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
ws_snd_decode_init(AVCodecContext * avctx)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
ws_snd_decode_frame(AVCodecContext * avctx,void * data,int * got_frame_ptr,AVPacket * avpkt)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 = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_CHANNEL_CONF,
181 .caps_internal = FF_CODEC_CAP_INIT_THREADSAFE,
182 };
183