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ffmpeg / libavcodec / h263dec.c @ d771bcae

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1 de6d9b64 Fabrice Bellard
/*
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 * H263 decoder
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 * Copyright (c) 2001 Gerard Lantau.
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 *
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 * This program is free software; you can redistribute it and/or modify
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 * it under the terms of the GNU General Public License as published by
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 * the Free Software Foundation; either version 2 of the License, or
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 * (at your option) any later version.
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 *
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 * This program 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
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 * GNU General Public License for more details.
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 *
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 * You should have received a copy of the GNU General Public License
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 * along with this program; if not, write to the Free Software
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 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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 */
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#include <stdlib.h>
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#include <stdio.h>
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#include <string.h>
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#include "dsputil.h"
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#include "avcodec.h"
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#include "mpegvideo.h"
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//#define DEBUG
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static int h263_decode_init(AVCodecContext *avctx)
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{
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    MpegEncContext *s = avctx->priv_data;
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    s->out_format = FMT_H263;
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    s->width = avctx->width;
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    s->height = avctx->height;
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    /* select sub codec */
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    switch(avctx->codec->id) {
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    case CODEC_ID_H263:
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        break;
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    case CODEC_ID_OPENDIVX:
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        s->time_increment_bits = 4; /* default value for broken headers */
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        s->h263_pred = 1;
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        break;
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    case CODEC_ID_MSMPEG4:
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        s->h263_msmpeg4 = 1;
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        s->h263_pred = 1;
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        break;
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    case CODEC_ID_H263I:
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        s->h263_intel = 1;
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        break;
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    default:
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        return -1;
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    }
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    /* for h263, we allocate the images after having read the header */
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    if (MPV_common_init(s) < 0)
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        return -1;
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    if (s->h263_msmpeg4)
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        msmpeg4_decode_init_vlc(s);
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    else
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        h263_decode_init_vlc(s);
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    return 0;
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}
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static int h263_decode_end(AVCodecContext *avctx)
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{
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    MpegEncContext *s = avctx->priv_data;
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    MPV_common_end(s);
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    return 0;
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}
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static int h263_decode_frame(AVCodecContext *avctx, 
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                             void *data, int *data_size,
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                             UINT8 *buf, int buf_size)
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{
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    MpegEncContext *s = avctx->priv_data;
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    int ret;
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    DCTELEM block[6][64];
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    AVPicture *pict = data; 
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#ifdef DEBUG
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    printf("*****frame %d size=%d\n", avctx->frame_number, buf_size);
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    printf("bytes=%x %x %x %x\n", buf[0], buf[1], buf[2], buf[3]);
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#endif
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    /* no supplementary picture */
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    if (buf_size == 0) {
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        *data_size = 0;
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        return 0;
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    }
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    init_get_bits(&s->gb, buf, buf_size);
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    /* let's go :-) */
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    if (s->h263_msmpeg4) {
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        ret = msmpeg4_decode_picture_header(s);
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    } else if (s->h263_pred) {
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        ret = mpeg4_decode_picture_header(s);
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    } else if (s->h263_intel) {
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        ret = intel_h263_decode_picture_header(s);
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    } else {
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        ret = h263_decode_picture_header(s);
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    }
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    if (ret < 0)
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        return -1;
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    MPV_frame_start(s);
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#ifdef DEBUG
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    printf("qscale=%d\n", s->qscale);
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#endif
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    /* decode each macroblock */
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    for(s->mb_y=0; s->mb_y < s->mb_height; s->mb_y++) {
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        for(s->mb_x=0; s->mb_x < s->mb_width; s->mb_x++) {
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#ifdef DEBUG
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            printf("**mb x=%d y=%d\n", s->mb_x, s->mb_y);
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#endif
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            /* DCT & quantize */
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            if (s->h263_msmpeg4) {
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                msmpeg4_dc_scale(s);
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            } else if (s->h263_pred) {
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                h263_dc_scale(s);
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            } else {
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                /* default quantization values */
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                s->y_dc_scale = 8;
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                s->c_dc_scale = 8;
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            }
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            memset(block, 0, sizeof(block));
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            s->mv_dir = MV_DIR_FORWARD;
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            s->mv_type = MV_TYPE_16X16; 
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            if (s->h263_msmpeg4) {
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                if (msmpeg4_decode_mb(s, block) < 0)
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                    return -1;
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            } else {
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                if (h263_decode_mb(s, block) < 0)
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                    return -1;
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            }
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            MPV_decode_mb(s, block);
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        }
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    }
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    MPV_frame_end(s);
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    pict->data[0] = s->current_picture[0];
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    pict->data[1] = s->current_picture[1];
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    pict->data[2] = s->current_picture[2];
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    pict->linesize[0] = s->linesize;
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    pict->linesize[1] = s->linesize / 2;
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    pict->linesize[2] = s->linesize / 2;
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    avctx->quality = s->qscale;
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    *data_size = sizeof(AVPicture);
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    return buf_size;
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}
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AVCodec opendivx_decoder = {
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    "opendivx",
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    CODEC_TYPE_VIDEO,
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    CODEC_ID_OPENDIVX,
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    sizeof(MpegEncContext),
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    h263_decode_init,
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    NULL,
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    h263_decode_end,
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    h263_decode_frame,
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};
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AVCodec h263_decoder = {
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    "h263",
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    CODEC_TYPE_VIDEO,
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    CODEC_ID_H263,
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    sizeof(MpegEncContext),
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    h263_decode_init,
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    NULL,
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    h263_decode_end,
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    h263_decode_frame,
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};
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AVCodec msmpeg4_decoder = {
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    "msmpeg4",
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    CODEC_TYPE_VIDEO,
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    CODEC_ID_MSMPEG4,
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    sizeof(MpegEncContext),
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    h263_decode_init,
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    NULL,
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    h263_decode_end,
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    h263_decode_frame,
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};
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AVCodec h263i_decoder = {
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    "h263i",
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    CODEC_TYPE_VIDEO,
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    CODEC_ID_H263I,
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    sizeof(MpegEncContext),
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    h263_decode_init,
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    NULL,
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    h263_decode_end,
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    h263_decode_frame,
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};