2 * MPEG1 / MPEG2 video parser
3 * Copyright (c) 2000,2001 Fabrice Bellard
4 * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at>
6 * This file is part of Libav.
8 * Libav 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 * Libav 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 Libav; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
24 #include "mpegvideo.h"
26 struct MpvParseContext
{
28 AVRational frame_rate
;
29 int progressive_sequence
;
34 static void mpegvideo_extract_headers(AVCodecParserContext
*s
,
35 AVCodecContext
*avctx
,
36 const uint8_t *buf
, int buf_size
)
38 struct MpvParseContext
*pc
= s
->priv_data
;
39 const uint8_t *buf_end
= buf
+ buf_size
;
41 int frame_rate_index
, ext_type
, bytes_left
;
42 int frame_rate_ext_n
, frame_rate_ext_d
;
43 int top_field_first
, repeat_first_field
, progressive_frame
;
44 int horiz_size_ext
, vert_size_ext
, bit_rate_ext
;
46 //FIXME replace the crap with get_bits()
49 while (buf
< buf_end
) {
51 buf
= avpriv_mpv_find_start_code(buf
, buf_end
, &start_code
);
52 bytes_left
= buf_end
- buf
;
54 case PICTURE_START_CODE
:
55 if (bytes_left
>= 2) {
56 s
->pict_type
= (buf
[1] >> 3) & 7;
60 if (bytes_left
>= 7) {
61 pc
->width
= (buf
[0] << 4) | (buf
[1] >> 4);
62 pc
->height
= ((buf
[1] & 0x0f) << 8) | buf
[2];
63 if(!avctx
->width
|| !avctx
->height
|| !avctx
->coded_width
|| !avctx
->coded_height
){
64 avcodec_set_dimensions(avctx
, pc
->width
, pc
->height
);
67 frame_rate_index
= buf
[3] & 0xf;
68 pc
->frame_rate
.den
= avctx
->time_base
.den
= ff_mpeg12_frame_rate_tab
[frame_rate_index
].num
;
69 pc
->frame_rate
.num
= avctx
->time_base
.num
= ff_mpeg12_frame_rate_tab
[frame_rate_index
].den
;
70 avctx
->bit_rate
= ((buf
[4]<<10) | (buf
[5]<<2) | (buf
[6]>>6))*400;
71 avctx
->codec_id
= AV_CODEC_ID_MPEG1VIDEO
;
75 if (bytes_left
>= 1) {
76 ext_type
= (buf
[0] >> 4);
78 case 0x1: /* sequence extension */
79 if (bytes_left
>= 6) {
80 horiz_size_ext
= ((buf
[1] & 1) << 1) | (buf
[2] >> 7);
81 vert_size_ext
= (buf
[2] >> 5) & 3;
82 bit_rate_ext
= ((buf
[2] & 0x1F)<<7) | (buf
[3]>>1);
83 frame_rate_ext_n
= (buf
[5] >> 5) & 3;
84 frame_rate_ext_d
= (buf
[5] & 0x1f);
85 pc
->progressive_sequence
= buf
[1] & (1 << 3);
86 avctx
->has_b_frames
= !(buf
[5] >> 7);
88 pc
->width
|=(horiz_size_ext
<< 12);
89 pc
->height
|=( vert_size_ext
<< 12);
90 avctx
->bit_rate
+= (bit_rate_ext
<< 18) * 400;
92 avcodec_set_dimensions(avctx
, pc
->width
, pc
->height
);
93 avctx
->time_base
.den
= pc
->frame_rate
.den
* (frame_rate_ext_n
+ 1) * 2;
94 avctx
->time_base
.num
= pc
->frame_rate
.num
* (frame_rate_ext_d
+ 1);
95 avctx
->codec_id
= AV_CODEC_ID_MPEG2VIDEO
;
98 case 0x8: /* picture coding extension */
99 if (bytes_left
>= 5) {
100 top_field_first
= buf
[3] & (1 << 7);
101 repeat_first_field
= buf
[3] & (1 << 1);
102 progressive_frame
= buf
[4] & (1 << 7);
104 /* check if we must repeat the frame */
106 if (repeat_first_field
) {
107 if (pc
->progressive_sequence
) {
112 } else if (progressive_frame
) {
124 /* we stop parsing when we encounter a slice. It ensures
125 that this function takes a negligible amount of time */
126 if (start_code
>= SLICE_MIN_START_CODE
&&
127 start_code
<= SLICE_MAX_START_CODE
)
135 static int mpegvideo_parse(AVCodecParserContext
*s
,
136 AVCodecContext
*avctx
,
137 const uint8_t **poutbuf
, int *poutbuf_size
,
138 const uint8_t *buf
, int buf_size
)
140 struct MpvParseContext
*pc1
= s
->priv_data
;
141 ParseContext
*pc
= &pc1
->pc
;
144 if(s
->flags
& PARSER_FLAG_COMPLETE_FRAMES
){
147 next
= ff_mpeg1_find_frame_end(pc
, buf
, buf_size
, s
);
149 if (ff_combine_frame(pc
, next
, &buf
, &buf_size
) < 0) {
156 /* we have a full frame : we just parse the first few MPEG headers
157 to have the full timing information. The time take by this
158 function should be negligible for uncorrupted streams */
159 mpegvideo_extract_headers(s
, avctx
, buf
, buf_size
);
160 av_dlog(NULL
, "pict_type=%d frame_rate=%0.3f repeat_pict=%d\n",
161 s
->pict_type
, (double)avctx
->time_base
.den
/ avctx
->time_base
.num
, s
->repeat_pict
);
164 *poutbuf_size
= buf_size
;
168 static int mpegvideo_split(AVCodecContext
*avctx
,
169 const uint8_t *buf
, int buf_size
)
174 for(i
=0; i
<buf_size
; i
++){
175 state
= (state
<<8) | buf
[i
];
176 if(state
!= 0x1B3 && state
!= 0x1B5 && state
< 0x200 && state
>= 0x100)
182 AVCodecParser ff_mpegvideo_parser
= {
183 .codec_ids
= { AV_CODEC_ID_MPEG1VIDEO
, AV_CODEC_ID_MPEG2VIDEO
},
184 .priv_data_size
= sizeof(struct MpvParseContext
),
185 .parser_parse
= mpegvideo_parse
,
186 .parser_close
= ff_parse_close
,
187 .split
= mpegvideo_split
,