1/*
2 * JPEG2000 parser
3 * Copyright (c) 2020 Gautam Ramakrishnan
4 *
5 * This file is part of FFmpeg.
6 *
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22/**
23 * @file
24 * JPEG2000 parser.
25 */
26
27#include "parser.h"
28
29/* Whether frame is jp2 file or codestream
30*/
31enum frame_type {
32    jp2_file = 1,
33    j2k_cstream
34};
35
36typedef struct JPEG2000ParserContext {
37    ParseContext pc;
38    uint64_t bytes_read;
39    uint64_t fheader_state;
40    uint32_t skip_bytes; // skip bytes inside codestream data
41    enum frame_type ft; // 1 if file, 2 if codestream
42    uint8_t fheader_read; // are we reading
43    uint8_t reading_file_header;
44    uint8_t skipped_codestream;
45    uint8_t read_tp;
46    uint8_t in_codestream;
47} JPEG2000ParserContext;
48
49static inline void reset_context(JPEG2000ParserContext *m)
50{
51    ParseContext *pc = &m->pc;
52
53    pc->frame_start_found= 0;
54    pc->state64 = 0;
55    m->bytes_read = 0;
56    m->ft = 0;
57    m->skipped_codestream = 0;
58    m->fheader_read = 0;
59    m->skip_bytes = 0;
60    m->read_tp = 0;
61    m->in_codestream = 0;
62}
63
64/* Returns 1 if marker has any data which can be skipped
65*/
66static uint8_t info_marker(uint16_t marker)
67{
68    static const uint8_t lut[256] = {
69        1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
70        1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
71        1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
72        1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
73        1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, // 0xFF4F
74        1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
75        1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
76        1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
77        1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
78        0, 1, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, // 0xFF90 0xFF92 0xFF93
79        1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
80        1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
81        1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
82        1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, // 0xFFD9
83        1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
84        1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
85    };
86    return marker < 0xFF00 ? 0 : lut[marker & 0xFF];
87}
88
89/**
90 * Find the end of the current frame in the bitstream.
91 * @return the position of the first byte of the next frame, or -1
92 */
93static int find_frame_end(JPEG2000ParserContext *m, const uint8_t *buf, int buf_size)
94{
95    ParseContext *pc= &m->pc;
96    int i;
97    uint64_t state64 = pc->state64;
98    uint64_t bytes_read = m->bytes_read;
99
100    if (buf_size == 0) {
101        return 0;
102    }
103
104    for (i = 0; i < buf_size; i++) {
105        state64 = state64 << 8 | buf[i];
106        bytes_read++;
107        if (m->skip_bytes) {
108            // handle long skips
109            if (m->skip_bytes > 8) {
110                // need -9 else buf_size - i == 8 ==> i == buf_size after this,
111                // and thus i == buf_size + 1 after the loop
112                int skip = FFMIN(FFMIN((int64_t)m->skip_bytes - 8, buf_size - i - 9), INT_MAX);
113                if (skip > 0) {
114                    m->skip_bytes -= skip;
115                    i += skip;
116                    bytes_read += skip;
117                }
118            }
119            m->skip_bytes--;
120            continue;
121        }
122        if (m->read_tp) { // Find out how many bytes inside Tile part codestream to skip.
123            if (m->read_tp == 1) {
124                m->skip_bytes = (state64 & 0xFFFFFFFF) - 9 > 0?
125                                (state64 & 0xFFFFFFFF) - 9 : 0;
126            }
127            m->read_tp--;
128            continue;
129        }
130        if (m->fheader_read) {
131            if (m->fheader_read == 1) {
132                if (state64 == 0x6A5020200D0A870A) { // JP2 signature box value.
133                    if (pc->frame_start_found) {
134                        pc->frame_start_found = 0;
135                        reset_context(m);
136                        return i - 11;
137                    } else {
138                        pc->frame_start_found = 1;
139                        m->ft = jp2_file;
140                    }
141                }
142            }
143            m->fheader_read--;
144        }
145        if ((state64 & 0xFFFFFFFF) == 0x0000000C && bytes_read >= 3) { // Indicates start of JP2 file. Check signature next.
146            m->fheader_read = 8;
147        } else if ((state64 & 0xFFFF) == 0xFF4F) {
148            m->in_codestream = 1;
149            if (!pc->frame_start_found) {
150                pc->frame_start_found = 1;
151                m->ft = j2k_cstream;
152            } else if (pc->frame_start_found && m->ft == jp2_file && m->skipped_codestream) {
153                reset_context(m);
154                return i - 1;
155            }
156        } else if ((state64 & 0xFFFF) == 0xFFD9) {
157            if (pc->frame_start_found && m->ft == jp2_file) {
158                m->skipped_codestream = 1;
159            } else if (pc->frame_start_found && m->ft == j2k_cstream) {
160                reset_context(m);
161                return i + 1; // End of frame detected, return frame size.
162            }
163            m->in_codestream = 0;
164        } else if (m->in_codestream) {
165            if ((state64 & 0xFFFF) == 0xFF90) { // Are we in tile part header?
166                m->read_tp = 8;
167            } else if (info_marker((state64 & 0xFFFF0000)>>16) && pc->frame_start_found && (state64 & 0xFFFF)) {
168                // Calculate number of bytes to skip to get to end of the next marker.
169                m->skip_bytes = (state64 & 0xFFFF)-1;
170
171                // If the next marker is an info marker, skip to the end of of the marker length.
172                if (i + m->skip_bytes + 1 < buf_size) {
173                    uint32_t next_state = (buf[i + m->skip_bytes] << 8) | buf[i + m->skip_bytes + 1];
174                    if (info_marker(next_state)) {
175                        // Skip an additional 2 bytes to get to the end of the marker length.
176                        m->skip_bytes += 2;
177                    }
178                }
179            }
180        }
181    }
182
183    pc->state64 = state64;
184    m->bytes_read = bytes_read;
185    return END_NOT_FOUND;
186}
187
188static int jpeg2000_parse(AVCodecParserContext *s,
189                          AVCodecContext *avctx,
190                          const uint8_t **poutbuf, int *poutbuf_size,
191                          const uint8_t *buf, int buf_size)
192{
193    JPEG2000ParserContext *m = s->priv_data;
194    ParseContext *pc = &m->pc;
195    int next;
196
197    if(s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
198        next= buf_size;
199    } else {
200        next= find_frame_end(m, buf, buf_size);
201
202        if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
203            *poutbuf = NULL;
204            *poutbuf_size = 0;
205            return buf_size;
206        }
207    }
208
209    *poutbuf = buf;
210    *poutbuf_size = buf_size;
211    return next;
212}
213
214const AVCodecParser ff_jpeg2000_parser = {
215    .codec_ids      = { AV_CODEC_ID_JPEG2000 },
216    .priv_data_size = sizeof(JPEG2000ParserContext),
217    .parser_parse   = jpeg2000_parse,
218    .parser_close   = ff_parse_close,
219};
220