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libavcodec/adxdec.c

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00001 /*
00002  * ADX ADPCM codecs
00003  * Copyright (c) 2001,2003 BERO
00004  *
00005  * This file is part of FFmpeg.
00006  *
00007  * FFmpeg is free software; you can redistribute it and/or
00008  * modify it under the terms of the GNU Lesser General Public
00009  * License as published by the Free Software Foundation; either
00010  * version 2.1 of the License, or (at your option) any later version.
00011  *
00012  * FFmpeg is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00015  * Lesser General Public License for more details.
00016  *
00017  * You should have received a copy of the GNU Lesser General Public
00018  * License along with FFmpeg; if not, write to the Free Software
00019  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00020  */
00021 
00022 #include "libavutil/intreadwrite.h"
00023 #include "avcodec.h"
00024 #include "adx.h"
00025 
00035 static av_cold int adx_decode_init(AVCodecContext *avctx)
00036 {
00037     avctx->sample_fmt = SAMPLE_FMT_S16;
00038     return 0;
00039 }
00040 
00041 /* 18 bytes <-> 32 samples */
00042 
00043 static void adx_decode(short *out,const unsigned char *in,PREV *prev)
00044 {
00045     int scale = AV_RB16(in);
00046     int i;
00047     int s0,s1,s2,d;
00048 
00049 //    printf("%x ",scale);
00050 
00051     in+=2;
00052     s1 = prev->s1;
00053     s2 = prev->s2;
00054     for(i=0;i<16;i++) {
00055         d = in[i];
00056         // d>>=4; if (d&8) d-=16;
00057         d = ((signed char)d >> 4);
00058         s0 = (BASEVOL*d*scale + SCALE1*s1 - SCALE2*s2)>>14;
00059         s2 = s1;
00060         s1 = av_clip_int16(s0);
00061         *out++=s1;
00062 
00063         d = in[i];
00064         //d&=15; if (d&8) d-=16;
00065         d = ((signed char)(d<<4) >> 4);
00066         s0 = (BASEVOL*d*scale + SCALE1*s1 - SCALE2*s2)>>14;
00067         s2 = s1;
00068         s1 = av_clip_int16(s0);
00069         *out++=s1;
00070     }
00071     prev->s1 = s1;
00072     prev->s2 = s2;
00073 
00074 }
00075 
00076 static void adx_decode_stereo(short *out,const unsigned char *in,PREV *prev)
00077 {
00078     short tmp[32*2];
00079     int i;
00080 
00081     adx_decode(tmp   ,in   ,prev);
00082     adx_decode(tmp+32,in+18,prev+1);
00083     for(i=0;i<32;i++) {
00084         out[i*2]   = tmp[i];
00085         out[i*2+1] = tmp[i+32];
00086     }
00087 }
00088 
00089 /* return data offset or 0 */
00090 static int adx_decode_header(AVCodecContext *avctx,const unsigned char *buf,size_t bufsize)
00091 {
00092     int offset;
00093 
00094     if (buf[0]!=0x80) return 0;
00095     offset = (AV_RB32(buf)^0x80000000)+4;
00096     if (bufsize<offset || memcmp(buf+offset-6,"(c)CRI",6)) return 0;
00097 
00098     avctx->channels    = buf[7];
00099     avctx->sample_rate = AV_RB32(buf+8);
00100     avctx->bit_rate    = avctx->sample_rate*avctx->channels*18*8/32;
00101 
00102     return offset;
00103 }
00104 
00105 static int adx_decode_frame(AVCodecContext *avctx,
00106                 void *data, int *data_size,
00107                 AVPacket *avpkt)
00108 {
00109     const uint8_t *buf0 = avpkt->data;
00110     int buf_size = avpkt->size;
00111     ADXContext *c = avctx->priv_data;
00112     short *samples = data;
00113     const uint8_t *buf = buf0;
00114     int rest = buf_size;
00115 
00116     if (!c->header_parsed) {
00117         int hdrsize = adx_decode_header(avctx,buf,rest);
00118         if (hdrsize==0) return -1;
00119         c->header_parsed = 1;
00120         buf  += hdrsize;
00121         rest -= hdrsize;
00122     }
00123 
00124     /* 18 bytes of data are expanded into 32*2 bytes of audio,
00125        so guard against buffer overflows */
00126     if(rest/18 > *data_size/64)
00127         rest = (*data_size/64) * 18;
00128 
00129     if (c->in_temp) {
00130         int copysize = 18*avctx->channels - c->in_temp;
00131         memcpy(c->dec_temp+c->in_temp,buf,copysize);
00132         rest -= copysize;
00133         buf  += copysize;
00134         if (avctx->channels==1) {
00135             adx_decode(samples,c->dec_temp,c->prev);
00136             samples += 32;
00137         } else {
00138             adx_decode_stereo(samples,c->dec_temp,c->prev);
00139             samples += 32*2;
00140         }
00141     }
00142     //
00143     if (avctx->channels==1) {
00144         while(rest>=18) {
00145             adx_decode(samples,buf,c->prev);
00146             rest-=18;
00147             buf+=18;
00148             samples+=32;
00149         }
00150     } else {
00151         while(rest>=18*2) {
00152             adx_decode_stereo(samples,buf,c->prev);
00153             rest-=18*2;
00154             buf+=18*2;
00155             samples+=32*2;
00156         }
00157     }
00158     //
00159     c->in_temp = rest;
00160     if (rest) {
00161         memcpy(c->dec_temp,buf,rest);
00162         buf+=rest;
00163     }
00164     *data_size = (uint8_t*)samples - (uint8_t*)data;
00165 //    printf("%d:%d ",buf-buf0,*data_size); fflush(stdout);
00166     return buf-buf0;
00167 }
00168 
00169 AVCodec adpcm_adx_decoder = {
00170     "adpcm_adx",
00171     AVMEDIA_TYPE_AUDIO,
00172     CODEC_ID_ADPCM_ADX,
00173     sizeof(ADXContext),
00174     adx_decode_init,
00175     NULL,
00176     NULL,
00177     adx_decode_frame,
00178     .long_name = NULL_IF_CONFIG_SMALL("SEGA CRI ADX ADPCM"),
00179 };
00180 

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