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webpdec: Fix decoding of the huffman group indices.

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Per the specification, "The red and green components of a pixel
define the meta Huffman code used in a particular block of the ARGB
image."
This commit is contained in:
Justin Ruggles 2014-07-03 11:28:17 -04:00
parent 9279826008
commit c6698dfe7c
1 changed files with 6 additions and 2 deletions
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8
libavcodec/webp.c
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@ -476,7 +476,9 @@ static int decode_entropy_image(WebPContext *s)
max = 0;
for (y = 0; y < img->frame->height; y++) {
for (x = 0; x < img->frame->width; x++) {
int p = GET_PIXEL_COMP(img->frame, x, y, 2);
int p0 = GET_PIXEL_COMP(img->frame, x, y, 1);
int p1 = GET_PIXEL_COMP(img->frame, x, y, 2);
int p = p0 << 8 | p1;
max = FFMAX(max, p);
}
}
@ -561,7 +563,9 @@ static HuffReader *get_huffman_group(WebPContext *s, ImageContext *img,
if (gimg->size_reduction > 0) {
int group_x = x >> gimg->size_reduction;
int group_y = y >> gimg->size_reduction;
group = GET_PIXEL_COMP(gimg->frame, group_x, group_y, 2);
int g0 = GET_PIXEL_COMP(gimg->frame, group_x, group_y, 1);
int g1 = GET_PIXEL_COMP(gimg->frame, group_x, group_y, 2);
group = g0 << 8 | g1;
}
return &img->huffman_groups[group * HUFFMAN_CODES_PER_META_CODE];