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Code Issues Releases Activity

avcodec/gif_parser: fix possible wrong splitting of frames

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And properly signal keyframes.
This commit is contained in:
Paul B Mahol 2023-05-20 14:56:06 +02:00
parent b6066ceb8b
commit d81b6cbd42
1 changed files with 22 additions and 12 deletions
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34
libavcodec/gif_parser.c
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@ -24,9 +24,6 @@
* GIF parser
*/
#include "libavutil/bswap.h"
#include "libavutil/common.h"
#include "gif.h"
#include "parser.h"
@ -50,11 +47,13 @@ typedef struct GIFParseContext {
int block_size;
int etype;
int delay;
int keyframe;
} GIFParseContext;
static int gif_find_frame_end(GIFParseContext *g, const uint8_t *buf,
int buf_size, void *logctx)
{
ParseContext *pc = &g->pc;
int index, next = END_NOT_FOUND;
for (index = 0; index < buf_size; index++) {
@ -63,9 +62,10 @@ static int gif_find_frame_end(GIFParseContext *g, const uint8_t *buf,
!memcmp(buf + index, gif89a_sig, 6)) {
g->state = GIF_HEADER;
g->found_sig++;
g->keyframe = 1;
} else if (buf[index] == GIF_EXTENSION_INTRODUCER) {
g->state = GIF_EXTENSION;
g->found_start = 1;
g->found_start = pc->frame_start_found = 1;
} else if (buf[index] == GIF_IMAGE_SEPARATOR) {
g->state = GIF_IMAGE;
} else if (buf[index] == GIF_TRAILER) {
@ -93,7 +93,7 @@ static int gif_find_frame_end(GIFParseContext *g, const uint8_t *buf,
} else if (g->state == GIF_EXTENSION) {
if (g->found_start && g->found_end && g->found_sig) {
next = index;
g->found_start = 0;
g->found_start = pc->frame_start_found = 0;
g->found_end = 0;
g->index = 0;
g->gct_flag = 0;
@ -140,7 +140,7 @@ static int gif_find_frame_end(GIFParseContext *g, const uint8_t *buf,
}
g->index++;
} else if (g->state == GIF_IMAGE) {
if (g->index == 8) {
if (g->index == 9) {
g->gct_flag = !!(buf[index] & 0x80);
g->gct_size = 3 * (1 << ((buf[index] & 0x07) + 1));
}
@ -165,14 +165,24 @@ static int gif_parse(AVCodecParserContext *s, AVCodecContext *avctx,
GIFParseContext *g = s->priv_data;
int next;
next = gif_find_frame_end(g, buf, buf_size, avctx);
if (ff_combine_frame(&g->pc, next, &buf, &buf_size) < 0) {
*poutbuf = NULL;
*poutbuf_size = 0;
return buf_size;
*poutbuf_size = 0;
*poutbuf = NULL;
if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
next = buf_size;
} else {
next = gif_find_frame_end(g, buf, buf_size, avctx);
if (ff_combine_frame(&g->pc, next, &buf, &buf_size) < 0) {
*poutbuf = NULL;
*poutbuf_size = 0;
return buf_size;
}
}
s->duration = g->delay;
s->duration = g->delay ? g->delay : 10;
s->key_frame = g->keyframe;
s->pict_type = g->keyframe ? AV_PICTURE_TYPE_I : AV_PICTURE_TYPE_P;
g->keyframe = 0;
*poutbuf = buf;
*poutbuf_size = buf_size;