Motion video signal processing for recording or reproducing – Local trick play processing – With randomly accessible medium
Reexamination Certificate
1998-07-08
2002-12-31
Chevalier, Robert (Department: 2615)
Motion video signal processing for recording or reproducing
Local trick play processing
With randomly accessible medium
C386S349000, C386S349000
Reexamination Certificate
active
06501904
ABSTRACT:
FILED OF THE INVENTION
The present invention relates to a video signal recording and reproducing apparatus that compresses video signals having different formats with a high efficiency, and records as well as reproduces the compressed video signals.
BACKGROUND OF THE INVENTION
Recently, several new broadcasting systems, such as HDTV (high definition television), ATV (advanced television), etc. have been developed in the engineering field of broadcasting industry, and some of the new systems are now in operation.
On the other hand, various systems are proposed to be the next generation broadcasting system, e.g., a progressive signal method, in other words, a 480p signal method, which is converted from the interlace signal method of NTSC system where 525 scanning lines are employed. Meanwhile, the 480p signal method handles 525 scanning lines in the progressive method; however, a number of active lines are 480, thus the system is named for this number. The conventional interlace system is called “480i” in order to distinguish from the progressive method. The 480p signal method is now prescribed as the DTV (digital television) standard of the U.S.
The 480p signal of progressive signal method is described hereinafter.
FIG. 16
is a schematic diagram depicting signal modes of interlace and progressive method. By the interlace mode, 30 frames of picture data are produced per second, one picture data (one frame) is scanned with every other scanning line of 525 lines, thus 60 picture data (field) per second, each frame scanned with 262.5 lines, are transmitted. A digital studio standard employing the interlace mode is prescribed in Recommendation ITU-R.601-3, of which sampling frequency is, luminance signal: 13.5 MHz, color difference signal: 6.75 MHz. This “4:2:2 signal” is referred to “4:2:2-i signal” hereinafter to identify that this signal is in the interlace mode.
The progressive method, on the other hand, produces 60 picture data (frame) per second, and one picture data is scanned by 525 scanning lines (including 480 active lines) without interlacing. The progressive signal, of which picture is formed with 525 scanning lines, is digitized by a “8:4:4 signal” format, i.e., doubled sampling frequency of the digital studio standard in the interlace mode. The sampling frequency of the progressive signal is thus, luminance signal: 27 MHz, color difference signal: 13.5 MHz., which is twice as much as that of the “4:2:2 signal”. The “8:4:4 signal” is now studied to divide into a main signal and a sub-signal for transmitting, i.e., the main signal comprising one luminance signal and two color difference signals, and the sub-signal comprising also one luminance signal and two color difference signal so that the sub-signal interpolates the main signal. The “8:4:4 signal” is thus divided into the main and sub signals which are assigned to every other scanning line respectively. The main signal and sub signal of this method are an independent interlace signal having 525 scanning lines per frame, and are the same as the “4:2:2 signal”. The coupled main signal and sub signal is hereinafter referred to “4:2:2:4:2:2 signal” or “4:2:2p signal”.
FIG. 18
depicts a sampling structure of the “4:2:2p signal” on a screen. As shown in
FIG. 18
, a video signal is divided into the main signal and sub signal in both an even frame and an odd frame. The main signals and sub signals are alternately arranged on vertical and horizontal lines in temporal-spatial wise.
When the “8:4:4 signal” or “4:2:2p signal” is transmitted, the color difference signal of “8:4:4 signal” undergoes, e.g., a vertical filter as shown in
FIG. 17
in vertical direction in order to limit its bandwidth before transmitting the color difference signal in each line, for the color difference signal carries less information than the luminance signal does, therefore the human visual property does not sense deterioration of the color difference signal. In
FIG. 17
, the filter comprises 1H delay line
120
,
121
delaying a signal for one horizontal scanning period, a multiplier
122
,
124
and an adder
123
. The numbers printed in the boxes representing the multipliers
122
and
124
in
FIG. 17
are coefficients of multiplication. The color difference signal is limited in its band by e.g., the vertical filter as shown in
FIG. 17
, then the signals are decimated in each line, then the color difference signal only on the main signal side are transmitted, while that on the sub signal side is not transmitted.
The above transmitted signal is called “4:2:2:4:0:0 signal” or “4:2:0p” signal because the sub signal does not carry the color difference signal. The “4:2:0p signal” is prescribed as SMPTE294M standard. When the progressive signal is converted into the “4:2:0p signal” in transmission, recording or playing back, the transmission band can be effectively reduced without deteriorating a visual quality of the video signal.
On the other hand, the color difference signal decimated on the sub-signal side can be reproduced by providing the main signal with an interpolation filter as shown in
FIG. 19
or
20
.
FIG. 20
shows the easiest way for the reproduction. In
FIG. 19
, the filter comprises 1H delay lines
130
,
131
and
132
delaying a signal for one horizontal scanning period respectively, multipliers
133
,
134
,
135
,
136
and
138
, and an adder
137
. The numbers printed in the boxes representing the multipliers are coefficients of multiplication. In
FIG. 20
, the filter comprises 1H delay line
140
active in one horizontal scanning period, an adder
141
and a multiplier
142
. The number printed in the box
142
representing the multiplier is a coefficient of multiplication. Since the color difference signal on the sub-signal side can be reproduced by the filter shown in
FIG. 19
or
20
, the “4:2:0p signal” can be converted into the “4:2:2p signal”, further, the “4:2:2p signal” can be converted with ease into the “4:2:2-i signal” by adding the main and sub signals and dividing 2 into the addition result, as
FIG. 21
shows an example. In
FIG. 21
, a filter comprises an adder
150
and a multiplier
151
. The number printed in the box of multiplier
151
is a coefficient of multiplication.
Besides the “480p signal” method, various methods are proposed in HDTV (high definition television) system and other systems aiming for the higher resolution than that of the present system. For instance, 1125i/1035i (1125 scanning lines including 1035 active lines), 1125i/1080i method in the interlace system, and 750p/720p (750 scanning lines including 720 active lines) in the progressive signal method of HDTV system are proposed.
Various proposals of TV systems accompany the developing of hardware corresponding to the systems such as acquisition devices, equipment for studios. The next generation broadcasting system; however, has just undergone a test operation, therefore, materials produced by the acquisition devices are converted into the present television system to be on-air. For instance, a program is produced by HDTV cameras and VCRs, and the program is on-air through the satellite broadcasting as HDTV, and also the program is converted into the present television system and on-air through the terrestrial broadcasting.
It sometimes happens that a program is produced using devices and equipment corresponding to various broadcasting methods, e.g., a program is produced by combined hardware including devices for high resolution television such as HDTV, 480p and other devices for the present television system, and the program thus produced is on-air through the present broadcasting system.
In such a case, the program must be undergone the process shown in
FIG. 15
before on-air.
The conventional method shown in
FIG. 15
is now detailed.
In
FIG. 15
, a first VCR
100
is used in “480i signal” system of interlace mode, and reproduces the “4:2:2-i signal” where a sampling frequency ratio of luminance signal vs. color difference signals is 4:2:2. A second VCR
101
is used in “480p signal” system of progressive signal, and repr
Bannai Tatsushi
Kuroda Tokuji
Chevalier Robert
Matsushita Electric - Industrial Co., Ltd.
RatnerPrestia
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