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/*
* American Laser Games MM Video Decoder
* Copyright (c) 2006 Peter Ross
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file mm.c
* American Laser Games MM Video Decoder
* by Peter Ross (suxen_drol at hotmail dot com)
*
* The MM format was used by IBM-PC ports of ALG's "arcade shooter" games,
* including Mad Dog McCree and Crime Patrol.
*
* Technical details here:
* http://wiki.multimedia.cx/index.php?title=American_Laser_Games_MM
*/
#include "avcodec.h"
#define MM_PREAMBLE_SIZE 6
#define MM_TYPE_INTER 0x5
#define MM_TYPE_INTRA 0x8
#define MM_TYPE_INTRA_HH 0xc
#define MM_TYPE_INTER_HH 0xd
#define MM_TYPE_INTRA_HHV 0xe
#define MM_TYPE_INTER_HHV 0xf
typedef struct MmContext {
AVCodecContext *avctx;
AVFrame frame;
} MmContext;
static int mm_decode_init(AVCodecContext *avctx)
{
MmContext *s = avctx->priv_data;
s->avctx = avctx;
if (s->avctx->palctrl == NULL) {
av_log(avctx, AV_LOG_ERROR, "mmvideo: palette expected.\n");
return -1;
}
avctx->pix_fmt = PIX_FMT_PAL8;
avctx->has_b_frames = 0;
if (avcodec_check_dimensions(avctx, avctx->width, avctx->height))
return -1;
s->frame.reference = 1;
if (avctx->get_buffer(avctx, &s->frame)) {
av_log(s->avctx, AV_LOG_ERROR, "mmvideo: get_buffer() failed\n");
return -1;
}
return 0;
}
static void mm_decode_intra(MmContext * s, int half_horiz, int half_vert, const uint8_t *buf, int buf_size)
{
int i, x, y;
i=0; x=0; y=0;
while(i<buf_size) {
int run_length, color;
if (buf[i] & 0x80) {
run_length = 1;
color = buf[i];
i++;
}else{
run_length = (buf[i] & 0x7f) + 2;
color = buf[i+1];
i+=2;
}
if (half_horiz)
run_length *=2;
if (color) {
memset(s->frame.data[0] + y*s->frame.linesize[0] + x, color, run_length);
if (half_vert)
memset(s->frame.data[0] + (y+1)*s->frame.linesize[0] + x, color, run_length);
}
x+= run_length;
if (x >= s->avctx->width) {
x=0;
y += half_vert ? 2 : 1;
}
}
}
static void mm_decode_inter(MmContext * s, int half_horiz, int half_vert, const uint8_t *buf, int buf_size)
{
const int data_ptr = 2 + LE_16(&buf[0]);
int d, r, y;
d = data_ptr; r = 2; y = 0;
while(r < data_ptr) {
int i, j;
int length = buf[r] & 0x7f;
int x = buf[r+1] + ((buf[r] & 0x80) << 1);
r += 2;
if (length==0) {
y += x;
continue;
}
for(i=0; i<length; i++) {
for(j=0; j<8; j++) {
int replace = (buf[r+i] >> (7-j)) & 1;
if (replace) {
int color = buf[d];
s->frame.data[0][y*s->frame.linesize[0] + x] = color;
if (half_horiz)
s->frame.data[0][y*s->frame.linesize[0] + x + 1] = color;
if (half_vert) {
s->frame.data[0][(y+1)*s->frame.linesize[0] + x] = color;
if (half_horiz)
s->frame.data[0][(y+1)*s->frame.linesize[0] + x + 1] = color;
}
d++;
}
x += half_horiz ? 2 : 1;
}
}
r += length;
y += half_vert ? 2 : 1;
}
}
static int mm_decode_frame(AVCodecContext *avctx,
void *data, int *data_size,
uint8_t *buf, int buf_size)
{
MmContext *s = avctx->priv_data;
AVPaletteControl *palette_control = avctx->palctrl;
int type;
if (palette_control->palette_changed) {
memcpy(s->frame.data[1], palette_control->palette, AVPALETTE_SIZE);
palette_control->palette_changed = 0;
}
type = LE_16(&buf[0]);
buf += MM_PREAMBLE_SIZE;
buf_size -= MM_PREAMBLE_SIZE;
switch(type) {
case MM_TYPE_INTRA : mm_decode_intra(s, 0, 0, buf, buf_size); break;
case MM_TYPE_INTRA_HH : mm_decode_intra(s, 1, 0, buf, buf_size); break;
case MM_TYPE_INTRA_HHV : mm_decode_intra(s, 1, 1, buf, buf_size); break;
case MM_TYPE_INTER : mm_decode_inter(s, 0, 0, buf, buf_size); break;
case MM_TYPE_INTER_HH : mm_decode_inter(s, 1, 0, buf, buf_size); break;
case MM_TYPE_INTER_HHV : mm_decode_inter(s, 1, 1, buf, buf_size); break;
default :
return -1;
}
*data_size = sizeof(AVFrame);
*(AVFrame*)data = s->frame;
return buf_size;
}
static int mm_decode_end(AVCodecContext *avctx)
{
MmContext *s = avctx->priv_data;
if(s->frame.data[0])
avctx->release_buffer(avctx, &s->frame);
return 0;
}
AVCodec mmvideo_decoder = {
"mmvideo",
CODEC_TYPE_VIDEO,
CODEC_ID_MMVIDEO,
sizeof(MmContext),
mm_decode_init,
NULL,
mm_decode_end,
mm_decode_frame,
CODEC_CAP_DR1,
};
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