[FFmpeg-cvslog] lavc/pngdec: always create a copy for APNG_DISPOSE_OP_BACKGROUND
Anton Khirnov
git at videolan.org
Fri Apr 9 00:02:40 EEST 2021
ffmpeg | branch: release/4.4 | Anton Khirnov <anton at khirnov.net> | Thu Apr 8 10:46:54 2021 +0200| [2a7f1bc282ddebee296bc0ca48a85bf01b626b3b] | committer: Michael Niedermayer
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 at gmail.com>
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
(cherry picked from commit b593abda6c642cb0c3959752dd235c2faf66837f)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=2a7f1bc282ddebee296bc0ca48a85bf01b626b3b
---
libavcodec/pngdec.c | 18 +++++++++++-------
1 file 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);
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