Video predictive decoding method and apparatus
View Patent ↗A video predictive decoding method and apparatus for predicting a current block of a picture. The method includes storing at least one previous product in a memory. The previous product corresponds to a block of a plurality of blocks of the picture. The previous product is the product of a quantized AC coefficient and a quantization scale of the block that the previous product corresponds to. The method further includes determining which block to use as a prediction block from the plurality of blocks, reading from the memory at least one previous product corresponding to the prediction block, and calculating at least one quantized AC coefficient of the current block using the at least one previous product read from the memory.
1. A video decoding method implemented in a video decoding device for predicting a current block of a picture comprising:
storing at least one previous product in a memory, wherein the previous product corresponds to a block of a plurality of blocks of the picture, and the previous product is the product of a quantized AC coefficient and a quantization scale of the block that the previous product corresponds to;
determining which block to use as a prediction block from the plurality of blocks;
reading from the memory at least one previous product corresponding to the prediction block; and
calculating at least one quantized AC coefficient of the current block using the at least one previous product read from the memory.
2. The method of claim 1 wherein each quantized AC coefficient is a discrete cosine transform coefficient corresponding to a quantization operation.
3. The method of claim 1 wherein the at least one previous product is generated during an inverse quantization operation of the block to which the previous product corresponds.
4. The method of claim 3 wherein each quantized AC coefficient is the quantized AC coefficient QF[v][u] corresponding to the indexes [v, u], the quantization scale is the quantization scale QP, and the method further comprises:
transforming the quantized AC coefficient QF[v][u] into a second order intermediate coefficient F″[v][u] during the inverse quantization operation using one of the following operation equations:
(a). a first quantization method:
F
″
[
v
]
[
u
]
=
{
0
,
if
QF
[
v
]
[
u
]
=
0
(
(
2
×
MP
[
v
]
[
u
]
+
k
×
QP
)
×
W
[
w
]
[
v
]
[
u
]
)
/
16
,
if
QF
[
v
]
[
u
]
≠
0
wherein
k
=
{
0
,
intra
block
Sign
(
QF
[
v
]
[
u
]
)
,
non
-
intra
block
wherein the index w of the weighted matrix W[w][v][u] is equal to 0 or 1, the values corresponding to an intra coded block and a non-intra coded block respectively, and the function Sign(x) is defined as follows:
Sign
(
x
)
=
{
1
,
x
>=
0
-
1
,
x
<
0
;or
(b). a second quantization method:
F
″
[
v
]
[
u
]
=
{
0
,
if
QF
[
v
]
[
u
]
=
0
(
2
×
MP
[
v
]
[
u
]
+
QP
)
,
if
QF
[
v
]
[
u
]
≠
0
and
QP
is
odd
(
2
×
MP
[
v
]
[
u
]
+
QP
)
-
1
,
if
QF
[
v
]
[
u
]
≠
0
and
QP
is
even
F
″
[
v
]
[
u
]
=
Sign
(
QF
[
v
]
[
u
]
)
×
F
″
[
v
]
[
u
]
wherein the product MP[v][u]=QF[v][u]*QP, the at least one previous product is a sub set of the products MP[v][u] with the indexes [v, u] varied, and the function Sign(x) is defined as follows:
Sign
(
x
)
=
{
1
,
x
>=
0
-
1
,
x
<
0
5. The method of claim 1 wherein when the block determined to be used as the prediction block is outside a boundary of either a video object plane or a video packet corresponding to the picture, the method directly resets a prediction term of the quantized AC coefficient of the current block as zero to calculate the quantized AC coefficient of the current block rather than reading the at least one previous product of the prediction block from the memory.
6. The method of claim 1 wherein the prediction block is a left adjacent block or an upper adjacent block of the current block.
7. The method of claim 6 wherein when the prediction block is a left adjacent block of the current block, the memory is a register of a pipeline-based circuit.
8. The method of claim 1 wherein each quantized AC coefficient is the quantized AC coefficient QF[v][u] corresponding to the indexes [v,u], and the quantization scale is the quantization scale QP.
9. The method of claim 8 wherein when the prediction block is a left adjacent block (A) of the current block, the at least one previous product read is a product MPA[v] =QFA [v][0]*QPA corresponding to the left adjacent block, wherein QFA [v][0] is a first column quantized AC coefficient of the left adjacent block (A) and QPA is a quantization scale of the left adjacent block (A); and when the prediction block is a upper adjacent block (C) of the current block, the at least one previous product read is a product MPC[u]=QFC [0][u]*QPC corresponding to the upper adjacent block, wherein QFC [0][u] is a first row quantized AC coefficient of the upper adjacent block (C) and QPC is a quantization scale of the upper adjacent block (C).
10. The method of claim 9 wherein when the prediction block is a left adjacent block of the current block, the quantized AC coefficient QFX [v][0] of the current block (X) equals to PQFX [v][0]+MPA[v]//QPX, wherein QFX [v][0] is a first column quantized AC coefficient of the current block (X); when the prediction block is an upper adjacent block (C) of the current block, the quantized AC coefficient QFX [0][u] of the current block (X) equals to PQFX [0][u]+MPC[u]//QPX, wherein QFX [0][u] is a first row quantized AC coefficient of the current block (X); and the quantization scale QPX is a quantization scale of the current block, PQFX [v][0] and PQFX [0][u] are inverse scan calculation results generated during a previous stage decoding process of the current block, and the operator // denotes a division operation with the result thereof rounded to the nearest integer.
11. The method of claim 10 wherein the calculating step further comprises: calculating at least one first column quantized AC coefficient QFX[v][0] or at least one first row quantized AC coefficient QFX[0][u] of the current block using the at least one previous product MPA[v] or MPC[u] read; the method further comprises:
performing a saturation operation of the quantized AC coefficient QF [v][u], so the quantized AC coefficient QF [v][u] of the current block can be saturated in a predetermined numerical interval.
12. The method of claim 1 wherein the calculating step further comprises: calculating at least one first column quantized AC coefficient or at least one first row quantized AC coefficient of the current block using the at least one previous product read; the method further comprises:
performing a saturation operation of the quantized AC coefficient, so the quantized AC coefficient of the current block can be saturated in a predetermined numerical interval.