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FFmpeg/libavcodec/jpegxs_parser.c
James Almer 1c804b349e avcodec/jpegxs_parser: fix bitstream assembly logic 
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>
2025-12-16 10:38:56 -03:00

252 lines
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/*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* 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(JPEGXSParseContext *jpegxs, const uint8_t *buf,
int buf_size)
{
ParseContext *pc = &jpegxs->pc;
int pic_found, i = 0;
uint32_t state;
pic_found = pc->frame_start_found;
state = pc->state;
if (!pic_found) {
for (i = 0; i < buf_size; i++) {
state = (state << 8) | buf[i];
if ((uint16_t)state == JPEGXS_MARKER_SOC) {
i++;
pic_found = 1;
break;
}
}
}
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) {
// EOC candidate
i++;
jpegxs->eoc_found = 1;
break;
}
}
}
pc->frame_start_found = pic_found;
pc->state = state;
return END_NOT_FOUND;
}
static int jpegxs_parse_frame(AVCodecParserContext *s, AVCodecContext *avctx,
const uint8_t *buf, int buf_size)
{
GetByteContext gbc;
GetBitContext gb;
int8_t bpc[3], log2_chroma_w[3], log2_chroma_h[3];
int size, marker, components;
s->key_frame = 1;
s->pict_type = AV_PICTURE_TYPE_I;
if (buf_size < 4)
return 0;
bytestream2_init(&gbc, buf, buf_size);
marker = bytestream2_get_be16(&gbc);
if (marker != JPEGXS_MARKER_SOC)
return 0;
marker = bytestream2_get_be16(&gbc);
if (marker != JPEGXS_MARKER_CAP)
return 0;
size = bytestream2_get_be16(&gbc);
bytestream2_skip(&gbc, FFMAX(size - 2, 0));
marker = bytestream2_get_be16(&gbc);
if (marker != JPEGXS_MARKER_PIH)
return 0;
size = bytestream2_get_be16(&gbc);
bytestream2_skip(&gbc, 4); // Lcod
bytestream2_skip(&gbc, 2); // Ppih
bytestream2_skip(&gbc, 2); // Plev
size -= 8;
s->width = bytestream2_get_be16(&gbc);
s->height = bytestream2_get_be16(&gbc);
size -= 4;
bytestream2_skip(&gbc, 2); // Cw
bytestream2_skip(&gbc, 2); // Hsl
size -= 4;
components = bytestream2_get_byte(&gbc);
if (components != 1 && components != 3)
return 0;
size--;
bytestream2_skip(&gbc, FFMAX(size - 2, 0));
while (bytestream2_get_bytes_left(&gbc) > 0) {
marker = bytestream2_get_be16(&gbc);
switch(marker) {
case JPEGXS_MARKER_CDT:
size = bytestream2_get_be16(&gbc);
init_get_bits8(&gb, gbc.buffer, FFMIN(FFMAX(size - 2, 0), bytestream2_get_bytes_left(&gbc)));
for (int i = 0; i < components; i++) {
bpc[i] = get_bits(&gb, 8);
if (i && bpc[i] != bpc[i-1])
return 0;
log2_chroma_w[i] = get_bits(&gb, 4);
log2_chroma_h[i] = get_bits(&gb, 4);
if (log2_chroma_h[i] > log2_chroma_w[i])
return 0;
if (i == 2 && (log2_chroma_h[2] != log2_chroma_h[1] ||
log2_chroma_w[2] != log2_chroma_w[1]))
return 0;
}
switch (bpc[0]) {
case 8:
if (components == 1) s->format = AV_PIX_FMT_GRAY8;
else if (log2_chroma_w[1] == 1 && log2_chroma_h[1] == 1) s->format = AV_PIX_FMT_YUV444P;
else if (log2_chroma_w[1] == 2 && log2_chroma_h[1] == 1) s->format = AV_PIX_FMT_YUV422P;
else s->format = AV_PIX_FMT_YUV420P;
break;
case 10:
if (components == 1) s->format = AV_PIX_FMT_GRAY10;
else if (log2_chroma_w[1] == 1 && log2_chroma_h[1] == 1) s->format = AV_PIX_FMT_YUV444P10;
else if (log2_chroma_w[1] == 2 && log2_chroma_h[1] == 1) s->format = AV_PIX_FMT_YUV422P10;
else s->format = AV_PIX_FMT_YUV420P10;
break;
case 12:
if (components == 1) s->format = AV_PIX_FMT_GRAY12;
else if (log2_chroma_w[1] == 1 && log2_chroma_h[1] == 1) s->format = AV_PIX_FMT_YUV444P12;
else if (log2_chroma_w[1] == 2 && log2_chroma_h[1] == 1) s->format = AV_PIX_FMT_YUV422P12;
else s->format = AV_PIX_FMT_YUV420P12;
break;
case 14:
if (components == 1) s->format = AV_PIX_FMT_GRAY14;
else if (log2_chroma_w[1] == 1 && log2_chroma_h[1] == 1) s->format = AV_PIX_FMT_YUV444P14;
else if (log2_chroma_w[1] == 2 && log2_chroma_h[1] == 1) s->format = AV_PIX_FMT_YUV422P14;
else s->format = AV_PIX_FMT_YUV420P14;
break;
default:
s->format = AV_PIX_FMT_NONE;
break;
}
return 0;
default:
size = bytestream2_get_be16(&gbc);
bytestream2_skip(&gbc, FFMAX(size - 2, 0));
break;
}
}
return 0;
}
static int jpegxsvideo_parse(AVCodecParserContext *s,
AVCodecContext *avctx,
const uint8_t **poutbuf, int *poutbuf_size,
const uint8_t *buf, int buf_size)
{
JPEGXSParseContext *jpegxs = s->priv_data;
ParseContext *pc = &jpegxs->pc;
int next;
next = jpegxs_find_frame_end(jpegxs, buf, buf_size);
if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
*poutbuf = NULL;
*poutbuf_size = 0;
return buf_size;
}
jpegxs_parse_frame(s, avctx, buf, buf_size);
*poutbuf = buf;
*poutbuf_size = buf_size;
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(JPEGXSParseContext),
.parse = jpegxsvideo_parse,
.close = jpegxsparse_close,
};
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