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
  22 #include "libavutil/intreadwrite.h"
  23 #include "avcodec.h"
  24
  25 /**
  26  * @file libavcodec/ws-snd1.c
  27  * Westwood SNDx codecs.
  28  *
  29  * Reference documents about VQA format and its audio codecs
  30  * can be found here:
  31  * http://www.multimedia.cx
  32  */
  33
  34 static const char ws_adpcm_2bit[] = { -2, -1, 0, 1};
  35 static const char ws_adpcm_4bit[] = {
  36     -9, -8, -6, -5, -4, -3, -2, -1,
  37      0,  1,  2,  3,  4,  5,  6,  8 };
  38
  39 #define CLIP8(a) if(a>127)a=127;if(a<-128)a=-128;
  40
  41 static av_cold int ws_snd_decode_init(AVCodecContext * avctx)
  42 {
  43 //    WSSNDContext *c = avctx->priv_data;
  44
  45     avctx->sample_fmt = SAMPLE_FMT_S16;
  46     return 0;
  47 }
  48
  49 static int ws_snd_decode_frame(AVCodecContext *avctx,
  50                 void *data, int *data_size,
  51                 const uint8_t *buf, int buf_size)
  52 {
  53 //    WSSNDContext *c = avctx->priv_data;
  54
  55     int in_size, out_size;
  56     int sample = 0;
  57     int i;
  58     short *samples = data;
  59
  60     if (!buf_size)
  61         return 0;
  62
  63     out_size = AV_RL16(&buf[0]);
  64     *data_size = out_size * 2;
  65     in_size = AV_RL16(&buf[2]);
  66     buf += 4;
  67
  68     if (out_size > *data_size) {
  69         av_log(avctx, AV_LOG_ERROR, "Frame is too large to fit in buffer\n");
  70         return -1;
  71     }
  72     if (in_size > buf_size) {
  73         av_log(avctx, AV_LOG_ERROR, "Frame data is larger than input buffer\n");
  74         return -1;
  75     }
  76     if (in_size == out_size) {
  77         for (i = 0; i < out_size; i++)
  78             *samples++ = (*buf++ - 0x80) << 8;
  79         return buf_size;
  80     }
  81
  82     while (out_size > 0) {
  83         int code;
  84         uint8_t count;
  85         code = (*buf) >> 6;
  86         count = (*buf) & 0x3F;
  87         buf++;
  88         switch(code) {
  89         case 0: /* ADPCM 2-bit */
  90             for (count++; count > 0; count--) {
  91                 code = *buf++;
  92                 sample += ws_adpcm_2bit[code & 0x3];
  93                 CLIP8(sample);
  94                 *samples++ = sample << 8;
  95                 sample += ws_adpcm_2bit[(code >> 2) & 0x3];
  96                 CLIP8(sample);
  97                 *samples++ = sample << 8;
  98                 sample += ws_adpcm_2bit[(code >> 4) & 0x3];
  99                 CLIP8(sample);
 100                 *samples++ = sample << 8;
 101                 sample += ws_adpcm_2bit[(code >> 6) & 0x3];
 102                 CLIP8(sample);
 103                 *samples++ = sample << 8;
 104                 out_size -= 4;
 105             }
 106             break;
 107         case 1: /* ADPCM 4-bit */
 108             for (count++; count > 0; count--) {
 109                 code = *buf++;
 110                 sample += ws_adpcm_4bit[code & 0xF];
 111                 CLIP8(sample);
 112                 *samples++ = sample << 8;
 113                 sample += ws_adpcm_4bit[code >> 4];
 114                 CLIP8(sample);
 115                 *samples++ = sample << 8;
 116                 out_size -= 2;
 117             }
 118             break;
 119         case 2: /* no compression */
 120             if (count & 0x20) { /* big delta */
 121                 char t;
 122                 t = count;
 123                 t <<= 3;
 124                 sample += t >> 3;
 125                 *samples++ = sample << 8;
 126                 out_size--;
 127             } else { /* copy */
 128                 for (count++; count > 0; count--) {
 129                     *samples++ = (*buf++ - 0x80) << 8;
 130                     out_size--;
 131                 }
 132                 sample = buf[-1] - 0x80;
 133             }
 134             break;
 135         default: /* run */
 136             for(count++; count > 0; count--) {
 137                 *samples++ = sample << 8;
 138                 out_size--;
 139             }
 140         }
 141     }
 142
 143     return buf_size;
 144 }
 145
 146 AVCodec ws_snd1_decoder = {
 147     "ws_snd1",
 148     CODEC_TYPE_AUDIO,
 149     CODEC_ID_WESTWOOD_SND1,
 150     0,
 151     ws_snd_decode_init,
 152     NULL,
 153     NULL,
 154     ws_snd_decode_frame,
 155     .long_name = NULL_IF_CONFIG_SMALL("Westwood Audio (SND1)"),
 156 };