3 * Copyright (c) 2006-2007 Konstantin Shishkov
4 * Partly based on vc9.c (c) 2005 Anonymous, Alex Beregszaszi, Michael Niedermayer
6 * This file is part of FFmpeg.
8 * FFmpeg is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Lesser General Public
10 * License as published by the Free Software Foundation; either
11 * version 2.1 of the License, or (at your option) any later version.
13 * FFmpeg is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * Lesser General Public License for more details.
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with FFmpeg; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
25 * VC-1 and WMV3 parser
28 #include "libavutil/attributes.h"
33 /** The maximum number of bytes of a sequence, entry point or
34 * frame header whose values we pay any attention to */
35 #define UNESCAPED_THRESHOLD 37
37 /** The maximum number of bytes of a sequence, entry point or
38 * frame header which must be valid memory (because they are
39 * used to update the bitstream cache in skip_bits() calls)
41 #define UNESCAPED_LIMIT 144
48 } VC1ParseSearchState
;
53 uint8_t prev_start_code
;
55 uint8_t unesc_buffer
[UNESCAPED_LIMIT
];
57 VC1ParseSearchState search_state
;
60 static void vc1_extract_header(AVCodecParserContext
*s
, AVCodecContext
*avctx
,
61 const uint8_t *buf
, int buf_size
)
63 /* Parse the header we just finished unescaping */
64 VC1ParseContext
*vpc
= s
->priv_data
;
67 vpc
->v
.s
.avctx
= avctx
;
68 vpc
->v
.parse_only
= 1;
69 init_get_bits(&gb
, buf
, buf_size
* 8);
70 switch (vpc
->prev_start_code
) {
71 case VC1_CODE_SEQHDR
& 0xFF:
72 ff_vc1_decode_sequence_header(avctx
, &vpc
->v
, &gb
);
74 case VC1_CODE_ENTRYPOINT
& 0xFF:
75 ff_vc1_decode_entry_point(avctx
, &vpc
->v
, &gb
);
77 case VC1_CODE_FRAME
& 0xFF:
78 if(vpc
->v
.profile
< PROFILE_ADVANCED
)
79 ret
= ff_vc1_parse_frame_header (&vpc
->v
, &gb
);
81 ret
= ff_vc1_parse_frame_header_adv(&vpc
->v
, &gb
);
86 /* keep AV_PICTURE_TYPE_BI internal to VC1 */
87 if (vpc
->v
.s
.pict_type
== AV_PICTURE_TYPE_BI
)
88 s
->pict_type
= AV_PICTURE_TYPE_B
;
90 s
->pict_type
= vpc
->v
.s
.pict_type
;
92 if (avctx
->ticks_per_frame
> 1){
93 // process pulldown flags
95 // Pulldown flags are only valid when 'broadcast' has been set.
96 // So ticks_per_frame will be 2
100 }else if (vpc
->v
.rptfrm
){
102 s
->repeat_pict
= vpc
->v
.rptfrm
* 2 + 1;
108 if (vpc
->v
.broadcast
&& vpc
->v
.interlace
&& !vpc
->v
.psf
)
109 s
->field_order
= vpc
->v
.tff
? AV_FIELD_TT
: AV_FIELD_BB
;
111 s
->field_order
= AV_FIELD_PROGRESSIVE
;
117 static int vc1_parse(AVCodecParserContext
*s
,
118 AVCodecContext
*avctx
,
119 const uint8_t **poutbuf
, int *poutbuf_size
,
120 const uint8_t *buf
, int buf_size
)
122 /* Here we do the searching for frame boundaries and headers at
123 * the same time. Only a minimal amount at the start of each
124 * header is unescaped. */
125 VC1ParseContext
*vpc
= s
->priv_data
;
126 int pic_found
= vpc
->pc
.frame_start_found
;
127 uint8_t *unesc_buffer
= vpc
->unesc_buffer
;
128 size_t unesc_index
= vpc
->unesc_index
;
129 VC1ParseSearchState search_state
= vpc
->search_state
;
130 int start_code_found
= 0;
131 int next
= END_NOT_FOUND
;
132 int i
= vpc
->bytes_to_skip
;
134 if (pic_found
&& buf_size
== 0) {
135 /* EOF considered as end of frame */
136 memset(unesc_buffer
+ unesc_index
, 0, UNESCAPED_THRESHOLD
- unesc_index
);
137 vc1_extract_header(s
, avctx
, unesc_buffer
, unesc_index
);
140 while (i
< buf_size
) {
142 start_code_found
= 0;
143 while (i
< buf_size
&& unesc_index
< UNESCAPED_THRESHOLD
) {
145 unesc_buffer
[unesc_index
++] = b
;
146 if (search_state
<= ONE_ZERO
)
147 search_state
= b
? NO_MATCH
: search_state
+ 1;
148 else if (search_state
== TWO_ZEROS
) {
153 unesc_index
--; // swallow emulation prevention byte
154 search_state
= NO_MATCH
;
157 else { // search_state == ONE
158 // Header unescaping terminates early due to detection of next start code
159 search_state
= NO_MATCH
;
160 start_code_found
= 1;
164 if ((s
->flags
& PARSER_FLAG_COMPLETE_FRAMES
) &&
165 unesc_index
>= UNESCAPED_THRESHOLD
&&
166 vpc
->prev_start_code
== (VC1_CODE_FRAME
& 0xFF))
168 // No need to keep scanning the rest of the buffer for
169 // start codes if we know it contains a complete frame and
170 // we've already unescaped all we need of the frame header
171 vc1_extract_header(s
, avctx
, unesc_buffer
, unesc_index
);
174 if (unesc_index
>= UNESCAPED_THRESHOLD
&& !start_code_found
) {
175 while (i
< buf_size
) {
176 if (search_state
== NO_MATCH
) {
177 i
+= vpc
->v
.vc1dsp
.startcode_find_candidate(buf
+ i
, buf_size
- i
);
179 search_state
= ONE_ZERO
;
184 if (search_state
== ONE_ZERO
)
185 search_state
= b
? NO_MATCH
: TWO_ZEROS
;
186 else if (search_state
== TWO_ZEROS
) {
188 search_state
= b
== 1 ? ONE
: NO_MATCH
;
190 else { // search_state == ONE
191 search_state
= NO_MATCH
;
192 start_code_found
= 1;
198 if (start_code_found
) {
199 vc1_extract_header(s
, avctx
, unesc_buffer
, unesc_index
);
201 vpc
->prev_start_code
= b
;
204 if (!(s
->flags
& PARSER_FLAG_COMPLETE_FRAMES
)) {
205 if (!pic_found
&& (b
== (VC1_CODE_FRAME
& 0xFF) || b
== (VC1_CODE_FIELD
& 0xFF))) {
208 else if (pic_found
&& b
!= (VC1_CODE_FIELD
& 0xFF) && b
!= (VC1_CODE_SLICE
& 0xFF)) {
210 pic_found
= b
== (VC1_CODE_FRAME
& 0xFF);
217 vpc
->pc
.frame_start_found
= pic_found
;
218 vpc
->unesc_index
= unesc_index
;
219 vpc
->search_state
= search_state
;
221 if (s
->flags
& PARSER_FLAG_COMPLETE_FRAMES
) {
224 if (ff_combine_frame(&vpc
->pc
, next
, &buf
, &buf_size
) < 0) {
225 vpc
->bytes_to_skip
= 0;
232 /* If we return with a valid pointer to a combined frame buffer
233 * then on the next call then we'll have been unhelpfully rewound
234 * by up to 4 bytes (depending upon whether the start code
235 * overlapped the input buffer, and if so by how much). We don't
236 * want this: it will either cause spurious second detections of
237 * the start code we've already seen, or cause extra bytes to be
238 * inserted at the start of the unescaped buffer. */
239 vpc
->bytes_to_skip
= 4;
240 if (next
< 0 && next
!= END_NOT_FOUND
)
241 vpc
->bytes_to_skip
+= next
;
244 *poutbuf_size
= buf_size
;
248 static int vc1_split(AVCodecContext
*avctx
,
249 const uint8_t *buf
, int buf_size
)
255 for(i
=0; i
<buf_size
; i
++){
256 state
= (state
<<8) | buf
[i
];
257 if(IS_MARKER(state
)){
258 if(state
== VC1_CODE_SEQHDR
|| state
== VC1_CODE_ENTRYPOINT
){
268 static av_cold
int vc1_parse_init(AVCodecParserContext
*s
)
270 VC1ParseContext
*vpc
= s
->priv_data
;
271 vpc
->v
.s
.slice_context_count
= 1;
272 vpc
->v
.first_pic_header_flag
= 1;
273 vpc
->prev_start_code
= 0;
274 vpc
->bytes_to_skip
= 0;
275 vpc
->unesc_index
= 0;
276 vpc
->search_state
= NO_MATCH
;
277 return ff_vc1_init_common(&vpc
->v
);
280 AVCodecParser ff_vc1_parser
= {
281 .codec_ids
= { AV_CODEC_ID_VC1
},
282 .priv_data_size
= sizeof(VC1ParseContext
),
283 .parser_init
= vc1_parse_init
,
284 .parser_parse
= vc1_parse
,
285 .parser_close
= ff_parse_close
,