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ffmpeg / libavcodec / intelh263dec.c @ eea4fa05

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/*
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 * H.263i decoder
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 *
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 * This file is part of FFmpeg.
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 *
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 * FFmpeg is free software; you can redistribute it and/or
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 * modify it under the terms of the GNU Lesser General Public
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 * License as published by the Free Software Foundation; either
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 * version 2.1 of the License, or (at your option) any later version.
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 *
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 * FFmpeg is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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 * Lesser General Public License for more details.
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 *
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 * You should have received a copy of the GNU Lesser General Public
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 * License along with FFmpeg; if not, write to the Free Software
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 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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 */
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#include "mpegvideo.h"
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#include "h263.h"
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/* don't understand why they choose a different header ! */
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int ff_intel_h263_decode_picture_header(MpegEncContext *s)
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{
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    int format;
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    /* picture header */
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    if (get_bits_long(&s->gb, 22) != 0x20) {
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        av_log(s->avctx, AV_LOG_ERROR, "Bad picture start code\n");
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        return -1;
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    }
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    s->picture_number = get_bits(&s->gb, 8); /* picture timestamp */
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    if (get_bits1(&s->gb) != 1) {
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        av_log(s->avctx, AV_LOG_ERROR, "Bad marker\n");
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        return -1;      /* marker */
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    }
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    if (get_bits1(&s->gb) != 0) {
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        av_log(s->avctx, AV_LOG_ERROR, "Bad H263 id\n");
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        return -1;      /* h263 id */
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    }
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    skip_bits1(&s->gb);         /* split screen off */
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    skip_bits1(&s->gb);         /* camera  off */
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    skip_bits1(&s->gb);         /* freeze picture release off */
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    format = get_bits(&s->gb, 3);
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    if (format == 0 || format == 6) {
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        av_log(s->avctx, AV_LOG_ERROR, "Intel H263 free format not supported\n");
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        return -1;
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    }
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    s->h263_plus = 0;
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    s->pict_type = FF_I_TYPE + get_bits1(&s->gb);
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    s->unrestricted_mv = get_bits1(&s->gb);
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    s->h263_long_vectors = s->unrestricted_mv;
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    if (get_bits1(&s->gb) != 0) {
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        av_log(s->avctx, AV_LOG_ERROR, "SAC not supported\n");
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        return -1;      /* SAC: off */
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    }
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    s->obmc= get_bits1(&s->gb);
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    s->pb_frame = get_bits1(&s->gb);
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    if (format < 6) {
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        s->width = h263_format[format][0];
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        s->height = h263_format[format][1];
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        s->avctx->sample_aspect_ratio.num=12;s->avctx->sample_aspect_ratio.den=11;
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    }
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    else {
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        format = get_bits(&s->gb, 3);
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        if(format == 0 || format == 7){
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            av_log(s->avctx, AV_LOG_ERROR, "Wrong Intel H263 format\n");
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            return -1;
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        }
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        if(get_bits(&s->gb, 2))
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            av_log(s->avctx, AV_LOG_ERROR, "Bad value for reserved field\n");
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        s->loop_filter = get_bits1(&s->gb);
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        if(get_bits1(&s->gb))
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            av_log(s->avctx, AV_LOG_ERROR, "Bad value for reserved field\n");
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        if(get_bits1(&s->gb))
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            s->pb_frame = 2;
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        if(get_bits(&s->gb, 5))
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            av_log(s->avctx, AV_LOG_ERROR, "Bad value for reserved field\n");
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        if(get_bits(&s->gb, 5) != 1)
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            av_log(s->avctx, AV_LOG_ERROR, "Invalid marker\n");
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    }
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    if(format == 6){
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        int ar = get_bits(&s->gb, 4);
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        skip_bits(&s->gb, 9); // display width
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        skip_bits1(&s->gb);
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        skip_bits(&s->gb, 9); // display height
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        if(ar == 15){
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            s->avctx->sample_aspect_ratio.num = get_bits(&s->gb, 8); // aspect ratio - width
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            s->avctx->sample_aspect_ratio.den = get_bits(&s->gb, 8); // aspect ratio - height
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        }
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        else {
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            s->avctx->sample_aspect_ratio = ff_h263_pixel_aspect[ar];
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        }
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        if(s->avctx->sample_aspect_ratio.num == 0)
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            av_log(s->avctx, AV_LOG_ERROR, "Invalid aspect ratio\n");
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    }
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    s->chroma_qscale= s->qscale = get_bits(&s->gb, 5);
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    skip_bits1(&s->gb); /* Continuous Presence Multipoint mode: off */
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    if(s->pb_frame){
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        skip_bits(&s->gb, 3); //temporal reference for B-frame
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        skip_bits(&s->gb, 2); //dbquant
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    }
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    /* PEI */
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    while (get_bits1(&s->gb) != 0) {
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        skip_bits(&s->gb, 8);
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    }
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    s->f_code = 1;
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    s->y_dc_scale_table=
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    s->c_dc_scale_table= ff_mpeg1_dc_scale_table;
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    ff_h263_show_pict_info(s);
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    return 0;
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}
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AVCodec ff_h263i_decoder = {
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    "h263i",
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    AVMEDIA_TYPE_VIDEO,
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    CODEC_ID_H263I,
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    sizeof(MpegEncContext),
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    ff_h263_decode_init,
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    NULL,
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    ff_h263_decode_end,
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    ff_h263_decode_frame,
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    CODEC_CAP_DRAW_HORIZ_BAND | CODEC_CAP_DR1,
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    .long_name = NULL_IF_CONFIG_SMALL("Intel H.263"),
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    .pix_fmts= ff_pixfmt_list_420,
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};
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