[FFmpeg-cvslog] avcodec/s3tc: fix decoding when dimensions are not a multiple of 4
Tom Butterworth
git at videolan.org
Thu May 7 19:09:33 CEST 2015
ffmpeg | branch: master | Tom Butterworth <bangnoise at gmail.com> | Thu May 7 16:17:10 2015 +0100| [873d7e0e632645e67fdfd0e35fb27d477b11307a] | committer: Michael Niedermayer
avcodec/s3tc: fix decoding when dimensions are not a multiple of 4
Image dimensions were rounded down causing rows to wrap early if dimensions were not a multiple of 4.
Signed-off-by: Michael Niedermayer <michaelni at gmx.at>
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=873d7e0e632645e67fdfd0e35fb27d477b11307a
---
libavcodec/s3tc.c | 23 +++++++++++++----------
1 file changed, 13 insertions(+), 10 deletions(-)
diff --git a/libavcodec/s3tc.c b/libavcodec/s3tc.c
index 4743d78..9886b1d 100644
--- a/libavcodec/s3tc.c
+++ b/libavcodec/s3tc.c
@@ -26,6 +26,7 @@
#include "s3tc.h"
static inline void dxt1_decode_pixels(GetByteContext *gb, uint32_t *d,
+ unsigned int w, unsigned int h,
unsigned int qstride, unsigned int flag,
uint64_t alpha) {
unsigned int x, y, c0, c1, a = (!flag * 255u) << 24;
@@ -62,14 +63,16 @@ static inline void dxt1_decode_pixels(GetByteContext *gb, uint32_t *d,
colors[2] = rb2 + g2 + a;
pixels = bytestream2_get_le32(gb);
- for (y=0; y<4; y++) {
- for (x=0; x<4; x++) {
+ for (y=0; y<h; y++) {
+ for (x=0; x<w; x++) {
a = (alpha & 0x0f) << 28;
a += a >> 4;
d[x] = a + colors[pixels&3];
pixels >>= 2;
alpha >>= 4;
}
+ for (; x<4; x++)
+ pixels >>= 2;
d += qstride;
}
}
@@ -77,21 +80,21 @@ static inline void dxt1_decode_pixels(GetByteContext *gb, uint32_t *d,
void ff_decode_dxt1(GetByteContext *gb, uint8_t *dst,
const unsigned int w, const unsigned int h,
const unsigned int stride) {
- unsigned int bx, by, qstride = stride/4;
+ unsigned int x, y, qstride = stride/4;
uint32_t *d = (uint32_t *) dst;
- for (by=0; by < h/4; by++, d += stride-w)
- for (bx = 0; bx < w / 4; bx++, d += 4)
- dxt1_decode_pixels(gb, d, qstride, 0, 0LL);
+ for (y=0; y < h; y += 4, d += stride-w)
+ for (x = 0; x < w; d += FFMIN(4, w-x), x += 4)
+ dxt1_decode_pixels(gb, d, FFMIN(4, w-x), FFMIN(4, h-y), qstride, 0, 0LL);
}
void ff_decode_dxt3(GetByteContext *gb, uint8_t *dst,
const unsigned int w, const unsigned int h,
const unsigned int stride) {
- unsigned int bx, by, qstride = stride/4;
+ unsigned int x, y, qstride = stride/4;
uint32_t *d = (uint32_t *) dst;
- for (by=0; by < h/4; by++, d += stride-w)
- for (bx = 0; bx < w / 4; bx++, d += 4)
- dxt1_decode_pixels(gb, d, qstride, 1, bytestream2_get_le64(gb));
+ for (y=0; y < h; y += 4, d += stride-w)
+ for (x = 0; x < w; d += FFMIN(4, w-x), x += 4)
+ dxt1_decode_pixels(gb, d, FFMIN(4, w-x), FFMIN(4, h-y), qstride, 1, bytestream2_get_le64(gb));
}
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