Pulse or digital communications – Bandwidth reduction or expansion – Television or motion video signal
Reexamination Certificate
2000-06-09
2001-07-31
Kelley, Chris (Department: 2713)
Pulse or digital communications
Bandwidth reduction or expansion
Television or motion video signal
C386S349000
Reexamination Certificate
active
06269119
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to sound-picture synchronous compression and synchronous reproduction systems in which sound information and picture information are subjected to synchronous compression and synchronous reproduction in a real-time manner. Specifically, the sound-picture synchronous compression and synchronous reproduction system (hereinafter, simply referred to as a sound-picture synchronous compression-reproduction system) is actualized using a sound-picture synchronous compression device and a sound-picture synchronous reproduction device. This invention is based on patent application No. Hei 9-27140 filed in Japan, the content of which is incorporated herein by reference.
2. Prior Art
The sound-picture synchronous compression-reproduction system is actualized by a pair of sound-picture synchronous compression device and sound-picture synchronous reproduction which use CPUs (an abbreviation for “Central Processing Unit”) as well as DSPs (an abbreviation for “Digital Signal Processor”). In the sound-picture synchronous compression device, sound information and picture information are subjected to synchronous compression in real time. So, the compressed sound information and compressed picture information are transmitted via transmission lines to the sound-picture synchronous reproduction device, wherein they are subjected to synchronous reproduction in real time.
Normally, sounds and pictures are transmitted in a digitized manner via telephone lines and are then recorded on recording media by using compressive encoding because an amount of data thereof is enormous. The compression technique for the pictures frequently uses an encoding method designed on the basis of the DCT (an abbreviation for “Discrete Cosine Transform”), which uses a property that spatial frequencies of the pictures tend to be concentrated into low-frequency ranges. This encoding method is employed by the international standard, namely, MPEG (an abbreviation for “Motion Picture Experts Group”) Video, recommendation H. 263.
In addition, the compression technique for the sounds frequently uses a so-called perception encoding method which omits inaudible information, which cannot be heard by human ears, by using auditory psychology. This encoding method is employed by the international standard, namely, MPEG Audio, recommendation G. 723.
FIG. 10A
to
FIG. 10F
show hierarchy for encoding formats based on the standard of MPEG Video. Codes of the MPEG Video are assigned to levels of a hierarchical structure as shown in
FIG. 10A
to
FIG. 10F. A
top level of hierarchy corresponds to a video sequence which is configured by multiple GOPs (an abbreviation for “Group Of Picture”). Each GOP is configured by multiple pictures.
There are provided three kinds of pictures, namely, I picture, P picture and B picture. Herein, the I picture corresponds to intra-frame codes; the P picture corresponds to interframe codes with respect to a forward direction only; and the B picture correspond to interframe codes with respect to both of forward and backward directions. The picture consists of multiple slices corresponding to regions which are determined by partitioning an overall area of the picture. Each slice is configured by multiple macro blocks which are arranged from the right to the left or from the top to the bottom.
A block of 16×16 dots (or pixels) is divided into blocks of 8×8 dots, which are used for representation of luminance components (i.e., Y
1
, Y
2
, Y
3
and Y
4
). In addition, blocks of 8×8 dots are used for representation of chrominance components (i.e., Cb, Cr) in connection with the region of the luminance components. Thus, the macro block is constructed by six blocks of 8×8 dots in total. Therefore, the block of 8×8 dots is used as a minimum unit for encoding.
FIG. 11
shows an example of the hierarchy for encoding formats based on the standard of MPEG Audio. Codes of the MPEG Audio are constructed using “AAU” (an abbreviation for “Audio Access Unit”), which is a minimum unit for encoding.
Now, a description will be given with respect to the conventional technique for compression of sound codes and picture codes.
FIG. 12
is a block diagram showing an example of a sound-picture synchronous compression device which performs synchronous compression and transmission on sounds and pictures. In
FIG. 12
, a CPU
2
executes programs of a device control block
4
so as to control the device as a whole. A user operates a keyboard
3
to input commands and instructions to the device. States of execution of the programs are visually displayed on a screen of a display
1
.
Picture data are taken by a camera
6
and are input to the device by means of a picture input block
5
. Sound data are created by a microphone
8
and are input to the device by means of a sound input block
7
. The sound data are subjected to compression by a sound compression block
10
. The picture data are subjected to compression by a picture compression block
9
. The compressed sound code corresponding to the compressed sound data as well as the compressed picture code corresponding to the compressed picture data are mixed together using a single code by a code nixing block
11
. Then, mixed codes are transmitted onto a transmission line by a transmitter block
12
as well as a modem
13
.
FIG. 13
is a block diagram showing an example of a sound-picture synchronous reproduction device which performs receiving and synchronous reproduction on sound-picture codes transmitted thereto. In
FIG. 13
, a CPU
22
executes programs of a device control block
24
to control the device as a whole. A user operates a keyboard
23
to input commands and instructions to the device. States of execution of the programs are visually displayed on a screen of a display
21
.
A receiver block
32
receives mixed codes transmitted thereto from a modem
33
as sound codes and picture codes to be reproduced. Then, a code separation block
31
separates the mixed codes into sound codes and picture codes respectively. The sound codes are subjected to expansion (or reproduction) by a sound reproduction block
30
. The picture codes are subjected to reproduction by a picture reproduction block
29
. Then, contents of picture data corresponding to the reproduced picture codes are visually displayed on a screen of a monitor
26
by a picture output block
25
. A sound output block
27
provides a speaker
28
with sound data corresponding to the reproduced sound codes. So, the speaker
28
produces the corresponding sounds.
The aforementioned example of the system for sound-picture compression and reproduction performs communications of codes. Herein, data processing should be performed in a real-time manner. In general, a number of operations (or calculations) are required in processing for the compression and reproduction. To enable real-time processing, the conventional system which uses the software for compression and reproduction of sounds and pictures reduces a number of frames representing pictures which are subjected to processing. Herein, parallel operation instructions of the CPU and DSP are used to perform multiple operations at once, so it is possible to accomplish high-speed performance in the above processing.
FIG. 14
shows an example of the parallel operation instructions. Herein, a 64-bit register R
0
stores 4-word values a
3
, a
2
, a
1
and a
0
, while a register R
1
stores 4-word values b
3
, b
2
, b
1
and b
0
. Those 4-word values are added together, so addition results are stored in the register R
0
. According to the parallel operation instructions described above, addition is performed with respect to four words at once, so it is possible to perform high-speed processing.
Functions of real-time OS (an abbreviation for “Operating System”) can be used for the compression and reproduction of the sounds and pictures. Herein, if the sound processing and picture processing are switched over periodically by a certain period of time, it is possible to
Foley & Lardner
Kelley Chris
NEC Corporation
Philippe Gims
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