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
,