Apparatus and method for encoding and decoding moving picture using adaptive scanning
Provided is an apparatus and method for encoding/decoding a moving picture based on adaptive scanning. The moving picture apparatus and method can increase a compression rate based on adaptive scanning by performing intra prediction onto blocks of a predetermined size, and scanning coefficients acquired from Discrete Cosine Transform (DCT) of a residue signal and quantization differently according to the intra prediction mode. The moving picture encoding apparatus includes: a mode selector for selecting and outputting a prediction mode; a predictor for predicting pixel values of pixels to be encoded of an input video based on the prediction mode to thereby output a residue signal block; a transform/quantization unit for performing DCT onto the residue signal block and quantizing the transformed residue signal block; and an encoder for adaptively scanning and encoding the quantized residue signal block based on the prediction mode.
1. A method of decoding motion pictures based on adaptive scanning, the method comprising:
performing entropy decoding of an encoded bitstream to obtain entropy-decoded signals;
determining a scanning method for the entropy-decoded signals;
recovering a picture from the entropy-decoded signals according to the scanning method; and
outputting the recovered picture;
wherein the scanning method is an adaptive scanning method according to an intra prediction mode for the entropy-decoded signals and comprises:
scanning entropy-decoded signals of a first row with priority so that all of the entropy-decoded signals of the first row are scanned prior to scanning entropy-decoded signals of any other row in response to the intra prediction mode being a vertical mode; and
scanning entropy-decoded signals of a first column with priority so that all of the entropy-decoded signals of the first column are scanned prior to scanning entropy-decoded signals of any other column in response to the intra prediction mode being a horizontal mode.
2. The method of claim 1 , wherein the method further comprises dequantizing and inverse-transforming the entropy-decoded signals after determining the scanning method for the entropy-decoded signals.
3. The method of claim 1 , wherein the recovering comprises first scanning entropy-decoded signals of blocks in a first row of blocks.
4. The method of claim 1 , wherein each of the entropy-decoded signals is a transformed and quantized residue signal representing a difference between a pixel value and a predicted pixel value.
5. A method of encoding images using adaptive scanning, the method comprising:
predicting pixel values of pixels of an input image based on an intra prediction mode;
outputting a residue signal block based on the predicted pixel values;
transforming the residue signal block to generate a transformed residue signal block;
quantizing the transformed residue signal block to generate a transformed and quantized residue signal block; and
adaptively scanning the transformed and quantized residue signal block based on the intra prediction mode;
wherein the adaptively scanning comprises:
scanning all coefficients of a first row of the transformed and quantized residue signal block before scanning any coefficient in any other row of the transformed and quantized residue signal block in response to the intra prediction mode being a vertical mode; and
scanning all coefficients of a first column of the transformed and quantized residue signal block before scanning any coefficient in any other column of the transformed and quantized residue signal block in response to the intra prediction mode being a horizontal mode.
6. The method of claim 5 , further comprising performing entropy encoding of coefficients of the transformed and quantized residue signal block acquired and arrayed by adaptively scanning the transformed and quantized residue signal block based on the intra prediction mode.
7. A non-transitory computer-readable medium storing a bitstream, the bitstream comprising:
block information; and
an intra prediction mode indicator;
wherein the block information is used to produce entropy-decoded signals; and
the intra prediction mode indicator indicates:
entropy-decoded signals of a first row are scanned with priority so that all of the entropy-decoded signals of the first row are scanned prior to scanning entropy-decoded signals of any other row in response to the intra prediction mode indicator indicating an intra prediction mode is a vertical mode; and
entropy-decoded signals of a first column are scanned with priority so that all of the entropy-decoded signals of the first column are scanned prior to scanning entropy-decoded signals of any other column in response to the intra prediction mode indicator indicating the intra prediction mode is a horizontal mode.
8. The non-transitory computer-readable medium of claim 7 , wherein the entropy-decoded signals are dequantized and inverse-transformed after a scanning method for the entropy-decoded signals is determined.
9. The non-transitory computer-readable medium of claim 7 , wherein each of the entropy-decoded signals is a transformed and quantized residue signal representing a difference between a pixel value and a predicted pixel value.