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/*
* JPEG2000 parser
* Copyright (c) 2020 Gautam Ramakrishnan
*
* 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
* JPEG2000 parser.
*/
#include "parser.h"
/* Whether frame is jp2 file or codestream
*/
enum frame_type {
jp2_file = 1,
j2k_cstream
};
typedef struct JPEG2000ParserContext {
ParseContext pc;
uint64_t bytes_read;
uint64_t fheader_state;
uint32_t skip_bytes; // skip bytes inside codestream data
enum frame_type ft; // 1 if file, 2 if codestream
uint8_t fheader_read; // are we reading
uint8_t reading_file_header;
uint8_t skipped_codestream;
uint8_t read_tp;
uint8_t in_codestream;
} JPEG2000ParserContext;
static inline void reset_context(JPEG2000ParserContext *m)
{
ParseContext *pc = &m->pc;
pc->frame_start_found= 0;
pc->state = 0;
m->bytes_read = 0;
m->ft = 0;
m->skipped_codestream = 0;
m->fheader_read = 0;
m->skip_bytes = 0;
m->read_tp = 0;
m->in_codestream = 0;
}
/* Returns 1 if marker has any data which can be skipped
*/
static uint8_t info_marker(uint16_t marker)
{
if (marker == 0xFF92 || marker == 0xFF4F ||
marker == 0xFF90 || marker == 0xFF93 ||
marker == 0xFFD9)
return 0;
else
if (marker > 0xFF00) return 1;
return 0;
}
/**
* 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 find_frame_end(JPEG2000ParserContext *m, const uint8_t *buf, int buf_size)
{
ParseContext *pc= &m->pc;
int i;
uint32_t state, next_state;
uint64_t state64;
state= pc->state;
state64 = pc->state64;
if (buf_size == 0) {
return 0;
}
for (i = 0; i < buf_size; i++) {
state = state << 8 | buf[i];
state64 = state64 << 8 | buf[i];
m->bytes_read++;
if (m->skip_bytes) {
m->skip_bytes--;
continue;
}
if (m->read_tp) { // Find out how many bytes inside Tile part codestream to skip.
if (m->read_tp == 1) {
m->skip_bytes = (state64 & 0xFFFFFFFF) - 9 > 0?
(state64 & 0xFFFFFFFF) - 9 : 0;
}
m->read_tp--;
continue;
}
if (m->fheader_read) {
if (m->fheader_read == 1) {
if (state64 == 0x6A5020200D0A870A) { // JP2 signature box value.
if (pc->frame_start_found) {
pc->frame_start_found = 0;
reset_context(m);
return i - 11;
} else {
pc->frame_start_found = 1;
m->ft = jp2_file;
}
}
}
m->fheader_read--;
}
if (state == 0x0000000C && m->bytes_read >= 3) { // Indicates start of JP2 file. Check signature next.
m->fheader_read = 8;
} else if ((state & 0xFFFF) == 0xFF4F) {
m->in_codestream = 1;
if (!pc->frame_start_found) {
pc->frame_start_found = 1;
m->ft = j2k_cstream;
} else if (pc->frame_start_found && m->ft == jp2_file && m->skipped_codestream) {
reset_context(m);
return i - 1;
}
} else if ((state & 0xFFFF) == 0xFFD9) {
if (pc->frame_start_found && m->ft == jp2_file) {
m->skipped_codestream = 1;
} else if (pc->frame_start_found && m->ft == j2k_cstream) {
reset_context(m);
return i + 1; // End of frame detected, return frame size.
}
m->in_codestream = 0;
} else if (m->in_codestream && (state & 0xFFFF) == 0xFF90) { // Are we in tile part header?
m->read_tp = 8;
} else if (pc->frame_start_found && info_marker((state & 0xFFFF0000)>>16) && m->in_codestream && (state & 0xFFFF)) {
// Calculate number of bytes to skip to get to end of the next marker.
m->skip_bytes = (state & 0xFFFF)-1;
// If the next marker is an info marker, skip to the end of of the marker length.
if (i + m->skip_bytes + 1 < buf_size) {
next_state = (buf[i + m->skip_bytes] << 8) | buf[i + m->skip_bytes + 1];
if (info_marker(next_state)) {
// Skip an additional 2 bytes to get to the end of the marker length.
m->skip_bytes += 2;
}
}
}
}
pc->state = state;
pc->state64 = state64;
return END_NOT_FOUND;
}
static int jpeg2000_parse(AVCodecParserContext *s,
AVCodecContext *avctx,
const uint8_t **poutbuf, int *poutbuf_size,
const uint8_t *buf, int buf_size)
{
JPEG2000ParserContext *m = s->priv_data;
ParseContext *pc = &m->pc;
int next;
if(s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
next= buf_size;
} else {
next= find_frame_end(m, buf, buf_size);
if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
*poutbuf = NULL;
*poutbuf_size = 0;
return buf_size;
}
}
*poutbuf = buf;
*poutbuf_size = buf_size;
return next;
}
const AVCodecParser ff_jpeg2000_parser = {
.codec_ids = { AV_CODEC_ID_JPEG2000 },
.priv_data_size = sizeof(JPEG2000ParserContext),
.parser_parse = jpeg2000_parse,
.parser_close = ff_parse_close,
};
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