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 "buffer_tree.h"
24 #include "oss_write.cmdline.h"
27 /** Always use 16 bit little endian. */
28 #define FORMAT AFMT_S16_LE
30 /** Data specific to the oss writer. */
31 struct private_oss_write_data {
32 /** The file handle of the device. */
35 * The samplerate given by command line option or the decoder
36 * of the writer node group.
40 * The number of channels, given by command line option or the
41 * decoder of the writer node group.
44 /** Four bytes for stereo streams, two bytes for mono streams. */
48 static int oss_pre_select(struct sched *s, struct writer_node *wn)
50 struct private_oss_write_data *powd = wn->private_data;
51 struct writer_node_group *wng = wn->wng;
53 if (*wng->loaded - wn->written < powd->bytes_per_frame)
55 para_fd_set(powd->fd, &s->wfds, &s->max_fileno);
59 static int oss_post_select(struct sched *s, struct writer_node *wn)
62 struct private_oss_write_data *powd = wn->private_data;
63 struct writer_node_group *wng = wn->wng;
64 size_t frames, bytes = *wng->loaded - wn->written;
65 char *data = *wng->bufp + wn->written;
67 if (*wng->input_error < 0 && bytes < powd->bytes_per_frame) {
68 wn->written = *wng->loaded;
69 return *wng->input_error;
71 frames = bytes / powd->bytes_per_frame;
72 if (!frames) /* less than a single frame available */
74 if (!FD_ISSET(powd->fd, &s->wfds))
76 ret = write_nonblock(powd->fd, data, frames * powd->bytes_per_frame, 0);
84 static void oss_close(struct writer_node *wn)
86 struct private_oss_write_data *powd = wn->private_data;
93 * The Open Sound System Programmer's Guide sayeth:
95 * Set sampling parameters always so that number of channels (mono/stereo) is
96 * set before selecting sampling rate (speed). Failing to do this will make
97 * your program incompatible with cards such as the SoundBlaster Pro which
98 * supports 44.1 kHz in mono but just 22.05 kHz in stereo. A program which
99 * selects 44.1 kHz speed and then sets the device to stereo mode will
100 * incorrectly believe that the device is still in 44.1 kHz mode when actually
101 * the speed is decreased to 22.05 kHz.
103 static int oss_open(struct writer_node *wn)
105 int ret, format = FORMAT, channels, samplerate;
106 struct oss_write_args_info *conf = wn->conf;
107 struct writer_node_group *wng = wn->wng;
108 struct private_oss_write_data *powd;
110 PARA_INFO_LOG("opening %s\n", conf->device_arg);
111 ret = para_open(conf->device_arg, O_WRONLY, 0);
114 powd = para_calloc(sizeof(*powd));
115 wn->private_data = powd;
117 ret = mark_fd_nonblocking(powd->fd);
121 ret = ioctl(powd->fd, SNDCTL_DSP_SETFMT, &format);
123 ret = -ERRNO_TO_PARA_ERROR(errno);
126 ret = -E_BAD_SAMPLE_FORMAT;
127 if (format != FORMAT)
129 /* set number of channels */
130 if (!conf->channels_given && wng->channels)
131 channels = *wng->channels;
133 channels = conf->channels_arg;
134 ret = -E_BAD_CHANNEL_COUNT;
137 powd->channels = channels;
138 ret = ioctl(powd->fd, SNDCTL_DSP_CHANNELS, &channels);
140 ret = -ERRNO_TO_PARA_ERROR(errno);
143 if (powd->channels != channels)
145 powd->bytes_per_frame = channels * 2;
150 * If we request a higher sampling rate than is supported by the
151 * device, the the highest possible speed is automatically used. The
152 * value actually used is returned as the new value of the argument.
154 if (!conf->samplerate_given && wng->samplerate)
155 samplerate = *wng->samplerate;
157 samplerate = conf->samplerate_arg;
158 powd->samplerate = samplerate;
159 ret = ioctl(powd->fd, SNDCTL_DSP_SPEED, &samplerate);
161 ret = -ERRNO_TO_PARA_ERROR(errno);
164 if (samplerate != powd->samplerate) {
165 int min = PARA_MIN(samplerate, powd->samplerate),
166 max = PARA_MAX(samplerate, powd->samplerate);
168 * Check whether the returned sample rate differs significantly
169 * from the requested one.
171 ret = -E_BAD_SAMPLERATE;
172 if (100 * max > 110 * min) /* more than 10% deviation */
174 PARA_NOTICE_LOG("using %dHz rather than %dHz\n", samplerate,
185 __malloc static void *oss_parse_config(const char *options)
188 struct oss_write_args_info *conf = para_calloc(sizeof(*conf));
190 PARA_INFO_LOG("options: %s, %zd\n", options, strcspn(options, " \t"));
191 ret = oss_cmdline_parser_string(options, conf, "oss_write");
201 * The init function of the oss writer.
203 * \param w Pointer to the writer to initialize.
207 void oss_write_init(struct writer *w)
209 struct oss_write_args_info dummy;
211 oss_cmdline_parser_init(&dummy);
213 w->close = oss_close;
214 w->pre_select = oss_pre_select;
215 w->post_select = oss_post_select;
216 w->parse_config = oss_parse_config;
218 w->help = (struct ggo_help) {
219 .short_help = oss_write_args_info_help,
220 .detailed_help = oss_write_args_info_detailed_help
222 oss_cmdline_parser_free(&dummy);