4 * Copyright (c) 2007-2008 Marco Gerards <marco@gnu.org>
5 * Copyright (c) 2008 BBC, Anuradha Suraparaju <asuraparaju@gmail.com>
7 * This file is part of FFmpeg.
9 * FFmpeg is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU Lesser General Public
11 * License as published by the Free Software Foundation; either
12 * version 2.1 of the License, or (at your option) any later version.
14 * FFmpeg is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17 * Lesser General Public License for more details.
19 * You should have received a copy of the GNU Lesser General Public
20 * License along with FFmpeg; if not, write to the Free Software
21 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
27 * @author Marco Gerards <marco@gnu.org>
32 #include "libavutil/intreadwrite.h"
33 #include "libavutil/mem.h"
37 #define DIRAC_PARSE_INFO_PREFIX 0x42424344
40 * Find the end of the current frame in the bitstream.
41 * @return the position of the first byte of the next frame or -1
43 typedef struct DiracParseContext {
47 int header_bytes_needed;
56 static int find_frame_end(DiracParseContext *pc,
57 const uint8_t *buf, int buf_size)
59 uint32_t state = pc->state;
63 for (i = 0; i < buf_size; i++) {
64 state = (state << 8) | buf[i];
65 if (state == DIRAC_PARSE_INFO_PREFIX) {
68 pc->header_bytes_needed = 9;
77 for (; i < buf_size; i++) {
78 if (state == DIRAC_PARSE_INFO_PREFIX) {
79 if ((buf_size - i) >= pc->header_bytes_needed) {
81 return i + pc->header_bytes_needed;
83 pc->header_bytes_needed = 9 - (buf_size - i);
87 state = (state << 8) | buf[i];
94 typedef struct DiracParseUnit {
100 static int unpack_parse_unit(DiracParseUnit *pu, DiracParseContext *pc,
103 uint8_t *start = pc->buffer + offset;
104 uint8_t *end = pc->buffer + pc->index;
105 if (start < pc->buffer || (start + 13 > end))
107 pu->pu_type = start[4];
109 pu->next_pu_offset = AV_RB32(start + 5);
110 pu->prev_pu_offset = AV_RB32(start + 9);
112 if (pu->pu_type == 0x10 && pu->next_pu_offset == 0)
113 pu->next_pu_offset = 13;
118 static int dirac_combine_frame(AVCodecParserContext *s, AVCodecContext *avctx,
119 int next, const uint8_t **buf, int *buf_size)
121 int parse_timing_info = (s->pts == AV_NOPTS_VALUE &&
122 s->dts == AV_NOPTS_VALUE);
123 DiracParseContext *pc = s->priv_data;
125 if (pc->overread_index) {
126 memcpy(pc->buffer, pc->buffer + pc->overread_index,
127 pc->index - pc->overread_index);
128 pc->index -= pc->overread_index;
129 pc->overread_index = 0;
130 if (*buf_size == 0 && pc->buffer[4] == 0x10) {
132 *buf_size = pc->index;
138 /* Found a possible frame start but not a frame end */
140 av_fast_realloc(pc->buffer, &pc->buffer_size,
141 pc->index + (*buf_size - pc->sync_offset));
143 return AVERROR(ENOMEM);
144 pc->buffer = new_buffer;
145 memcpy(pc->buffer + pc->index, (*buf + pc->sync_offset),
146 *buf_size - pc->sync_offset);
147 pc->index += *buf_size - pc->sync_offset;
150 /* Found a possible frame start and a possible frame end */
151 DiracParseUnit pu1, pu;
152 void *new_buffer = av_fast_realloc(pc->buffer, &pc->buffer_size,
155 return AVERROR(ENOMEM);
156 pc->buffer = new_buffer;
157 memcpy(pc->buffer + pc->index, *buf, next);
160 /* Need to check if we have a valid Parse Unit. We can't go by the
161 * sync pattern 'BBCD' alone because arithmetic coding of the residual
162 * and motion data can cause the pattern triggering a false start of
163 * frame. So check if the previous parse offset of the next parse unit
164 * is equal to the next parse offset of the current parse unit then
165 * we can be pretty sure that we have a valid parse unit */
166 if (!unpack_parse_unit(&pu1, pc, pc->index - 13) ||
167 !unpack_parse_unit(&pu, pc, pc->index - 13 - pu1.prev_pu_offset) ||
168 pu.next_pu_offset != pu1.prev_pu_offset ||
169 pc->index < pc->dirac_unit_size + 13LL + pu1.prev_pu_offset
172 *buf_size = next - 9;
173 pc->header_bytes_needed = 9;
177 /* All non-frame data must be accompanied by frame data. This is to
178 * ensure that pts is set correctly. So if the current parse unit is
179 * not frame data, wait for frame data to come along */
181 pc->dirac_unit = pc->buffer + pc->index - 13 -
182 pu1.prev_pu_offset - pc->dirac_unit_size;
184 pc->dirac_unit_size += pu.next_pu_offset;
186 if ((pu.pu_type & 0x08) != 0x08) {
187 pc->header_bytes_needed = 9;
192 /* Get the picture number to set the pts and dts*/
193 if (parse_timing_info) {
194 uint8_t *cur_pu = pc->buffer +
195 pc->index - 13 - pu1.prev_pu_offset;
196 int pts = AV_RB32(cur_pu + 13);
197 if (s->last_pts == 0 && s->last_dts == 0)
200 s->dts = s->last_dts + 1;
202 if (!avctx->has_b_frames && (cur_pu[4] & 0x03))
203 avctx->has_b_frames = 1;
205 if (avctx->has_b_frames && s->pts == s->dts)
206 s->pict_type = AV_PICTURE_TYPE_B;
208 /* Finally have a complete Dirac data unit */
209 *buf = pc->dirac_unit;
210 *buf_size = pc->dirac_unit_size;
212 pc->dirac_unit_size = 0;
213 pc->overread_index = pc->index - 13;
214 pc->header_bytes_needed = 9;
219 static int dirac_parse(AVCodecParserContext *s, AVCodecContext *avctx,
220 const uint8_t **poutbuf, int *poutbuf_size,
221 const uint8_t *buf, int buf_size)
223 DiracParseContext *pc = s->priv_data;
229 if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
232 *poutbuf_size = buf_size;
233 /* Assume that data has been packetized into an encapsulation unit. */
235 next = find_frame_end(pc, buf, buf_size);
236 if (!pc->is_synced && next == -1)
237 /* No frame start found yet. So throw away the entire buffer. */
240 if (dirac_combine_frame(s, avctx, next, &buf, &buf_size) < 0)
245 *poutbuf_size = buf_size;
249 static void dirac_parse_close(AVCodecParserContext *s)
251 DiracParseContext *pc = s->priv_data;
253 if (pc->buffer_size > 0)
254 av_freep(&pc->buffer);
257 AVCodecParser ff_dirac_parser = {
258 .codec_ids = { AV_CODEC_ID_DIRAC },
259 .priv_data_size = sizeof(DiracParseContext),
260 .parser_parse = dirac_parse,
261 .parser_close = dirac_parse_close,