PeerStreamer

/*

 * American Laser Games MM Video Decoder

 * Copyright (c) 2006,2008 Peter Ross

 *

 * This file is part of FFmpeg.

 *

 * FFmpeg 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 2.1 of the License, or (at your option) any later version.

 *

 * FFmpeg 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 FFmpeg; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

 */

/**

 * @file

 * American Laser Games MM Video Decoder

 * by Peter Ross (pross@xvid.org)

 *

 * 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 "libavutil/intreadwrite.h"

#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

#define MM_TYPE_PALETTE     0x31

typedef struct MmContext {

    AVCodecContext *avctx;

    AVFrame frame;

    int palette[AVPALETTE_COUNT];

} MmContext;

static av_cold int mm_decode_init(AVCodecContext *avctx)

{

    MmContext *s = avctx->priv_data;

    s->avctx = avctx;

    avctx->pix_fmt = PIX_FMT_PAL8;

    s->frame.reference = 1;

    if (avctx->get_buffer(avctx, &s->frame)) {

        av_log(s->avctx, AV_LOG_ERROR, "get_buffer() failed\n");

        return -1;

    }

    return 0;

}

static void mm_decode_pal(MmContext *s, const uint8_t *buf, const uint8_t *buf_end)

{

    int i;

    buf += 4;

    for (i=0; i<128 && buf+2<buf_end; i++) {

        s->palette[i] = AV_RB24(buf);

        s->palette[i+128] = s->palette[i]<<2;

        buf += 3;

    }

}

/**

 * @param half_horiz Half horizontal resolution (0 or 1)

 * @param half_vert Half vertical resolution (0 or 1)

 */

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 (y >= s->avctx->height)

            return;

        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 += 1 + half_vert;

        }

    }

}

/*

 * @param half_horiz Half horizontal resolution (0 or 1)

 * @param half_vert Half vertical resolution (0 or 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 + AV_RL16(&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;

        }

        if (y + half_vert >= s->avctx->height)

            return;

        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 += 1 + half_horiz;

            }

        }

        r += length;

        y += 1 + half_vert;

    }

}

static int mm_decode_frame(AVCodecContext *avctx,

                            void *data, int *data_size,

                            AVPacket *avpkt)

{

    const uint8_t *buf = avpkt->data;

    int buf_size = avpkt->size;

    MmContext *s = avctx->priv_data;

    const uint8_t *buf_end = buf+buf_size;

    int type;

    type = AV_RL16(&buf[0]);

    buf += MM_PREAMBLE_SIZE;

    buf_size -= MM_PREAMBLE_SIZE;

    switch(type) {

    case MM_TYPE_PALETTE   : mm_decode_pal(s, buf, buf_end); return buf_size;

    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;

    }

    memcpy(s->frame.data[1], s->palette, AVPALETTE_SIZE);

    *data_size = sizeof(AVFrame);

    *(AVFrame*)data = s->frame;

    return buf_size;

}

static av_cold 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 ff_mmvideo_decoder = {

    "mmvideo",

    AVMEDIA_TYPE_VIDEO,

    CODEC_ID_MMVIDEO,

    sizeof(MmContext),

    mm_decode_init,

    NULL,

    mm_decode_end,

    mm_decode_frame,

    CODEC_CAP_DR1,

    .long_name = NULL_IF_CONFIG_SMALL("American Laser Games MM Video"),

};