2006-02-12 07:49:40 +01:00
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/*
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* American Laser Games MM Video Decoder
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* Copyright (c) 2006 Peter Ross
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*
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* This library 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 of the License, or (at your option) any later version.
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*
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* This library 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 this library; if not, write to the Free Software
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2006-07-26 03:12:26 +02:00
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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2006-02-12 07:49:40 +01:00
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*/
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/**
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* @file mm.c
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* American Laser Games MM Video Decoder
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* by Peter Ross (suxen_drol at hotmail dot com)
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*
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* The MM format was used by IBM-PC ports of ALG's "arcade shooter" games,
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* including Mad Dog McCree and Crime Patrol.
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*
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* Technical details here:
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* http://wiki.multimedia.cx/index.php?title=American_Laser_Games_MM
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*/
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#include "avcodec.h"
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#define MM_PREAMBLE_SIZE 6
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#define MM_TYPE_INTER 0x5
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#define MM_TYPE_INTRA 0x8
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#define MM_TYPE_INTRA_HH 0xc
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#define MM_TYPE_INTER_HH 0xd
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#define MM_TYPE_INTRA_HHV 0xe
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#define MM_TYPE_INTER_HHV 0xf
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typedef struct MmContext {
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AVCodecContext *avctx;
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AVFrame frame;
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} MmContext;
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static int mm_decode_init(AVCodecContext *avctx)
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{
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MmContext *s = avctx->priv_data;
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s->avctx = avctx;
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if (s->avctx->palctrl == NULL) {
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av_log(avctx, AV_LOG_ERROR, "mmvideo: palette expected.\n");
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return -1;
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}
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avctx->pix_fmt = PIX_FMT_PAL8;
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avctx->has_b_frames = 0;
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if (avcodec_check_dimensions(avctx, avctx->width, avctx->height))
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return -1;
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s->frame.reference = 1;
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if (avctx->get_buffer(avctx, &s->frame)) {
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av_log(s->avctx, AV_LOG_ERROR, "mmvideo: get_buffer() failed\n");
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return -1;
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}
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return 0;
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}
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static void mm_decode_intra(MmContext * s, int half_horiz, int half_vert, const uint8_t *buf, int buf_size)
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{
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int i, x, y;
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i=0; x=0; y=0;
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while(i<buf_size) {
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int run_length, color;
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if (buf[i] & 0x80) {
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run_length = 1;
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color = buf[i];
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i++;
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}else{
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run_length = (buf[i] & 0x7f) + 2;
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color = buf[i+1];
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i+=2;
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}
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if (half_horiz)
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run_length *=2;
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if (color) {
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memset(s->frame.data[0] + y*s->frame.linesize[0] + x, color, run_length);
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if (half_vert)
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memset(s->frame.data[0] + (y+1)*s->frame.linesize[0] + x, color, run_length);
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}
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x+= run_length;
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if (x >= s->avctx->width) {
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x=0;
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y += half_vert ? 2 : 1;
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}
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}
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}
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static void mm_decode_inter(MmContext * s, int half_horiz, int half_vert, const uint8_t *buf, int buf_size)
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{
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const int data_ptr = 2 + LE_16(&buf[0]);
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int d, r, y;
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d = data_ptr; r = 2; y = 0;
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while(r < data_ptr) {
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int i, j;
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int length = buf[r] & 0x7f;
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int x = buf[r+1] + ((buf[r] & 0x80) << 1);
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r += 2;
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if (length==0) {
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y += x;
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continue;
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}
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for(i=0; i<length; i++) {
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for(j=0; j<8; j++) {
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int replace = (buf[r+i] >> (7-j)) & 1;
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if (replace) {
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int color = buf[d];
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s->frame.data[0][y*s->frame.linesize[0] + x] = color;
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if (half_horiz)
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s->frame.data[0][y*s->frame.linesize[0] + x + 1] = color;
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if (half_vert) {
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s->frame.data[0][(y+1)*s->frame.linesize[0] + x] = color;
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if (half_horiz)
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s->frame.data[0][(y+1)*s->frame.linesize[0] + x + 1] = color;
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}
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d++;
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}
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x += half_horiz ? 2 : 1;
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}
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}
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r += length;
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y += half_vert ? 2 : 1;
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}
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}
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static int mm_decode_frame(AVCodecContext *avctx,
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void *data, int *data_size,
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uint8_t *buf, int buf_size)
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{
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MmContext *s = avctx->priv_data;
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AVPaletteControl *palette_control = avctx->palctrl;
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int type;
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if (palette_control->palette_changed) {
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memcpy(s->frame.data[1], palette_control->palette, AVPALETTE_SIZE);
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palette_control->palette_changed = 0;
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}
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type = LE_16(&buf[0]);
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buf += MM_PREAMBLE_SIZE;
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buf_size -= MM_PREAMBLE_SIZE;
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switch(type) {
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case MM_TYPE_INTRA : mm_decode_intra(s, 0, 0, buf, buf_size); break;
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case MM_TYPE_INTRA_HH : mm_decode_intra(s, 1, 0, buf, buf_size); break;
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case MM_TYPE_INTRA_HHV : mm_decode_intra(s, 1, 1, buf, buf_size); break;
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case MM_TYPE_INTER : mm_decode_inter(s, 0, 0, buf, buf_size); break;
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case MM_TYPE_INTER_HH : mm_decode_inter(s, 1, 0, buf, buf_size); break;
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case MM_TYPE_INTER_HHV : mm_decode_inter(s, 1, 1, buf, buf_size); break;
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default :
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return -1;
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}
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*data_size = sizeof(AVFrame);
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*(AVFrame*)data = s->frame;
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return buf_size;
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}
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static int mm_decode_end(AVCodecContext *avctx)
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{
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MmContext *s = avctx->priv_data;
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if(s->frame.data[0])
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avctx->release_buffer(avctx, &s->frame);
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return 0;
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}
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AVCodec mmvideo_decoder = {
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"mmvideo",
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CODEC_TYPE_VIDEO,
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CODEC_ID_MMVIDEO,
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sizeof(MmContext),
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mm_decode_init,
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NULL,
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mm_decode_end,
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mm_decode_frame,
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CODEC_CAP_DR1,
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};
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