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
  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 typedef struct WSSndContext {
  45     AVFrame frame;
  46 } WSSndContext;
  47
  48 static av_cold int ws_snd_decode_init(AVCodecContext *avctx)
  49 {
  50     WSSndContext *s = avctx->priv_data;
  51
  52     avctx->channels       = 1;
  53     avctx->channel_layout = AV_CH_LAYOUT_MONO;
  54     avctx->sample_fmt     = AV_SAMPLE_FMT_U8;
  55
  56     avcodec_get_frame_defaults(&s->frame);
  57     avctx->coded_frame = &s->frame;
  58
  59     return 0;
  60 }
  61
  62 static int ws_snd_decode_frame(AVCodecContext *avctx, void *data,
  63                                int *got_frame_ptr, AVPacket *avpkt)
  64 {
  65     WSSndContext *s = avctx->priv_data;
  66     const uint8_t *buf = avpkt->data;
  67     int buf_size       = avpkt->size;
  68
  69     int in_size, out_size, ret;
  70     int sample = 128;
  71     uint8_t *samples;
  72     uint8_t *samples_end;
  73
  74     if (!buf_size)
  75         return 0;
  76
  77     if (buf_size < 4) {
  78         av_log(avctx, AV_LOG_ERROR, "packet is too small\n");
  79         return AVERROR(EINVAL);
  80     }
  81
  82     out_size = AV_RL16(&buf[0]);
  83     in_size  = AV_RL16(&buf[2]);
  84     buf += 4;
  85
  86     if (in_size > buf_size) {
  87         av_log(avctx, AV_LOG_ERROR, "Frame data is larger than input buffer\n");
  88         return -1;
  89     }
  90
  91     /* get output buffer */
  92     s->frame.nb_samples = out_size;
  93     if ((ret = ff_get_buffer(avctx, &s->frame)) < 0) {
  94         av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
  95         return ret;
  96     }
  97     samples     = s->frame.data[0];
  98     samples_end = samples + out_size;
  99
 100     if (in_size == out_size) {
 101         memcpy(samples, buf, out_size);
 102         *got_frame_ptr   = 1;
 103         *(AVFrame *)data = s->frame;
 104         return buf_size;
 105     }
 106
 107     while (samples < samples_end && buf - avpkt->data < buf_size) {
 108         int code, smp, size;
 109         uint8_t count;
 110         code  = *buf >> 6;
 111         count = *buf & 0x3F;
 112         buf++;
 113
 114         /* make sure we don't write past the output buffer */
 115         switch (code) {
 116         case 0:  smp = 4 * (count + 1);                break;
 117         case 1:  smp = 2 * (count + 1);                break;
 118         case 2:  smp = (count & 0x20) ? 1 : count + 1; break;
 119         default: smp = count + 1;                      break;
 120         }
 121         if (samples_end - samples < smp)
 122             break;
 123
 124         /* make sure we don't read past the input buffer */
 125         size = ((code == 2 && (count & 0x20)) || code == 3) ? 0 : count + 1;
 126         if ((buf - avpkt->data) + size > buf_size)
 127             break;
 128
 129         switch (code) {
 130         case 0: /* ADPCM 2-bit */
 131             for (count++; count > 0; count--) {
 132                 code = *buf++;
 133                 sample += ( code       & 0x3) - 2;
 134                 sample = av_clip_uint8(sample);
 135                 *samples++ = sample;
 136                 sample += ((code >> 2) & 0x3) - 2;
 137                 sample = av_clip_uint8(sample);
 138                 *samples++ = sample;
 139                 sample += ((code >> 4) & 0x3) - 2;
 140                 sample = av_clip_uint8(sample);
 141                 *samples++ = sample;
 142                 sample +=  (code >> 6)        - 2;
 143                 sample = av_clip_uint8(sample);
 144                 *samples++ = sample;
 145             }
 146             break;
 147         case 1: /* ADPCM 4-bit */
 148             for (count++; count > 0; count--) {
 149                 code = *buf++;
 150                 sample += ws_adpcm_4bit[code & 0xF];
 151                 sample = av_clip_uint8(sample);
 152                 *samples++ = sample;
 153                 sample += ws_adpcm_4bit[code >> 4];
 154                 sample = av_clip_uint8(sample);
 155                 *samples++ = sample;
 156             }
 157             break;
 158         case 2: /* no compression */
 159             if (count & 0x20) { /* big delta */
 160                 int8_t t;
 161                 t = count;
 162                 t <<= 3;
 163                 sample += t >> 3;
 164                 sample = av_clip_uint8(sample);
 165                 *samples++ = sample;
 166             } else { /* copy */
 167                 memcpy(samples, buf, smp);
 168                 samples += smp;
 169                 buf     += smp;
 170                 sample = buf[-1];
 171             }
 172             break;
 173         default: /* run */
 174             memset(samples, sample, smp);
 175             samples += smp;
 176         }
 177     }
 178
 179     s->frame.nb_samples = samples - s->frame.data[0];
 180     *got_frame_ptr   = 1;
 181     *(AVFrame *)data = s->frame;
 182
 183     return buf_size;
 184 }
 185
 186 AVCodec ff_ws_snd1_decoder = {
 187     .name           = "ws_snd1",
 188     .type           = AVMEDIA_TYPE_AUDIO,
 189     .id             = AV_CODEC_ID_WESTWOOD_SND1,
 190     .priv_data_size = sizeof(WSSndContext),
 191     .init           = ws_snd_decode_init,
 192     .decode         = ws_snd_decode_frame,
 193     .capabilities   = CODEC_CAP_DR1,
 194     .long_name      = NULL_IF_CONFIG_SMALL("Westwood Audio (SND1)"),
 195 };