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WebP/Lossy: Reduce size of MacroblockMetadata from 80 to 20 bytes

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For a 1024x1024 image, saves about a quarter MB of memory use while
decoding (compared to the decompressed image data itself needing
4 MiB).  Not a huge win, but also very easy to do, so might as well.

No behavior change, no measurable performance impact.
This commit is contained in:
Nico Weber 2023-06-01 08:10:30 -04:00 • committed by Andreas Kling
parent 4df3b5e1d2
commit 24aa302e88
2 changed files with 3 additions and 3 deletions
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2
Userland/Libraries/LibGfx/ImageFormats/WebPLoaderLossy.cpp
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@ -405,7 +405,7 @@ ErrorOr<u8> tree_decode(BooleanDecoder& decoder, ReadonlySpan<TreeIndex> tree, R
struct MacroblockMetadata {
// https://datatracker.ietf.org/doc/html/rfc6386#section-10 "Segment-Based Feature Adjustments"
// Read only if `update_mb_segmentation_map` is set.
int segment_id { 0 }; // 0, 1, 2, or 3. Fits in two bits.
u8 segment_id { 0 }; // 0, 1, 2, or 3. Fits in two bits.
// https://datatracker.ietf.org/doc/html/rfc6386#section-11.1 "mb_skip_coeff"
bool skip_coefficients { false };

4
Userland/Libraries/LibGfx/ImageFormats/WebPLoaderLossyTables.h
View file

@ -22,7 +22,7 @@ const TreeIndex MACROBLOCK_SEGMENT_TREE[2 * (4 - 1)] = {
// https://datatracker.ietf.org/doc/html/rfc6386#section-8.2 "Tree Coding Example"
// Repeated in https://datatracker.ietf.org/doc/html/rfc6386#section-11.2 "Luma Modes"
enum IntraMacroblockMode {
enum IntraMacroblockMode : u8 {
DC_PRED, /* predict DC using row above and column to the left */
V_PRED, /* predict rows using row above */
H_PRED, /* predict columns using column to the left */
@ -45,7 +45,7 @@ static TreeIndex constexpr KEYFRAME_YMODE_TREE[2 * (num_ymodes - 1)] = {
static Prob constexpr KEYFRAME_YMODE_PROBABILITIES[num_ymodes - 1] = { 145, 156, 163, 128 };
// https://datatracker.ietf.org/doc/html/rfc6386#section-11.2 "Luma Modes"
enum IntraBlockMode {
enum IntraBlockMode : u8 {
B_DC_PRED, /* predict DC using row above and column
to the left */
B_TM_PRED, /* propagate second differences a la