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comparison decoders/midi.c @ 108:803ba4dabbce

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Initial add, from Torbj�rn Andersson.
author Ryan C. Gordon <icculus@icculus.org>
date Wed, 03 Oct 2001 20:17:13 +0000
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children 70baf29577d8
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107:427541211bfd 108:803ba4dabbce
1 /*
2 * SDL_sound -- An abstract sound format decoding API.
3 * Copyright (C) 2001 Ryan C. Gordon.
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 2.1 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 * MIDI decoder for SDL_sound, using TiMidity.
22 *
23 * This is a rough, proof-of-concept implementation. A number of things need
24 * to be fixed or at the very least looked at:
25 *
26 * - I have only tested this with TiMidity++. Does TiMidity use the same
27 * command-line options?
28 * - No attempt is made to ensure that the input really is MIDI. Eek. Does
29 * anyone here know how to recognize MIDI?
30 * - Error handling is a joke.
31 * - Did I make any stupid errors in the process communication?
32 * - TiMidity++ spews a number of messages (to stderr?) which should be
33 * silenced eventually.
34 * - This has to be the least portable decoder that has ever been written.
35 * - Etc.
36 *
37 * Oh, and the whole thing should be rewritten as a generic "send data to
38 * external decoder" thing so this version should either be scrapped or
39 * cannibalized for ideas. :-)
40 *
41 * Please see the file LICENSE in the source's root directory.
42 *
43 * This file written by Torbjörn Andersson. (d91tan@Update.UU.SE)
44 */
45
46 #if HAVE_CONFIG_H
47 # include <config.h>
48 #endif
49
50 #ifdef SOUND_SUPPORTS_MIDI
51
52 #include <stdio.h>
53 #include <stdlib.h>
54 #include <string.h>
55 #include <assert.h>
56 #include <unistd.h>
57 #include <signal.h>
58 #include <sys/types.h>
59 #include <sys/wait.h>
60 #include "SDL_sound.h"
61
62 #define __SDL_SOUND_INTERNAL__
63 #include "SDL_sound_internal.h"
64
65
66 static int MIDI_init(void);
67 static void MIDI_quit(void);
68 static int MIDI_open(Sound_Sample *sample, const char *ext);
69 static void MIDI_close(Sound_Sample *sample);
70 static Uint32 MIDI_read(Sound_Sample *sample);
71
72 const Sound_DecoderFunctions __Sound_DecoderFunctions_MIDI =
73 {
74 {
75 "MIDI",
76 "MIDI music through the TiMidity MIDI to WAVE converter",
77 "Torbjörn Andersson <d91tan@Update.UU.SE>",
78 "http://www.goice.co.jp/member/mo/timidity/"
79 },
80
81 MIDI_init, /* init() method */
82 MIDI_quit, /* quit() method */
83 MIDI_open, /* open() method */
84 MIDI_close, /* close() method */
85 MIDI_read /* read() method */
86 };
87
88 /* this is what we store in our internal->decoder_private field... */
89 typedef struct
90 {
91 int fd_audio;
92 } midi_t;
93
94
95 static void sig_pipe(int signo)
96 {
97 signal(signo, sig_pipe);
98 } /* sig_pipe */
99
100
101 static int MIDI_init(void)
102 {
103 if (signal(SIGPIPE, sig_pipe) == SIG_ERR)
104 {
105 Sound_SetError("MIDI: Could not set up SIGPIPE signal handler.");
106 return(0);
107 } /* if */
108 return(1);
109 } /* MIDI_init */
110
111
112 static void MIDI_quit(void)
113 {
114 /* it's a no-op. */
115 } /* MIDI_quit */
116
117
118 static int MIDI_open(Sound_Sample *sample, const char *ext)
119 {
120 Sound_SampleInternal *internal = (Sound_SampleInternal *) sample->opaque;
121 SDL_RWops *rw = internal->rw;
122 midi_t *m;
123 Uint8 buf[BUFSIZ];
124 ssize_t retval;
125 int fd1[2];
126 int fd2[2];
127 pid_t pid;
128
129 /* TiMidity does all the conversions we need. */
130 memcpy(&sample->actual, &sample->desired, sizeof (Sound_AudioInfo));
131 sample->flags = SOUND_SAMPLEFLAG_NONE;
132
133 if (pipe(fd1) < 0 || pipe(fd2) < 0)
134 {
135 Sound_SetError("MIDI: Pipe error.");
136 return(0);
137 } /* if */
138
139 pid = fork();
140 if (pid < 0)
141 {
142 Sound_SetError("MIDI: Fork error.");
143 return(0);
144 } /* if */
145
146 if (pid == 0)
147 {
148 /* child */
149 char arg_freq[10]; /* !!! FIXME: Large enough? */
150 char arg_format[10];
151 char *arg_list[] =
152 { "timidity", "-s", NULL, NULL, "-o", "-", "-", NULL };
153
154 arg_list[2] = arg_freq;
155 arg_list[3] = arg_format;
156
157 close(fd1[1]);
158 close(fd2[0]);
159
160 /* !!! FIXME: Errors should be propagated back to the parent */
161
162 if (fd1[0] != STDIN_FILENO)
163 {
164 if (dup2(fd1[0], STDIN_FILENO) != STDIN_FILENO)
165 return(0);
166 close(fd1[0]);
167 } /* if */
168
169 if (fd2[1] != STDOUT_FILENO)
170 {
171 if (dup2(fd2[1], STDOUT_FILENO) != STDOUT_FILENO)
172 return(0);
173 close(fd2[1]);
174 } /* if */
175
176 /* Construct command-line arguments matching the audio format */
177 sprintf(arg_freq, "%d", sample->actual.rate);
178 sprintf(arg_format, "-Or%c%c%cl",
179 (sample->actual.format & 0x0008) ? '8' : '1',
180 (sample->actual.format & 0x8000) ? 's' : 'u',
181 (sample->actual.channels == 1) ? 'M' : 'S');
182 if ((sample->actual.format & 0x0010) &&
183 (sample->actual.format & 0x7fff) != (AUDIO_S16SYS & 0x7fff))
184 strcat(arg_format, "x");
185
186 if (execvp("timidity", arg_list) < 0)
187 return(0);
188
189 SNDDBG(("MIDI: Is this line ever reached?"));
190 return(1);
191 } /* if */
192
193 /* parent */
194 close(fd1[0]);
195 close(fd2[1]);
196
197 /* Copy the entire file to the child process */
198 for (;;)
199 {
200 retval = SDL_RWread(internal->rw, buf, 1, BUFSIZ);
201 if (retval == 0)
202 break;
203
204 if (write(fd1[1], buf, retval) != retval)
205 {
206 Sound_SetError("MIDI: Could not send data to child process.");
207 return(0);
208 }
209 } /* for */
210
211 close(fd1[1]);
212
213 /* !!! FIXME: We still need some way of recognizing valid MIDI data */
214
215 m = (midi_t *) malloc(sizeof(midi_t));
216 BAIL_IF_MACRO(m == NULL, ERR_OUT_OF_MEMORY, 0);
217 internal->decoder_private = (void *) m;
218
219 /* This is where we'll read the converted audio data. */
220 m->fd_audio = fd2[0];
221
222 SNDDBG(("MIDI: Accepting data stream.\n"));
223 return(1); /* we'll handle this data. */
224 } /* MIDI_open */
225
226
227 static void MIDI_close(Sound_Sample *sample)
228 {
229 Sound_SampleInternal *internal = (Sound_SampleInternal *) sample->opaque;
230
231 close(((midi_t *) internal->decoder_private)->fd_audio);
232 free(internal->decoder_private);
233 } /* MIDI_close */
234
235
236 static Uint32 MIDI_read(Sound_Sample *sample)
237 {
238 ssize_t retval;
239 Sound_SampleInternal *internal = (Sound_SampleInternal *) sample->opaque;
240 midi_t *m = (midi_t *) internal->decoder_private;
241
242 /*
243 * We don't actually do any decoding, so we read the converted data
244 * directly into the internal buffer.
245 */
246 retval = read(m->fd_audio, internal->buffer, internal->buffer_size);
247
248 /* Make sure the read went smoothly... */
249 if (retval == 0)
250 sample->flags |= SOUND_SAMPLEFLAG_EOF;
251
252 else if (retval == -1)
253 sample->flags |= SOUND_SAMPLEFLAG_ERROR;
254
255 /* (next call this EAGAIN may turn into an EOF or error.) */
256 else if (retval < internal->buffer_size)
257 sample->flags |= SOUND_SAMPLEFLAG_EAGAIN;
258
259 return(retval);
260 } /* MIDI_read */
261
262 #endif /* SOUND_SUPPORTS_MIDI */
263
264 /* end of midi.c ... */
265