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  if (get_bits_left(&s->gb) == 64) { /* special dummy frames */
30  return FRAME_SKIPPED;
31  }
32 
33  /* picture header */
34  if (get_bits_long(&s->gb, 22) != 0x20) {
35  av_log(s->avctx, AV_LOG_ERROR, "Bad picture start code\n");
36  return -1;
37  }
38  s->picture_number = get_bits(&s->gb, 8); /* picture timestamp */
39 
40  if (get_bits1(&s->gb) != 1) {
41  av_log(s->avctx, AV_LOG_ERROR, "Bad marker\n");
42  return -1; /* marker */
43  }
44  if (get_bits1(&s->gb) != 0) {
45  av_log(s->avctx, AV_LOG_ERROR, "Bad H263 id\n");
46  return -1; /* h263 id */
47  }
48  skip_bits1(&s->gb); /* split screen off */
49  skip_bits1(&s->gb); /* camera off */
50  skip_bits1(&s->gb); /* freeze picture release off */
51 
52  format = get_bits(&s->gb, 3);
53  if (format == 0 || format == 6) {
54  av_log(s->avctx, AV_LOG_ERROR, "Intel H263 free format not supported\n");
55  return -1;
56  }
57  s->h263_plus = 0;
58 
59  s->pict_type = AV_PICTURE_TYPE_I + get_bits1(&s->gb);
60 
61  s->h263_long_vectors = get_bits1(&s->gb);
62 
63  if (get_bits1(&s->gb) != 0) {
64  av_log(s->avctx, AV_LOG_ERROR, "SAC not supported\n");
65  return -1; /* SAC: off */
66  }
67  s->obmc= get_bits1(&s->gb);
68  s->unrestricted_mv = s->obmc || s->h263_long_vectors;
69  s->pb_frame = get_bits1(&s->gb);
70 
71  if (format < 6) {
72  s->width = ff_h263_format[format][0];
73  s->height = ff_h263_format[format][1];
74  s->avctx->sample_aspect_ratio.num = 12;
75  s->avctx->sample_aspect_ratio.den = 11;
76  } else {
77  format = get_bits(&s->gb, 3);
78  if(format == 0 || format == 7){
79  av_log(s->avctx, AV_LOG_ERROR, "Wrong Intel H263 format\n");
80  return -1;
81  }
82  if(get_bits(&s->gb, 2))
83  av_log(s->avctx, AV_LOG_ERROR, "Bad value for reserved field\n");
84  s->loop_filter = get_bits1(&s->gb) * !s->avctx->lowres;
85  if(get_bits1(&s->gb))
86  av_log(s->avctx, AV_LOG_ERROR, "Bad value for reserved field\n");
87  if(get_bits1(&s->gb))
88  s->pb_frame = 2;
89  if(get_bits(&s->gb, 5))
90  av_log(s->avctx, AV_LOG_ERROR, "Bad value for reserved field\n");
91  if(get_bits(&s->gb, 5) != 1)
92  av_log(s->avctx, AV_LOG_ERROR, "Invalid marker\n");
93  }
94  if(format == 6){
95  int ar = get_bits(&s->gb, 4);
96  skip_bits(&s->gb, 9); // display width
97  skip_bits1(&s->gb);
98  skip_bits(&s->gb, 9); // display height
99  if(ar == 15){
100  s->avctx->sample_aspect_ratio.num = get_bits(&s->gb, 8); // aspect ratio - width
101  s->avctx->sample_aspect_ratio.den = get_bits(&s->gb, 8); // aspect ratio - height
102  } else {
103  s->avctx->sample_aspect_ratio = ff_h263_pixel_aspect[ar];
104  }
105  if (s->avctx->sample_aspect_ratio.num == 0)
106  av_log(s->avctx, AV_LOG_ERROR, "Invalid aspect ratio.\n");
107  }
108 
109  s->chroma_qscale= s->qscale = get_bits(&s->gb, 5);
110  skip_bits1(&s->gb); /* Continuous Presence Multipoint mode: off */
111 
112  if(s->pb_frame){
113  skip_bits(&s->gb, 3); //temporal reference for B-frame
114  skip_bits(&s->gb, 2); //dbquant
115  }
116 
117  /* PEI */
118  if (skip_1stop_8data_bits(&s->gb) < 0)
119  return AVERROR_INVALIDDATA;
120  s->f_code = 1;
121 
122  s->y_dc_scale_table=
123  s->c_dc_scale_table= ff_mpeg1_dc_scale_table;
124 
125  ff_h263_show_pict_info(s);
126 
127  return 0;
128 }
129 
130  AVCodec ff_h263i_decoder = {
131  .name = "h263i",
132  .long_name = NULL_IF_CONFIG_SMALL("Intel H.263"),
133  .type = AVMEDIA_TYPE_VIDEO,
134  .id = AV_CODEC_ID_H263I,
135  .priv_data_size = sizeof(MpegEncContext),
136  .init = ff_h263_decode_init,
137  .close = ff_h263_decode_end,
138  .decode = ff_h263_decode_frame,
139  .capabilities = CODEC_CAP_DRAW_HORIZ_BAND | CODEC_CAP_DR1,
140  .pix_fmts = (const enum AVPixelFormat[]) {
141  AV_PIX_FMT_YUV420P,
142  AV_PIX_FMT_NONE
143  },
144 };
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