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  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 <stdint.h>
  23.  
  24. #include "libavutil/channel_layout.h"
  25. #include "libavutil/common.h"
  26. #include "libavutil/intreadwrite.h"
  27. #include "avcodec.h"
  28. #include "internal.h"
  29.  
  30. /**
  31.  * @file
  32.  * Westwood SNDx codecs
  33.  *
  34.  * Reference documents about VQA format and its audio codecs
  35.  * can be found here:
  36.  * http://www.multimedia.cx
  37.  */
  38.  
  39. static const int8_t ws_adpcm_4bit[] = {
  40.     -9, -8, -6, -5, -4, -3, -2, -1,
  41.      0,  1,  2,  3,  4,  5,  6,  8
  42. };
  43.  
  44. static av_cold int ws_snd_decode_init(AVCodecContext *avctx)
  45. {
  46.     avctx->channels       = 1;
  47.     avctx->channel_layout = AV_CH_LAYOUT_MONO;
  48.     avctx->sample_fmt     = AV_SAMPLE_FMT_U8;
  49.  
  50.     return 0;
  51. }
  52.  
  53. static int ws_snd_decode_frame(AVCodecContext *avctx, void *data,
  54.                                int *got_frame_ptr, AVPacket *avpkt)
  55. {
  56.     AVFrame *frame     = data;
  57.     const uint8_t *buf = avpkt->data;
  58.     int buf_size       = avpkt->size;
  59.  
  60.     int in_size, out_size, ret;
  61.     int sample = 128;
  62.     uint8_t *samples;
  63.     uint8_t *samples_end;
  64.  
  65.     if (!buf_size)
  66.         return 0;
  67.  
  68.     if (buf_size < 4) {
  69.         av_log(avctx, AV_LOG_ERROR, "packet is too small\n");
  70.         return AVERROR(EINVAL);
  71.     }
  72.  
  73.     out_size = AV_RL16(&buf[0]);
  74.     in_size  = AV_RL16(&buf[2]);
  75.     buf += 4;
  76.  
  77.     if (in_size > buf_size) {
  78.         av_log(avctx, AV_LOG_ERROR, "Frame data is larger than input buffer\n");
  79.         return AVERROR_INVALIDDATA;
  80.     }
  81.  
  82.     /* get output buffer */
  83.     frame->nb_samples = out_size;
  84.     if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
  85.         return ret;
  86.     samples     = frame->data[0];
  87.     samples_end = samples + out_size;
  88.  
  89.     if (in_size == out_size) {
  90.         memcpy(samples, buf, out_size);
  91.         *got_frame_ptr = 1;
  92.         return buf_size;
  93.     }
  94.  
  95.     while (samples < samples_end && buf - avpkt->data < buf_size) {
  96.         int code, smp, size;
  97.         uint8_t count;
  98.         code  = *buf >> 6;
  99.         count = *buf & 0x3F;
  100.         buf++;
  101.  
  102.         /* make sure we don't write past the output buffer */
  103.         switch (code) {
  104.         case 0:  smp = 4 * (count + 1);                break;
  105.         case 1:  smp = 2 * (count + 1);                break;
  106.         case 2:  smp = (count & 0x20) ? 1 : count + 1; break;
  107.         default: smp = count + 1;                      break;
  108.         }
  109.         if (samples_end - samples < smp)
  110.             break;
  111.  
  112.         /* make sure we don't read past the input buffer */
  113.         size = ((code == 2 && (count & 0x20)) || code == 3) ? 0 : count + 1;
  114.         if ((buf - avpkt->data) + size > buf_size)
  115.             break;
  116.  
  117.         switch (code) {
  118.         case 0: /* ADPCM 2-bit */
  119.             for (count++; count > 0; count--) {
  120.                 code = *buf++;
  121.                 sample += ( code       & 0x3) - 2;
  122.                 sample = av_clip_uint8(sample);
  123.                 *samples++ = sample;
  124.                 sample += ((code >> 2) & 0x3) - 2;
  125.                 sample = av_clip_uint8(sample);
  126.                 *samples++ = sample;
  127.                 sample += ((code >> 4) & 0x3) - 2;
  128.                 sample = av_clip_uint8(sample);
  129.                 *samples++ = sample;
  130.                 sample +=  (code >> 6)        - 2;
  131.                 sample = av_clip_uint8(sample);
  132.                 *samples++ = sample;
  133.             }
  134.             break;
  135.         case 1: /* ADPCM 4-bit */
  136.             for (count++; count > 0; count--) {
  137.                 code = *buf++;
  138.                 sample += ws_adpcm_4bit[code & 0xF];
  139.                 sample = av_clip_uint8(sample);
  140.                 *samples++ = sample;
  141.                 sample += ws_adpcm_4bit[code >> 4];
  142.                 sample = av_clip_uint8(sample);
  143.                 *samples++ = sample;
  144.             }
  145.             break;
  146.         case 2: /* no compression */
  147.             if (count & 0x20) { /* big delta */
  148.                 int8_t t;
  149.                 t = count;
  150.                 t <<= 3;
  151.                 sample += t >> 3;
  152.                 sample = av_clip_uint8(sample);
  153.                 *samples++ = sample;
  154.             } else { /* copy */
  155.                 memcpy(samples, buf, smp);
  156.                 samples += smp;
  157.                 buf     += smp;
  158.                 sample = buf[-1];
  159.             }
  160.             break;
  161.         default: /* run */
  162.             memset(samples, sample, smp);
  163.             samples += smp;
  164.         }
  165.     }
  166.  
  167.     frame->nb_samples = samples - frame->data[0];
  168.     *got_frame_ptr    = 1;
  169.  
  170.     return buf_size;
  171. }
  172.  
  173. AVCodec ff_ws_snd1_decoder = {
  174.     .name           = "ws_snd1",
  175.     .long_name      = NULL_IF_CONFIG_SMALL("Westwood Audio (SND1)"),
  176.     .type           = AVMEDIA_TYPE_AUDIO,
  177.     .id             = AV_CODEC_ID_WESTWOOD_SND1,
  178.     .init           = ws_snd_decode_init,
  179.     .decode         = ws_snd_decode_frame,
  180.     .capabilities   = CODEC_CAP_DR1,
  181. };
  182.