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authorAnton Khirnov <anton@khirnov.net>2021-04-08 10:46:54 +0200
committerMichael Niedermayer <michael@niedermayer.cc>2021-04-08 22:55:16 +0200
commit2a7f1bc282ddebee296bc0ca48a85bf01b626b3b (patch)
treed61867c24664f4f8eb682629c202067124ed08bb
parent25e794a1ea13ad0ed9f5c4792ab3727fe7a3ace1 (diff)
downloadffmpeg-2a7f1bc282ddebee296bc0ca48a85bf01b626b3b.tar.gz
lavc/pngdec: always create a copy for APNG_DISPOSE_OP_BACKGROUND
Calling av_frame_make_writable() from decoders is tricky, especially when frame threading is used. It is much simpler and safer to just make a private copy of the frame. This is not expected to have a major performance impact, since APNG_DISPOSE_OP_BACKGROUND is not used often and av_frame_make_writable() would typically make a copy anyway. Found-by: James Almer <jamrial@gmail.com> Signed-off-by: Michael Niedermayer <michael@niedermayer.cc> (cherry picked from commit b593abda6c642cb0c3959752dd235c2faf66837f) Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
-rw-r--r--libavcodec/pngdec.c18
1 files changed, 11 insertions, 7 deletions
diff --git a/libavcodec/pngdec.c b/libavcodec/pngdec.c
index 0ff81d740c..f3b212d508 100644
--- a/libavcodec/pngdec.c
+++ b/libavcodec/pngdec.c
@@ -89,6 +89,8 @@ typedef struct PNGDecContext {
int has_trns;
uint8_t transparent_color_be[6];
+ uint8_t *background_buf;
+ unsigned background_buf_allocated;
uint32_t palette[256];
uint8_t *crow_buf;
uint8_t *last_row;
@@ -1091,19 +1093,20 @@ static int handle_p_frame_apng(AVCodecContext *avctx, PNGDecContext *s,
ff_thread_await_progress(&s->last_picture, INT_MAX, 0);
// need to reset a rectangle to background:
- // create a new writable copy
if (s->last_dispose_op == APNG_DISPOSE_OP_BACKGROUND) {
- int ret = av_frame_make_writable(s->last_picture.f);
- if (ret < 0)
- return ret;
+ av_fast_malloc(&s->background_buf, &s->background_buf_allocated,
+ src_stride * p->height);
+ if (!s->background_buf)
+ return AVERROR(ENOMEM);
- src = s->last_picture.f->data[0];
- src_stride = s->last_picture.f->linesize[0];
+ memcpy(s->background_buf, src, src_stride * p->height);
for (y = s->last_y_offset; y < s->last_y_offset + s->last_h; y++) {
- memset(s->last_picture.f->data[0] + src_stride * y +
+ memset(s->background_buf + src_stride * y +
s->bpp * s->last_x_offset, 0, s->bpp * s->last_w);
}
+
+ src = s->background_buf;
}
// copy unchanged rectangles from the last frame
@@ -1738,6 +1741,7 @@ static av_cold int png_dec_end(AVCodecContext *avctx)
s->last_row_size = 0;
av_freep(&s->tmp_row);
s->tmp_row_size = 0;
+ av_freep(&s->background_buf);
av_freep(&s->iccp_data);
av_dict_free(&s->frame_metadata);