Pulse or digital communications – Bandwidth reduction or expansion – Television or motion video signal
Reexamination Certificate
1999-01-15
2002-04-30
Lee, Young (Department: 2613)
Pulse or digital communications
Bandwidth reduction or expansion
Television or motion video signal
Reexamination Certificate
active
06381274
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method of encoding a video signal which includes a quantization step. This invention also relates to an apparatus for encoding a video signal which uses a quantization process.
2. Description of the Related Art
Japanese published unexamined patent application 7-284097 discloses an apparatus for encoding a video signal which uses a quantization process. The apparatus of Japanese application 7-284097 divides an input video signal into time segments corresponding to equal intervals respectively, and implements signal processing on an interval-by-interval basis.
In more detail, the apparatus of Japanese application 7-284097 has first and second paths along which a same input video signal is transmitted while being processed. A first encoding circuit in the first path encodes the video signal for every interval. The encoding by the first encoding circuit includes quantization using a fixed quantization width. Information of the amount D
1
of encoding-resultant data generated by the first encoding circuit for every interval is stored into a memory circuit in the first path. The information of the data amount (the actual data amount) D
1
is transmitted from the memory circuit to a target data amount setting circuit. The target data amount setting circuit determines a target data amount D
2
for every interval on the basis of the actual data amount D
1
by referring to the following equation.
D
2
=
D
1
·
DALL/&Sgr;D
1
where DALL denotes the total amount of data corresponding to the video signal, and &Sgr;D
1
denotes the summation of the actual data amounts D
1
for all the intervals.
In the apparatus of Japanese application 7-284097, a second encoding circuit in the second path encodes the video signal for every interval. The encoding by the second encoding circuit includes quantization responsive to a variable quantization width. Generally, as the quantization width increases, the amount D
3
of encoding-resultant data generated by the second encoding circuit for every interval decreases. A first total data amount detection circuit connected to the second encoding circuit is informed of the data amount (the actual data amount) D
3
. The first total data amount detection circuit calculates the summation &Sgr;D
3
of the data amounts (the actual data amounts) D
3
for the intervals up to the present interval. A second total data amount detection circuit connected to the target data amount setting circuit is informed of the target data amount D
2
. The second total data amount detection circuit calculates the summation &Sgr;D
2
of the target data amounts D
2
for the intervals up to the present interval.
In the apparatus of Japanese application 7-284097, a comparison circuit is informed of the target total data amount &Sgr;D
2
and the actual total data amount &Sgr;D
3
by the first and second total data amount detection circuits. The comparison circuit compares the total data amounts &Sgr;D
2
and &Sgr;D
3
with each other. The comparison circuit informs a target data amount correction circuit of the comparison result. The target data amount correction circuit corrects the target data amount D
2
into a final target data amount in response to the comparison result. The final target data amount is reported to the second encoding circuit from the target data amount setting circuit. The quantization width used by the quantizer in the second encoding circuit is controlled in response to the final target data amount. Accordingly, the amount D
3
of encoding-resultant data generated by the second encoding circuit for every interval depends on the final target data amount. The encoding-resultant data generated by the second encoding circuit is used as an apparatus output video signal.
In the apparatus of Japanese application 7-284097, the correction of the target data amount D
2
by the target data amount correction circuit is designed to implement the following processes. In the case where the target total data amount &Sgr;D
2
is greater than the actual total data amount &Sgr;D
3
, the target data amount D
2
is corrected to slightly increase the final target data amount during intervals after the present interval. In the case where the target total data amount &Sgr;D
2
is smaller than the actual total data amount &Sgr;D
3
, the target data amount D
2
is corrected to slightly decrease the final target data amount during intervals after the present interval. Accordingly, the actual total data amount &Sgr;D
3
is regulated substantially at the target total data amount &Sgr;D
2
.
In the apparatus of Japanese application 7-284097, during an interval after the interval for which the amount of data corresponding to the video signal is significantly great, the quantization width used by the second encoding circuit tends to be set to an unduly large value. On the other hand, during an interval after the interval for which the amount of data corresponding to the video signal is significantly small, the quantization width tends to be set to an unduly small value.
SUMMARY OF THE INVENTION
It is a first object of this invention to provide a method of encoding a video signal which can stably control a quantization width during intervals after the interval where the amount of data corresponding to the video signal is significantly great or small.
It is a second object of this invention to provide an apparatus for encoding a video signal which can stably control a quantization width during intervals after the interval where the amount of data corresponding to the video signal is significantly great or small.
A first aspect of this invention provides a method of encoding input picture data representing a succession of pictures each composed of plural blocks. The method comprises the steps of quantizing the input picture data into first quantization-resultant data in response to a fixed quantization width; encoding the first quantization-resultant data into first code data of a variable length code for every block; generating information of an accumulation transition in an amount of the first code data for every block; calculating a code amount accumulation transition value from the accumulation-transition information and a predetermined target code amount for every block, the predetermined target code amount being defined with respect to every picture; quantizing the input picture data into second quantization-resultant data in response to a variable quantization width; encoding the second quantization-resultant data into second code data of the variable length code for every block; detecting an actual amount of the second code data for every block; calculating an error between the code amount accumulation transition value and the detected actual amount of the second code data for every block; and controlling the variable quantization width in response to the calculated error for every block to maintain an actual amount of the second code data substantially at the target code amount for every picture.
A second aspect of this invention provides a method of encoding input picture data representing a succession of frames each divided into plural frame portions. Each of the frame portions is composed of blocks. The method comprises the steps of dividing the input picture data into first division-resultant picture data portions corresponding to the respective frame portions; quantizing the first division-resultant picture data portions into first quantization-resultant data portions in response to a fixed quantization width in parallel; encoding the first quantization-resultant data portions into first code data portions of a variable length code in parallel for every block; generating information of an accumulation transition in an amount of each of the first code data portions for every block; calculating a code amount accumulation transition value from the accumulation-transition information and a predetermined target code amount for every block, the predetermined target code amount being defined with respect to e
Connolly Bove & Lodge & Hutz LLP
Lee Young
Victor Company of Japan Ltd.
LandOfFree
Method and apparatus for encoding video signal does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for encoding video signal, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for encoding video signal will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2850994