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avcodec/jpegxs_parser: fix bitstream assembly logic

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JPEG-XS streams can have the bytes corresponding to certain markers as part of
slice data, and no considerations were made for it, so we need to add checks
for false positives.

This fixes assembling several samples.

Signed-off-by: James Almer <jamrial@gmail.com>
This commit is contained in:
James Almer
2025-12-15 19:13:02 -03:00
parent 477e2dbc39
commit 1c804b349e
1 changed files with 55 additions and 11 deletions
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66
libavcodec/jpegxs_parser.c
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@@ -16,19 +16,28 @@
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "libavutil/mem.h"
#include "bytestream.h"
#include "get_bits.h"
#include "jpegxs.h"
#include "parser.h"
#include "parser_internal.h"
typedef struct JPEGXSParseContext {
ParseContext pc;
int eoc_found;
} JPEGXSParseContext;
/**
* Find the end of the current frame in the bitstream.
* @return the position of the first byte of the next frame, or -1
*/
static int jpegxs_find_frame_end(ParseContext *pc, const uint8_t *buf,
static int jpegxs_find_frame_end(JPEGXSParseContext *jpegxs, const uint8_t *buf,
int buf_size)
{
ParseContext *pc = &jpegxs->pc;
int pic_found, i = 0;
uint32_t state;
@@ -46,15 +55,41 @@ static int jpegxs_find_frame_end(ParseContext *pc, const uint8_t *buf,
}
}
if (pic_found) {
if (buf_size == 0)
return 0;
if (buf_size == 0) {
if (jpegxs->eoc_found) {
pc->frame_start_found = jpegxs->eoc_found = 0;
pc->state = -1;
}
return 0;
}
while (pic_found && i < buf_size) {
if (jpegxs->eoc_found) {
for(; i < buf_size; i++) {
state = (state << 8) | buf[i];
if ((state >> 16) == JPEGXS_MARKER_EOC) {
if ((uint16_t)state == JPEGXS_MARKER_SOC) {
// New image
pc->frame_start_found = jpegxs->eoc_found = 0;
pc->state = -1;
return i - 1;
} else {
// False positive
i++;
jpegxs->eoc_found = 0;
break;
}
}
}
}
for(; i < buf_size; i++) {
state = (state << 8) | buf[i];
if ((uint16_t)state == JPEGXS_MARKER_EOC) {
pc->frame_start_found = 0;
pc->state = -1;
return i + 1;
// EOC candidate
i++;
jpegxs->eoc_found = 1;
break;
}
}
}
@@ -181,10 +216,11 @@ static int jpegxsvideo_parse(AVCodecParserContext *s,
const uint8_t **poutbuf, int *poutbuf_size,
const uint8_t *buf, int buf_size)
{
ParseContext *pc = s->priv_data;
JPEGXSParseContext *jpegxs = s->priv_data;
ParseContext *pc = &jpegxs->pc;
int next;
next = jpegxs_find_frame_end(pc, buf, buf_size);
next = jpegxs_find_frame_end(jpegxs, buf, buf_size);
if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
*poutbuf = NULL;
@@ -199,9 +235,17 @@ static int jpegxsvideo_parse(AVCodecParserContext *s,
return next;
}
static av_cold void jpegxsparse_close(AVCodecParserContext *s)
{
JPEGXSParseContext *jpegxs = s->priv_data;
ParseContext *pc = &jpegxs->pc;
av_freep(&pc->buffer);
}
const FFCodecParser ff_jpegxs_parser = {
PARSER_CODEC_LIST(AV_CODEC_ID_JPEGXS),
.priv_data_size = sizeof(ParseContext),
.priv_data_size = sizeof(JPEGXSParseContext),
.parse = jpegxsvideo_parse,
.close = ff_parse_close,
.close = jpegxsparse_close,
};