
input section 1 outputs the multiplexed TS bit stream 3 to the MPEG
transport decoder 17. The MPEG transport decoder 17 selects only a
broadcast program selected in accordance with information about the
selected program designated in advance by the microcomputer 14, and
outputs the TS bit stream 4 of the selected program. The total
storage time for the TS bit stream 4 of the selected broadcast
program is inputted in advance by various methods including G-Code,
EPG, and user's time setting and the like, and thus is known by the
microcomputer 14 prior to storing and recording of the broadcast
program.
[0040] The TS bit stream 4 of the selected broadcast program
outputted from the MPEG transport decoder 17 is inputted to the
stream controller 6. This stream controller 6 stores and records
the inputted TS bit stream 4 of the broadcast program in a storage
medium driven by the drive section 16 such as DVD-R, DVD-RAM,
DVD-RW, Blu-Ray disk or contained hard disk. This stream controller
6 has the function of determining a bit-rate of the TS bit stream 4
of the broadcast program to be stored prior to the broadcast
program being stored in the storage medium. In order to exhibit
this function, the stream controller 6 has an inputted bit-rate
determiner (determination circuit) 19 therein, and an external
buffer memory 5 is connected thereto. The stream controller 6
starts to store the inputted TS bit stream 4 of the selected
broadcast program in the external buffer memory (storage memory) 5
before outputting the same to the drive section 16. Under this
state, the inputted bit-rate determiner (determination circuit) 19
monitors, in real time, the bit-rate of the TS bit stream 4 of the
selected broadcast program on the basis of a storage time and
storage amount in the external buffer memory 5, and outputs the
determined bit-rate to the microcomputer 14.
[0041] The microcomputer 14 determines a required capacity of the
storage medium on the basis of the determined bit-rate and the
storing and recording time for the broadcast program to be stored,
compares the required capacity of the storage medium to an empty
area in the storage medium in the drive section 16 or a freely
limited area determined in the microcomputer 14 by a user (which
will be referred to as a remaining storage capacity hereinafter),
and determines whether or not the broadcast program to be stored
can be stored and recorded in the storage medium. The specific
example of such determination will be described with reference to
FIG. 2.
[0042] FIG. 2 illustrates a flowchart of the determination and
processings after the determination. Referring to FIG. 2, firstly
in step S0, the storage time for the broadcast program to be stored
is multiplied by the bit-rate monitored in real time by the
bit-rate determiner 19 in order to calculate a required capacity of
the storage medium for the digitized broadcast program. A required
capacity calculation circuit 50 is configured by step S0.
[0043] Next, in step S1, the calculated required capacity of the
storage medium (result of multiplication) is compared with the
remaining storage capacity of the storage medium to determine the
magnitude relationship between the required capacity of the storage
medium and the remaining storage capacity thereof. Namely, it is
determined whether or not the required capacity of the storage
medium is smaller than the remaining storage capacity and thus the
broadcast program to be stored can be stored in the storage medium.
A determination circuit 51 is configured by step S1.
[0044] If the remaining capacity of the storage medium is smaller
as the result of comparison of magnitude, the process proceeds to
step S2. In step S2, a determination is made as to whether the
broadcast program to be stored is re-encoded at smaller bit-rate.
If the re-encoding processing is performed, this re-encoding
processing is performed by two kinds of methods. In accordance with
one method, the broadcast to be stored is decoded in a compressed
database band and then encoded again. In accordance with the other
method, a part of bit stream of the broadcast is deleted in order
to obtain a predetermined small bit-rate. Specifically explaining,
in step S4, a determination is made as to whether the broadcast is
subjected to the decoding processing to be returned in a baseband.
If the answer to the determination in step S4 is NO., in step S5, a
part of bits of the broadcast program to be stored is deleted so as
to be missed therefrom. Various methods are provided for this
deletion and may include, e.g., a method for deleting bits
subjected to padding processing for controlling a fixed rate. If
the answer to the determination as to whether the broadcast is
returned in a baseband is YES, in step S6, whether or not a
resolution conversion/frame rate decimation is performed is
determined. If the answer to the determination in step S6 is NO, in
step S7, the broadcast program returned in a baseband is subjected
to the re-encoding processing so as to obtain a bit-rate which
enables storing and recording within the remaining storage
capacity, and the resultant re-encoded broadcast program is stored
and recorded. If the answer to the determination as to whether the
resolution conversion/frame rate decimation is performed is YES, in
step S8, the frame rate decimation and pixel reduction are
performed, and the re-encoding processing is performed upon the
broadcast program to be stored in order to convert the bit-rate
thereof into a predetermined small bit-rate so that the broadcast
program can be stored within the remaining storage capacity of the
storage medium. In this way, the required storage capacity of the
storage medium is compressed. Then, the re-encoded broadcast
program is stored in the storage medium in the drive section 16.
Examples of the resolution conversion processing may include a
method for converting the number of horizontal pixels from 720 to
544 or 720 to 352 by using a filter and a method for converting the
number of vertical pixels. In the latter case, for example, a
method for converting 480 vertical pixels into 240 pixels is known.
The most simple method is to drop any field of pixels formed of Top
Bottom. A bit-rate conversion circuit 52 is configured by steps S4
to S8.
[0045] If it is determined in step S2 that the re-encoding
processing is not performed, in step S3, a broadcast program which
has already been stored in the storage medium is deleted.
Alternatively, the stored broadcast program is re-encoded to be
compressed again in order to ensure a larger remaining storage
capacity of the storage medium. A deletion circuit 54 and a
re-compression circuit 55 are configured by step S3.
[0046] In the deletion or re-compression processing in step S3, if
two or more broadcast programs have been already stored in the
storage medium, priority is established in order to determine which
of these broadcast programs should be deleted or re-compressed.
[0047] In accordance with the method for establishing priority, a
broadcast program which is temporarily stored in the storage medium
and then copied in other storage medium is set as the first
priority for deletion/re-compression processing. A broadcast
program which is stored in the storage medium but is not played
back at all even after a predetermined period of time freely set by
a user is determined as the second priority. A broadcast program
which is stored in the storage medium and then played back by a
user is set as the third priority. A broadcast program which was
stored in the storage medium at the earliest date is set as the
fourth priority. If a broadcast program satisfying these settings
exists, the priority is established in an even further detailed
manner.
[0048] Although various methods for establishing the priority
exist, an example of them will be illustrated in FIG. 3 in this
embodiment. Referring to FIG. 3, a determination is made in step
S20 as to whether or not two or more stored broadcast programs are
provided. If a plurality of stored broadcast programs do not exist
and only one broadcast program exists, in step S21, this broadcast
program is deleted or re-compressed. If there provided a plurality
of broadcast programs, in step S22, whether or not two or more
broadcast programs that are copied in other storage medium exist is
determined. If only one broadcast program is copied in the other
storage medium, in step S23, the copied broadcast program is
deleted or re-compressed. If there provided a plurality of copied
broadcast programs, a determination is made in step S24 as to
whether or not two or more broadcast programs recorded earlier than
a date freely set by a user exist. If there is provided only one
broadcast program recorded earlier than the date, in step S25, this
broadcast program is deleted or re-compressed. If there are
provided two or more broadcast programs recorded earlier than the
set date, in step S26, a determination is made as to whether or not
there exist two or more broadcast programs that have been once
decoded and played back by a user since their storage. If there is
provided only one broadcast program that has been decoded and
played back since its storage, in step S27, this played back
broadcast program is deleted or re-compressed. If there exist two
or more broadcast programs that have been played back once, in step
S28, a broadcast program which was stored in the storage medium at
the earliest date is deleted or re-compressed.
[0049] Then, returning to step S1 in FIG. 2, if the answer to the
determination in step S1 is NO, i.e., if the broadcast program to
be stored can be successfully stored in the storage medium and the
remaining storage capacity is larger than the required capacity of
the storage medium and thus remains, in step S9, a determination is
made as to whether or not the broadcast program is stored and
recorded with its original bit-rate, i.e., without converting the
bit-rate of the broadcast program to be stored. If it is determined
that the broadcast program is stored and recorded with its original
bit-rate, in step S10, this broadcast program is recorded. If it is
determined that the broadcast program is not recorded with its
original bit-rate, in step S11, opposite to the processing in step
S8 a frame interpolation and pixel interpolation processings are
performed in order to convert the bit-rate into a larger bit-rate,
so that high image quality is accomplished. Then, the resultant
broadcast program is stored and recorded in the storage medium. A
second bit-rate changing circuit 53 is configured by step S11. This
processing may be performed with the highest possibility when an
MPEG4 image is recorded as an MPEG2 image. In accordance with the
MPEG4 image, unlike REC656 (30 Frame/sec, 720 horizontal pixels and
480 vertical pixels) serving as a format obtained by digitizing a
general NTSC image, QCIF and CIF are provided as an image size and
15 Frame/sec is provided as a frame rate. Such image size and frame
rate are converted by a filter into REC656 size, and then the MPEG4
image is re-encoded.
[0050] Returning to FIG. 1, the structure of the device for
ensuring the storage time for digital broadcast is continuously
described. The MPEG decoder 10 is a decoder for returning a
compressed MPEG1, MPEG2 or MPEG4 broadcast in a baseband. This
decoder 10 may utilize, in addition to MPEG, JPEG, Motion JPEG or a
compression system which is not defined by ISO. The MPEG decoder 10
has the function of deleting padding bits described in step S5 in
FIG. 2 as well as the function of decoding the broadcast program
stored in the storage medium in a baseband at the time of playing
back the same.
[0051] The image resolution/frame rate converter 9 illustrated in
FIG. 1 performs, as well as the reduction and interpolation
processings for horizontal resolution and the conversion of
vertical resolution, the frame rate decimation and interpolation.
An NTSC/PAL/SECAM encoder 8 is used to convert digital broadcast
data into an analog signal in order to output to a television
monitor, and converts, in order to correspond to broadcasting
systems for all over the world, an NTSC system used in the United
States and Japan, a PAL system used in European countries and China
and an SECAM system used in the former USSR into the respective
analog systems. In the case of not standard broadcasting but
broadcasting with high resolution, an encoder corresponding to such
broadcasting is required.
[0052] An NTSC/PAL/SECAM decoder 7 converts an analog signal from
an analog tuner 15 into a digital signal, and corresponds to the
NTSC system, the PAL system and the SECAM broadcasting. The analog
broadcast is usually disturbed in a weak electric field, and a
vertical or horizontal retrace line interval becomes long or short.
This phenomenon may be occurred by a line input such as an input
from VTR as well as an input from the analog tuner 15. A TBC
circuit 18 corrects this phenomenon. The TBC circuit 18 usually
accomplishes the correction by writing a once disturbed signal in a
frame memory and reading out the signal. Depending on the range of
correction, the correction can be realized simply by writing in a
line memory. The output from the TBC circuit 18 is compressed and
encoded in the MPEG encoder 11. The compression system in the MPEG
encoder 11 may be, in addition to MPEG1, MPEG2 and MPEG4, JPEG,
Motion JPEG and a compression system which is not defined by ISO.
The compressed stream is written via the stream controller 6 into
the storage medium on the drive 16.
[0053] The stream controller 6, the image resolution/frame rate
converter 9, the MPEG decoder 10, the MPEG encoder 11 and the
microcomputer 14 are integrated into one chip.
[0054] The MPEG encoder 11 and the MPEG decoder 10 are existing
devices required for recording/playing back an analog broadcast or
an analog line input. In accordance with this embodiment, a
record/play-back system for existing devices including such devices
is utilized for the decoding and encoding processings in steps S3,
S7, S8 and S11 illustrated in FIG. 2. Thus, in accordance with this
embodiment, existing devices can be shared and thus the present
invention can be provided inexpensively.
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