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
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
34static const char ws_adpcm_2bit[] = { -2, -1, 0, 1};
35static 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
41static 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
49static int ws_snd_decode_frame(AVCodecContext *avctx,
50                void *data, int *data_size,
51                AVPacket *avpkt)
52{
53    const uint8_t *buf = avpkt->data;
54    int buf_size = avpkt->size;
55//    WSSNDContext *c = avctx->priv_data;
56
57    int in_size, out_size;
58    int sample = 0;
59    int i;
60    short *samples = data;
61
62    if (!buf_size)
63        return 0;
64
65    out_size = AV_RL16(&buf[0]);
66    *data_size = out_size * 2;
67    in_size = AV_RL16(&buf[2]);
68    buf += 4;
69
70    if (out_size > *data_size) {
71        av_log(avctx, AV_LOG_ERROR, "Frame is too large to fit in buffer\n");
72        return -1;
73    }
74    if (in_size > buf_size) {
75        av_log(avctx, AV_LOG_ERROR, "Frame data is larger than input buffer\n");
76        return -1;
77    }
78    if (in_size == out_size) {
79        for (i = 0; i < out_size; i++)
80            *samples++ = (*buf++ - 0x80) << 8;
81        return buf_size;
82    }
83
84    while (out_size > 0) {
85        int code;
86        uint8_t count;
87        code = (*buf) >> 6;
88        count = (*buf) & 0x3F;
89        buf++;
90        switch(code) {
91        case 0: /* ADPCM 2-bit */
92            for (count++; count > 0; count--) {
93                code = *buf++;
94                sample += ws_adpcm_2bit[code & 0x3];
95                CLIP8(sample);
96                *samples++ = sample << 8;
97                sample += ws_adpcm_2bit[(code >> 2) & 0x3];
98                CLIP8(sample);
99                *samples++ = sample << 8;
100                sample += ws_adpcm_2bit[(code >> 4) & 0x3];
101                CLIP8(sample);
102                *samples++ = sample << 8;
103                sample += ws_adpcm_2bit[(code >> 6) & 0x3];
104                CLIP8(sample);
105                *samples++ = sample << 8;
106                out_size -= 4;
107            }
108            break;
109        case 1: /* ADPCM 4-bit */
110            for (count++; count > 0; count--) {
111                code = *buf++;
112                sample += ws_adpcm_4bit[code & 0xF];
113                CLIP8(sample);
114                *samples++ = sample << 8;
115                sample += ws_adpcm_4bit[code >> 4];
116                CLIP8(sample);
117                *samples++ = sample << 8;
118                out_size -= 2;
119            }
120            break;
121        case 2: /* no compression */
122            if (count & 0x20) { /* big delta */
123                char t;
124                t = count;
125                t <<= 3;
126                sample += t >> 3;
127                *samples++ = sample << 8;
128                out_size--;
129            } else { /* copy */
130                for (count++; count > 0; count--) {
131                    *samples++ = (*buf++ - 0x80) << 8;
132                    out_size--;
133                }
134                sample = buf[-1] - 0x80;
135            }
136            break;
137        default: /* run */
138            for(count++; count > 0; count--) {
139                *samples++ = sample << 8;
140                out_size--;
141            }
142        }
143    }
144
145    return buf_size;
146}
147
148AVCodec ws_snd1_decoder = {
149    "ws_snd1",
150    AVMEDIA_TYPE_AUDIO,
151    CODEC_ID_WESTWOOD_SND1,
152    0,
153    ws_snd_decode_init,
154    NULL,
155    NULL,
156    ws_snd_decode_frame,
157    .long_name = NULL_IF_CONFIG_SMALL("Westwood Audio (SND1)"),
158};
159