220 lines
7.5 KiB
C
220 lines
7.5 KiB
C
/*
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* JPEG2000 parser
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* Copyright (c) 2020 Gautam Ramakrishnan
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/**
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* @file
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* JPEG2000 parser.
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*/
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#include "parser.h"
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/* Whether frame is jp2 file or codestream
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*/
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enum frame_type {
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jp2_file = 1,
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j2k_cstream
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};
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typedef struct JPEG2000ParserContext {
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ParseContext pc;
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uint64_t bytes_read;
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uint64_t fheader_state;
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uint32_t skip_bytes; // skip bytes inside codestream data
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enum frame_type ft; // 1 if file, 2 if codestream
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uint8_t fheader_read; // are we reading
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uint8_t reading_file_header;
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uint8_t skipped_codestream;
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uint8_t read_tp;
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uint8_t in_codestream;
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} JPEG2000ParserContext;
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static inline void reset_context(JPEG2000ParserContext *m)
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{
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ParseContext *pc = &m->pc;
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pc->frame_start_found= 0;
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pc->state64 = 0;
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m->bytes_read = 0;
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m->ft = 0;
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m->skipped_codestream = 0;
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m->fheader_read = 0;
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m->skip_bytes = 0;
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m->read_tp = 0;
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m->in_codestream = 0;
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}
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/* Returns 1 if marker has any data which can be skipped
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*/
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static uint8_t info_marker(uint16_t marker)
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{
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static const uint8_t lut[256] = {
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1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
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1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
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1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
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1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
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1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, // 0xFF4F
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1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
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1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
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1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
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1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
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0, 1, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, // 0xFF90 0xFF92 0xFF93
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1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
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1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
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1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
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1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, // 0xFFD9
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1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
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1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
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};
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return marker < 0xFF00 ? 0 : lut[marker & 0xFF];
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}
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/**
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* Find the end of the current frame in the bitstream.
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* @return the position of the first byte of the next frame, or -1
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*/
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static int find_frame_end(JPEG2000ParserContext *m, const uint8_t *buf, int buf_size)
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{
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ParseContext *pc= &m->pc;
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int i;
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uint64_t state64 = pc->state64;
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uint64_t bytes_read = m->bytes_read;
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if (buf_size == 0) {
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return 0;
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}
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for (i = 0; i < buf_size; i++) {
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state64 = state64 << 8 | buf[i];
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bytes_read++;
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if (m->skip_bytes) {
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// handle long skips
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if (m->skip_bytes > 8) {
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// need -9 else buf_size - i == 8 ==> i == buf_size after this,
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// and thus i == buf_size + 1 after the loop
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int skip = FFMIN(FFMIN((int64_t)m->skip_bytes - 8, buf_size - i - 9), INT_MAX);
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if (skip > 0) {
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m->skip_bytes -= skip;
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i += skip;
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bytes_read += skip;
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}
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}
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m->skip_bytes--;
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continue;
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}
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if (m->read_tp) { // Find out how many bytes inside Tile part codestream to skip.
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if (m->read_tp == 1) {
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m->skip_bytes = (state64 & 0xFFFFFFFF) - 9 > 0?
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(state64 & 0xFFFFFFFF) - 9 : 0;
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}
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m->read_tp--;
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continue;
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}
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if (m->fheader_read) {
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if (m->fheader_read == 1) {
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if (state64 == 0x6A5020200D0A870A) { // JP2 signature box value.
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if (pc->frame_start_found) {
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pc->frame_start_found = 0;
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reset_context(m);
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return i - 11;
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} else {
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pc->frame_start_found = 1;
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m->ft = jp2_file;
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}
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}
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}
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m->fheader_read--;
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}
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if ((state64 & 0xFFFFFFFF) == 0x0000000C && bytes_read >= 3) { // Indicates start of JP2 file. Check signature next.
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m->fheader_read = 8;
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} else if ((state64 & 0xFFFF) == 0xFF4F) {
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m->in_codestream = 1;
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if (!pc->frame_start_found) {
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pc->frame_start_found = 1;
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m->ft = j2k_cstream;
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} else if (pc->frame_start_found && m->ft == jp2_file && m->skipped_codestream) {
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reset_context(m);
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return i - 1;
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}
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} else if ((state64 & 0xFFFF) == 0xFFD9) {
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if (pc->frame_start_found && m->ft == jp2_file) {
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m->skipped_codestream = 1;
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} else if (pc->frame_start_found && m->ft == j2k_cstream) {
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reset_context(m);
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return i + 1; // End of frame detected, return frame size.
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}
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m->in_codestream = 0;
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} else if (m->in_codestream) {
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if ((state64 & 0xFFFF) == 0xFF90) { // Are we in tile part header?
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m->read_tp = 8;
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} else if (info_marker((state64 & 0xFFFF0000)>>16) && pc->frame_start_found && (state64 & 0xFFFF)) {
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// Calculate number of bytes to skip to get to end of the next marker.
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m->skip_bytes = (state64 & 0xFFFF)-1;
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// If the next marker is an info marker, skip to the end of of the marker length.
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if (i + m->skip_bytes + 1 < buf_size) {
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uint32_t next_state = (buf[i + m->skip_bytes] << 8) | buf[i + m->skip_bytes + 1];
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if (info_marker(next_state)) {
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// Skip an additional 2 bytes to get to the end of the marker length.
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m->skip_bytes += 2;
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}
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}
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}
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}
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}
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pc->state64 = state64;
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m->bytes_read = bytes_read;
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return END_NOT_FOUND;
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}
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static int jpeg2000_parse(AVCodecParserContext *s,
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AVCodecContext *avctx,
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const uint8_t **poutbuf, int *poutbuf_size,
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const uint8_t *buf, int buf_size)
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{
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JPEG2000ParserContext *m = s->priv_data;
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ParseContext *pc = &m->pc;
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int next;
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if(s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
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next= buf_size;
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} else {
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next= find_frame_end(m, buf, buf_size);
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if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
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*poutbuf = NULL;
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*poutbuf_size = 0;
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return buf_size;
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}
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}
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*poutbuf = buf;
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*poutbuf_size = buf_size;
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return next;
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}
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const AVCodecParser ff_jpeg2000_parser = {
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.codec_ids = { AV_CODEC_ID_JPEG2000 },
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.priv_data_size = sizeof(JPEG2000ParserContext),
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.parser_parse = jpeg2000_parse,
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.parser_close = ff_parse_close,
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};
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