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ffmpeg / libavcodec / adxdec.c @ 99ed41a8

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/*
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 * ADX ADPCM codecs
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 * Copyright (c) 2001,2003 BERO
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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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#include "libavutil/intreadwrite.h"
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#include "avcodec.h"
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#include "adx.h"
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/**
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 * @file adxdec.c
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 * SEGA CRI adx codecs.
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 *
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 * Reference documents:
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 * http://ku-www.ss.titech.ac.jp/~yatsushi/adx.html
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 * adx2wav & wav2adx http://www.geocities.co.jp/Playtown/2004/
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 */
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static av_cold int adx_decode_init(AVCodecContext *avctx)
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{
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    avctx->sample_fmt = SAMPLE_FMT_S16;
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    return 0;
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}
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/* 18 bytes <-> 32 samples */
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static void adx_decode(short *out,const unsigned char *in,PREV *prev)
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{
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    int scale = AV_RB16(in);
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    int i;
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    int s0,s1,s2,d;
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//    printf("%x ",scale);
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    in+=2;
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    s1 = prev->s1;
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    s2 = prev->s2;
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    for(i=0;i<16;i++) {
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        d = in[i];
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        // d>>=4; if (d&8) d-=16;
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        d = ((signed char)d >> 4);
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        s0 = (BASEVOL*d*scale + SCALE1*s1 - SCALE2*s2)>>14;
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        s2 = s1;
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        s1 = av_clip_int16(s0);
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        *out++=s1;
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        d = in[i];
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        //d&=15; if (d&8) d-=16;
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        d = ((signed char)(d<<4) >> 4);
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        s0 = (BASEVOL*d*scale + SCALE1*s1 - SCALE2*s2)>>14;
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        s2 = s1;
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        s1 = av_clip_int16(s0);
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        *out++=s1;
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    }
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    prev->s1 = s1;
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    prev->s2 = s2;
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}
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static void adx_decode_stereo(short *out,const unsigned char *in,PREV *prev)
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{
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    short tmp[32*2];
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    int i;
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    adx_decode(tmp   ,in   ,prev);
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    adx_decode(tmp+32,in+18,prev+1);
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    for(i=0;i<32;i++) {
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        out[i*2]   = tmp[i];
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        out[i*2+1] = tmp[i+32];
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    }
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}
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/* return data offset or 0 */
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static int adx_decode_header(AVCodecContext *avctx,const unsigned char *buf,size_t bufsize)
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{
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    int offset;
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    if (buf[0]!=0x80) return 0;
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    offset = (AV_RB32(buf)^0x80000000)+4;
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    if (bufsize<offset || memcmp(buf+offset-6,"(c)CRI",6)) return 0;
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    avctx->channels    = buf[7];
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    avctx->sample_rate = AV_RB32(buf+8);
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    avctx->bit_rate    = avctx->sample_rate*avctx->channels*18*8/32;
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    return offset;
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}
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static int adx_decode_frame(AVCodecContext *avctx,
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                void *data, int *data_size,
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                const uint8_t *buf0, int buf_size)
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{
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    ADXContext *c = avctx->priv_data;
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    short *samples = data;
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    const uint8_t *buf = buf0;
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    int rest = buf_size;
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    if (!c->header_parsed) {
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        int hdrsize = adx_decode_header(avctx,buf,rest);
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        if (hdrsize==0) return -1;
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        c->header_parsed = 1;
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        buf  += hdrsize;
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        rest -= hdrsize;
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    }
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    /* 18 bytes of data are expanded into 32*2 bytes of audio,
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       so guard against buffer overflows */
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    if(rest/18 > *data_size/64)
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        rest = (*data_size/64) * 18;
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    if (c->in_temp) {
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        int copysize = 18*avctx->channels - c->in_temp;
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        memcpy(c->dec_temp+c->in_temp,buf,copysize);
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        rest -= copysize;
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        buf  += copysize;
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        if (avctx->channels==1) {
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            adx_decode(samples,c->dec_temp,c->prev);
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            samples += 32;
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        } else {
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            adx_decode_stereo(samples,c->dec_temp,c->prev);
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            samples += 32*2;
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        }
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    }
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    //
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    if (avctx->channels==1) {
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        while(rest>=18) {
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            adx_decode(samples,buf,c->prev);
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            rest-=18;
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            buf+=18;
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            samples+=32;
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        }
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    } else {
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        while(rest>=18*2) {
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            adx_decode_stereo(samples,buf,c->prev);
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            rest-=18*2;
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            buf+=18*2;
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            samples+=32*2;
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        }
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    }
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    //
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    c->in_temp = rest;
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    if (rest) {
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        memcpy(c->dec_temp,buf,rest);
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        buf+=rest;
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    }
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    *data_size = (uint8_t*)samples - (uint8_t*)data;
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//    printf("%d:%d ",buf-buf0,*data_size); fflush(stdout);
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    return buf-buf0;
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}
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AVCodec adpcm_adx_decoder = {
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    "adpcm_adx",
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    CODEC_TYPE_AUDIO,
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    CODEC_ID_ADPCM_ADX,
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    sizeof(ADXContext),
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    adx_decode_init,
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    NULL,
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    NULL,
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    adx_decode_frame,
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    .long_name = NULL_IF_CONFIG_SMALL("SEGA CRI ADX"),
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};
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