124 lines
3.5 KiB
C
124 lines
3.5 KiB
C
/*
|
|
* PNG parser
|
|
* Copyright (c) 2009 Peter Holik
|
|
*
|
|
* 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
|
|
*/
|
|
|
|
/**
|
|
* @file
|
|
* PNG parser
|
|
*/
|
|
|
|
#include "parser.h"
|
|
|
|
#define PNGSIG 0x89504e470d0a1a0a
|
|
#define MNGSIG 0x8a4d4e470d0a1a0a
|
|
|
|
typedef struct PNGParseContext
|
|
{
|
|
ParseContext pc;
|
|
uint32_t index;
|
|
uint32_t chunk_length;
|
|
uint32_t remaining_size;
|
|
} PNGParseContext;
|
|
|
|
static int png_parse(AVCodecParserContext *s, AVCodecContext *avctx,
|
|
const uint8_t **poutbuf, int *poutbuf_size,
|
|
const uint8_t *buf, int buf_size)
|
|
{
|
|
PNGParseContext *ppc = s->priv_data;
|
|
int next = END_NOT_FOUND;
|
|
int i = 0;
|
|
|
|
s->pict_type = AV_PICTURE_TYPE_NONE;
|
|
|
|
*poutbuf_size = 0;
|
|
if (buf_size == 0)
|
|
return 0;
|
|
|
|
if (!ppc->pc.frame_start_found) {
|
|
uint64_t state64 = ppc->pc.state64;
|
|
for (; i < buf_size; i++) {
|
|
state64 = (state64 << 8) | buf[i];
|
|
if (state64 == PNGSIG || state64 == MNGSIG) {
|
|
i++;
|
|
ppc->pc.frame_start_found = 1;
|
|
break;
|
|
}
|
|
}
|
|
ppc->pc.state64 = state64;
|
|
} else
|
|
if (ppc->remaining_size) {
|
|
i = FFMIN(ppc->remaining_size, buf_size);
|
|
ppc->remaining_size -= i;
|
|
if (ppc->remaining_size)
|
|
goto flush;
|
|
if (ppc->index == -1) {
|
|
next = i;
|
|
goto flush;
|
|
}
|
|
}
|
|
|
|
for (;ppc->pc.frame_start_found && i < buf_size; i++) {
|
|
ppc->pc.state = (ppc->pc.state<<8) | buf[i];
|
|
if (ppc->index == 3) {
|
|
ppc->chunk_length = ppc->pc.state;
|
|
if (ppc->chunk_length > 0x7fffffff) {
|
|
ppc->index = ppc->pc.frame_start_found = 0;
|
|
goto flush;
|
|
}
|
|
ppc->chunk_length += 4;
|
|
} else if (ppc->index == 7) {
|
|
if (ppc->chunk_length >= buf_size - i)
|
|
ppc->remaining_size = ppc->chunk_length - buf_size + i + 1;
|
|
if (ppc->pc.state == MKBETAG('I', 'E', 'N', 'D')) {
|
|
if (ppc->remaining_size)
|
|
ppc->index = -1;
|
|
else
|
|
next = ppc->chunk_length + i + 1;
|
|
break;
|
|
} else {
|
|
ppc->index = 0;
|
|
if (ppc->remaining_size)
|
|
break;
|
|
else
|
|
i += ppc->chunk_length;
|
|
continue;
|
|
}
|
|
}
|
|
ppc->index++;
|
|
}
|
|
flush:
|
|
if (ff_combine_frame(&ppc->pc, next, &buf, &buf_size) < 0)
|
|
return buf_size;
|
|
|
|
ppc->index = ppc->pc.frame_start_found = 0;
|
|
|
|
*poutbuf = buf;
|
|
*poutbuf_size = buf_size;
|
|
return next;
|
|
}
|
|
|
|
AVCodecParser ff_png_parser = {
|
|
{ CODEC_ID_PNG },
|
|
sizeof(PNGParseContext),
|
|
NULL,
|
|
png_parse,
|
|
ff_parse_close,
|
|
};
|