Pulse or digital communications – Bandwidth reduction or expansion – Television or motion video signal
Reexamination Certificate
1999-02-16
2002-11-26
Diep, Nhon (Department: 2613)
Pulse or digital communications
Bandwidth reduction or expansion
Television or motion video signal
C375S213000
Reexamination Certificate
active
06487248
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a decoding device, and more particularly, a video decoding device of a digital TV receiver.
2. Background of the Related Art
A moving pictures expert group (hereinafter “MPEG”) standard is recommended as an international standard for compressing and encoding of a digital moving video, preferably in a multimedia environment including digital versatile discs (DVDs) and digital TVs. Particularly, in current digital TVs, a high definition (hereinafter “HD”) grade of MPEG compression and restoration is accepted as a standard. Hence, an existing National Television System Committee (hereinafter “NTSC”) system type analog TV will be replaced with the digital TV.
Since the price of the HDTV is expensive at the start of the market initiation, a user's demand for a standard definition (hereinafter, referred to as “SD”) grade of TV will continue for a long period of time during the replacement of the NTSC type analog TV with the HDTV. The SD grade of TV, e.g., SDTV means a TV, or a settop box, which down-converts an HD grade of signal to display the down-converted signal on an SD grade of monitor, will be widely used. In addition to the HD grade of signal, the SDTV can receive the SD grade of signal. A standard for distinguishing the HD grade of signal and the SD grade of signal is dependent upon the number of picture elements (pels) which influences the determination of the video representation performance (a quality of image).
For instance, the SDTV or the settop box down-converts 1920 pels by 1080 lines 60 Hz interlaced scanning of the HD grade of signal to 720 pels by 480 lines 60 Hz interlaced scanning of the SD grade of signal, thus to display the down-converted HD grade of signal. Of course, the SDTV can display the 720 pels by 480 lines 60 Hz interlaced scanning of the SD grade of signal, without any conversion.
FIG. 1
is a block diagram illustrating a video decoding device in a digital HDTV receiver in the background art. In the typical video decoding device, one pel consists of 8 bits, one macroblock has data structure of 16×16 pels, and the bitstream having the corresponding level to each grade which contains motion vector information is processed.
A variable length decoder (hereinafter “VLD”)
101
performs a variable length decoding for bitstream of data inputted and divides the decoded result into motion vectors, quantizing values, and discrete cosine transform (hereinafter “DCT”) coefficients. An inverse quantizer (hereinafter “IQ”)
102
performs an inverse quantization for the DCT coefficients outputted from the VLD
101
and outputs the inverse-quantized result to an inverse DCT (hereinafter “IDCT”)
103
.
The IDCT
103
performs an inverse DCT on the inverse-quantized DCT coefficients and outputs the IDCT processed result to an adder
104
. The adder
104
adds motion compensated data to the IDCT processed data to thereby restore the added data to the complete video and then stores the restored video in a frame memory
106
. The restored video signal is outputted for display and simultaneously fed back to a motion compensator
105
for the motion compensation. The motion compensator
105
outputs an appropriate pel value of the frame memory
106
to the adder
104
by using the motion vectors outputted from the VLD
101
.
For the HDTV receiver, the video decoding device receives and restores the HD grade of data and also receives and decodes the SD grade of data, without any problem. However, the video decoding device of the SDTV receiver can receive and restore the SD grade of data without any problem, but the SDTV requires conversion of the HD grade of data to the SD grade of data. In other words, the video decoding device of the SD grade of TV receiver performs data conversion of the HD grade of data into the SD grade of data. The data conversion process is completed through downsampling, i.e., filtering/decimation.
FIG. 2
is a block diagram illustrating the video decoding device of the SD grade of TV receiver for such a conversion. The data block size of 8×8 (shown as
201
) is reduced to data block size of 4×4. An IDCT/downsampler
202
performs the inverse discrete cosine transform for the vertical 8 pels in the data block size of 8×8 and for the horizontal 4 pels therein, to thereby reduce the data block size of 8×8 to the data block size of 8×4.
The thirty-two DCT coefficients, as shown by the black dot from the upper end of the data block
201
, are selected, and the inverse discrete cosine transform is performed to the 8×4 size of data block for the selected coefficients, thereby obtaining the downsampled image data. The coefficients in the data block size of 8×8 indicated by the white dots are discarded. As can be appreciated by one of ordinary skill, the methods of selecting the coefficients may vary.
The image data which is downsampled to the data block size of 8×4 is stored to a frame (or field) memory
204
through an adder
203
. To perform motion compensation, the image data of the frame memory
204
is horizontally upsampled to the data block size of 8×8 in an upsampler
205
. The upsampled image data is motion-compensated in a motion compensating circuit
206
by using the motion vectors information. Since the compensated data has the data block size of 8×8, a downsampler
207
performs a horizontal downsampling for the compensated data to a block size 8×4. As a result, the data downsampled to the block size of 8×4 is added to the adder
203
. Accordingly, the adder
203
outputs a desired video, e.g., the video downsampled to the data block size of 8×4.
The output value of the frame memory
204
is vertically downsampled to the data block size of 4×4 in a downsampler
208
. The downsampled data is outputted to a format converter
209
, which converts the downsampled data block size of 4×4 to be matched with the required size and aspect ratio to generate a final video output.
For example, assuming that the input video is the HD grade of 1080 lines and 1920 pels per line, the IDCT/downsampler
202
outputs 1080 lines and 960 pels per line and the downsampler
208
outputs 540 lines and 960 pels per line. Finally, the format converter
209
outputs 480 lines and 720 pels per line.
However, the conventional decoding device of the SD grade of digital TV receiver has various disadvantages. For example, since the HD grade of data is downsampled horizontally to ½ size, the size of the frame memory is reduced to ½ compared to the HD grade of decoder. Hence, the existing SD grade of decoder needs 4,590 kByte size memory which is half of the 9,180 kByte size memory of the HD grade of decoder. However, the 4,590 kByte size of the SDTV video decoder is larger than the standard 4 MByte DRAM, which increases cost.
SUMMARY OF THE INVENTION
An object of the present invention is to at least obviate one or more of the problems due to limitations and disadvantages of the related art or other conventional art.
Another object of the present invention is to decrease the memory size.
A further object of the present invention is to use standard memory size.
A further object of the invention is to convert HD signals to SD signals.
Still another object of the present invention is to decrease costs.
Another object of the invention is to provide a video decoding device of a digital TV receiver which separates pictures I and P from a picture B, downsamples each of the separated pictures and converts the downsampled pictures into a display size matched to a screen size and format, thus to have a small size of frame memory.
The present invention can be achieved in a whole or in parts by a video decoding device of a digital TV receiver that converts the picture B which is not an anchor frame into the display size matched to a screen aspect ratio and performs data encoding for the converted picture to thereby store the encoded result in a memory, and on the other hand, it performs
Bae Seong Ok
Cho Sanghee
Lee Heesub
Lim Il-Taek
Lim Kyoung-won
Diep Nhon
Fleshner & Kim LLP
LG Electronics Inc.
LandOfFree
Video decoding device of a TV receiver does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Video decoding device of a TV receiver, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Video decoding device of a TV receiver will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2993980