U.S. patent application number 09/801499 was filed with the patent office on 2001-07-12 for repeat use data inserting apparatus and digital broadcast transmitting system.
This patent application is currently assigned to SONY CORPORATION. Invention is credited to Kitazawa, Toshihiko.
Application Number | 20010007558 09/801499 |
Document ID | / |
Family ID | 17654733 |
Filed Date | 2001-07-12 |
United States Patent
Application |
20010007558 |
Kind Code |
A1 |
Kitazawa, Toshihiko |
July 12, 2001 |
Repeat use data inserting apparatus and digital broadcast
transmitting system
Abstract
A repeat use data inserting apparatus for repeatedly inserting
repeat use data into program data in accordance with appropriate
timings. The apparatus comprises a data holding unit and a data
multiplexing unit. The data holding unit holds the repeat use data
made of a plurality of material data in the form of separately
encoded streams. The data multiplexing unit multiplexes separately
encoded streams of a plurality of material data constituting the
program data during a period other than a data insertion period
during which the repeat use data is inserted into the program data.
The data multiplexing unit further inserts repeatedly the repeat
use data into the program data during the data insertion period by
multiplexing the separately encoded streams of the plurality of
material data constituting the repeat use data held in the data
holding unit.
Inventors: |
Kitazawa, Toshihiko;
(Kanagawa, JP) |
Correspondence
Address: |
William S. Frommer, Esq.
Frommer Lawrence & Haug LLP
10th Fl.
745 Fifth Avenue
New York
NY
10151
US
|
Assignee: |
SONY CORPORATION
|
Family ID: |
17654733 |
Appl. No.: |
09/801499 |
Filed: |
March 7, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09801499 |
Mar 7, 2001 |
|
|
|
08949286 |
Oct 21, 1997 |
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Current U.S.
Class: |
370/390 ;
348/E7.063; 370/432; 375/E7.272 |
Current CPC
Class: |
H04N 21/23614 20130101;
H04N 21/812 20130101; H04N 7/165 20130101; H04N 21/4348
20130101 |
Class at
Publication: |
370/390 ;
370/432 |
International
Class: |
H04L 012/28; H04L
012/56 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 24, 1996 |
JP |
P08-282608 |
Claims
What is claimed is:
1. A repeat use data inserting apparatus for repeatedly inserting
repeat use data into program data in accordance with appropriate
timings, comprising: data holding means for holding said repeat use
data made of a plurality of material data in the form of separately
encoded streams; and data multiplexing means for multiplexing
separately encoded streams of a plurality of material data
constituting said program data during a period other than a data
insertion period during which said repeat use data is inserted into
said program data, said data multiplexing means further inserting
repeatedly said repeat use data into said program data during said
data insertion period by multiplexing the separately encoded
streams of said plurality of material data constituting said repeat
use data held in said data holding means.
2. A repeat use data inserting apparatus according to claim 1,
further comprising temporary holding means for reading and
temporarily holding the repeat use data from said data holding
means during a period other than said data insertion period;
wherein said data multiplexing means uses the repeat use data held
in said temporary holding means in place of the repeat use data
held in said data holding means.
3. A repeat use data inserting apparatus according to claim 2,
wherein said temporary holding means includes: holding means for
temporarily holding said repeat use data; remaining data detecting
means for detecting the quantity of the repeat use data left in
said holding means; and transfer means for transferring the repeat
use data from said data holding means to said holding means during
a period other than said data insertion period in accordance with a
detection output from said remaining data detecting means, so that
the repeat use data held in said holding means will reach a
predetermined quantity.
4. A repeat use data inserting apparatus according to claim 1,
further comprising size data holding means for holding size data
about each of said plurality of material data constituting said
repeat use data; wherein said data multiplexing means multiplexes,
on the basis of said size data held in said size data holding
means, the separately encoded streams of said plurality of material
data constituting said repeat use data held in said data holding
means.
5. A digital broadcast transmitting system for repeatedly inserting
repeat use data into program data so as to unify said repeat use
data and said program data into one data stream and for
transmitting the unified data stream, said digital broadcast
transmitting system comprising: program data encoding means for
separately encoding a plurality of material data constituting said
program data in order to generate the separately encoded streams of
the material data; data holding means for holding said repeat use
data made of a plurality of material data in the form of separately
encoded streams; and data multiplexing means for multiplexing,
during a period other than a data insertion period during which
said repeat use data is inserted into said program data, the
separately encoded streams of said plurality of material data
constituting said program data output from said program data
encoding means, said data multiplexing means further inserting
repeatedly said repeat use data into said program data in
accordance with appropriate timings during said data insertion
period by multiplexing the separately encoded streams of said
plurality of material data constituting said repeat use data held
in said data holding means.
6. A digital broadcast transmitting system according to claim 5,
further comprising temporary holding means for reading and
temporarily holding the repeat use data from said data holding
means during a period other than said data insertion period;
wherein said data multiplexing means uses the repeat use data held
in said temporary holding means in place of the repeat use data
held in said data holding means.
7. A digital broadcast transmitting system according to claim 6,
wherein said temporary holding means includes: holding means for
temporarily holding said repeat use data; remaining data detecting
means for detecting the quantity of the repeat use data left in
said holding means; and transfer means for transferring the repeat
use data from said data holding means to said holding means during
a period other than said data insertion period in accordance with a
detection output from said remaining data detecting means, so that
the repeat use data held in said holding means will reach a
predetermined quantity.
8. A digital broadcast transmitting system according to claim 5,
further comprising size data holding means for holding size data
about each of said plurality of material data constituting said
repeat use data; wherein said data multiplexing means multiplexes,
on the basis of said size data held in said size data holding
means, the separately encoded streams of said plurality of material
data constituting said repeat use data held in said data holding
means.
9. A digital broadcast transmitting system according to claim 5,
wherein said program data encoding means receives a plurality of
channels of program data and separately encodes each of said
plurality of channels of program data; and wherein said data
multiplexing means receives said plurality of channels of program
data encoded by said data encoding means, and multiplexes each of
said plurality of channels of program data with said repeat use
data; said digital broadcast transmitting system further comprising
multi-channel developing means for developing into multiple
channels sad plurality of channels of multiplexed outputs from said
data multiplexing means.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a repeat use data inserting
apparatus for inserting repeat use data into program data in
accordance with appropriate timings, as well as to a digital
broadcast transmitting system which comprises the repeat use data
inserting apparatus and which transmits a unified stream of program
data and repeat use data prepared by the repeat use data inserting
apparatus.
[0002] Recent years have seen the commercialization of
multi-channel digital broadcasting systems using advanced digital
compression techniques to transmit numerous channels of program
data in a single data stream. The multi-channel digital
broadcasting system needs to have the capability of repeatedly
inserting so-called repeat use data into each of a plurality of
channels of program data in accordance with suitable timings. In
the context of this specification, repeat use data refers to
repeatedly used data during broadcast such as news clips and
commercial messages.
SUMMARY OF THE INVENTION
[0003] It is an object of the present invention to provide a repeat
use data inserting apparatus and a digital broadcast transmitting
system using the apparatus, whereby the storage capacity and
transfer rate for repeat use data are reduced, the process for
changing time base information is eliminated, momentary
interruption of video or audio data is averted, and generation of
noise is suppressed.
[0004] One aspect of the present invention provides a repeat use
data inserting apparatus for repeatedly inserting repeat use data
into program data in accordance with appropriate timings, and a
digital broadcast transmitting system for use with that apparatus,
the repeat use data inserting apparatus comprising: data holding
means for holding the repeat use data made of a plurality of
material data in the form of separately encoded streams; and data
multiplexing means for multiplexing separately encoded streams of a
plurality of material data constituting the program data during a
period other than a data insertion period during which the repeat
use data is inserted into the program data, the data multiplexing
means further inserting repeatedly the repeat use data into the
program data during the data insertion period by multiplexing the
separately encoded streams of the plurality of material data
constituting the repeat use data held in the data holding
means.
[0005] In the repeat data inserting apparatus and digital broadcast
transmitting system of the invention, the repeat use data is held
by the data holding means in the form of separately encoded stream
of the plurality of material data. In that setup, during a period
other than the data insertion period, the data multiplexing means
multiplexes the separately encoded streams of the plurality of
material data constituting the program data. During the data
insertion period, the data multiplexing means multiplexes the
separately encoded streams of the plurality of material data
constituting the repeat use data held in the data holding
means.
[0006] The program data and the repeat use data are multiplexed as
described, and so are the separately encoded streams constituting
the material data. As a result, a bit stream of repeat use data is
repeatedly inserted into a bit stream of program data, whereby a
unified stream of data is acquired.
[0007] Other objects and further features of the invention will be
apparent from the following detailed description when read in
conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a block diagram of a repeat use data inserting
apparatus and a digital broadcast transmitting system embodying the
invention;
[0009] FIG. 2 is a conceptual view showing how program data are
typically subjected to multiplexing and separating processes;
[0010] FIG. 3 is a schematic view sketching how program data and
repeat use data are multiplexed;
[0011] FIG. 4 is a block diagram showing how encoder-multiplexers
and a server are illustratively configured;
[0012] FIG. 5 is a schematic view of a data storage structure in a
hard disk array;
[0013] FIGS. 6A, 6B and 6C are views of typical file structures for
commercial data;
[0014] FIG. 7 is a flowchart of steps in which a multiplexing
controller operates illustratively;
[0015] FIG. 8 is a flowchart of steps in which a disk controller
operates illustratively;
[0016] FIG. 9 is a view of a typical commercial list;
[0017] FIG. 10 is a schematic view showing the storage capacity of
an FIFO memory unit;
[0018] FIGS. 11A, 11B and 11C are schematic views showing how video
data held in the FIFO memory unit vary;
[0019] FIG. 12 is a block diagram of a system adopting a
hitherto-proposed arrangement for inserting repeat use data into
program data; and
[0020] FIG. 13 is a block diagram of a system adopting another
hitherto-proposed arrangement for inserting repeat use data into
program data.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0021] A repeat use data inserting apparatus and a digital
broadcast transmitting system both embodying the invention will now
be described in detail with reference to the accompanying
drawings.
[0022] So far, repeat use data is inserted into program data
through the use of one of two data inserting arrangements proposed
as follows: the first arrangement involves having repeat use data
not compressed upon insertion into the program data. The second
arrangement requires that repeat use data be subject to compressed
encoding and multiplexing before being inserted into program
data.
[0023] FIG. 12 is a block diagram of a multi-channel digital
broadcasting system adopting the first arrangement for inserting
repeat use data into program data.
[0024] The multi-channel digital broadcasting system of FIG. 12
comprises a digital broadcast transmitting system 100 installed in
a broadcasting center, a communication satellite 200 for relaying
transmitted data from the digital broadcast transmitting system
100, and a digital broadcast receiving system 300 installed in each
viewer's household to receive the data relayed by the communication
satellite 200.
[0025] The digital broadcast transmitting system 100 has N video
tape recorders (VTRs) 110(1) through 110(N) for N channels (N is an
integer of at least 2), a changeover switch 120, N
encoder-multiplexers 130(1) through 130(N) for the N channels, a
multi-channel developing unit 140, a transmitting antenna 150, and
a server 160 for managing uncompressed repeat use data. Each
digital broadcast receiving system 300 includes a receiving antenna
310 and a receiving terminal 320.
[0026] In the setup above, during a period where repeat use data is
inserted into n (n=1-N) channels of program data (the period is
called a data insertion period), uncompressed repeat use data from
the server 160 is fed through the changeover switch 120 to the
corresponding encoder-multiplexers 130(n). During a period other
than the data insertion period (called a data noninsertion period),
the program data from as many as n VTRs 110(n) for n channels are
supplied through the changeover switch 120 to the
encoder-multiplexers 130(n).
[0027] The data fed to the encoder-multiplexers 130(n) are
compressed and encoded in terms of individual material data types
(video data, audio data, etc.) before being multiplexed. The
compression, encoding and multiplexing processes are implemented
illustratively on the basis of MPEG (Moving Picture Experts Group)
2 specifications.
[0028] Multiplexed outputs comprising N channels of data are
developed into multiple channels by the multi-channel developing
unit 140 before being transmitted via the transmitting antenna 150.
The transmitted data is relayed by the communication satellite 200
and received by the receiving antenna 310. The receiving terminal
320 separates data of a desired channel from the received data,
decodes the separated output and reproduces the decoded data.
[0029] FIG. 13 is a block diagram of a multi-channel digital
broadcasting system adopting the second arrangement for inserting
repeat use data into program data.
[0030] The system of FIG. 13 includes a digital broadcast
transmitting system 400, a communication satellite 500 and a
digital broadcast receiving system 600. The digital broadcast
transmitting system 400 comprises VTRs 410(1) through 410(N), a
changeover switch 420, encoder-multiplexers 430(1) through 430(N),
a multi-channel developing unit 440, a transmitting antenna 450,
and a server 460 for managing repeat use data. The digital
broadcast receiving system 600 has a receiving antenna 610 and a
receiving terminal 620.
[0031] In the system of FIG. 13, the server 460 manages the repeat
use data that are encoded and multiplexed. That is, the server 460
manages the repeat use data in the form of an MPEG2-based final bit
stream called a transport stream. The repeat use data are fed to
the multi-channel developing unit 440 during the data insertion
period on n channels, to be multiplexed with the n channels of
program data.
[0032] The above-described two arrangements for inserting repeat
use data into program data have the following problems:
[0033] (1) The first arrangement uses uncompressed repeat use data.
This amounts to an enormous quantity of repeat use data that must
be accommodated by a storage medium of a sufficiently large
capacity.
[0034] Generally, individual repeat use data items are limited in
quantity. On the other hand, a multi-channel broadcast setup
typically requires having about 1,000 items of repeat use data
stored in the storage medium dedicated to such data. The total
amount of repeat use data to be stored is huge even though the
individual data items are small. Thus the first arrangement for
inserting repeat use data into program data requires the use of a
storage medium of a considerably large capacity.
[0035] Furthermore, the first arrangement above requires
establishing for repeat use data a transfer rate high enough to
cover all channels. The reason for this is that it is sometimes
necessary to broadcast different commercial messages and news clips
simultaneously on all channels. Thus the first arrangement for
repeat use data insertion requires the use of a high-speed storage
medium for holding repeat use data.
[0036] (2) The second arrangement for inserting repeat use data
into program data involves having repeat use data compressed for
storage. This means that the storage medium for accommodating
repeat use data may be small in capacity and that the transfer rate
for repeat use data may be lowered. Still, the need to have the
repeat use data stored in a multiplexed fashion requires changing
time base information (i.e., time management information) whenever
the data are inserted into program data.
[0037] The second arrangement above has another problem. When
program data and repeat use data are switched at a given point in
time and transmitted, the video or audio part of the program can be
interrupted momentarily or can generate noise upon such switchover.
This is because the multi-channel digital broadcasting system, in
an attempt to reduce the capacity of a buffer memory on the part of
the receiving system 600, causes the transmitting system 400 to
multiplex video data and audio data using time differences.
[0038] FIG. 1 is a block diagram of a digital broadcast
transmitting system comprising a repeat use data inserting
apparatus, the system and the apparatus embodying the
invention.
[0039] The transmitting system of FIG. 1 comprises VTRs 710(1)
through 710(N) corresponding to N channels (N is an integer of at
least 2) and generating program data, encoder-multiplexers 720(1)
through 720(N) that encode and multiplex the program data from the
VTRs 710(1) through 710(N), a changeover switch 730 that connects
the VTRs 710(1) through 710(N) with the encoder-multiplexers 720(1)
through 720(N), a multi-channel developing unit 740 that develops
multiplexed outputs from the encoder-multiplexers 720(1) through
720(N) into multiple channels, a transmitting antenna 750 that
transmits the multi-channel output from the multi-channel
developing unit 740, and a server 760 that manages repeat use
data.
[0040] The server 760 manages the repeat use data in the form of
separately encoded streams (elementary streams) representing a
plurality of material data. The material data constituting the
repeat use data typically include video data and audio data. The
material data are generally compressed and encoded in accordance
with MPEG2 specifications.
[0041] The setup above works as follows: during a data noninsertion
period on n channels (n=1-N), the program data from the VTRs 710(n)
for the n channels are fed via the changeover switch 730 to the
encoder-multiplexers 720(n).
[0042] Having reached the encoder-multiplexers 720(n), the program
data are compressed and encoded thereby in terms of individual
material data types according to MPEG2 specifications. The process
provides separately encoded streams reflecting the individual
material data. Video data and audio data generally make up the
material data constituting the program data.
[0043] A plurality of separately encoded streams from the data
compression and encoding process above are multiplexed in
accordance with MPEG2 specifications. This provides a single stream
that unifies the separately encoded streams. The single stream is
called a transport stream, one of MPEG2-based packet streams.
[0044] During a data insertion period, the encoder-multiplexers
720(n) are supplied with the separately encoded streams
representing a plurality of material data constituting the repeat
use data held in the server 760. The separately encoded streams fed
to the encoder-multiplexers 720(n) are multiplexed thereby
according to MPEG2 specifications. The process provides a single
stream (transport stream) that unifies the separately encoded
streams.
[0045] As described, the encoder-multiplexers 720(n) for the n
channels multiplex the program data and repeat use data over the n
channels, as well as the separately encoded streams representing
the plurality of data constituting the data. In this manner, the
process turns program data bit streams into a single stream into
which repeat use data bit streams are inserted in accordance with
predetermined timings.
[0046] In the multiplexing process, time base information is
provided in order to synchronize the video and audio data. The time
base information includes a decoding time stamp (DTS) indicating
when to decode video data and audio data, a presentation time stamp
(PTS) specifying when to reproduce and output the decoded video and
audio data, and system clock reference (SCR) as well as program
clock reference (PCR) designating the clock reference for decoding,
reproduction and output.
[0047] The single stream coming out of the encoder-multiplexers
720(1) through 720(N) for the N channels is developed by the
multi-channel developing unit 740 into multiple channels. That is,
the unified stream representing the N channels is first multiplexed
and then encoded and modulated in preparation for transmission. The
multi-channel output is transmitted via the transmitting antenna
750.
[0048] FIG. 2 is a conceptual view showing a multiplexing and a
separating process dealing with separately encoded streams
representing a plurality of material data constituting program
data. The setup of FIG. 2 indicates audio data that is typically
composed of two kinds of audio data, one in Japanese and the other
in English.
[0049] Separately encoded streams ST11 through ST13 representing
the three kinds of material data are multiplexed by the
encoder-multiplexers 720(n). The process provides a single stream
ST20 that unifies the three encoded streams ST11 through ST13. The
unified stream ST20 is later separated into the separately encoded
streams ST11 through ST13 by a receiving terminal included in the
digital broadcast receiving system. The separately encoded streams
denoting the repeat use data are also multiplexed and then
separated in a similar manner, which will not be described
further.
[0050] FIG. 3 is a schematic view sketching how program data and
repeat use data are multiplexed. FIG. 3 shows an example in which
program data is constituted by movie data and repeat use data is
made of commercial data CM (commercial messages). Furthermore, the
movie data comprises video data, audio data in Japanese. and audio
data in English; the commercial data includes video data and audio
data in Japanese.
[0051] As shown in FIG. 3, during data noninsertion periods TN(1),
TN(2), etc., the separately encoded streams representing the three
material data constituting the movie data are multiplexed. During
data insertion periods TI(1), etc., on the other hand, the
separately encoded streams representing the two material data
constituting the commercial data are multiplexed. The movie data
and commercial data are thus multiplexed, and so are the separately
encoded streams denoting the plurality of material data
constituting these data. The process eventually provides a single
stream that unifies the separately encoded streams representing the
movie data and the streams representing the commercial data.
[0052] FIG. 4 is a block diagram showing how the
encoder-multiplexers 720(n) and the server 760 in FIG. 1 are
illustratively configured.
[0053] As shown in FIG. 4, each encoder-multiplexer 720(n) includes
a video encoder 721(n) that compresses and encodes video data VD
constituting the program data from the VTR 710(n), and an audio
encoder 722(n) that likewise compresses and encodes audio data AD.
FIG. 4 shows an example in which one type of audio data AD is
furnished.
[0054] The encoder-multiplexer 720(n) further comprises a video
first-in first-out (FIFO) memory unit 724(n) for temporarily
accommodating the video data VD constituting the repeat use data
from the server 760, an audio FIFO memory unit 725(n) for
temporarily holding the audio data AD from the server 760, and an
FIFO control circuit 726(n) for detecting the quantity of the
remaining data in the FIFO memory units 724(n) and 725(n).
[0055] In addition, the encoder-multiplexer 720(n) has a
multiplexer 727(n) and a multiplexing controller 728(n) that
controls the multiplexer 727(n) in operation. The multiplexer
727(n) multiplexes, in accordance with MPEG2 specifications, two
separately encoded streams coming from the encoders 721(n) and
722(n) and another two separately encoded streams from the FIFO
memory units 724(n) and 725(n). The multiplexing controller 728 is
implemented illustratively by use of a central processing unit
(CPU).
[0056] The server 760 comprises a hard disk array 761 for holding
the repeat use data, and a disk controller 762 for controlling the
hard disk array 761. The disk controller 762 is implemented
illustratively by use of a computer.
[0057] FIG. 5 is a schematic view of a data storage structure in
the hard disk array 761. The example of FIG. 5 shows repeat use
data typically composed of commercial data. As illustrated, the
hard disk array 761 has a file established for each of commercial
messages CM(m) (m=1, 2, etc.).
[0058] As shown in FIGS. 6A through 6C, each file accommodating a
commercial message CM(m) comprises a video file VF(m) (see FIG. 6A)
for storing video data VD, an audio file AF(m) (see FIG. 6B) for
holding audio data AD, and a size file SF(m) (see FIG. 6C) for
retaining size data VSD and ASD.
[0059] The video file VF(m) has the video data VD stored in
increments of frames. The audio file AF(m) has the audio data AD
stored also in increments of frames. The size file SF(m) contains
the size data VSD designating video data sizes and the size data
ASD specifying audio data sizes, the two types of size data being
stored in increments of frames.
[0060] The video data VD and audio data AD are stored in the form
of separately encoded streams. The size data VSD and ASD, as they
are stored, indicate the sizes in effect when the video data VD and
audio data AD were compressed and encoded. The compression and
encoding process above is carried out illustratively by one of the
encoder-multiplexers 720(1) through 720(N) for program data while
no program data is being compressed or encoded.
[0061] The setup above works as follows: during a data noninsertion
period for each of n channel, the video data VD constituting the
program data from the VTR 710(n) in FIG. 1 is fed to the video
encoder 721(n); the audio data AD also making up the program data
is fed to the audio encoder 722(n). The video data VD and audio
data AD supplied to the encoders 721(n) and 722(n) are compressed
and encoded thereby in accordance with MPEG2 specifications. The
process provides separately encoded streams representing the video
data VD and audio data AD. The two separately encoded streams are
multiplexed by the multiplexer 727(n) into a unified stream (called
a transport stream).
[0062] Also during the data noninsertion period for each of the n
channels, the FIFO memory units 724(n) and 725(n) are supplied with
the separately encoded streams representing the video data VD and
audio data VD constituting the commercial data held in the hard
disk array 761. The separately encoded streams thus transferred to
the FIFO memory units 724(n) and 275(n), reflecting the video data
VD and audio data AD, are multiplexed by the multiplexer 727(n).
The multiplexing process provides a single stream (transport
stream) that unifies the two separately encoded streams.
[0063] The multiplexer 727(n) is controlled in operation by the
multiplexing controller 728(n). The transfer of the separately
encoded streams from the hard disk array 761 to the FIFO memory
units 724(n) and 725(n) is controlled by the disk controller
762.
[0064] FIG. 7 is a flowchart of steps in which the multiplexing
controller 728(n) operates illustratively. In the example of FIG.
7, it is assumed that repeat use data is commercial data. How the
multiplexing controller 728(n) works will now be described with
reference to FIG. 7.
[0065] In operation, the multiplexing controller 728(n) first
requests the disk controller 762 to transfer commercial data (step
S101). In turn, the data constituting the commercial message CM(m)
held in the hard disk array 761 is transferred therefrom to the
FIFO memory units 724(n) and 725(n).
[0066] In the case above, the FIFO memory unit 724(n) is fed with
the separately encoded stream representing the video data VD held
in the video file VF(m) for the commercial message CM(m); the FIFO
memory unit 725(n) is supplied with the separately encoded stream
representing the audio data AD held in the audio file AF(m). The
data transfer process is carried out until the storage capacities
of the FIFO memory units 724(n) and 725(n) are exhausted. The
storage capacities are preset so as to accommodate data comprising
a plurality of commercial messages CM(m). This means that the FIFO
memory units 724(n) and 725(n) will hold data constituting multiple
commercial messages CM(m).
[0067] The multiplexing controller 728(n) then controls
multiplexing of program data (step S102). Under control of the
controller 728(n), the multiplexer 727(n) multiplexes the
separately encoded streams of the video data VD and audio data VD
compressed and encoded by the encoders 721(n) and 722(n).
[0068] More specifically, the multiplexing process is controlled as
follows: the multiplexing controller 728(n) asks the encoders
721(n) and 722(n) for size data VSD and ASD representing the sizes
of the video data VD and audio data AD. In response, the encoders
721(n) and 722(n) supplies the multiplexing controller 728(n) with
the size data VSD and ASD representing a plurality of frames (e.g.,
15 frames) of video data VD and audio data AD.
[0069] Given the size data VSD and ASD about the multiple-frame
data, the multiplexing controller 728(n) devises a plan to
multiplex the video data VD and audio data AD. The multiplexing
plan is a plan that specifies the quantities of video data VD and
audio data AD to be multiplexed and the timings used for such
multiplexing. The plan is provided so that video data VD may be
compressed and encoded by a variable-length compression and
encoding method. Without such a plan, the multiplexing process
would involve unevenly transmitted excesses and shortages of video
data VD leading to an imbalance between video data VD and audio
data AD.
[0070] The multiplexing plan is established in increments not of a
single frame but of a plurality of frames. This is because the plan
needs to be optimized so as to take into consideration changes in
data size per frame.
[0071] On the basis of the multiplexing plan thus devised, the
multiplexing controller 728(n) requests the encoders 721(n) and
722(n) to transfer separately encoded streams representing a
plurality of frames. At the same time, the multiplexing controller
728(n) requests the multiplexer 727(n) to multiplex the plurality
of frames of separately encoded streams. As a result, the encoders
721(n) and 722(n) output the multiple frames of separately encoded
streams in accordance with the multiplexing plan. These separately
encoded streams are multiplexed by the multiplexer 727(n) according
to the multiplexing plan.
[0072] When control over the multiple-frame multiplexing process is
terminated, the multiplexing controller 728(n) checks to see if it
is time to switch from program data to commercial data (step S103).
That is, a check is made to see if the starting time of a data
insertion period has arrived. If the time to switch to commercial
data has yet to be reached, the-multiplexing controller 728(n) goes
back to step S102 to resume control over the multiplexing process.
In step S102, the next batch of multiple frames is subjected to the
multiplexing process. In this manner, the multiplexing process is
allowed to continue under control of the multiplexing controller
728(n) until it is time to switch to commercial data.
[0073] When it is time to switch to commercial data, the
multiplexing controller 728(n) requests the disk controller 762 to
transfer the size data VSD and ASD denoting the sizes of commercial
data (step S104). In turn, the multiplexing controller 728(n) is
supplied with the size data VSD about video data and the size data
ASD about audio data held in the size file SF(m) in the hard disk
array 761. In this case, too, the size data VSD and ASD are
furnished in increments of a plurality of frames.
[0074] On the basis of the size data VSD and ASD representing the
multiple frames from the disk controller 762, the multiplexing
controller 728(n) devises a plan to multiplex the plurality of
frames of video data VD and audio data AD constituting the
commercial data in question (step S105).
[0075] In accordance with the multiplexing plan thus provided, the
multiplexing controller 728(n) requests the FIFO memory units
724(n) and 725(n) to transfer separately encoded streams
representing the multiple frames. At the same time, the
multiplexing controller 728(n) requests the multiplexer 727(n) to
multiplex the plurality of frames of separately encoded streams.
This causes the FIFO memory units 724(n) and 725(n) to output the
multiple frames of separately encoded streams according to the
multiplexing plan. These separately encoded streams are multiplexed
by the multiplexer 727 in accordance with the multiplexing
plan.
[0076] When control over the multiple-frame multiplexing process is
terminated, the multiplexing controller 728(n) checks to see if the
processing of one commercial message has ended (step S107). That
is, a check is made to see if the ending time of the data insertion
period has arrived. If the multiplexing process of one commercial
message has yet to be terminated, the multiplexing controller
728(n) goes back to step S104 to resume control over the
multiplexing process. The next batch of multiple frames is then
subjected to the multiplexing process. In this manner, the
multiplexing process is allowed to continue under control of the
multiplexing controller 728(n) until the processing of one
commercial message comes to an end.
[0077] When the multiplexing process of one commercial message has
ended, the multiplexing controller 728(n) returns to step S101. The
multiplexing controller 728(n) again starts controlling the
multiplexing process of the program data and repeat use data. In
like manner, every time the multiplexing process of one commercial
message has ended, the steps described above are repeated.
[0078] FIG. 8 is a flowchart of steps in which the disk controller
762 operates illustratively. How the disk controller 762 works will
now be described with reference to FIG. 8.
[0079] The steps in FIG. 8 are carried out every time the disk
controller 762 receives a commercial data transfer request (output
in step S101 of FIG. 7) from the multiplexing controller 728(n).
Initially, the disk controller 762 calculates currently available
capacities of the FIFO memory units 724(n) and 725(n) on the basis
of the remaining commercial data detected by the FIFO control
circuit 726(n)(step S201). If the received transfer request is a
first request, the available capacities of the FIFO memory units
724(n) and 725(n) should match their storage capacities. If the
transfer request is a second or a subsequent request, the currently
available capacities match the data quantity of the commercial
message CM(m) whose multiplexing process has just been
terminated.
[0080] The disk controller 762 then references a commercial list of
the n channels to determine the commercial message CM(m) whose data
should be transferred from the hard disk array 761 to the FIFO
memory units 724(n) and 725(n)(step S202). The commercial list is a
list that designates the sequence in which commercial messages
CM(m) are to be output. The list is stored illustratively in an
internal memory of the disk controller 762.
[0081] The disk controller 762 then prepares the data making up the
commercial message CM(n) determined in step S202 by an amount
matching the available capacities calculated in step S201 (step
s203). Specifically, those video data VD and audio data AD that
match in quantity the currently available capacities of the FIFO
memory units 724(n) and 725(n) are read from the video file VF(m)
and audio file AF(m) in the hard disk array 761.
[0082] The disk controller 762 transfers the prepared video data VD
and audio data AD to the FIFO memory units 724(n) and 725(n). This
should fill the two memory units with data to capacity.
[0083] The disk controller 762 checks to see if a request for the
transfer of size data VSD and ASD (i.e., transfer request output in
step S104 of FIG. 7) is received from the multiplexing controller
728(n)(step S205). The check is repeated until a transfer request
has been sent in.
[0084] With a transfer request received, the disk controller 762
transfers to the multiplexing controller 728(n) the size data VSD
and ASD on the commercial message CM(m) subject to multiplexing
(step S206). The transfer is effected every time the size data VSD
and ASD are read from the size file SF(m) in the hard disk array
761. With each transfer request received, size data VSD and ASD
representing a plurality of frames are transferred. The transfer of
size data is continued until no further transfer request is
received.
[0085] With no further transfer request received, the process of
transferring size data VSD and ASD comes to an end. When the
transfer process is terminated, the disk controller 762 stops its
control operation. Upon receipt of a new request for the transfer
of commercial data from the multiplexing controller 728(n), the
steps above are again carried out.
[0086] FIG. 9 is a view of a typical commercial list for n
channels. The list in FIG. 9 shows a case in which commercial
messages CM(m) numbered 1, 2, 3, 4, etc., are sent out in the order
of CM(1), CM(2), CM(3), CM(6), CM(4), etc.
[0087] FIG. 10 is a schematic view showing how the FIFO memory unit
724(n) is related in terms of storage capacity to the amount of
video data VD to be accommodated thereinto. The video data VD in
FIG. 10 are arranged in the same sequence in which the
corresponding commercial messages CM(m) are output. As illustrated,
the storage capacity of the FIFO memory unit 724(n) is set to be
large enough to hold video data VD representing a plurality of
commercial messages CM(m).
[0088] FIGS. 11A through 11C are schematic views showing how video
data stored in the FIFO memory unit 724(n) vary. FIG. 11A shows a
case in which the multiplexing controller 728(n) has yet to issue a
request for the transfer of commercial data. In this case, the FIFO
memory unit 724(n) has no video data VD stored therein.
[0089] FIG. 11B shows a case in which the multiplexing controller
728(n) has generated a first transfer request. In this case, the
FIFO memory unit 724(n) accommodates illustratively video data VD
representing two entire commercial messages CM(1) and CM(2) and
video data VD constituting part of a commercial message CM(3).
[0090] FIG. 11C shows a case in which the multiplexing controller
728(n) has generated a second transfer request. In this case, the
FIFO memory unit 724(n) is replenished with the amount of data
corresponding to the vacancy left when the commercial message CM(1)
was read out. As indicated in FIG. 11C, the memory unit is
replenished with video data VD constituting the rest of the
commercial message CM(3) and video data VD representing part of a
commercial message CM(6). Now the FIFO memory unit 724(n) is set
illustratively with the video data VD representing the entire
commercial messages CM(2) and CM(3) as well as the video data VD
constituting part of the commercial message CM(6).
[0091] In like manner, every time the multiplexing controller
728(n) generates a transfer request, the data-replenishing
operation above is carried out. This keeps the FIFO memory unit
724(n) filled with video data. Similar processing, which will not
be described further, is also performed on the FIFO memory unit
725(n) for audio data AD.
[0092] As described and according to the embodiments of the
invention above, repeat use data may be stored as compressed. This
feature reduces the amount of stored repeat use data, which in turn
cuts back on the storage capacity for accommodating the data and
lowers the transfer rate at which repeat use data are
transferred.
[0093] With the embodiments of the invention, repeat use data may
be stored in the form of separately encoded streams yet to be
multiplexed. This feature dispenses with circuits for changing time
base information, averts momentary interruption of video or audio
data of the program, and suppresses generation of noise.
[0094] The embodiments above multiplex repeat use data by simply
installing several additional multiplexers 727(n) for multiplexing
program data. This arrangement forestalls increases in the scale of
circuits.
[0095] The embodiments comprise the FIFO memory units 724(n) and
725(n) for buffer use which are fed with repeat use data during the
data noninsertion period. This feature further reduces the transfer
rate for repeat use data. Specifically, the transfer rate of the
inventive structure is reduced to about T1/T2 (T1 stands for repeat
use data output time and T2 for program data output time) compared
with the second arrangement described earlier for inserting repeat
use data into program data. This makes it possible to implement the
hard disk array 761 in the form of a hard disk array of a
significantly lower speed than the one ordinarily used. In
addition, a low-transfer-rate cable such as an RS232C cable may be
utilized for data transfer between the server 760, which is
generally set up in a remote location, and the encoder-multiplexers
720(n).
[0096] Furthermore, the embodiments preserve the size data VSD and
ASD acquired when repeat use data are compressed and encoded. This
feature eliminates the need for a circuit to detect sizes of repeat
use data.
[0097] More specifically, if the size data VSD and ASD about repeat
use data were not retained, it would be necessary to detect the
sizes of these data by referencing them upon read-out from the hard
disk array 761. Such a structure would require separately
installing a size detecting circuit. By contrast, the inventive
structure holds the size data VSD and ASD obtained upon compression
and encoding of repeat data, which makes a size detecting circuit
unnecessary. Thus the embodiments help simply the entire circuit
constitution.
[0098] Where a plan to multiplex repeat use data is to be
established, the inventive structure devises the plan on the bases
of the size data representing a plurality of frames. This makes it
possible to take into consideration the changes in data size per
frame. The feature permits providing a more appropriate
multiplexing plan than the ordinary setup of devising a
multiplexing plan based on the single-frame size data.
[0099] Although the description above contains many specificities,
these should not be construed as limiting the scope of the
invention but as merely providing illustrations of the presently
preferred embodiments of this invention.
[0100] For example, the embodiments above have the FIFO memory
units 724(n) and 725(n) as well as the FIFO control circuit 726(n)
incorporated in each of the encoder-multiplexers 720(n).
Alternatively, the incorporated components may be included in the
server 760 instead.
[0101] With the above embodiments, the file SF dedicated to size
data is furnished so as to accommodate the size data VSD and ASD
about repeat use data. As an alternative, the size data may be
contained in the video file VF or in the audio file AF.
[0102] The embodiments above comprise a single stage of buffer
memory units (FIFO memory units 724(n) and 725(n) in the
description above) for temporary storage of repeat use data.
Alternatively, two stages of buffer memory units may be provided
instead, the first stage making up a large-capacity buffer memory
arrangement and the second stage constituting a small-capacity
buffer memory setup.
[0103] Thus it is to be understood that changes and variations may
be made without departing from the spirit and scope of the claims
that follow.
[0104] The major benefits of this invention may be recapitulated as
follows: according to the repeat use data inserting apparatus or
digital broadcast transmitting system of the invention, repeat use
data are stored as compressed. This feature reduces the amount of
stored repeat use data, which in turn cuts back on the storage
capacity for accommodating the data and lowers the transfer rate at
which repeat use data are transferred.
[0105] According to the repeat use data inserting apparatus or
digital broadcast transmitting system of the invention, repeat use
data are stored in the form of separately encoded streams yet to be
multiplexed. This feature dispenses with circuits for changing time
base information, averts momentary interruption of video or audio
data of the program, and suppresses generation of noise.
[0106] Also according to the repeat use data inserting apparatus or
digital broadcast transmitting system of the invention, repeat use
data are multiplexed by simply providing some additional means for
multiplexing program data. This forestalls increases in the overall
scale of circuits.
[0107] According to the repeat use data inserting apparatus or
digital broadcast transmitting system of the invention, temporary
storage means is provided to accommodate temporarily repeat storage
data for each channel. During the data noninsertion period, repeat
use data are transferred to the temporary storage means. This
feature further lowers the necessary transfer rate for repeat use
data, which makes it possible to implement the repeat use data
holding means in the form of data holding means of a significantly
lower speed than the one ordinarily used.
[0108] Further according to the repeat use data inserting apparatus
or digital broadcast transmitting system of the invention, repeat
use data are preserved along with their size data. This feature
eliminates the need for a circuit to detect sizes of repeat use
data.
* * * * *