FFmpeg/libavcodec/h263dec.c

/*
 * H263 decoder
 * Copyright (c) 2001 Gerard Lantau.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include "dsputil.h"
#include "avcodec.h"
#include "mpegvideo.h"

//#define DEBUG

static int h263_decode_init(AVCodecContext *avctx)
{
    MpegEncContext *s = avctx->priv_data;
    int i;

    s->avctx = avctx;
    s->out_format = FMT_H263;

    s->width = avctx->width;
    s->height = avctx->height;

    /* select sub codec */
    switch(avctx->codec->id) {
    case CODEC_ID_H263:
        s->gob_number = 0;
        s->first_gob_line = 0;
        break;
    case CODEC_ID_MPEG4:
        s->time_increment_bits = 4; /* default value for broken headers */
        s->h263_pred = 1;
        s->has_b_frames = 1; //default, might be overriden in the vol header during header parsing
        break;
    case CODEC_ID_MSMPEG4V1:
        s->h263_msmpeg4 = 1;
        s->h263_pred = 1;
        s->msmpeg4_version=1;
        break;
    case CODEC_ID_MSMPEG4V2:
        s->h263_msmpeg4 = 1;
        s->h263_pred = 1;
        s->msmpeg4_version=2;
        break;
    case CODEC_ID_MSMPEG4V3:
        s->h263_msmpeg4 = 1;
        s->h263_pred = 1;
        s->msmpeg4_version=3;
        break;
    case CODEC_ID_WMV1:
        s->h263_msmpeg4 = 1;
        s->h263_pred = 1;
        s->msmpeg4_version=4;
        break;
    case CODEC_ID_H263I:
        s->h263_intel = 1;
        break;
    default:
        return -1;
    }
    s->codec_id= avctx->codec->id;
    
    /* for h263, we allocate the images after having read the header */
    if (avctx->codec->id != CODEC_ID_H263 && avctx->codec->id != CODEC_ID_MPEG4)
        if (MPV_common_init(s) < 0)
            return -1;

    if (s->h263_msmpeg4)
        msmpeg4_decode_init_vlc(s);
    else
        h263_decode_init_vlc(s);
    
    return 0;
}

static int h263_decode_end(AVCodecContext *avctx)
{
    MpegEncContext *s = avctx->priv_data;

    MPV_common_end(s);
    return 0;
}

static int h263_decode_frame(AVCodecContext *avctx, 
                             void *data, int *data_size,
                             UINT8 *buf, int buf_size)
{
    MpegEncContext *s = avctx->priv_data;
    int ret;
    AVPicture *pict = data; 

#ifdef DEBUG
    printf("*****frame %d size=%d\n", avctx->frame_number, buf_size);
    printf("bytes=%x %x %x %x\n", buf[0], buf[1], buf[2], buf[3]);
#endif
    
    /* no supplementary picture */
    if (buf_size == 0) {
        *data_size = 0;
        return 0;
    }

    if(s->bitstream_buffer_size) //divx 5.01+ frame reorder
        init_get_bits(&s->gb, s->bitstream_buffer, s->bitstream_buffer_size);
    else
        init_get_bits(&s->gb, buf, buf_size);

    /* let's go :-) */
    if (s->h263_msmpeg4) {
        ret = msmpeg4_decode_picture_header(s);
    } else if (s->h263_pred) {
        ret = mpeg4_decode_picture_header(s);
        s->has_b_frames= !s->low_delay;
    } else if (s->h263_intel) {
        ret = intel_h263_decode_picture_header(s);
    } else {
        ret = h263_decode_picture_header(s);
    }

        /* After H263 & mpeg4 header decode we have the height, width,*/
        /* and other parameters. So then we could init the picture   */
        /* FIXME: By the way H263 decoder is evolving it should have */
        /* an H263EncContext                                         */
    if (!s->context_initialized) {
        avctx->width = s->width;
        avctx->height = s->height;
        avctx->aspect_ratio_info= s->aspect_ratio_info;
        if (MPV_common_init(s) < 0)
            return -1;
    } else if (s->width != avctx->width || s->height != avctx->height) {
        /* H.263 could change picture size any time */
        MPV_common_end(s);
        if (MPV_common_init(s) < 0)
            return -1;
    }

    if(ret==FRAME_SKIPED) return 0;
    if (ret < 0)
        return -1;
    /* skip b frames if we dont have reference frames */
    if(s->num_available_buffers<2 && s->pict_type==B_TYPE) return 0;
        
    MPV_frame_start(s);

#ifdef DEBUG
    printf("qscale=%d\n", s->qscale);
#endif

    /* decode each macroblock */
    s->block_wrap[0]=
    s->block_wrap[1]=
    s->block_wrap[2]=
    s->block_wrap[3]= s->mb_width*2 + 2;
    s->block_wrap[4]=
    s->block_wrap[5]= s->mb_width + 2;
    for(s->mb_y=0; s->mb_y < s->mb_height; s->mb_y++) {
        /* Check for GOB headers on H.263 */
        /* FIXME: In the future H.263+ will have intra prediction */
        /* and we are gonna need another way to detect MPEG4      */
        if (s->mb_y && !s->h263_pred) {
            s->first_gob_line = h263_decode_gob_header(s);
        }

        s->block_index[0]= s->block_wrap[0]*(s->mb_y*2 + 1) - 1;
        s->block_index[1]= s->block_wrap[0]*(s->mb_y*2 + 1);
        s->block_index[2]= s->block_wrap[0]*(s->mb_y*2 + 2) - 1;
        s->block_index[3]= s->block_wrap[0]*(s->mb_y*2 + 2);
        s->block_index[4]= s->block_wrap[4]*(s->mb_y + 1)                    + s->block_wrap[0]*(s->mb_height*2 + 2);
        s->block_index[5]= s->block_wrap[4]*(s->mb_y + 1 + s->mb_height + 2) + s->block_wrap[0]*(s->mb_height*2 + 2);
        for(s->mb_x=0; s->mb_x < s->mb_width; s->mb_x++) {
            s->block_index[0]+=2;
            s->block_index[1]+=2;
            s->block_index[2]+=2;
            s->block_index[3]+=2;
            s->block_index[4]++;
            s->block_index[5]++;
#ifdef DEBUG
            printf("**mb x=%d y=%d\n", s->mb_x, s->mb_y);
#endif
            //fprintf(stderr,"\nFrame: %d\tMB: %d",avctx->frame_number, (s->mb_y * s->mb_width) + s->mb_x);
            /* DCT & quantize */
            if (s->h263_msmpeg4) {
                msmpeg4_dc_scale(s);
            } else if (s->h263_pred) {
                h263_dc_scale(s);
            } else {
                /* default quantization values */
                s->y_dc_scale = 8;
                s->c_dc_scale = 8;
            }
            clear_blocks(s->block[0]);
            
            s->mv_dir = MV_DIR_FORWARD;
            s->mv_type = MV_TYPE_16X16; 
            if (s->h263_msmpeg4) {
		if (msmpeg4_decode_mb(s, s->block) < 0) {
		    fprintf(stderr,"\nError at MB: %d\n", (s->mb_y * s->mb_width) + s->mb_x);
                    return -1;
		}
            } else {
                if (h263_decode_mb(s, s->block) < 0) {
                    fprintf(stderr,"\nError at MB: %d\n", (s->mb_y * s->mb_width) + s->mb_x);
                    return -1;
                }
            }
            MPV_decode_mb(s, s->block);
        }
        if (    avctx->draw_horiz_band 
            && (s->num_available_buffers>=1 || (!s->has_b_frames)) ) {
            UINT8 *src_ptr[3];
            int y, h, offset;
            y = s->mb_y * 16;
            h = s->height - y;
            if (h > 16)
                h = 16;
            offset = y * s->linesize;
            if(s->pict_type==B_TYPE || (!s->has_b_frames)){
                src_ptr[0] = s->current_picture[0] + offset;
                src_ptr[1] = s->current_picture[1] + (offset >> 2);
                src_ptr[2] = s->current_picture[2] + (offset >> 2);
            } else {
                src_ptr[0] = s->last_picture[0] + offset;
                src_ptr[1] = s->last_picture[1] + (offset >> 2);
                src_ptr[2] = s->last_picture[2] + (offset >> 2);
            }
            avctx->draw_horiz_band(avctx, src_ptr, s->linesize,
                                   y, s->width, h);
        }
    }
    
    if (s->h263_msmpeg4 && s->msmpeg4_version<4 && s->pict_type==I_TYPE)
        if(msmpeg4_decode_ext_header(s, buf_size) < 0) return -1;
    
    /* divx 5.01+ bistream reorder stuff */
    if(s->codec_id==CODEC_ID_MPEG4 && s->bitstream_buffer_size==0){
        int current_pos= get_bits_count(&s->gb)/8;
        if(   buf_size - current_pos > 5 
           && buf_size - current_pos < BITSTREAM_BUFFER_SIZE){
            memcpy(s->bitstream_buffer, buf + current_pos, buf_size - current_pos);
            s->bitstream_buffer_size= buf_size - current_pos;
        }
    }else
        s->bitstream_buffer_size=0;
  
    MPV_frame_end(s);
    
    if(s->pict_type==B_TYPE || (!s->has_b_frames)){
        pict->data[0] = s->current_picture[0];
        pict->data[1] = s->current_picture[1];
        pict->data[2] = s->current_picture[2];
    } else {
        pict->data[0] = s->last_picture[0];
        pict->data[1] = s->last_picture[1];
        pict->data[2] = s->last_picture[2];
    }
    pict->linesize[0] = s->linesize;
    pict->linesize[1] = s->linesize / 2;
    pict->linesize[2] = s->linesize / 2;

    avctx->quality = s->qscale;

    /* Return the Picture timestamp as the frame number */
    /* we substract 1 because it is added on utils.c    */
    avctx->frame_number = s->picture_number - 1;

    /* dont output the last pic after seeking 
       note we allready added +1 for the current pix in MPV_frame_end(s) */
    if(s->num_available_buffers>=2 || (!s->has_b_frames))
        *data_size = sizeof(AVPicture);

    return buf_size;
}

AVCodec mpeg4_decoder = {
    "mpeg4",
    CODEC_TYPE_VIDEO,
    CODEC_ID_MPEG4,
    sizeof(MpegEncContext),
    h263_decode_init,
    NULL,
    h263_decode_end,
    h263_decode_frame,
    CODEC_CAP_DRAW_HORIZ_BAND,
};

AVCodec h263_decoder = {
    "h263",
    CODEC_TYPE_VIDEO,
    CODEC_ID_H263,
    sizeof(MpegEncContext),
    h263_decode_init,
    NULL,
    h263_decode_end,
    h263_decode_frame,
    CODEC_CAP_DRAW_HORIZ_BAND,
};

AVCodec msmpeg4v1_decoder = {
    "msmpeg4v1",
    CODEC_TYPE_VIDEO,
    CODEC_ID_MSMPEG4V1,
    sizeof(MpegEncContext),
    h263_decode_init,
    NULL,
    h263_decode_end,
    h263_decode_frame,
    CODEC_CAP_DRAW_HORIZ_BAND,
};

AVCodec msmpeg4v2_decoder = {
    "msmpeg4v2",
    CODEC_TYPE_VIDEO,
    CODEC_ID_MSMPEG4V2,
    sizeof(MpegEncContext),
    h263_decode_init,
    NULL,
    h263_decode_end,
    h263_decode_frame,
    CODEC_CAP_DRAW_HORIZ_BAND,
};

AVCodec msmpeg4v3_decoder = {
    "msmpeg4",
    CODEC_TYPE_VIDEO,
    CODEC_ID_MSMPEG4V3,
    sizeof(MpegEncContext),
    h263_decode_init,
    NULL,
    h263_decode_end,
    h263_decode_frame,
    CODEC_CAP_DRAW_HORIZ_BAND,
};

AVCodec wmv1_decoder = {
    "wmv1",
    CODEC_TYPE_VIDEO,
    CODEC_ID_WMV1,
    sizeof(MpegEncContext),
    h263_decode_init,
    NULL,
    h263_decode_end,
    h263_decode_frame,
    CODEC_CAP_DRAW_HORIZ_BAND,
};

AVCodec h263i_decoder = {
    "h263i",
    CODEC_TYPE_VIDEO,
    CODEC_ID_H263I,
    sizeof(MpegEncContext),
    h263_decode_init,
    NULL,
    h263_decode_end,
    h263_decode_frame,
    CODEC_CAP_DRAW_HORIZ_BAND,
};