FFmpeg: libavcodec/intelh263dec.c Source File

FFmpeg
intelh263dec.c
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1 /*
2  * H.263i decoder
3  *
4  * This file is part of FFmpeg.
5  *
6  * FFmpeg is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public
8  * License as published by the Free Software Foundation; either
9  * version 2.1 of the License, or (at your option) any later version.
10  *
11  * FFmpeg is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with FFmpeg; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 #include "mpegvideo.h"
22 #include "h263.h"
23 
24 /* don't understand why they choose a different header ! */
25  int ff_intel_h263_decode_picture_header(MpegEncContext *s)
26 {
27  int format;
28 
29  /* picture header */
30  if (get_bits_long(&s->gb, 22) != 0x20) {
31  av_log(s->avctx, AV_LOG_ERROR, "Bad picture start code\n");
32  return -1;
33  }
34  s->picture_number = get_bits(&s->gb, 8); /* picture timestamp */
35 
36  if (get_bits1(&s->gb) != 1) {
37  av_log(s->avctx, AV_LOG_ERROR, "Bad marker\n");
38  return -1; /* marker */
39  }
40  if (get_bits1(&s->gb) != 0) {
41  av_log(s->avctx, AV_LOG_ERROR, "Bad H263 id\n");
42  return -1; /* h263 id */
43  }
44  skip_bits1(&s->gb); /* split screen off */
45  skip_bits1(&s->gb); /* camera off */
46  skip_bits1(&s->gb); /* freeze picture release off */
47 
48  format = get_bits(&s->gb, 3);
49  if (format == 0 || format == 6) {
50  av_log(s->avctx, AV_LOG_ERROR, "Intel H263 free format not supported\n");
51  return -1;
52  }
53  s->h263_plus = 0;
54 
55  s->pict_type = AV_PICTURE_TYPE_I + get_bits1(&s->gb);
56 
57  s->h263_long_vectors = get_bits1(&s->gb);
58 
59  if (get_bits1(&s->gb) != 0) {
60  av_log(s->avctx, AV_LOG_ERROR, "SAC not supported\n");
61  return -1; /* SAC: off */
62  }
63  s->obmc= get_bits1(&s->gb);
64  s->unrestricted_mv = s->obmc || s->h263_long_vectors;
65  s->pb_frame = get_bits1(&s->gb);
66 
67  if (format < 6) {
68  s->width = ff_h263_format[format][0];
69  s->height = ff_h263_format[format][1];
70  s->avctx->sample_aspect_ratio.num = 12;
71  s->avctx->sample_aspect_ratio.den = 11;
72  } else {
73  format = get_bits(&s->gb, 3);
74  if(format == 0 || format == 7){
75  av_log(s->avctx, AV_LOG_ERROR, "Wrong Intel H263 format\n");
76  return -1;
77  }
78  if(get_bits(&s->gb, 2))
79  av_log(s->avctx, AV_LOG_ERROR, "Bad value for reserved field\n");
80  s->loop_filter = get_bits1(&s->gb) * !s->avctx->lowres;
81  if(get_bits1(&s->gb))
82  av_log(s->avctx, AV_LOG_ERROR, "Bad value for reserved field\n");
83  if(get_bits1(&s->gb))
84  s->pb_frame = 2;
85  if(get_bits(&s->gb, 5))
86  av_log(s->avctx, AV_LOG_ERROR, "Bad value for reserved field\n");
87  if(get_bits(&s->gb, 5) != 1)
88  av_log(s->avctx, AV_LOG_ERROR, "Invalid marker\n");
89  }
90  if(format == 6){
91  int ar = get_bits(&s->gb, 4);
92  skip_bits(&s->gb, 9); // display width
93  skip_bits1(&s->gb);
94  skip_bits(&s->gb, 9); // display height
95  if(ar == 15){
96  s->avctx->sample_aspect_ratio.num = get_bits(&s->gb, 8); // aspect ratio - width
97  s->avctx->sample_aspect_ratio.den = get_bits(&s->gb, 8); // aspect ratio - height
98  } else {
99  s->avctx->sample_aspect_ratio = ff_h263_pixel_aspect[ar];
100  }
101  if (s->avctx->sample_aspect_ratio.num == 0)
102  av_log(s->avctx, AV_LOG_ERROR, "Invalid aspect ratio.\n");
103  }
104 
105  s->chroma_qscale= s->qscale = get_bits(&s->gb, 5);
106  skip_bits1(&s->gb); /* Continuous Presence Multipoint mode: off */
107 
108  if(s->pb_frame){
109  skip_bits(&s->gb, 3); //temporal reference for B-frame
110  skip_bits(&s->gb, 2); //dbquant
111  }
112 
113  /* PEI */
114  while (get_bits1(&s->gb) != 0) {
115  skip_bits(&s->gb, 8);
116  }
117  s->f_code = 1;
118 
119  s->y_dc_scale_table=
120  s->c_dc_scale_table= ff_mpeg1_dc_scale_table;
121 
122  ff_h263_show_pict_info(s);
123 
124  return 0;
125 }
126 
127  AVCodec ff_h263i_decoder = {
128  .name = "h263i",
129  .type = AVMEDIA_TYPE_VIDEO,
130  .id = AV_CODEC_ID_H263I,
131  .priv_data_size = sizeof(MpegEncContext),
132  .init = ff_h263_decode_init,
133  .close = ff_h263_decode_end,
134  .decode = ff_h263_decode_frame,
135  .capabilities = CODEC_CAP_DRAW_HORIZ_BAND | CODEC_CAP_DR1,
136  .long_name = NULL_IF_CONFIG_SMALL("Intel H.263"),
137  .pix_fmts = ff_pixfmt_list_420,
138 };
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