extern/ffmpeg/libavcodec/ws-snd1.c

   1 /*
   2  * Westwood SNDx codecs
   3  * Copyright (c) 2005 Konstantin Shishkov
   4  *
   5  * This library is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU Lesser General Public
   7  * License as published by the Free Software Foundation; either
   8  * version 2 of the License, or (at your option) any later version.
   9  *
  10  * This library is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * Lesser General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU Lesser General Public
  16  * License along with this library; if not, write to the Free Software
  17  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  18  */
  19 #include "avcodec.h"
  20
  21 /**
  22  * @file ws-snd.c
  23  * Westwood SNDx codecs.
  24  *
  25  * Reference documents about VQA format and its audio codecs
  26  * can be found here:
  27  * http://www.multimedia.cx
  28  */
  29
  30 typedef struct {
  31 } WSSNDContext;
  32
  33 static const char ws_adpcm_2bit[] = { -2, -1, 0, 1};
  34 static const char ws_adpcm_4bit[] = {
  35     -9, -8, -6, -5, -4, -3, -2, -1,
  36      0,  1,  2,  3,  4,  5,  6,  8 };
  37
  38 #define CLIP8(a) if(a>127)a=127;if(a<-128)a=-128;
  39
  40 static int ws_snd_decode_init(AVCodecContext * avctx)
  41 {
  42 //    WSSNDContext *c = avctx->priv_data;
  43
  44     return 0;
  45 }
  46
  47 static int ws_snd_decode_frame(AVCodecContext *avctx,
  48                 void *data, int *data_size,
  49                 uint8_t *buf, int buf_size)
  50 {
  51 //    WSSNDContext *c = avctx->priv_data;
  52
  53     int in_size, out_size;
  54     int sample = 0;
  55     int i;
  56     short *samples = data;
  57
  58     if (!buf_size)
  59         return 0;
  60
  61     out_size = LE_16(&buf[0]);
  62     *data_size = out_size * 2;
  63     in_size = LE_16(&buf[2]);
  64     buf += 4;
  65
  66     if (in_size == out_size) {
  67         for (i = 0; i < out_size; i++)
  68             *samples++ = (*buf++ - 0x80) << 8;
  69         return buf_size;
  70     }
  71
  72     while (out_size > 0) {
  73         int code;
  74         uint8_t count;
  75         code = (*buf) >> 6;
  76         count = (*buf) & 0x3F;
  77         buf++;
  78         switch(code) {
  79         case 0: /* ADPCM 2-bit */
  80             for (count++; count > 0; count--) {
  81                 code = *buf++;
  82                 sample += ws_adpcm_2bit[code & 0x3];
  83                 CLIP8(sample);
  84                 *samples++ = sample << 8;
  85                 sample += ws_adpcm_2bit[(code >> 2) & 0x3];
  86                 CLIP8(sample);
  87                 *samples++ = sample << 8;
  88                 sample += ws_adpcm_2bit[(code >> 4) & 0x3];
  89                 CLIP8(sample);
  90                 *samples++ = sample << 8;
  91                 sample += ws_adpcm_2bit[(code >> 6) & 0x3];
  92                 CLIP8(sample);
  93                 *samples++ = sample << 8;
  94                 out_size -= 4;
  95             }
  96             break;
  97         case 1: /* ADPCM 4-bit */
  98             for (count++; count > 0; count--) {
  99                 code = *buf++;
 100                 sample += ws_adpcm_4bit[code & 0xF];
 101                 CLIP8(sample);
 102                 *samples++ = sample << 8;
 103                 sample += ws_adpcm_4bit[code >> 4];
 104                 CLIP8(sample);
 105                 *samples++ = sample << 8;
 106                 out_size -= 2;
 107             }
 108             break;
 109         case 2: /* no compression */
 110             if (count & 0x20) { /* big delta */
 111                 char t;
 112                 t = count;
 113                 t <<= 3;
 114                 sample += t >> 3;
 115                 *samples++ = sample << 8;
 116                 out_size--;
 117             } else { /* copy */
 118                 for (count++; count > 0; count--) {
 119                     *samples++ = (*buf++ - 0x80) << 8;
 120                     out_size--;
 121                 }
 122                 sample = buf[-1] - 0x80;
 123             }
 124             break;
 125         default: /* run */
 126             for(count++; count > 0; count--) {
 127                 *samples++ = sample << 8;
 128                 out_size--;
 129             }
 130         }
 131     }
 132
 133     return buf_size;
 134 }
 135
 136 AVCodec ws_snd1_decoder = {
 137     "ws_snd1",
 138     CODEC_TYPE_AUDIO,
 139     CODEC_ID_WESTWOOD_SND1,
 140     sizeof(WSSNDContext),
 141     ws_snd_decode_init,
 142     NULL,
 143     NULL,
 144     ws_snd_decode_frame,
 145 };