handle 0-length buffers
[libav.git] / libavcodec / dpcm.c
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1/*
2 * Assorted DPCM codecs
3 * Copyright (c) 2003 The ffmpeg Project.
4 *
5 * This library is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU Lesser General Public
7 * License as published by the Free Software Foundation; either
8 * version 2 of the License, or (at your option) any later version.
9 *
10 * This library is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * Lesser General Public License for more details.
14 *
15 * You should have received a copy of the GNU Lesser General Public
16 * License along with this library; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18 */
19
20/**
21 * @file: dpcm.c
22 * Assorted DPCM (differential pulse code modulation) audio codecs
23 * by Mike Melanson (melanson@pcisys.net)
9937e686 24 * Xan DPCM decoder by Mario Brito (mbrito@student.dei.uc.pt)
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25 * for more information on the specific data formats, visit:
26 * http://www.pcisys.net/~melanson/codecs/simpleaudio.html
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27 *
28 * Note about using the Xan DPCM decoder: Xan DPCM is used in AVI files
29 * found in the Wing Commander IV computer game. These AVI files contain
30 * WAVEFORMAT headers which report the audio format as 0x01: raw PCM.
31 * Clearly incorrect. To detect Xan DPCM, you will probably have to
32 * special-case your AVI demuxer to use Xan DPCM if the file uses 'Xxan'
33 * (Xan video) for its video codec. Alternately, such AVI files also contain
34 * the fourcc 'Axan' in the 'auds' chunk of the AVI header.
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35 */
36
37#include "avcodec.h"
38
39typedef struct DPCMContext {
40 int channels;
41 short roq_square_array[256];
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42} DPCMContext;
43
44#define SATURATE_S16(x) if (x < -32768) x = -32768; \
45 else if (x > 32767) x = 32767;
46#define SE_16BIT(x) if (x & 0x8000) x -= 0x10000;
47#define LE_16(x) ((((uint8_t*)(x))[1] << 8) | ((uint8_t*)(x))[0])
48#define LE_32(x) ((((uint8_t*)(x))[3] << 24) | \
49 (((uint8_t*)(x))[2] << 16) | \
50 (((uint8_t*)(x))[1] << 8) | \
51 ((uint8_t*)(x))[0])
52
53static int interplay_delta_table[] = {
54 0, 1, 2, 3, 4, 5, 6, 7,
55 8, 9, 10, 11, 12, 13, 14, 15,
56 16, 17, 18, 19, 20, 21, 22, 23,
57 24, 25, 26, 27, 28, 29, 30, 31,
58 32, 33, 34, 35, 36, 37, 38, 39,
59 40, 41, 42, 43, 47, 51, 56, 61,
60 66, 72, 79, 86, 94, 102, 112, 122,
61 133, 145, 158, 173, 189, 206, 225, 245,
62 267, 292, 318, 348, 379, 414, 452, 493,
63 538, 587, 640, 699, 763, 832, 908, 991,
64 1081, 1180, 1288, 1405, 1534, 1673, 1826, 1993,
65 2175, 2373, 2590, 2826, 3084, 3365, 3672, 4008,
66 4373, 4772, 5208, 5683, 6202, 6767, 7385, 8059,
67 8794, 9597, 10472, 11428, 12471, 13609, 14851, 16206,
68 17685, 19298, 21060, 22981, 25078, 27367, 29864, 32589,
69 -29973, -26728, -23186, -19322, -15105, -10503, -5481, -1,
70 1, 1, 5481, 10503, 15105, 19322, 23186, 26728,
71 29973, -32589, -29864, -27367, -25078, -22981, -21060, -19298,
72 -17685, -16206, -14851, -13609, -12471, -11428, -10472, -9597,
73 -8794, -8059, -7385, -6767, -6202, -5683, -5208, -4772,
74 -4373, -4008, -3672, -3365, -3084, -2826, -2590, -2373,
75 -2175, -1993, -1826, -1673, -1534, -1405, -1288, -1180,
76 -1081, -991, -908, -832, -763, -699, -640, -587,
77 -538, -493, -452, -414, -379, -348, -318, -292,
78 -267, -245, -225, -206, -189, -173, -158, -145,
79 -133, -122, -112, -102, -94, -86, -79, -72,
80 -66, -61, -56, -51, -47, -43, -42, -41,
81 -40, -39, -38, -37, -36, -35, -34, -33,
82 -32, -31, -30, -29, -28, -27, -26, -25,
83 -24, -23, -22, -21, -20, -19, -18, -17,
84 -16, -15, -14, -13, -12, -11, -10, -9,
85 -8, -7, -6, -5, -4, -3, -2, -1
86
87};
88
89static int dpcm_decode_init(AVCodecContext *avctx)
90{
91 DPCMContext *s = avctx->priv_data;
92 int i;
93 short square;
94
95 s->channels = avctx->channels;
96
97 switch(avctx->codec->id) {
98
99 case CODEC_ID_ROQ_DPCM:
100 /* initialize square table */
101 for (i = 0; i < 128; i++) {
102 square = i * i;
103 s->roq_square_array[i] = square;
104 s->roq_square_array[i + 128] = -square;
105 }
106 break;
107
108 default:
109 break;
110 }
111
112 return 0;
113}
114
115static int dpcm_decode_frame(AVCodecContext *avctx,
116 void *data, int *data_size,
117 uint8_t *buf, int buf_size)
118{
119 DPCMContext *s = avctx->priv_data;
120 int in, out = 0;
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121 int predictor[2];
122 int channel_number = 0;
123 short *output_samples = data;
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124 int shift[2];
125 unsigned char byte;
126 short diff;
3ef8be2b 127
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128 if (!buf_size)
129 return 0;
130
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131 switch(avctx->codec->id) {
132
133 case CODEC_ID_ROQ_DPCM:
134 if (s->channels == 1)
135 predictor[0] = LE_16(&buf[6]);
136 else {
137 predictor[0] = buf[7] << 8;
138 predictor[1] = buf[6] << 8;
139 }
140 SE_16BIT(predictor[0]);
141 SE_16BIT(predictor[1]);
142
143 /* decode the samples */
144 for (in = 8, out = 0; in < buf_size; in++, out++) {
145 predictor[channel_number] += s->roq_square_array[buf[in]];
146 SATURATE_S16(predictor[channel_number]);
147 output_samples[out] = predictor[channel_number];
148
149 /* toggle channel */
150 channel_number ^= s->channels - 1;
151 }
152 break;
153
154 case CODEC_ID_INTERPLAY_DPCM:
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155 in = 6; /* skip over the stream mask and stream length */
156 predictor[0] = LE_16(&buf[in]);
157 in += 2;
158 SE_16BIT(predictor[0])
159 output_samples[out++] = predictor[0];
160 if (s->channels == 2) {
161 predictor[1] = LE_16(&buf[in]);
3ef8be2b 162 in += 2;
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163 SE_16BIT(predictor[1])
164 output_samples[out++] = predictor[1];
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165 }
166
167 while (in < buf_size) {
168 predictor[channel_number] += interplay_delta_table[buf[in++]];
169 SATURATE_S16(predictor[channel_number]);
170 output_samples[out++] = predictor[channel_number];
171
172 /* toggle channel */
173 channel_number ^= s->channels - 1;
174 }
175
3ef8be2b 176 break;
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177
178 case CODEC_ID_XAN_DPCM:
179 in = 0;
180 shift[0] = shift[1] = 4;
181 predictor[0] = LE_16(&buf[in]);
182 in += 2;
183 SE_16BIT(predictor[0]);
184 if (s->channels == 2) {
185 predictor[1] = LE_16(&buf[in]);
186 in += 2;
187 SE_16BIT(predictor[1]);
188 }
189
190 while (in < buf_size) {
191 byte = buf[in++];
192 diff = (byte & 0xFC) << 8;
193 if ((byte & 0x03) == 3)
194 shift[channel_number]++;
195 else
196 shift[channel_number] -= (2 * (byte & 3));
197 /* saturate the shifter to a lower limit of 0 */
198 if (shift[channel_number] < 0)
199 shift[channel_number] = 0;
200
201 diff >>= shift[channel_number];
202 predictor[channel_number] += diff;
203
204 SATURATE_S16(predictor[channel_number]);
205 output_samples[out++] = predictor[channel_number];
206
207 /* toggle channel */
208 channel_number ^= s->channels - 1;
209 }
210 break;
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211 }
212
213 *data_size = out * sizeof(short);
214 return buf_size;
215}
216
217AVCodec roq_dpcm_decoder = {
218 "roq_dpcm",
219 CODEC_TYPE_AUDIO,
220 CODEC_ID_ROQ_DPCM,
221 sizeof(DPCMContext),
222 dpcm_decode_init,
223 NULL,
224 NULL,
225 dpcm_decode_frame,
226};
227
228AVCodec interplay_dpcm_decoder = {
229 "interplay_dpcm",
230 CODEC_TYPE_AUDIO,
231 CODEC_ID_INTERPLAY_DPCM,
232 sizeof(DPCMContext),
233 dpcm_decode_init,
234 NULL,
235 NULL,
236 dpcm_decode_frame,
237};
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238
239AVCodec xan_dpcm_decoder = {
240 "xan_dpcm",
241 CODEC_TYPE_AUDIO,
242 CODEC_ID_XAN_DPCM,
243 sizeof(DPCMContext),
244 dpcm_decode_init,
245 NULL,
246 NULL,
247 dpcm_decode_frame,
248};