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avcodec/mjpegdec: Avoid copying data when flipping image

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Basically reverts af15c17daa5d8d2940c0263ba4d3ecec761c11ee.
Flipping a picture by modifying the pointers is so common
that even users of direct rendering should take it into account.

Reviewed-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
This commit is contained in:
Andreas Rheinhardt 2022-04-14 16:43:53 +02:00
parent 888a02a126
commit 118b36f418
1 changed files with 6 additions and 16 deletions
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22
libavcodec/mjpegdec.c
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@ -2770,28 +2770,18 @@ the_end:
} }
} }
if (s->flipped && !s->rgb) { if (s->flipped && !s->rgb) {
int j;
ret = av_pix_fmt_get_chroma_sub_sample(s->avctx->pix_fmt, &hshift, &vshift); ret = av_pix_fmt_get_chroma_sub_sample(s->avctx->pix_fmt, &hshift, &vshift);
if (ret) if (ret)
return ret; return ret;
av_assert0(s->nb_components == av_pix_fmt_count_planes(s->picture_ptr->format)); av_assert0(s->nb_components == av_pix_fmt_count_planes(frame->format));
for (index=0; index<s->nb_components; index++) { for (index=0; index<s->nb_components; index++) {
uint8_t *dst = s->picture_ptr->data[index]; int h = frame->height;
int w = s->picture_ptr->width; if (index && index < 3)
int h = s->picture_ptr->height;
if(index && index<3){
w = AV_CEIL_RSHIFT(w, hshift);
h = AV_CEIL_RSHIFT(h, vshift); h = AV_CEIL_RSHIFT(h, vshift);
} if (frame->data[index]) {
if(dst){ frame->data[index] += (h - 1) * frame->linesize[index];
uint8_t *dst2 = dst + s->picture_ptr->linesize[index]*(h-1); frame->linesize[index] *= -1;
for (i=0; i<h/2; i++) {
for (j=0; j<w; j++)
FFSWAP(int, dst[j], dst2[j]);
dst += s->picture_ptr->linesize[index];
dst2 -= s->picture_ptr->linesize[index];
}
} }
} }
} }