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ffmpeg / libavcodec / mmvideo.c @ d36beb3f

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/*
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 * American Laser Games MM Video Decoder
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 * Copyright (c) 2006,2008 Peter Ross
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 *
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 * This file is part of FFmpeg.
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 *
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 * FFmpeg 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 2.1 of the License, or (at your option) any later version.
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 *
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 * FFmpeg 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 FFmpeg; if not, write to the Free Software
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 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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 */
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/**
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 * @file
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 * American Laser Games MM Video Decoder
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 * by Peter Ross (pross@xvid.org)
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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 "libavutil/intreadwrite.h"
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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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#define MM_TYPE_PALETTE     0x31
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typedef struct MmContext {
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    AVCodecContext *avctx;
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    AVFrame frame;
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    int palette[AVPALETTE_COUNT];
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} MmContext;
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static av_cold 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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    avctx->pix_fmt = PIX_FMT_PAL8;
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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, "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_pal(MmContext *s, const uint8_t *buf, const uint8_t *buf_end)
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{
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    int i;
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    buf += 4;
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    for (i=0; i<128 && buf+2<buf_end; i++) {
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        s->palette[i] = AV_RB24(buf);
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        s->palette[i+128] = s->palette[i]<<2;
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        buf += 3;
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    }
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}
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/**
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 * @param half_horiz Half horizontal resolution (0 or 1)
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 * @param half_vert Half vertical resolution (0 or 1)
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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 (y >= s->avctx->height)
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            return;
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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 += 1 + half_vert;
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        }
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    }
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}
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/*
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 * @param half_horiz Half horizontal resolution (0 or 1)
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 * @param half_vert Half vertical resolution (0 or 1)
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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 + AV_RL16(&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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        if (y + half_vert >= s->avctx->height)
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            return;
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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 += 1 + half_horiz;
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            }
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        }
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        r += length;
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        y += 1 + half_vert;
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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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                            AVPacket *avpkt)
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{
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    const uint8_t *buf = avpkt->data;
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    int buf_size = avpkt->size;
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    MmContext *s = avctx->priv_data;
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    const uint8_t *buf_end = buf+buf_size;
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    int type;
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    type = AV_RL16(&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_PALETTE   : mm_decode_pal(s, buf, buf_end); return buf_size;
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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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    memcpy(s->frame.data[1], s->palette, AVPALETTE_SIZE);
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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 av_cold 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 ff_mmvideo_decoder = {
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    "mmvideo",
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    AVMEDIA_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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    .long_name = NULL_IF_CONFIG_SMALL("American Laser Games MM Video"),
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};