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"
36 #define DIRAC_PARSE_INFO_PREFIX 0x42424344
39 * Find the end of the current frame in the bitstream.
40 * @return the position of the first byte of the next frame or -1
42 typedef struct DiracParseContext {
46 int header_bytes_needed;
55 static int find_frame_end(DiracParseContext *pc,
56 const uint8_t *buf, int buf_size)
58 uint32_t state = pc->state;
62 for (i = 0; i < buf_size; i++) {
63 state = (state << 8) | buf[i];
64 if (state == DIRAC_PARSE_INFO_PREFIX) {
67 pc->header_bytes_needed = 9;
76 for (; i < buf_size; i++) {
77 if (state == DIRAC_PARSE_INFO_PREFIX) {
78 if ((buf_size-i) >= pc->header_bytes_needed) {
80 return i + pc->header_bytes_needed;
82 pc->header_bytes_needed = 9-(buf_size-i);
86 state = (state << 8) | buf[i];
93 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 */
139 void *new_buffer = av_fast_realloc(pc->buffer, &pc->buffer_size,
140 pc->index + (*buf_size -
142 pc->buffer = new_buffer;
143 memcpy(pc->buffer+pc->index, (*buf + pc->sync_offset),
144 *buf_size - pc->sync_offset);
145 pc->index += *buf_size - pc->sync_offset;
148 /* Found a possible frame start and a possible frame end */
149 DiracParseUnit pu1, pu;
150 void *new_buffer = av_fast_realloc(pc->buffer, &pc->buffer_size,
152 pc->buffer = new_buffer;
153 memcpy(pc->buffer + pc->index, *buf, next);
156 /* Need to check if we have a valid Parse Unit. We can't go by the
157 * sync pattern 'BBCD' alone because arithmetic coding of the residual
158 * and motion data can cause the pattern triggering a false start of
159 * frame. So check if the previous parse offset of the next parse unit
160 * is equal to the next parse offset of the current parse unit then
161 * we can be pretty sure that we have a valid parse unit */
162 if (!unpack_parse_unit(&pu1, pc, pc->index - 13) ||
163 !unpack_parse_unit(&pu, pc, pc->index - 13 - pu1.prev_pu_offset) ||
164 pu.next_pu_offset != pu1.prev_pu_offset) {
167 pc->header_bytes_needed = 9;
171 /* All non-frame data must be accompanied by frame data. This is to
172 * ensure that pts is set correctly. So if the current parse unit is
173 * not frame data, wait for frame data to come along */
175 pc->dirac_unit = pc->buffer + pc->index - 13 -
176 pu1.prev_pu_offset - pc->dirac_unit_size;
178 pc->dirac_unit_size += pu.next_pu_offset;
180 if ((pu.pu_type&0x08) != 0x08) {
181 pc->header_bytes_needed = 9;
186 /* Get the picture number to set the pts and dts*/
187 if (parse_timing_info) {
188 uint8_t *cur_pu = pc->buffer +
189 pc->index - 13 - pu1.prev_pu_offset;
190 int pts = AV_RB32(cur_pu + 13);
191 if (s->last_pts == 0 && s->last_dts == 0)
194 s->dts = s->last_dts+1;
196 if (!avctx->has_b_frames && (cur_pu[4] & 0x03))
197 avctx->has_b_frames = 1;
199 if (avctx->has_b_frames && s->pts == s->dts)
200 s->pict_type = AV_PICTURE_TYPE_B;
202 /* Finally have a complete Dirac data unit */
203 *buf = pc->dirac_unit;
204 *buf_size = pc->dirac_unit_size;
206 pc->dirac_unit_size = 0;
207 pc->overread_index = pc->index-13;
208 pc->header_bytes_needed = 9;
213 static int dirac_parse(AVCodecParserContext *s, AVCodecContext *avctx,
214 const uint8_t **poutbuf, int *poutbuf_size,
215 const uint8_t *buf, int buf_size)
217 DiracParseContext *pc = s->priv_data;
223 if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
226 *poutbuf_size = buf_size;
227 /* Assume that data has been packetized into an encapsulation unit. */
229 next = find_frame_end(pc, buf, buf_size);
230 if (!pc->is_synced && next == -1) {
231 /* No frame start found yet. So throw away the entire buffer. */
235 if (dirac_combine_frame(s, avctx, next, &buf, &buf_size) < 0) {
241 *poutbuf_size = buf_size;
245 static void dirac_parse_close(AVCodecParserContext *s)
247 DiracParseContext *pc = s->priv_data;
249 if (pc->buffer_size > 0)
253 AVCodecParser ff_dirac_parser = {
254 .codec_ids = { AV_CODEC_ID_DIRAC },
255 .priv_data_size = sizeof(DiracParseContext),
256 .parser_parse = dirac_parse,
257 .parser_close = dirac_parse_close,