66820be1ade370acdb1eecc0dfb22646a3e7c7c2
[libav.git] / libavcodec / 8svx.c
1 /*
2 * 8SVX audio decoder
3 * Copyright (C) 2008 Jaikrishnan Menon
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 /**
23 * @file
24 * 8svx audio decoder
25 * @author Jaikrishnan Menon
26 * supports: fibonacci delta encoding
27 * : exponential encoding
28 */
29
30 #include "avcodec.h"
31
32 /** decoder context */
33 typedef struct EightSvxContext {
34 int16_t fib_acc;
35 const int16_t *table;
36 } EightSvxContext;
37
38 static const int16_t fibonacci[16] = { -34<<8, -21<<8, -13<<8, -8<<8, -5<<8, -3<<8, -2<<8, -1<<8,
39 0, 1<<8, 2<<8, 3<<8, 5<<8, 8<<8, 13<<8, 21<<8 };
40 static const int16_t exponential[16] = { -128<<8, -64<<8, -32<<8, -16<<8, -8<<8, -4<<8, -2<<8, -1<<8,
41 0, 1<<8, 2<<8, 4<<8, 8<<8, 16<<8, 32<<8, 64<<8 };
42
43 /** decode a frame */
44 static int eightsvx_decode_frame(AVCodecContext *avctx, void *data, int *data_size,
45 AVPacket *avpkt)
46 {
47 const uint8_t *buf = avpkt->data;
48 int buf_size = avpkt->size;
49 EightSvxContext *esc = avctx->priv_data;
50 int16_t *out_data = data;
51 int consumed = buf_size;
52 const uint8_t *buf_end = buf + buf_size;
53
54 if((*data_size >> 2) < buf_size)
55 return -1;
56
57 if(avctx->frame_number == 0) {
58 esc->fib_acc = buf[1] << 8;
59 buf_size -= 2;
60 buf += 2;
61 }
62
63 *data_size = buf_size << 2;
64
65 while(buf < buf_end) {
66 uint8_t d = *buf++;
67 esc->fib_acc += esc->table[d & 0x0f];
68 *out_data++ = esc->fib_acc;
69 esc->fib_acc += esc->table[d >> 4];
70 *out_data++ = esc->fib_acc;
71 }
72
73 return consumed;
74 }
75
76 /** initialize 8svx decoder */
77 static av_cold int eightsvx_decode_init(AVCodecContext *avctx)
78 {
79 EightSvxContext *esc = avctx->priv_data;
80
81 switch(avctx->codec->id) {
82 case CODEC_ID_8SVX_FIB:
83 esc->table = fibonacci;
84 break;
85 case CODEC_ID_8SVX_EXP:
86 esc->table = exponential;
87 break;
88 default:
89 return -1;
90 }
91 avctx->sample_fmt = AV_SAMPLE_FMT_S16;
92 return 0;
93 }
94
95 AVCodec eightsvx_fib_decoder = {
96 .name = "8svx_fib",
97 .type = AVMEDIA_TYPE_AUDIO,
98 .id = CODEC_ID_8SVX_FIB,
99 .priv_data_size = sizeof (EightSvxContext),
100 .init = eightsvx_decode_init,
101 .decode = eightsvx_decode_frame,
102 .long_name = NULL_IF_CONFIG_SMALL("8SVX fibonacci"),
103 };
104
105 AVCodec eightsvx_exp_decoder = {
106 .name = "8svx_exp",
107 .type = AVMEDIA_TYPE_AUDIO,
108 .id = CODEC_ID_8SVX_EXP,
109 .priv_data_size = sizeof (EightSvxContext),
110 .init = eightsvx_decode_init,
111 .decode = eightsvx_decode_frame,
112 .long_name = NULL_IF_CONFIG_SMALL("8SVX exponential"),
113 };