3 Ann Hell Ex Machina - Music Software
4 Copyright (C) 2003/2005 Angel Ortega <angel@triptico.com>
6 ss_output.c - Softsynth output interface
8 This program is free software; you can redistribute it and/or
9 modify it under the terms of the GNU General Public License
10 as published by the Free Software Foundation; either version 2
11 of the License, or (at your option) any later version.
13 This program is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
18 You should have received a copy of the GNU General Public License
19 along with this program; if not, write to the Free Software
20 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
22 http://www.triptico.com
35 #include "ss_output.h"
42 /* master output volume */
43 float ss_master_volume
=1.0;
45 /* output accounting */
46 int ss_output_frames
=0;
47 int ss_output_clipped
=0;
48 float ss_output_lowest
=0;
49 float ss_output_highest
=0;
51 /* optimal output volume */
52 float ss_optimal_volume
;
54 /* output filehandle */
58 usual channel mapping:
62 3 channel: left | right | center
63 quad: front left | front right | rear left | rear right
64 4 channel: left | center | right | surround
65 6 channel: left center | left | center | right center | right | surround
72 int ss_outdev(char * drv
, char * file
, int freq
, int n_channels
);
75 * ss_output_open - Opens an output device.
76 * @name: name of the driver
77 * @filename: name of the file or device
79 * Opens an output device. @name contains the name of the driver
80 * (i.e. "raw" or "wav"), @filename contains the (optional) name
81 * of the output file or device (i.e. a filename for "raw" or
82 * "wav" or "/dev/dsp" for a direct audio device like "oss").
83 * @Name can be the special pseudo-driver "default"
84 * to select the most appropriate (usually a platform-specific
85 * direct output device, or "wav" if no one exists).
86 * @filename can also be NULL; in that case, a driver dependent,
87 * default value is used.
89 * The _n_channels global variable can be changed on output if
90 * the driver doesn't support so much channels.
92 * Returns a negative number in case of error, or zero otherwise.
94 int ss_output_open(char * drvname
, char * filename
)
96 if(strcmp(drvname
, "default") == 0)
99 /* reset accounting */
100 ss_output_frames
=ss_output_clipped
=0;
101 ss_output_lowest
=ss_output_highest
=0.0;
103 ss_of
=ss_outdev(drvname
, filename
, ss_frequency
, ss_nchannels
);
109 void ss_output_init_frame(float samples
[])
113 for(n
=0;n
< SS_MAX_CHANNELS
;n
++)
119 * ss_output_write - Outputs a frame of samples.
120 * @samples: the frame of samples
122 * Outputs a frame of samples. The output samples are
123 * intermixed if needed, have the master volume applied and trimmed
124 * before being sent to the output driver itself.
126 * If the maximum number of channels the output driver supports
127 * is lower than the global _n_channels, they are sequentially intermixed
128 * (for example, when outputting 4 channel data to a stereo device,
129 * 0 and 2 channels will go to left and 1 and 3 to right).
131 * Returns a negative value in case of error, or 0 otherwise.
133 int ss_output_write(float samples
[])
136 float s
, fs
[SS_MAX_CHANNELS
];
137 short int is
[SS_MAX_CHANNELS
];
139 /* clean samples first */
140 for(n
=0;n
< ss_nchannels
;n
++)
143 /* move samples, 'down-channeling' if needed */
144 for(n
=0;n
< SS_MAX_CHANNELS
;n
++)
145 fs
[n
% ss_nchannels
] += samples
[n
];
147 /* final corrections */
148 for(n
=clip
=0;n
< ss_nchannels
;n
++)
152 /* store the lowest and highest
153 amplitude seen before master volume */
154 if(s
< ss_output_lowest
)
157 if(s
> ss_output_highest
)
160 /* apply master volume */
161 s
*= ss_master_volume
;
163 /* clip samples to signed 16 bit boundaries */
176 /* store in buffer */
180 /* update accounting */
187 write(ss_of
, is
, ss_nchannels
* sizeof(short int));
188 /* write(ss_of, is, 256);*/
195 * ss_output_close - Closes the output device.
197 * Closes the output driver.
199 int ss_output_close(void)
205 /* calculate optimal master volume for
207 ss_output_lowest
=fabs(ss_output_lowest
);
209 ss_optimal_volume
= ss_output_lowest
> ss_output_highest
?
210 32768.0 / ss_output_lowest
:
211 32767.0 / ss_output_highest
;