ffmpeg/libavcodec/intelh263dec.c

   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 };