FFmpeg/libavcodec/h263dec.c
Fabrice Bellard de6d9b6404 Initial revision
Originally committed as revision 5 to svn://svn.ffmpeg.org/ffmpeg/trunk
2001-07-22 14:18:56 +00:00

206 lines
4.9 KiB
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;
s->out_format = FMT_H263;
s->width = avctx->width;
s->height = avctx->height;
/* select sub codec */
switch(avctx->codec->id) {
case CODEC_ID_H263:
break;
case CODEC_ID_OPENDIVX:
s->time_increment_bits = 4; /* default value for broken headers */
s->h263_pred = 1;
break;
case CODEC_ID_MSMPEG4:
s->h263_msmpeg4 = 1;
s->h263_pred = 1;
break;
case CODEC_ID_H263I:
s->h263_intel = 1;
break;
default:
return -1;
}
/* for h263, we allocate the images after having read the header */
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;
DCTELEM block[6][64];
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;
}
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);
} else if (s->h263_intel) {
ret = intel_h263_decode_picture_header(s);
} else {
ret = h263_decode_picture_header(s);
}
if (ret < 0)
return -1;
MPV_frame_start(s);
#ifdef DEBUG
printf("qscale=%d\n", s->qscale);
#endif
/* decode each macroblock */
for(s->mb_y=0; s->mb_y < s->mb_height; s->mb_y++) {
for(s->mb_x=0; s->mb_x < s->mb_width; s->mb_x++) {
#ifdef DEBUG
printf("**mb x=%d y=%d\n", s->mb_x, s->mb_y);
#endif
/* 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;
}
memset(block, 0, sizeof(block));
s->mv_dir = MV_DIR_FORWARD;
s->mv_type = MV_TYPE_16X16;
if (s->h263_msmpeg4) {
if (msmpeg4_decode_mb(s, block) < 0)
return -1;
} else {
if (h263_decode_mb(s, block) < 0)
return -1;
}
MPV_decode_mb(s, block);
}
}
MPV_frame_end(s);
pict->data[0] = s->current_picture[0];
pict->data[1] = s->current_picture[1];
pict->data[2] = s->current_picture[2];
pict->linesize[0] = s->linesize;
pict->linesize[1] = s->linesize / 2;
pict->linesize[2] = s->linesize / 2;
avctx->quality = s->qscale;
*data_size = sizeof(AVPicture);
return buf_size;
}
AVCodec opendivx_decoder = {
"opendivx",
CODEC_TYPE_VIDEO,
CODEC_ID_OPENDIVX,
sizeof(MpegEncContext),
h263_decode_init,
NULL,
h263_decode_end,
h263_decode_frame,
};
AVCodec h263_decoder = {
"h263",
CODEC_TYPE_VIDEO,
CODEC_ID_H263,
sizeof(MpegEncContext),
h263_decode_init,
NULL,
h263_decode_end,
h263_decode_frame,
};
AVCodec msmpeg4_decoder = {
"msmpeg4",
CODEC_TYPE_VIDEO,
CODEC_ID_MSMPEG4,
sizeof(MpegEncContext),
h263_decode_init,
NULL,
h263_decode_end,
h263_decode_frame,
};
AVCodec h263i_decoder = {
"h263i",
CODEC_TYPE_VIDEO,
CODEC_ID_H263I,
sizeof(MpegEncContext),
h263_decode_init,
NULL,
h263_decode_end,
h263_decode_frame,
};