libavcodec/ws-snd1.c

   1 /*
   2  * Westwood SNDx codecs
   3  * Copyright (c) 2005 Konstantin Shishkov
   4  *
   5  * This file is part of FFmpeg.
   6  *
   7  * FFmpeg is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2.1 of the License, or (at your option) any later version.
  11  *
  12  * FFmpeg is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public
  18  * License along with FFmpeg; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21 #include "avcodec.h"
  22
  23 /**
  24  * @file ws-snd.c
  25  * Westwood SNDx codecs.
  26  *
  27  * Reference documents about VQA format and its audio codecs
  28  * can be found here:
  29  * http://www.multimedia.cx
  30  */
  31
  32 static const char ws_adpcm_2bit[] = { -2, -1, 0, 1};
  33 static const char ws_adpcm_4bit[] = {
  34     -9, -8, -6, -5, -4, -3, -2, -1,
  35      0,  1,  2,  3,  4,  5,  6,  8 };
  36
  37 #define CLIP8(a) if(a>127)a=127;if(a<-128)a=-128;
  38
  39 static int ws_snd_decode_init(AVCodecContext * avctx)
  40 {
  41 //    WSSNDContext *c = avctx->priv_data;
  42
  43     return 0;
  44 }
  45
  46 static int ws_snd_decode_frame(AVCodecContext *avctx,
  47                 void *data, int *data_size,
  48                 uint8_t *buf, int buf_size)
  49 {
  50 //    WSSNDContext *c = avctx->priv_data;
  51
  52     int in_size, out_size;
  53     int sample = 0;
  54     int i;
  55     short *samples = data;
  56
  57     if (!buf_size)
  58         return 0;
  59
  60     out_size = AV_RL16(&buf[0]);
  61     *data_size = out_size * 2;
  62     in_size = AV_RL16(&buf[2]);
  63     buf += 4;
  64
  65     if (out_size > *data_size) {
  66         av_log(avctx, AV_LOG_ERROR, "Frame is too large to fit in buffer\n");
  67         return -1;
  68     }
  69     if (in_size > buf_size) {
  70         av_log(avctx, AV_LOG_ERROR, "Frame data is larger than input buffer\n");
  71         return -1;
  72     }
  73     if (in_size == out_size) {
  74         for (i = 0; i < out_size; i++)
  75             *samples++ = (*buf++ - 0x80) << 8;
  76         return buf_size;
  77     }
  78
  79     while (out_size > 0) {
  80         int code;
  81         uint8_t count;
  82         code = (*buf) >> 6;
  83         count = (*buf) & 0x3F;
  84         buf++;
  85         switch(code) {
  86         case 0: /* ADPCM 2-bit */
  87             for (count++; count > 0; count--) {
  88                 code = *buf++;
  89                 sample += ws_adpcm_2bit[code & 0x3];
  90                 CLIP8(sample);
  91                 *samples++ = sample << 8;
  92                 sample += ws_adpcm_2bit[(code >> 2) & 0x3];
  93                 CLIP8(sample);
  94                 *samples++ = sample << 8;
  95                 sample += ws_adpcm_2bit[(code >> 4) & 0x3];
  96                 CLIP8(sample);
  97                 *samples++ = sample << 8;
  98                 sample += ws_adpcm_2bit[(code >> 6) & 0x3];
  99                 CLIP8(sample);
 100                 *samples++ = sample << 8;
 101                 out_size -= 4;
 102             }
 103             break;
 104         case 1: /* ADPCM 4-bit */
 105             for (count++; count > 0; count--) {
 106                 code = *buf++;
 107                 sample += ws_adpcm_4bit[code & 0xF];
 108                 CLIP8(sample);
 109                 *samples++ = sample << 8;
 110                 sample += ws_adpcm_4bit[code >> 4];
 111                 CLIP8(sample);
 112                 *samples++ = sample << 8;
 113                 out_size -= 2;
 114             }
 115             break;
 116         case 2: /* no compression */
 117             if (count & 0x20) { /* big delta */
 118                 char t;
 119                 t = count;
 120                 t <<= 3;
 121                 sample += t >> 3;
 122                 *samples++ = sample << 8;
 123                 out_size--;
 124             } else { /* copy */
 125                 for (count++; count > 0; count--) {
 126                     *samples++ = (*buf++ - 0x80) << 8;
 127                     out_size--;
 128                 }
 129                 sample = buf[-1] - 0x80;
 130             }
 131             break;
 132         default: /* run */
 133             for(count++; count > 0; count--) {
 134                 *samples++ = sample << 8;
 135                 out_size--;
 136             }
 137         }
 138     }
 139
 140     return buf_size;
 141 }
 142
 143 AVCodec ws_snd1_decoder = {
 144     "ws_snd1",
 145     CODEC_TYPE_AUDIO,
 146     CODEC_ID_WESTWOOD_SND1,
 147     0,
 148     ws_snd_decode_init,
 149     NULL,
 150     NULL,
 151     ws_snd_decode_frame,
 152 };