libavcodec/ws-snd1.c

   1 /*
   2  * Westwood SNDx codecs
   3  * Copyright (c) 2005 Konstantin Shishkov
   4  *
   5  * This file is part of Libav.
   6  *
   7  * Libav 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  * Libav 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 Libav; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21
  22 #include <stdint.h>
  23 #include "libavutil/intreadwrite.h"
  24 #include "avcodec.h"
  25
  26 /**
  27  * @file
  28  * Westwood SNDx codecs
  29  *
  30  * Reference documents about VQA format and its audio codecs
  31  * can be found here:
  32  * http://www.multimedia.cx
  33  */
  34
  35 static const int8_t ws_adpcm_4bit[] = {
  36     -9, -8, -6, -5, -4, -3, -2, -1,
  37      0,  1,  2,  3,  4,  5,  6,  8
  38 };
  39
  40 typedef struct WSSndContext {
  41     AVFrame frame;
  42 } WSSndContext;
  43
  44 static av_cold int ws_snd_decode_init(AVCodecContext *avctx)
  45 {
  46     WSSndContext *s = avctx->priv_data;
  47
  48     if (avctx->channels != 1) {
  49         av_log_ask_for_sample(avctx, "unsupported number of channels\n");
  50         return AVERROR(EINVAL);
  51     }
  52
  53     avctx->sample_fmt = AV_SAMPLE_FMT_U8;
  54
  55     avcodec_get_frame_defaults(&s->frame);
  56     avctx->coded_frame = &s->frame;
  57
  58     return 0;
  59 }
  60
  61 static int ws_snd_decode_frame(AVCodecContext *avctx, void *data,
  62                                int *got_frame_ptr, AVPacket *avpkt)
  63 {
  64     WSSndContext *s = avctx->priv_data;
  65     const uint8_t *buf = avpkt->data;
  66     int buf_size       = avpkt->size;
  67
  68     int in_size, out_size, ret;
  69     int sample = 128;
  70     uint8_t *samples;
  71     uint8_t *samples_end;
  72
  73     if (!buf_size)
  74         return 0;
  75
  76     if (buf_size < 4) {
  77         av_log(avctx, AV_LOG_ERROR, "packet is too small\n");
  78         return AVERROR(EINVAL);
  79     }
  80
  81     out_size = AV_RL16(&buf[0]);
  82     in_size  = AV_RL16(&buf[2]);
  83     buf += 4;
  84
  85     if (in_size > buf_size) {
  86         av_log(avctx, AV_LOG_ERROR, "Frame data is larger than input buffer\n");
  87         return -1;
  88     }
  89
  90     /* get output buffer */
  91     s->frame.nb_samples = out_size;
  92     if ((ret = avctx->get_buffer(avctx, &s->frame)) < 0) {
  93         av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
  94         return ret;
  95     }
  96     samples     = s->frame.data[0];
  97     samples_end = samples + out_size;
  98
  99     if (in_size == out_size) {
 100         memcpy(samples, buf, out_size);
 101         *got_frame_ptr   = 1;
 102         *(AVFrame *)data = s->frame;
 103         return buf_size;
 104     }
 105
 106     while (samples < samples_end && buf - avpkt->data < buf_size) {
 107         int code, smp, size;
 108         uint8_t count;
 109         code  = *buf >> 6;
 110         count = *buf & 0x3F;
 111         buf++;
 112
 113         /* make sure we don't write past the output buffer */
 114         switch (code) {
 115         case 0:  smp = 4 * (count + 1);                break;
 116         case 1:  smp = 2 * (count + 1);                break;
 117         case 2:  smp = (count & 0x20) ? 1 : count + 1; break;
 118         default: smp = count + 1;                      break;
 119         }
 120         if (samples_end - samples < smp)
 121             break;
 122
 123         /* make sure we don't read past the input buffer */
 124         size = ((code == 2 && (count & 0x20)) || code == 3) ? 0 : count + 1;
 125         if ((buf - avpkt->data) + size > buf_size)
 126             break;
 127
 128         switch (code) {
 129         case 0: /* ADPCM 2-bit */
 130             for (count++; count > 0; count--) {
 131                 code = *buf++;
 132                 sample += ( code       & 0x3) - 2;
 133                 sample = av_clip_uint8(sample);
 134                 *samples++ = sample;
 135                 sample += ((code >> 2) & 0x3) - 2;
 136                 sample = av_clip_uint8(sample);
 137                 *samples++ = sample;
 138                 sample += ((code >> 4) & 0x3) - 2;
 139                 sample = av_clip_uint8(sample);
 140                 *samples++ = sample;
 141                 sample +=  (code >> 6)        - 2;
 142                 sample = av_clip_uint8(sample);
 143                 *samples++ = sample;
 144             }
 145             break;
 146         case 1: /* ADPCM 4-bit */
 147             for (count++; count > 0; count--) {
 148                 code = *buf++;
 149                 sample += ws_adpcm_4bit[code & 0xF];
 150                 sample = av_clip_uint8(sample);
 151                 *samples++ = sample;
 152                 sample += ws_adpcm_4bit[code >> 4];
 153                 sample = av_clip_uint8(sample);
 154                 *samples++ = sample;
 155             }
 156             break;
 157         case 2: /* no compression */
 158             if (count & 0x20) { /* big delta */
 159                 int8_t t;
 160                 t = count;
 161                 t <<= 3;
 162                 sample += t >> 3;
 163                 sample = av_clip_uint8(sample);
 164                 *samples++ = sample;
 165             } else { /* copy */
 166                 memcpy(samples, buf, smp);
 167                 samples += smp;
 168                 buf     += smp;
 169                 sample = buf[-1];
 170             }
 171             break;
 172         default: /* run */
 173             memset(samples, sample, smp);
 174             samples += smp;
 175         }
 176     }
 177
 178     s->frame.nb_samples = samples - s->frame.data[0];
 179     *got_frame_ptr   = 1;
 180     *(AVFrame *)data = s->frame;
 181
 182     return buf_size;
 183 }
 184
 185 AVCodec ff_ws_snd1_decoder = {
 186     .name           = "ws_snd1",
 187     .type           = AVMEDIA_TYPE_AUDIO,
 188     .id             = CODEC_ID_WESTWOOD_SND1,
 189     .priv_data_size = sizeof(WSSndContext),
 190     .init           = ws_snd_decode_init,
 191     .decode         = ws_snd_decode_frame,
 192     .capabilities   = CODEC_CAP_DR1,
 193     .long_name      = NULL_IF_CONFIG_SMALL("Westwood Audio (SND1)"),
 194 };