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Diffstat (limited to 'apps/codecs/libmad/minimad.c')
-rw-r--r-- | apps/codecs/libmad/minimad.c | 222 |
1 files changed, 222 insertions, 0 deletions
diff --git a/apps/codecs/libmad/minimad.c b/apps/codecs/libmad/minimad.c new file mode 100644 index 0000000000..e32e0d6a38 --- /dev/null +++ b/apps/codecs/libmad/minimad.c | |||
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1 | /* | ||
2 | * libmad - MPEG audio decoder library | ||
3 | * Copyright (C) 2000-2004 Underbit Technologies, Inc. | ||
4 | * | ||
5 | * This program is free software; you can redistribute it and/or modify | ||
6 | * it under the terms of the GNU General Public License as published by | ||
7 | * the Free Software Foundation; either version 2 of the License, or | ||
8 | * (at your option) any later version. | ||
9 | * | ||
10 | * This program 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 | ||
13 | * GNU General Public License for more details. | ||
14 | * | ||
15 | * You should have received a copy of the GNU General Public License | ||
16 | * along with this program; if not, write to the Free Software | ||
17 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | ||
18 | * | ||
19 | * $Id$ | ||
20 | */ | ||
21 | |||
22 | # include <stdio.h> | ||
23 | # include <unistd.h> | ||
24 | # include <sys/stat.h> | ||
25 | # include <sys/mman.h> | ||
26 | |||
27 | # include "mad.h" | ||
28 | |||
29 | /* | ||
30 | * This is perhaps the simplest example use of the MAD high-level API. | ||
31 | * Standard input is mapped into memory via mmap(), then the high-level API | ||
32 | * is invoked with three callbacks: input, output, and error. The output | ||
33 | * callback converts MAD's high-resolution PCM samples to 16 bits, then | ||
34 | * writes them to standard output in little-endian, stereo-interleaved | ||
35 | * format. | ||
36 | */ | ||
37 | |||
38 | static int decode(unsigned char const *, unsigned long); | ||
39 | |||
40 | int main(int argc, char *argv[]) | ||
41 | { | ||
42 | struct stat stat; | ||
43 | void *fdm; | ||
44 | |||
45 | if (argc != 1) | ||
46 | return 1; | ||
47 | |||
48 | if (fstat(STDIN_FILENO, &stat) == -1 || | ||
49 | stat.st_size == 0) | ||
50 | return 2; | ||
51 | |||
52 | fdm = mmap(0, stat.st_size, PROT_READ, MAP_SHARED, STDIN_FILENO, 0); | ||
53 | if (fdm == MAP_FAILED) | ||
54 | return 3; | ||
55 | |||
56 | decode(fdm, stat.st_size); | ||
57 | |||
58 | if (munmap(fdm, stat.st_size) == -1) | ||
59 | return 4; | ||
60 | |||
61 | return 0; | ||
62 | } | ||
63 | |||
64 | /* | ||
65 | * This is a private message structure. A generic pointer to this structure | ||
66 | * is passed to each of the callback functions. Put here any data you need | ||
67 | * to access from within the callbacks. | ||
68 | */ | ||
69 | |||
70 | struct buffer { | ||
71 | unsigned char const *start; | ||
72 | unsigned long length; | ||
73 | }; | ||
74 | |||
75 | /* | ||
76 | * This is the input callback. The purpose of this callback is to (re)fill | ||
77 | * the stream buffer which is to be decoded. In this example, an entire file | ||
78 | * has been mapped into memory, so we just call mad_stream_buffer() with the | ||
79 | * address and length of the mapping. When this callback is called a second | ||
80 | * time, we are finished decoding. | ||
81 | */ | ||
82 | |||
83 | static | ||
84 | enum mad_flow input(void *data, | ||
85 | struct mad_stream *stream) | ||
86 | { | ||
87 | struct buffer *buffer = data; | ||
88 | |||
89 | if (!buffer->length) | ||
90 | return MAD_FLOW_STOP; | ||
91 | |||
92 | mad_stream_buffer(stream, buffer->start, buffer->length); | ||
93 | |||
94 | buffer->length = 0; | ||
95 | |||
96 | return MAD_FLOW_CONTINUE; | ||
97 | } | ||
98 | |||
99 | /* | ||
100 | * The following utility routine performs simple rounding, clipping, and | ||
101 | * scaling of MAD's high-resolution samples down to 16 bits. It does not | ||
102 | * perform any dithering or noise shaping, which would be recommended to | ||
103 | * obtain any exceptional audio quality. It is therefore not recommended to | ||
104 | * use this routine if high-quality output is desired. | ||
105 | */ | ||
106 | |||
107 | static inline | ||
108 | signed int scale(mad_fixed_t sample) | ||
109 | { | ||
110 | /* round */ | ||
111 | sample += (1L << (MAD_F_FRACBITS - 16)); | ||
112 | |||
113 | /* clip */ | ||
114 | if (sample >= MAD_F_ONE) | ||
115 | sample = MAD_F_ONE - 1; | ||
116 | else if (sample < -MAD_F_ONE) | ||
117 | sample = -MAD_F_ONE; | ||
118 | |||
119 | /* quantize */ | ||
120 | return sample >> (MAD_F_FRACBITS + 1 - 16); | ||
121 | } | ||
122 | |||
123 | /* | ||
124 | * This is the output callback function. It is called after each frame of | ||
125 | * MPEG audio data has been completely decoded. The purpose of this callback | ||
126 | * is to output (or play) the decoded PCM audio. | ||
127 | */ | ||
128 | |||
129 | static | ||
130 | enum mad_flow output(void *data, | ||
131 | struct mad_header const *header, | ||
132 | struct mad_pcm *pcm) | ||
133 | { | ||
134 | unsigned int nchannels, nsamples; | ||
135 | mad_fixed_t const *left_ch, *right_ch; | ||
136 | |||
137 | /* pcm->samplerate contains the sampling frequency */ | ||
138 | |||
139 | nchannels = pcm->channels; | ||
140 | nsamples = pcm->length; | ||
141 | left_ch = pcm->samples[0]; | ||
142 | right_ch = pcm->samples[1]; | ||
143 | |||
144 | while (nsamples--) { | ||
145 | signed int sample; | ||
146 | |||
147 | /* output sample(s) in 16-bit signed little-endian PCM */ | ||
148 | |||
149 | sample = scale(*left_ch++); | ||
150 | putchar((sample >> 0) & 0xff); | ||
151 | putchar((sample >> 8) & 0xff); | ||
152 | |||
153 | if (nchannels == 2) { | ||
154 | sample = scale(*right_ch++); | ||
155 | putchar((sample >> 0) & 0xff); | ||
156 | putchar((sample >> 8) & 0xff); | ||
157 | } | ||
158 | } | ||
159 | |||
160 | return MAD_FLOW_CONTINUE; | ||
161 | } | ||
162 | |||
163 | /* | ||
164 | * This is the error callback function. It is called whenever a decoding | ||
165 | * error occurs. The error is indicated by stream->error; the list of | ||
166 | * possible MAD_ERROR_* errors can be found in the mad.h (or stream.h) | ||
167 | * header file. | ||
168 | */ | ||
169 | |||
170 | static | ||
171 | enum mad_flow error(void *data, | ||
172 | struct mad_stream *stream, | ||
173 | struct mad_frame *frame) | ||
174 | { | ||
175 | struct buffer *buffer = data; | ||
176 | |||
177 | fprintf(stderr, "decoding error 0x%04x (%s) at byte offset %u\n", | ||
178 | stream->error, mad_stream_errorstr(stream), | ||
179 | stream->this_frame - buffer->start); | ||
180 | |||
181 | /* return MAD_FLOW_BREAK here to stop decoding (and propagate an error) */ | ||
182 | |||
183 | return MAD_FLOW_CONTINUE; | ||
184 | } | ||
185 | |||
186 | /* | ||
187 | * This is the function called by main() above to perform all the decoding. | ||
188 | * It instantiates a decoder object and configures it with the input, | ||
189 | * output, and error callback functions above. A single call to | ||
190 | * mad_decoder_run() continues until a callback function returns | ||
191 | * MAD_FLOW_STOP (to stop decoding) or MAD_FLOW_BREAK (to stop decoding and | ||
192 | * signal an error). | ||
193 | */ | ||
194 | |||
195 | static | ||
196 | int decode(unsigned char const *start, unsigned long length) | ||
197 | { | ||
198 | struct buffer buffer; | ||
199 | struct mad_decoder decoder; | ||
200 | int result; | ||
201 | |||
202 | /* initialize our private message structure */ | ||
203 | |||
204 | buffer.start = start; | ||
205 | buffer.length = length; | ||
206 | |||
207 | /* configure input, output, and error functions */ | ||
208 | |||
209 | mad_decoder_init(&decoder, &buffer, | ||
210 | input, 0 /* header */, 0 /* filter */, output, | ||
211 | error, 0 /* message */); | ||
212 | |||
213 | /* start decoding */ | ||
214 | |||
215 | result = mad_decoder_run(&decoder, MAD_DECODER_MODE_SYNC); | ||
216 | |||
217 | /* release the decoder */ | ||
218 | |||
219 | mad_decoder_finish(&decoder); | ||
220 | |||
221 | return result; | ||
222 | } | ||