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 av_cold int ws_snd_decode_init(AVCodecContext * avctx)
  40 {
  41 //    WSSNDContext *c = avctx->priv_data;
  42
  43     avctx->sample_fmt = SAMPLE_FMT_S16;
  44     return 0;
  45 }
  46
  47 static int ws_snd_decode_frame(AVCodecContext *avctx,
  48                 void *data, int *data_size,
  49                 const 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 = AV_RL16(&buf[0]);
  62     *data_size = out_size * 2;
  63     in_size = AV_RL16(&buf[2]);
  64     buf += 4;
  65
  66     if (out_size > *data_size) {
  67         av_log(avctx, AV_LOG_ERROR, "Frame is too large to fit in buffer\n");
  68         return -1;
  69     }
  70     if (in_size > buf_size) {
  71         av_log(avctx, AV_LOG_ERROR, "Frame data is larger than input buffer\n");
  72         return -1;
  73     }
  74     if (in_size == out_size) {
  75         for (i = 0; i < out_size; i++)
  76             *samples++ = (*buf++ - 0x80) << 8;
  77         return buf_size;
  78     }
  79
  80     while (out_size > 0) {
  81         int code;
  82         uint8_t count;
  83         code = (*buf) >> 6;
  84         count = (*buf) & 0x3F;
  85         buf++;
  86         switch(code) {
  87         case 0: /* ADPCM 2-bit */
  88             for (count++; count > 0; count--) {
  89                 code = *buf++;
  90                 sample += ws_adpcm_2bit[code & 0x3];
  91                 CLIP8(sample);
  92                 *samples++ = sample << 8;
  93                 sample += ws_adpcm_2bit[(code >> 2) & 0x3];
  94                 CLIP8(sample);
  95                 *samples++ = sample << 8;
  96                 sample += ws_adpcm_2bit[(code >> 4) & 0x3];
  97                 CLIP8(sample);
  98                 *samples++ = sample << 8;
  99                 sample += ws_adpcm_2bit[(code >> 6) & 0x3];
 100                 CLIP8(sample);
 101                 *samples++ = sample << 8;
 102                 out_size -= 4;
 103             }
 104             break;
 105         case 1: /* ADPCM 4-bit */
 106             for (count++; count > 0; count--) {
 107                 code = *buf++;
 108                 sample += ws_adpcm_4bit[code & 0xF];
 109                 CLIP8(sample);
 110                 *samples++ = sample << 8;
 111                 sample += ws_adpcm_4bit[code >> 4];
 112                 CLIP8(sample);
 113                 *samples++ = sample << 8;
 114                 out_size -= 2;
 115             }
 116             break;
 117         case 2: /* no compression */
 118             if (count & 0x20) { /* big delta */
 119                 char t;
 120                 t = count;
 121                 t <<= 3;
 122                 sample += t >> 3;
 123                 *samples++ = sample << 8;
 124                 out_size--;
 125             } else { /* copy */
 126                 for (count++; count > 0; count--) {
 127                     *samples++ = (*buf++ - 0x80) << 8;
 128                     out_size--;
 129                 }
 130                 sample = buf[-1] - 0x80;
 131             }
 132             break;
 133         default: /* run */
 134             for(count++; count > 0; count--) {
 135                 *samples++ = sample << 8;
 136                 out_size--;
 137             }
 138         }
 139     }
 140
 141     return buf_size;
 142 }
 143
 144 AVCodec ws_snd1_decoder = {
 145     "ws_snd1",
 146     CODEC_TYPE_AUDIO,
 147     CODEC_ID_WESTWOOD_SND1,
 148     0,
 149     ws_snd_decode_init,
 150     NULL,
 151     NULL,
 152     ws_snd_decode_frame,
 153     .long_name = NULL_IF_CONFIG_SMALL("Westwood Audio (SND1)"),
 154 };