Deblocking filtering control
A first filter decision value is calculated for a block of pixels in a video frame based on pixel values of pixels in a first line of pixels in the block. A second filter decision value is also calculated for the block based on pixel values of pixels in a corresponding first line of pixels in a neighboring block in the video frame. The first filter decision value is used to determine how many pixels in a line of pixels in the block to filter relative to a block boundary between the block and the neighboring block. The second filter decision value is used to determine how many pixels in a corresponding line of pixels in the neighboring block to filter relative to the block boundary.
1. An encoder device comprising:
a memory configured to store video frames; and
a processing circuit configured to:
calculate a first filter decision value for a block of multiple pixels in a video frame of the video frames, by only using pixels p 2 i , p 1 i and p 0 i , based on:
wherein p 0 i denotes a pixel value of a pixel closest to, in a first line of pixels in said block, a block boundary to a neighboring block of multiple pixels in said video frame, p 1 i denotes a pixel value of a pixel next closest to, in said first line of pixels, said block boundary and p 2 i denotes a pixel value of a pixel second next closest to, in said first line of pixels, said block boundary;
calculate a second filter decision value for a neighboring block, by only using pixels q 2 i , q 1 i , and q 0 i , based on:
wherein q 0 i denotes a pixel value of a pixel in said neighboring block closest to, in a corresponding first line of pixels in said neighboring block, said block boundary, q 1 i denotes a pixel value of a pixel of said neighboring block next closest to, in said corresponding first line of pixels, said block boundary and q 2 i denotes a pixel value of a pixel in said neighboring block second next closest to, in said corresponding first line of pixels, said block boundary;
determine how many pixels in a first line of pixels in said block to filter relative to said block boundary based on a comparison of said first filter decision value to a first threshold value; and
determine how many pixels in a corresponding first line of pixels in said neighboring block to filter relative to said block boundary based on a comparison of said second filter decision value to a second threshold value;
wherein the processing circuit is
configured to: calculate said first filter decision
value as:
|p2 0 −2p1 0 +p0 0 |+|p2 3 −2p1 3 +p0 3 |
wherein p 0 0 denotes said pixel value of said pixel closest to, in said first line of pixels, said block boundary, p 1 0 denotes said pixel value of said pixel next closest to, in said first line of pixels, said block boundary, p 2 0 denotes said pixel value of said pixel second next closest to, in said first line of pixels, said block boundary, p 0 3 denotes a pixel value of a pixel closest to, in a second line of pixels in said block, said block boundary, p 1 3 denotes a pixel value of a pixel next closest to, in said second line of pixels, said block boundary and p 2 3 denotes a pixel value of a pixel second next closest to, in said second line of pixels, said block boundary; and
calculate said second filter decision value as:
|q2 0 −2q1 0 +q0 0 |+|q2 3 −2q1 3 +q0 3 |
wherein q 0 0 denotes said pixel value of said pixel in said neighboring block closest to, in said corresponding first line of pixels, said block boundary, q 1 0 denotes said pixel value of said pixel of said neighboring block next closest to, in said corresponding first line of pixels, said block boundary, q 2 0 denotes said pixel value of said pixel in said neighboring block second next closest to, in said corresponding first line of pixels, said block boundary, q 0 3 denotes a pixel value of a pixel in said neighboring block closest to, in a corresponding second line of pixels in said neighboring block, said block boundary, q 1 3 denotes a pixel value of a pixel of said neighboring block next closest to, in said corresponding second line of pixels, said block boundary and q 2 3 denotes a pixel value of a pixel in said neighboring block second next closest to, in said corresponding second line of pixels, said block boundary.
2. The encoder device of claim 1 , wherein the processing circuit is configured to:
i) determine to filter two pixels in said first line of pixels in said block relative to said block boundary if said first filter decision value is below said first threshold value and ii) determine to filter one pixel in said first line of pixels in said block relative to said block boundary if said first filter decision value is equal to or exceeds said first threshold value; and
i) determine to filter two pixels in said corresponding first line of pixels in said neighboring block relative to said block boundary if said second filter decision value is below said second threshold value and ii) determine to filter one pixel in said corresponding first line of pixels in said neighboring block relative to said block boundary if said second filter decision value is equal to or exceeds said second threshold value.
3. The encoder device of claim 1 , wherein the processing circuit is configured to: compare said first filter decision value to a first threshold value; and
compare said second filter decision value to a second threshold value, wherein
i) determine to filter two pixels in said first line of pixels in said block relative to said block boundary if said first filter decision value is below said first threshold value and ii) determine to filter no pixels in said first line of pixels in said block relative to said block boundary if said first filter decision value is equal to or exceeds said first threshold value; and
i) determine to filter two pixels in said corresponding first line of pixels in said neighboring block relative to said block boundary if said second filter decision value is below said second threshold value and ii) determine to filter no pixels in said corresponding first line of pixels in said neighboring block relative to said block boundary if said second filter decision value is equal to or exceeds said second threshold value.
4. The encoder device of claim 1 , wherein the processing circuit is configured to i) determine said first threshold value based on a quantization parameter associated with said block, and ii) determine said second threshold value based on a quantization parameter associated with said neighboring block.
5. The encoder device of claim 1 , wherein the processing circuit is configured to:
calculate a first offset Δ based on
9
x
(
q
0
j
-
p
0
j
)
-
3
x
(
q
1
j
-
p
1
j
)
16
,
where in p 0 j denotes a pixel value of a pixel closest to, in said first line of pixels, said block boundary, p 1 j denotes a pixel value of a pixel next closest to, in said first line of pixels, said block boundary, q 0 j denotes a pixel value of a pixel in said
neighboring block closest to, in said corresponding first line of pixels, said block boundary and q 1 j denotes a pixel value of a pixel of said neighboring block next closest to, in said corresponding first line of pixels, said block boundary;
modify said pixel value of said pixel closest to said block boundary in said first line of pixels by adding said first offset calculated by said first offset calculator to said pixel value of said pixel closest to said block boundary in said first line of pixels;
modify said pixel value of said pixel in said neighboring block closest to said block boundary in said corresponding first line of pixels by subtracting said first offset calculated by said first offset calculator from said pixel value of said pixel in said neighboring block closest to said block boundary in said corresponding first line of pixels;
calculate, if said first filter decision value is below said first threshold value, a second offset based on
p
0
j
=
p
2
j
-
2
p
1
j
,
=
2
Δ
4
,
wherein p 2 j denotes a pixel value of a pixel second next closest to, in said first line of pixels, said block boundary; modify, if said first filter decision value is below said first threshold, said pixel value of
said pixel next closest to said block boundary in said first line of pixels by adding said second offset calculated by said second offset calculator to said pixel value of said pixel next closest to said block boundary in said first line of pixels;
calculate, if said second filter decision value is below said second threshold value, a third offset based on
q
0
j
=
q
2
j
-
2
q
1
j
,
=
2
Δ
4
,
wherein q 2 j denotes a pixel value of a pixel in said neighboring block second next closest to, in said corresponding first line of pixels, said block boundary; and
modify, if said second filter decision value is below said second threshold, said pixel value of said pixel in said neighboring block next closest to said block boundary in said corresponding first line of pixels by adding said third offset to said pixel value of said pixel in said neighboring block next closest to said block boundary in said corresponding first line of pixels.
6. The encoder device of claim 1 , wherein the processing circuit is configured to:
compare a sum of said first filter decision value and said second filter decision value to a threshold value, wherein
determine, if said sum of said first filter decision value and said second filter decision value is below said threshold value, how many pixels in said first line of pixels in said block to filter relative to said block boundary based on said first filter decision value; and
determine, if said sum of said first filter decision value and said second filter decision value is below said threshold value, how many pixels in said corresponding first line of pixels in said neighboring block to filter relative to said block boundary based on said second filter decision value.
7. A user equipment comprising:
the encoder of claim 1 for encoding said video frames into encoded video frames, wherein said memory is further configured to store said encoded video frames.