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ffmpeg / libavcodec / eamad.c @ 84dc2d8a

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/*
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 * Electronic Arts Madcow Video Decoder
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 * Copyright (c) 2007-2009 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 St, Fifth Floor, Boston, MA  02110-1301  USA
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 */
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/**
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 * @file libavcodec/eamad.c
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 * Electronic Arts Madcow Video Decoder
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 * by Peter Ross <pross@xvid.org>
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 *
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 * Technical details here:
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 * http://wiki.multimedia.cx/index.php?title=Electronic_Arts_MAD
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 */
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#include "avcodec.h"
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#include "get_bits.h"
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#include "dsputil.h"
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#include "aandcttab.h"
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#include "mpeg12.h"
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#include "mpeg12data.h"
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#define EA_PREAMBLE_SIZE    8
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#define MADk_TAG MKTAG('M', 'A', 'D', 'k')    /* MAD i-frame */
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#define MADm_TAG MKTAG('M', 'A', 'D', 'm')    /* MAD p-frame */
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#define MADe_TAG MKTAG('M', 'A', 'D', 'e')    /* MAD lqp-frame */
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typedef struct MadContext {
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    MpegEncContext s;
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    AVFrame frame;
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    AVFrame last_frame;
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    void *bitstream_buf;
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    unsigned int bitstream_buf_size;
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    DECLARE_ALIGNED(16, DCTELEM, block)[64];
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} MadContext;
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static void bswap16_buf(uint16_t *dst, const uint16_t *src, int count)
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{
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    int i;
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    for (i=0; i<count; i++)
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        dst[i] = bswap_16(src[i]);
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}
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static av_cold int decode_init(AVCodecContext *avctx)
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{
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    MadContext *t = avctx->priv_data;
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    MpegEncContext *s = &t->s;
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    s->avctx = avctx;
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    avctx->pix_fmt = PIX_FMT_YUV420P;
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    if (avctx->idct_algo == FF_IDCT_AUTO)
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        avctx->idct_algo = FF_IDCT_EA;
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    dsputil_init(&s->dsp, avctx);
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    ff_init_scantable(s->dsp.idct_permutation, &s->intra_scantable, ff_zigzag_direct);
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    ff_mpeg12_init_vlcs();
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    return 0;
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}
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static inline void comp(unsigned char *dst, int dst_stride,
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                        unsigned char *src, int src_stride, int add)
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{
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    int j, i;
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    for (j=0; j<8; j++)
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        for (i=0; i<8; i++)
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            dst[j*dst_stride + i] = av_clip_uint8(src[j*src_stride + i] + add);
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}
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static inline void comp_block(MadContext *t, int mb_x, int mb_y,
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                              int j, int mv_x, int mv_y, int add)
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{
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    MpegEncContext *s = &t->s;
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    if (j < 4) {
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        comp(t->frame.data[0] + (mb_y*16 + ((j&2)<<2))*t->frame.linesize[0] + mb_x*16 + ((j&1)<<3),
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             t->frame.linesize[0],
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             t->last_frame.data[0] + (mb_y*16 + ((j&2)<<2) + mv_y)*t->last_frame.linesize[0] + mb_x*16 + ((j&1)<<3) + mv_x,
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             t->last_frame.linesize[0], add);
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    } else if (!(s->avctx->flags & CODEC_FLAG_GRAY)) {
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        int index = j - 3;
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        comp(t->frame.data[index] + (mb_y*8)*t->frame.linesize[index] + mb_x * 8,
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             t->frame.linesize[index],
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             t->last_frame.data[index] + (mb_y * 8 + (mv_y/2))*t->last_frame.linesize[index] + mb_x * 8 + (mv_x/2),
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             t->last_frame.linesize[index], add);
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    }
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}
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static inline void idct_put(MadContext *t, DCTELEM *block, int mb_x, int mb_y, int j)
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{
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    MpegEncContext *s = &t->s;
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    if (j < 4) {
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        s->dsp.idct_put(
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            t->frame.data[0] + (mb_y*16 + ((j&2)<<2))*t->frame.linesize[0] + mb_x*16 + ((j&1)<<3),
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            t->frame.linesize[0], block);
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    } else if (!(s->avctx->flags & CODEC_FLAG_GRAY)) {
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        int index = j - 3;
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        s->dsp.idct_put(
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            t->frame.data[index] + (mb_y*8)*t->frame.linesize[index] + mb_x*8,
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            t->frame.linesize[index], block);
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    }
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}
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static inline void decode_block_intra(MadContext * t, DCTELEM * block)
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{
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    MpegEncContext *s = &t->s;
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    int level, i, j, run;
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    RLTable *rl = &ff_rl_mpeg1;
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    const uint8_t *scantable = s->intra_scantable.permutated;
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    int16_t *quant_matrix = s->intra_matrix;
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    block[0] = (128 + get_sbits(&s->gb, 8)) * quant_matrix[0];
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    /* The RL decoder is derived from mpeg1_decode_block_intra;
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       Escaped level and run values a decoded differently */
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    i = 0;
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    {
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        OPEN_READER(re, &s->gb);
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        /* now quantify & encode AC coefficients */
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        for (;;) {
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            UPDATE_CACHE(re, &s->gb);
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            GET_RL_VLC(level, run, re, &s->gb, rl->rl_vlc[0], TEX_VLC_BITS, 2, 0);
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            if (level == 127) {
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                break;
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            } else if (level != 0) {
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                i += run;
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                j = scantable[i];
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                level = (level*quant_matrix[j]) >> 4;
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                level = (level-1)|1;
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                level = (level ^ SHOW_SBITS(re, &s->gb, 1)) - SHOW_SBITS(re, &s->gb, 1);
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                LAST_SKIP_BITS(re, &s->gb, 1);
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            } else {
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                /* escape */
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                UPDATE_CACHE(re, &s->gb);
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                level = SHOW_SBITS(re, &s->gb, 10); SKIP_BITS(re, &s->gb, 10);
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                UPDATE_CACHE(re, &s->gb);
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                run = SHOW_UBITS(re, &s->gb, 6)+1; LAST_SKIP_BITS(re, &s->gb, 6);
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                i += run;
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                j = scantable[i];
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                if (level < 0) {
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                    level = -level;
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                    level = (level*quant_matrix[j]) >> 4;
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                    level = (level-1)|1;
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                    level = -level;
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                } else {
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                    level = (level*quant_matrix[j]) >> 4;
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                    level = (level-1)|1;
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                }
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            }
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            if (i > 63) {
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                av_log(s->avctx, AV_LOG_ERROR, "ac-tex damaged at %d %d\n", s->mb_x, s->mb_y);
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                return;
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            }
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            block[j] = level;
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        }
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        CLOSE_READER(re, &s->gb);
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    }
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}
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static int decode_motion(GetBitContext *gb)
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{
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    int value = 0;
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    if (get_bits1(gb)) {
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        if (get_bits1(gb))
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            value = -17;
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        value += get_bits(gb, 4) + 1;
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    }
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    return value;
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}
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static void decode_mb(MadContext *t, int inter)
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{
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    MpegEncContext *s = &t->s;
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    int mv_map = 0;
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    int mv_x, mv_y;
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    int j;
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    if (inter) {
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        int v = decode210(&s->gb);
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        if (v < 2) {
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            mv_map = v ? get_bits(&s->gb, 6) : 63;
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            mv_x = decode_motion(&s->gb);
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            mv_y = decode_motion(&s->gb);
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        } else {
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            mv_map = 0;
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        }
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    }
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    for (j=0; j<6; j++) {
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        if (mv_map & (1<<j)) {  // mv_x and mv_y are guarded by mv_map
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            int add = 2*decode_motion(&s->gb);
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            comp_block(t, s->mb_x, s->mb_y, j, mv_x, mv_y, add);
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        } else {
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            s->dsp.clear_block(t->block);
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            decode_block_intra(t, t->block);
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            idct_put(t, t->block, s->mb_x, s->mb_y, j);
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        }
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    }
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}
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static void calc_intra_matrix(MadContext *t, int qscale)
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{
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    MpegEncContext *s = &t->s;
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    int i;
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    if (s->avctx->idct_algo == FF_IDCT_EA) {
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        s->intra_matrix[0] = (ff_inv_aanscales[0]*ff_mpeg1_default_intra_matrix[0]) >> 11;
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        for (i=1; i<64; i++)
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            s->intra_matrix[i] = (ff_inv_aanscales[i]*ff_mpeg1_default_intra_matrix[i]*qscale + 32) >> 10;
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    } else {
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        s->intra_matrix[0] = ff_mpeg1_default_intra_matrix[0];
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        for (i=1; i<64; i++)
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            s->intra_matrix[i] = (ff_mpeg1_default_intra_matrix[i]*qscale) << 1;
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    }
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}
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static int 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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    const uint8_t *buf_end = buf+buf_size;
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    MadContext *t     = avctx->priv_data;
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    MpegEncContext *s = &t->s;
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    int chunk_type;
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    int inter;
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    if (buf_size < 17) {
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        av_log(avctx, AV_LOG_ERROR, "Input buffer too small\n");
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        *data_size = 0;
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        return -1;
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    }
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    chunk_type = AV_RL32(&buf[0]);
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    inter = (chunk_type == MADm_TAG || chunk_type == MADe_TAG);
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    buf += 8;
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    av_reduce(&avctx->time_base.num, &avctx->time_base.den,
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              AV_RL16(&buf[6]), 1000, 1<<30);
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    s->width  = AV_RL16(&buf[8]);
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    s->height = AV_RL16(&buf[10]);
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    calc_intra_matrix(t, buf[13]);
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    buf += 16;
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    if (avctx->width != s->width || avctx->height != s->height) {
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        if (avcodec_check_dimensions(avctx, s->width, s->height) < 0)
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            return -1;
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        avcodec_set_dimensions(avctx, s->width, s->height);
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        if (t->frame.data[0])
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            avctx->release_buffer(avctx, &t->frame);
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    }
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    t->frame.reference = 1;
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    if (!t->frame.data[0]) {
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        if (avctx->get_buffer(avctx, &t->frame) < 0) {
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            av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
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            return -1;
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        }
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    }
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    av_fast_malloc(&t->bitstream_buf, &t->bitstream_buf_size, (buf_end-buf) + FF_INPUT_BUFFER_PADDING_SIZE);
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    if (!t->bitstream_buf)
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        return AVERROR(ENOMEM);
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    bswap16_buf(t->bitstream_buf, (const uint16_t*)buf, (buf_end-buf)/2);
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    init_get_bits(&s->gb, t->bitstream_buf, 8*(buf_end-buf));
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    for (s->mb_y=0; s->mb_y < (avctx->height+15)/16; s->mb_y++)
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        for (s->mb_x=0; s->mb_x < (avctx->width +15)/16; s->mb_x++)
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            decode_mb(t, inter);
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    *data_size = sizeof(AVFrame);
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    *(AVFrame*)data = t->frame;
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    if (chunk_type != MADe_TAG)
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        FFSWAP(AVFrame, t->frame, t->last_frame);
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    return buf_size;
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}
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static av_cold int decode_end(AVCodecContext *avctx)
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{
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    MadContext *t = avctx->priv_data;
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    if (t->frame.data[0])
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        avctx->release_buffer(avctx, &t->frame);
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    if (t->last_frame.data[0])
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        avctx->release_buffer(avctx, &t->last_frame);
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    av_free(t->bitstream_buf);
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    return 0;
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}
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AVCodec eamad_decoder = {
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    "eamad",
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    CODEC_TYPE_VIDEO,
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    CODEC_ID_MAD,
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    sizeof(MadContext),
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    decode_init,
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    NULL,
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    decode_end,
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    decode_frame,
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    CODEC_CAP_DR1,
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    .long_name = NULL_IF_CONFIG_SMALL("Electronic Arts Madcow Video")
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};