1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
|
/*
* Simple mp3 player. Derived from libmad's example minimad.c.
*/
#include <u.h>
#include <libc.h>
#include "mad.h"
/* Current input file */
vlong offset;
double seekto = 0.0;
uvlong samples = 0;
int debug = 0;
int ifd = -1;
static enum mad_flow
input(void *, struct mad_stream *stream)
{
static uchar buf[32768];
int fd, n, m;
n = stream->bufend - stream->next_frame;
memmove(buf, stream->next_frame, n);
m = read(0, buf+n, sizeof buf-n);
offset += m;
if(m < 0)
sysfatal("reading input: %r");
if(m == 0)
return MAD_FLOW_STOP;
n += m;
mad_stream_buffer(stream, buf, n);
return MAD_FLOW_CONTINUE;
}
static enum mad_flow
header(void *, struct mad_header const* header)
{
if(seekto > 0){
uvlong after = samples + 32*MAD_NSBSAMPLES(header);
if((double)after/header->samplerate >= seekto){
fprint(2, "time: %g\n", (double)samples/header->samplerate);
seekto = 0;
}else{
samples = after;
return MAD_FLOW_IGNORE;
}
}
return MAD_FLOW_CONTINUE;
}
static enum mad_flow
output(void *, struct mad_header const* header, struct mad_pcm *pcm)
{
static int rate, chans;
static uchar *buf;
static int nbuf;
mad_fixed_t v, *s;
int i, j, n;
uchar *p;
if(seekto > 0)
return MAD_FLOW_IGNORE;
/* start converter if format changed */
if(rate != pcm->samplerate || chans != pcm->channels){
int pid, pfd[2];
char fmt[32];
rate = pcm->samplerate;
chans = pcm->channels;
snprint(fmt, sizeof(fmt), "s%dr%dc%d", MAD_F_FRACBITS+1, rate, chans);
if(ifd >= 0){
close(ifd);
waitpid();
}
if(pipe(pfd) < 0)
sysfatal("pipe: %r");
pid = fork();
if(pid < 0)
sysfatal("fork: %r");
if(pid == 0){
dup(pfd[1], 0);
close(pfd[1]);
close(pfd[0]);
execl("/bin/audio/pcmconv", "pcmconv", "-i", fmt, nil);
sysfatal("exec: %r");
}
close(pfd[1]);
ifd = pfd[0];
}
n = 4 * chans * pcm->length;
if(n > nbuf){
nbuf = n;
buf = realloc(buf, nbuf);
if(buf == nil)
sysfatal("realloc: %r");
memset(buf, 0, nbuf);
}
p = buf;
for(j=0; j < chans; j++){
s = pcm->samples[j];
p = buf + j*4;
for(i=0; i < pcm->length; i++){
v = *s++;
/* clipping */
if(v >= MAD_F_ONE)
v = MAD_F_ONE-1;
else if(v < -MAD_F_ONE)
v = -MAD_F_ONE;
p[0] = v, v>>=8;
p[1] = v, v>>=8;
p[2] = v, v>>=8;
p[3] = v;
p += chans*4;
}
}
if(n > 0)
write(ifd, buf, n);
return MAD_FLOW_CONTINUE;
}
static enum mad_flow
error(void *, struct mad_stream *stream, struct mad_frame *frame)
{
if(stream->error == MAD_ERROR_LOSTSYNC){
uchar *p;
ulong n;
p = stream->this_frame;
if(memcmp(p, "TAG", 3)==0){
mad_stream_skip(stream, 128);
return MAD_FLOW_CONTINUE;
}
if(memcmp(p, "ID3", 3)==0){
if(((p[6] | p[7] | p[8] | p[9]) & 0x80) == 0){
n = p[9] | p[8]<<7 | p[7]<<14 | p[6]<<21;
mad_stream_skip(stream, n+10);
return MAD_FLOW_CONTINUE;
}
}
}
if(debug)
fprint(2, "#%lld: %s\n",
offset-(stream->bufend-stream->next_frame),
mad_stream_errorstr(stream));
return MAD_FLOW_CONTINUE;
}
void
usage(void)
{
fprint(2, "usage: %s [ -d ]\n", argv0);
exits("usage");
}
void
main(int argc, char **argv)
{
struct mad_decoder decoder;
ARGBEGIN{
case 'd':
debug++;
break;
case 's':
seekto = atof(EARGF(usage()));
if(seekto >= 0.0)
break;
default:
usage();
}ARGEND
mad_decoder_init(&decoder, nil, input, header, nil, output, error, nil);
mad_decoder_run(&decoder, MAD_DECODER_MODE_SYNC);
mad_decoder_finish(&decoder);
if(ifd >= 0){
close(ifd);
waitpid();
}
exits(0);
}
|
