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mpegvideo_parser.c
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1 /*
2  * MPEG-1 / MPEG-2 video parser
3  * Copyright (c) 2000,2001 Fabrice Bellard
4  * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at>
5  *
6  * This file is part of FFmpeg.
7  *
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.
12  *
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.
17  *
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
21  */
22 
23 #include "parser.h"
24 #include "mpeg12.h"
25 #include "internal.h"
26 
31  int width, height;
32 };
33 
34 
36  AVCodecContext *avctx,
37  const uint8_t *buf, int buf_size)
38 {
39  struct MpvParseContext *pc = s->priv_data;
40  const uint8_t *buf_end = buf + buf_size;
41  uint32_t start_code;
42  int frame_rate_index, ext_type, bytes_left;
43  int frame_rate_ext_n, frame_rate_ext_d;
44  int top_field_first, repeat_first_field, progressive_frame;
45  int horiz_size_ext, vert_size_ext, bit_rate_ext;
46  int did_set_size=0;
47  int set_dim_ret = 0;
48  int bit_rate = 0;
49  int vbv_delay = 0;
50  int chroma_format;
52 //FIXME replace the crap with get_bits()
53  s->repeat_pict = 0;
54 
55  while (buf < buf_end) {
56  start_code= -1;
57  buf= avpriv_find_start_code(buf, buf_end, &start_code);
58  bytes_left = buf_end - buf;
59  switch(start_code) {
60  case PICTURE_START_CODE:
61  if (bytes_left >= 2) {
62  s->pict_type = (buf[1] >> 3) & 7;
63  if (bytes_left >= 4)
64  vbv_delay = ((buf[1] & 0x07) << 13) | (buf[2] << 5) | (buf[3] >> 3);
65  }
66  break;
67  case SEQ_START_CODE:
68  if (bytes_left >= 7) {
69  pc->width = (buf[0] << 4) | (buf[1] >> 4);
70  pc->height = ((buf[1] & 0x0f) << 8) | buf[2];
71  if(!avctx->width || !avctx->height || !avctx->coded_width || !avctx->coded_height){
72  set_dim_ret = ff_set_dimensions(avctx, pc->width, pc->height);
73  did_set_size=1;
74  }
75  pix_fmt = AV_PIX_FMT_YUV420P;
76  frame_rate_index = buf[3] & 0xf;
77  pc->frame_rate = avctx->framerate = ff_mpeg12_frame_rate_tab[frame_rate_index];
78  bit_rate = (buf[4]<<10) | (buf[5]<<2) | (buf[6]>>6);
80  avctx->ticks_per_frame = 1;
81  }
82  break;
83  case EXT_START_CODE:
84  if (bytes_left >= 1) {
85  ext_type = (buf[0] >> 4);
86  switch(ext_type) {
87  case 0x1: /* sequence extension */
88  if (bytes_left >= 6) {
89  horiz_size_ext = ((buf[1] & 1) << 1) | (buf[2] >> 7);
90  vert_size_ext = (buf[2] >> 5) & 3;
91  bit_rate_ext = ((buf[2] & 0x1F)<<7) | (buf[3]>>1);
92  frame_rate_ext_n = (buf[5] >> 5) & 3;
93  frame_rate_ext_d = (buf[5] & 0x1f);
94  pc->progressive_sequence = buf[1] & (1 << 3);
95  avctx->has_b_frames= !(buf[5] >> 7);
96 
97  chroma_format = (buf[1] >> 1) & 3;
98  switch (chroma_format) {
99  case 1: pix_fmt = AV_PIX_FMT_YUV420P; break;
100  case 2: pix_fmt = AV_PIX_FMT_YUV422P; break;
101  case 3: pix_fmt = AV_PIX_FMT_YUV444P; break;
102  }
103 
104  pc->width = (pc->width & 0xFFF) | (horiz_size_ext << 12);
105  pc->height = (pc->height& 0xFFF) | ( vert_size_ext << 12);
106  bit_rate = (bit_rate&0x3FFFF) | (bit_rate_ext << 18);
107  if(did_set_size)
108  set_dim_ret = ff_set_dimensions(avctx, pc->width, pc->height);
109  avctx->framerate.num = pc->frame_rate.num * (frame_rate_ext_n + 1);
110  avctx->framerate.den = pc->frame_rate.den * (frame_rate_ext_d + 1);
112  avctx->ticks_per_frame = 2;
113  }
114  break;
115  case 0x8: /* picture coding extension */
116  if (bytes_left >= 5) {
117  top_field_first = buf[3] & (1 << 7);
118  repeat_first_field = buf[3] & (1 << 1);
119  progressive_frame = buf[4] & (1 << 7);
120 
121  /* check if we must repeat the frame */
122  s->repeat_pict = 1;
123  if (repeat_first_field) {
124  if (pc->progressive_sequence) {
125  if (top_field_first)
126  s->repeat_pict = 5;
127  else
128  s->repeat_pict = 3;
129  } else if (progressive_frame) {
130  s->repeat_pict = 2;
131  }
132  }
133 
134  if (!pc->progressive_sequence) {
135  if (top_field_first)
137  else
139  } else
141  }
142  break;
143  }
144  }
145  break;
146  case -1:
147  goto the_end;
148  default:
149  /* we stop parsing when we encounter a slice. It ensures
150  that this function takes a negligible amount of time */
151  if (start_code >= SLICE_MIN_START_CODE &&
152  start_code <= SLICE_MAX_START_CODE)
153  goto the_end;
154  break;
155  }
156  }
157  the_end: ;
158  if (set_dim_ret < 0)
159  av_log(avctx, AV_LOG_ERROR, "Failed to set dimensions\n");
160 
161  if (avctx->codec_id == AV_CODEC_ID_MPEG2VIDEO && bit_rate) {
162  avctx->rc_max_rate = 400LL*bit_rate;
163  }
164  if (bit_rate &&
165  ((avctx->codec_id == AV_CODEC_ID_MPEG1VIDEO && bit_rate != 0x3FFFF) || vbv_delay != 0xFFFF)) {
166  avctx->bit_rate = 400LL*bit_rate;
167  }
168 
169  if (pix_fmt != AV_PIX_FMT_NONE) {
170  s->format = pix_fmt;
171  s->width = s->coded_width = pc->width;
172  s->height = s->coded_height = pc->height;
173  }
174 
175 #if FF_API_AVCTX_TIMEBASE
176  if (avctx->framerate.num)
177  avctx->time_base = av_inv_q(av_mul_q(avctx->framerate, (AVRational){avctx->ticks_per_frame, 1}));
178 #endif
179 }
180 
182  AVCodecContext *avctx,
183  const uint8_t **poutbuf, int *poutbuf_size,
184  const uint8_t *buf, int buf_size)
185 {
186  struct MpvParseContext *pc1 = s->priv_data;
187  ParseContext *pc= &pc1->pc;
188  int next;
189 
191  next= buf_size;
192  }else{
193  next= ff_mpeg1_find_frame_end(pc, buf, buf_size, s);
194 
195  if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
196  *poutbuf = NULL;
197  *poutbuf_size = 0;
198  return buf_size;
199  }
200 
201  }
202  /* we have a full frame : we just parse the first few MPEG headers
203  to have the full timing information. The time take by this
204  function should be negligible for uncorrupted streams */
205  mpegvideo_extract_headers(s, avctx, buf, buf_size);
206  ff_dlog(NULL, "pict_type=%d frame_rate=%0.3f repeat_pict=%d\n",
207  s->pict_type, av_q2d(avctx->framerate), s->repeat_pict);
208 
209  *poutbuf = buf;
210  *poutbuf_size = buf_size;
211  return next;
212 }
213 
214 static int mpegvideo_split(AVCodecContext *avctx,
215  const uint8_t *buf, int buf_size)
216 {
217  int i;
218  uint32_t state= -1;
219  int found=0;
220 
221  for(i=0; i<buf_size; i++){
222  state= (state<<8) | buf[i];
223  if(state == 0x1B3){
224  found=1;
225  }else if(found && state != 0x1B5 && state < 0x200 && state >= 0x100)
226  return i-3;
227  }
228  return 0;
229 }
230 
232 {
233  s->pict_type = AV_PICTURE_TYPE_NONE; // first frame might be partial
234  return 0;
235 }
236 
239  .priv_data_size = sizeof(struct MpvParseContext),
240  .parser_init = mpegvideo_parse_init,
241  .parser_parse = mpegvideo_parse,
242  .parser_close = ff_parse_close,
243  .split = mpegvideo_split,
244 };
#define NULL
Definition: coverity.c:32
AVRational framerate
Definition: avcodec.h:3358
const char * s
Definition: avisynth_c.h:768
static enum AVPixelFormat pix_fmt
#define SLICE_MAX_START_CODE
Definition: cavs.h:32
static int mpegvideo_parse(AVCodecParserContext *s, AVCodecContext *avctx, const uint8_t **poutbuf, int *poutbuf_size, const uint8_t *buf, int buf_size)
int coded_width
Bitstream width / height, may be different from width/height e.g.
Definition: avcodec.h:1861
planar YUV 4:4:4, 24bpp, (1 Cr & Cb sample per 1x1 Y samples)
Definition: pixfmt.h:67
int64_t bit_rate
the average bitrate
Definition: avcodec.h:1724
int ff_set_dimensions(AVCodecContext *s, int width, int height)
Check that the provided frame dimensions are valid and set them on the codec context.
Definition: utils.c:210
int width
Dimensions of the decoded video intended for presentation.
Definition: avcodec.h:5101
enum AVFieldOrder field_order
Definition: avcodec.h:5078
int num
Numerator.
Definition: rational.h:59
int codec_ids[5]
Definition: avcodec.h:5122
int coded_width
Dimensions of the coded video.
Definition: avcodec.h:5107
#define SLICE_MIN_START_CODE
Definition: mpegvideo.h:70
ParseContext pc
AVRational time_base
This is the fundamental unit of time (in seconds) in terms of which frame timestamps are represented...
Definition: avcodec.h:1796
Undefined.
Definition: avutil.h:267
uint8_t
static double av_q2d(AVRational a)
Convert an AVRational to a double.
Definition: rational.h:104
#define ff_dlog(a,...)
#define av_log(a,...)
const uint8_t * avpriv_find_start_code(const uint8_t *p, const uint8_t *end, uint32_t *state)
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:176
int has_b_frames
Size of the frame reordering buffer in the decoder.
Definition: avcodec.h:1981
int ff_combine_frame(ParseContext *pc, int next, const uint8_t **buf, int *buf_size)
Combine the (truncated) bitstream to a complete frame.
Definition: parser.c:245
planar YUV 4:2:2, 16bpp, (1 Cr & Cb sample per 2x1 Y samples)
Definition: pixfmt.h:66
void ff_parse_close(AVCodecParserContext *s)
Definition: parser.c:321
static const uint8_t start_code[]
Definition: h264dec.c:657
int width
picture width / height.
Definition: avcodec.h:1846
int ticks_per_frame
For some codecs, the time base is closer to the field rate than the frame rate.
Definition: avcodec.h:1805
#define EXT_START_CODE
Definition: cavs.h:33
static int mpegvideo_parse_init(AVCodecParserContext *s)
preferred ID for MPEG-1/2 video decoding
Definition: avcodec.h:196
AVRational frame_rate
enum AVCodecID codec_id
Definition: avcodec.h:1676
main external API structure.
Definition: avcodec.h:1659
void * buf
Definition: avisynth_c.h:690
int coded_height
Definition: avcodec.h:1861
Rational number (pair of numerator and denominator).
Definition: rational.h:58
int ff_mpeg1_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size, AVCodecParserContext *s)
Find the end of the current frame in the bitstream.
Definition: mpeg12.c:185
AVCodecParser ff_mpegvideo_parser
static av_always_inline AVRational av_inv_q(AVRational q)
Invert a rational.
Definition: rational.h:159
static void mpegvideo_extract_headers(AVCodecParserContext *s, AVCodecContext *avctx, const uint8_t *buf, int buf_size)
planar YUV 4:2:0, 12bpp, (1 Cr & Cb sample per 2x2 Y samples)
Definition: pixfmt.h:62
common internal api header.
static struct @229 state
#define PARSER_FLAG_COMPLETE_FRAMES
Definition: avcodec.h:4988
static int mpegvideo_split(AVCodecContext *avctx, const uint8_t *buf, int buf_size)
int den
Denominator.
Definition: rational.h:60
#define SEQ_START_CODE
Definition: mpegvideo.h:67
int format
The format of the coded data, corresponds to enum AVPixelFormat for video and for enum AVSampleFormat...
Definition: avcodec.h:5118
AVRational av_mul_q(AVRational b, AVRational c)
Multiply two rationals.
Definition: rational.c:80
int repeat_pict
This field is used for proper frame duration computation in lavf.
Definition: avcodec.h:4972
#define PICTURE_START_CODE
Definition: mpegvideo.h:69
AVPixelFormat
Pixel format.
Definition: pixfmt.h:60
const AVRational ff_mpeg12_frame_rate_tab[16]
Definition: mpeg12data.c:308
int64_t rc_max_rate
maximum bitrate
Definition: avcodec.h:2659