2 * Copyright (C) 2009 Andre Noll <maan@systemlinux.org>
4 * Licensed under the GPL v2. For licencing details see COPYING.
7 /** \file oss_write.c Paraslash's oss output plugin. */
10 #include <sys/ioctl.h>
13 #include <sys/soundcard.h>
22 #include "oss_write.cmdline.h"
25 /** Always use 16 bit little endian. */
26 #define FORMAT AFMT_S16_LE
28 /** Data specific to the oss writer. */
29 struct private_oss_write_data {
30 /** The file handle of the device. */
33 * The samplerate given by command line option or the decoder
34 * of the writer node group.
38 * The number of channels, given by command line option or the
39 * decoder of the writer node group.
42 /** Four bytes for stereo streams, two bytes for mono streams. */
46 static int oss_pre_select(struct sched *s, struct writer_node *wn)
48 struct private_oss_write_data *powd = wn->private_data;
49 struct writer_node_group *wng = wn->wng;
51 if (*wng->loaded - wn->written < powd->bytes_per_frame)
53 para_fd_set(powd->fd, &s->wfds, &s->max_fileno);
57 static int oss_post_select(struct sched *s, struct writer_node *wn)
60 struct private_oss_write_data *powd = wn->private_data;
61 struct writer_node_group *wng = wn->wng;
62 size_t frames, bytes = *wng->loaded - wn->written;
63 char *data = *wng->bufp + wn->written;
65 if (*wng->input_error < 0 && bytes < powd->bytes_per_frame) {
66 wn->written = *wng->loaded;
67 return *wng->input_error;
69 frames = bytes / powd->bytes_per_frame;
70 if (!frames) /* less than a single frame available */
72 if (!FD_ISSET(powd->fd, &s->wfds))
74 ret = write_nonblock(powd->fd, data, frames * powd->bytes_per_frame, 0);
82 static void oss_close(struct writer_node *wn)
84 struct private_oss_write_data *powd = wn->private_data;
91 * The Open Sound System Programmer's Guide sayeth:
93 * Set sampling parameters always so that number of channels (mono/stereo) is
94 * set before selecting sampling rate (speed). Failing to do this will make
95 * your program incompatible with cards such as the SoundBlaster Pro which
96 * supports 44.1 kHz in mono but just 22.05 kHz in stereo. A program which
97 * selects 44.1 kHz speed and then sets the device to stereo mode will
98 * incorrectly believe that the device is still in 44.1 kHz mode when actually
99 * the speed is decreased to 22.05 kHz.
101 static int oss_open(struct writer_node *wn)
103 int ret, format = FORMAT, channels, samplerate;
104 struct oss_write_args_info *conf = wn->conf;
105 struct writer_node_group *wng = wn->wng;
106 struct private_oss_write_data *powd;
108 PARA_INFO_LOG("opening %s\n", conf->device_arg);
109 ret = para_open(conf->device_arg, O_WRONLY, 0);
112 powd = para_calloc(sizeof(*powd));
113 wn->private_data = powd;
115 ret = mark_fd_nonblocking(powd->fd);
119 ret = ioctl(powd->fd, SNDCTL_DSP_SETFMT, &format);
121 ret = -ERRNO_TO_PARA_ERROR(errno);
124 ret = -E_BAD_SAMPLE_FORMAT;
125 if (format != FORMAT)
127 /* set number of channels */
128 if (!conf->channels_given && wng->channels)
129 channels = *wng->channels;
131 channels = conf->channels_arg;
132 ret = -E_BAD_CHANNEL_COUNT;
135 powd->channels = channels;
136 ret = ioctl(powd->fd, SNDCTL_DSP_CHANNELS, &channels);
138 ret = -ERRNO_TO_PARA_ERROR(errno);
141 if (powd->channels != channels)
143 powd->bytes_per_frame = channels * 2;
148 * If we request a higher sampling rate than is supported by the
149 * device, the the highest possible speed is automatically used. The
150 * value actually used is returned as the new value of the argument.
152 if (!conf->samplerate_given && wng->samplerate)
153 samplerate = *wng->samplerate;
155 samplerate = conf->samplerate_arg;
156 powd->samplerate = samplerate;
157 ret = ioctl(powd->fd, SNDCTL_DSP_SPEED, &samplerate);
159 ret = -ERRNO_TO_PARA_ERROR(errno);
162 if (samplerate != powd->samplerate) {
163 int min = PARA_MIN(samplerate, powd->samplerate),
164 max = PARA_MAX(samplerate, powd->samplerate);
166 * Check whether the returned sample rate differs significantly
167 * from the requested one.
169 ret = -E_BAD_SAMPLERATE;
170 if (100 * max > 110 * min) /* more than 10% deviation */
172 PARA_NOTICE_LOG("using %dHz rather than %dHz\n", samplerate,
183 __malloc static void *oss_parse_config(const char *options)
186 struct oss_write_args_info *conf = para_calloc(sizeof(*conf));
188 PARA_INFO_LOG("options: %s, %zd\n", options, strcspn(options, " \t"));
189 ret = oss_cmdline_parser_string(options, conf, "oss_write");
199 * The init function of the oss writer.
201 * \param w Pointer to the writer to initialize.
205 void oss_write_init(struct writer *w)
207 struct oss_write_args_info dummy;
209 oss_cmdline_parser_init(&dummy);
211 w->close = oss_close;
212 w->pre_select = oss_pre_select;
213 w->post_select = oss_post_select;
214 w->parse_config = oss_parse_config;
216 w->help = (struct ggo_help) {
217 .short_help = oss_write_args_info_help,
218 .detailed_help = oss_write_args_info_detailed_help
220 oss_cmdline_parser_free(&dummy);