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avcodec/scpr: fix top left prediction for special case when x is 0 for keyframes 

Signed-off-by: Paul B Mahol <onemda@gmail.com>
This commit is contained in:
Paul B Mahol 2017-03-03 12:17:46 +01:00
parent 16abc10b09
commit 6d93e7d1a3
1 changed files with 25 additions and 10 deletions
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35
libavcodec/scpr.c
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@ -295,7 +295,8 @@ static int decompress_i(AVCodecContext *avctx, uint32_t *dst, int linesize)
SCPRContext *s = avctx->priv_data;
GetByteContext *gb = &s->gb;
int cx = 0, cx1 = 0, k = 0, clr = 0;
int run, r, g, b, off, y = 0, x = 0, ret;
int run, r, g, b, off, y = 0, x = 0, z, ret;
unsigned backstep = linesize - avctx->width;
const int cxshift = s->cxshift;
unsigned lx, ly, ptype;
@ -424,18 +425,25 @@ static int decompress_i(AVCodecContext *avctx, uint32_t *dst, int linesize)
while (run-- > 0) {
uint8_t *odst = (uint8_t *)dst;
if (y < 1 || y >= avctx->height)
if (y < 1 || y >= avctx->height ||
(y == 1 && x == 0))
return AVERROR_INVALIDDATA;
if (x == 0) {
z = backstep;
} else {
z = 0;
}
r = odst[(ly * linesize + lx) * 4] +
odst[((y * linesize + x) + off) * 4 + 4] -
odst[((y * linesize + x) + off) * 4];
odst[((y * linesize + x) + off - z) * 4 + 4] -
odst[((y * linesize + x) + off - z) * 4];
g = odst[(ly * linesize + lx) * 4 + 1] +
odst[((y * linesize + x) + off) * 4 + 5] -
odst[((y * linesize + x) + off) * 4 + 1];
odst[((y * linesize + x) + off - z) * 4 + 5] -
odst[((y * linesize + x) + off - z) * 4 + 1];
b = odst[(ly * linesize + lx) * 4 + 2] +
odst[((y * linesize + x) + off) * 4 + 6] -
odst[((y * linesize + x) + off) * 4 + 2];
odst[((y * linesize + x) + off - z) * 4 + 6] -
odst[((y * linesize + x) + off - z) * 4 + 2];
clr = ((b & 0xFF) << 16) + ((g & 0xFF) << 8) + (r & 0xFF);
dst[y * linesize + x] = clr;
lx = x;
@ -449,10 +457,17 @@ static int decompress_i(AVCodecContext *avctx, uint32_t *dst, int linesize)
break;
case 5:
while (run-- > 0) {
if (y < 1 || y >= avctx->height)
if (y < 1 || y >= avctx->height ||
(y == 1 && x == 0))
return AVERROR_INVALIDDATA;
clr = dst[y * linesize + x + off];
if (x == 0) {
z = backstep;
} else {
z = 0;
}
clr = dst[y * linesize + x + off - z];
dst[y * linesize + x] = clr;
lx = x;
ly = y;