Coded data generation or conversion – Digital code to digital code converters
Reexamination Certificate
1999-05-20
2001-01-09
Tokar, Michael (Department: 2819)
Coded data generation or conversion
Digital code to digital code converters
Reexamination Certificate
active
06172621
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a coding apparatus for compressing and encoding digital video data and other data at a high speed, suitable for application to for example digital video cassette tape recorders (DVC) for home use, and a method of the same and a decoding apparatus for decoding the compressed and coded data at a high speed and a method of the same.
2. Description of the Related Art
As an example of the coding method and decoding method of images which are now being used, an explanation will be given of the method which has become the standard compression and coding method of moving picture images and which is being applied to home DVCs and other digital video apparatuses.
FIGS. 1A
to
1
E are views of the flow of encoding and decoding of digital video data.
At the time of encoding, first, as shown in
FIG. 1A
, the image of one frame to be encoded is divided into processing units referred to as “macroblocks” (MB). This processing is referred to as “blocking”.
Next, five macroblocks in one frame are selected according to a predetermined rule and dispersed while changing positions as shown in
FIG. 1B
to form a video segment. This processing is referred to as “shuffling”. The shuffling is carried out so as to make the amount of encoding uniform by dispersing continuous data. Note that the number of video segments in one frame generated by the shuffling becomes one-fifth of the total number of the macroblocks. Note that the algorithm of the shuffling (method of selection of five macroblocks) is determined in advance and does not change at the time of execution due to for example a change of the compression rate.
Next, discrete cosine transform (DCT), weighting, quantization, and variable length coding (VLC) are applied to the formed video segment to encode the five macroblocks (MB
0
to MB
4
) to five compressed data units of fixed length referred to as “sync blocks” as shown in FIG.
1
C.
When looking at the compressed data of the individual macroblocks at the time of this encoding, they sometimes cannot be contained in the corresponding sync blocks. This is because, at the time of quantization, the generated amount of encoding is controlled out so that the compressed data of the five macroblocks is contained in five sync blocks as a whole. Therefore, after the variable length decoding (VLD), the compressed data is moved among the five sync blocks. This processing is referred to as a framing.
The framed compressed data is sent to for example a video recording and reproduction apparatus or other recording system.
Next, an explanation will be made of the decoding.
The decoding proceeds by a reverse flow to that of the encoding.
First, the compressed data sent from a video apparatus or other reading system is processed by moving the compressed data among the five sync blocks as mentioned above in order to extract the compressed data of the macroblocks. This processing is referred to as deframing.
Next, the extracted compressed data of each macroblock is subjected to variable length decoding (VLD), inverse quantization, inverse weighting, and inverse discrete cosine transform (IDCT) to decode the video segments as shown in FIG.
1
D.
Next, the five macroblocks (MB
0
to MB
4
) comprising each video segment are returned as data of the original position in the frame. Namely, the data of each macroblock is stored at an address of the position of the image in a frame memory etc. This processing is referred to as deshuffling.
Finally, the frame which has been divided to macroblocks is converted to data of a raster scan system as shown in FIG.
1
E. This processing is referred to as deblocking.
Then, the deblocked image data is sent to the video input of for example a display.
Next, an explanation will be made of the configuration of the processing apparatus of the related art, the processing algorithm, and the flow of the processing for this encoding and decoding.
First, an explanation will be made of the encoding.
As the coding apparatus for carrying out the encoding as mentioned above, an apparatus having a configuration as shown in
FIG. 2
has been used.
A coding apparatus
80
shown in
FIG. 2
is configured by a blocking unit
81
, a shuffling unit
82
, a motion detection unit
83
, a DCT unit
84
, a classification unit
85
, a data amount estimation unit
86
, a quantization unit
87
, a VLC unit
88
, and a framing unit
89
connected as illustrated.
In such a coding apparatus
80
, sequentially input video data are divided into macroblocks at the blocking unit
81
which are then used to generate video segments at the shuffling unit
82
.
Next, motion is detected at the motion detection unit
83
, the coding mode of the DCT to be carried out at the DCT unit
84
is determined, and the DCT is actually carried out at the DCT unit
84
. Further, the DCT unit
84
carries out weighting by applying a predetermined filter to the obtained DCT.
Then, the classification unit
85
determines the class number for determining the quantization step, the data amount estimation unit
86
estimates the amount of data based on the class number to determine the quantization step, and the quantization unit
87
carries out the quantization with respect to the DCT result obtained at the DCT unit
84
.
The quantized DCT result is subjected to variable length coding at the VLC unit
88
and then subjected to framing at the framing unit
89
to generate sets of five sync blocks, and the generated compressed data is output from the coding apparatus
80
.
Further, a processing algorithm in a case where such encoding is carried out by a general purpose processing apparatus using for example a digital signal processor (DSP) is shown in FIG.
3
.
As shown in
FIG. 3
, when the encoding is started by the processing apparatus (step S
110
), first, blocking is carried out with respect to sequentially input video data to divide it into macroblocks (step S
111
) and then shuffling is carried out to generate the video segments (step S
112
).
Next, motion detection is carried out to detect the part having motion and determine the coding mode of the DCT (step S
113
), DCT is actually carried out and weighting is carried out with respect to the obtained DCT result by applied a predetermined filter (step S
114
).
Next, the class number for determining the quantization step is determined (step S
115
), the amount of data is estimated based on the class number to determine the quantization step (step S
116
), and quantization is carried out with respect to the DCT result obtained at step S
114
(step S
117
).
Next, the quantized DCT result is subjected to variable length coding (step S
118
) and framing is carried out to generate sets of five sync blocks (step S
119
).
The processings of step S
111
to step S
119
are sequentially carried out for one frame's worth of data (step S
120
) and further repeatedly carried out with respect to sequentially input frames (step S
121
). When the processing is carried out with respect to all frames to be encoded, the series of encoding is ended (step S
122
).
A timing chart of the processing in a CPU of the processing apparatus where coding is carried out according to the algorithm shown in
FIG. 3
is shown in FIG.
4
.
Note that, in
FIG. 4
, the processings VSj-BLK to SFL indicate processings of blocking (BLK) and shuffling (SFL) with respect to a (j+1)th video segment j (step S
111
and step S
112
in FIG.
3
); the processings VSj-DCT to Q indicate processings from the motion detection to the quantization (Q) with respect to the (j+1)th video segment j (step S
113
to step S
117
in FIG.
3
); and the processings VSj-VLC to FRM indicate processings of variable length coding (VLC) and framing (FRM) with respect to the (j+1)th video segment j (step S
118
and step S
119
in FIG.
3
).
As illustrated, the processing apparatus sequentially carries out the processing steps of the flow chart shown in
FIG. 3
for every video segment.
Next, an explanation will be made of the decoding.
As th
Le Don Phu
Limbach & Limbach L.L.P.
Sony Corporation
Tokar Michael
LandOfFree
Coding apparatus and method of same and decoding apparatus... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Coding apparatus and method of same and decoding apparatus..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Coding apparatus and method of same and decoding apparatus... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2535187