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avcodec/mss2: calculate draw region and revise split position

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for videos with wmv9 rectangles, the region drawn by ff_mss12_decode_rect
may be less than the entire video area. the wmv9 rectangles are used to
calculate the ff_mss12_decode_rect draw region.

Fixes tickets #3255 and #4043
This commit is contained in:
Peter Ross 2022-10-18 15:52:15 +11:00
parent 639b7af493
commit 31162eb949
1 changed files with 66 additions and 4 deletions
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70
libavcodec/mss2.c
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@ -468,6 +468,39 @@ struct Rectangle {
int coded, x, y, w, h;
};
struct Rectangle2 {
int left, right, top, bottom;
};
static void calc_draw_region(struct Rectangle2 * draw, const struct Rectangle2 * rect)
{
#define COMPARE(top, bottom, left, right) \
if (rect->top <= draw->top && rect->bottom >= draw->bottom) { \
if (rect->left <= draw->left && rect->right >= draw->left) \
draw->left = FFMIN(rect->right, draw->right); \
\
if (rect->right >= draw->right) { \
if (rect->left >= draw->left) { \
if (rect->left < draw->right) \
draw->right = rect->left; \
} else { \
draw->right = draw->left; \
} \
} \
}
COMPARE(top, bottom, left, right)
COMPARE(left, right, top, bottom)
}
static int calc_split_position(int split_position, const struct Rectangle2 * rect, int height)
{
if (rect->top || rect->bottom != height)
split_position = rect->top + split_position * (rect->bottom - rect->top) / height;
return av_clip(split_position, rect->top + 1, rect->bottom - 1);
}
#define MAX_WMV9_RECTANGLES 20
#define ARITH2_PADDING 2
@ -485,6 +518,7 @@ static int mss2_decode_frame(AVCodecContext *avctx, AVFrame *frame,
int keyframe, has_wmv9, has_mv, is_rle, is_555, ret;
struct Rectangle wmv9rects[MAX_WMV9_RECTANGLES], *r;
struct Rectangle2 draw;
int used_rects = 0, i, implicit_rect = 0, av_uninit(wmv9_mask);
if ((ret = init_get_bits8(&gb, buf, buf_size)) < 0)
@ -671,11 +705,32 @@ static int mss2_decode_frame(AVCodecContext *avctx, AVFrame *frame,
bytestream2_init(&gB, buf, buf_size + ARITH2_PADDING);
arith2_init(&acoder, &gB);
c->keyframe = keyframe;
if (c->corrupted = ff_mss12_decode_rect(&ctx->sc[0], &acoder, 0, 0,
avctx->width,
ctx->split_position))
draw.left = 0;
draw.top = 0;
draw.right = avctx->width;
draw.bottom = avctx->height;
if (wmv9_mask == -1) {
for (i = 0; i < used_rects; i++) {
struct Rectangle2 r;
r.left = wmv9rects[i].x;
r.top = wmv9rects[i].y;
r.right = r.left + wmv9rects[i].w;
r.bottom = r.top + wmv9rects[i].h;
calc_draw_region(&draw, &r);
}
}
if (draw.left >= avctx->width || draw.right > avctx->width ||
draw.top >= avctx->height || draw.bottom > avctx->height)
return AVERROR_INVALIDDATA;
if (c->slice_split && draw.bottom - draw.top >= 10) {
ctx->split_position = calc_split_position(ctx->split_position, &draw, avctx->height);
if (c->corrupted = ff_mss12_decode_rect(&ctx->sc[0], &acoder, 0, draw.top,
avctx->width,
ctx->split_position - draw.top))
return AVERROR_INVALIDDATA;
buf += arith2_get_consumed_bytes(&acoder);
buf_size -= arith2_get_consumed_bytes(&acoder);
if (c->slice_split) {
@ -686,7 +741,14 @@ static int mss2_decode_frame(AVCodecContext *avctx, AVFrame *frame,
if (c->corrupted = ff_mss12_decode_rect(&ctx->sc[1], &acoder, 0,
ctx->split_position,
avctx->width,
avctx->height - ctx->split_position))
draw.bottom - ctx->split_position))
return AVERROR_INVALIDDATA;
buf += arith2_get_consumed_bytes(&acoder);
buf_size -= arith2_get_consumed_bytes(&acoder);
}
} else {
if (c->corrupted = ff_mss12_decode_rect(&ctx->sc[0], &acoder, draw.left, draw.top,
draw.right - draw.left, draw.bottom - draw.top))
return AVERROR_INVALIDDATA;
buf += arith2_get_consumed_bytes(&acoder);