2 * Copyright (C) 2005-2009 Andre Noll <maan@systemlinux.org>
4 * Licensed under the GPL v2. For licencing details see COPYING.
7 /** \file alsa_write.c paraslash's alsa output plugin */
10 * Based in parts on aplay.c from the alsa-utils-1.0.8 package,
11 * Copyright (c) by Jaroslav Kysela <perex@suse.cz>, which is
12 * based on the vplay program by Michael Beck.
16 #include <sys/types.h>
18 #include <alsa/asoundlib.h>
28 #include "alsa_write.cmdline.h"
31 /** always use 16 bit little endian */
32 #define FORMAT SND_PCM_FORMAT_S16_LE
34 /** Data specific to the alsa writer. */
35 struct private_alsa_write_data
{
36 /** The alsa handle */
38 /** Determined and set by alsa_open(). */
40 /** The approximate maximum buffer duration in us. */
42 /* Number of frames that fit into the buffer. */
43 unsigned buffer_frames
;
45 * The samplerate given by command line option or the decoder
46 * of the writer node group.
50 * The number of channels, given by command line option or the
51 * decoder of the writer node group.
56 /* Install PCM software and hardware configuration. */
57 static int alsa_init(struct private_alsa_write_data
*pad
,
58 struct alsa_write_args_info
*conf
)
60 snd_pcm_hw_params_t
*hwparams
;
61 snd_pcm_sw_params_t
*swparams
;
62 snd_pcm_uframes_t buffer_size
, start_threshold
, stop_threshold
;
63 snd_pcm_uframes_t period_size
;
66 err
= snd_pcm_open(&pad
->handle
, conf
->device_arg
,
67 SND_PCM_STREAM_PLAYBACK
, SND_PCM_NONBLOCK
);
71 snd_pcm_hw_params_alloca(&hwparams
);
72 snd_pcm_sw_params_alloca(&swparams
);
73 if (snd_pcm_hw_params_any(pad
->handle
, hwparams
) < 0)
74 return -E_BROKEN_CONF
;
75 if (snd_pcm_hw_params_set_access(pad
->handle
, hwparams
,
76 SND_PCM_ACCESS_RW_INTERLEAVED
) < 0)
77 return -E_ACCESS_TYPE
;
78 if (snd_pcm_hw_params_set_format(pad
->handle
, hwparams
, FORMAT
) < 0)
79 return -E_SAMPLE_FORMAT
;
80 if (snd_pcm_hw_params_set_channels(pad
->handle
, hwparams
,
82 return -E_CHANNEL_COUNT
;
83 if (snd_pcm_hw_params_set_rate_near(pad
->handle
, hwparams
,
84 &pad
->samplerate
, NULL
) < 0)
86 err
= snd_pcm_hw_params_get_buffer_time_max(hwparams
,
87 &pad
->buffer_time
, NULL
);
88 if (err
< 0 || !pad
->buffer_time
)
89 return -E_GET_BUFFER_TIME
;
90 PARA_INFO_LOG("buffer time: %d\n", pad
->buffer_time
);
91 if (snd_pcm_hw_params_set_buffer_time_near(pad
->handle
, hwparams
,
92 &pad
->buffer_time
, NULL
) < 0)
93 return -E_SET_BUFFER_TIME
;
94 if (snd_pcm_hw_params(pad
->handle
, hwparams
) < 0)
96 snd_pcm_hw_params_get_period_size(hwparams
, &period_size
, NULL
);
97 snd_pcm_hw_params_get_buffer_size(hwparams
, &buffer_size
);
98 PARA_INFO_LOG("buffer size: %lu, period_size: %lu\n", buffer_size
,
100 if (period_size
== buffer_size
)
101 return -E_BAD_PERIOD
;
102 snd_pcm_sw_params_current(pad
->handle
, swparams
);
103 snd_pcm_sw_params_set_avail_min(pad
->handle
, swparams
, period_size
);
107 start_threshold
= PARA_MIN(buffer_size
,
108 (snd_pcm_uframes_t
)pad
->samplerate
);
109 if (snd_pcm_sw_params_set_start_threshold(pad
->handle
, swparams
,
110 start_threshold
) < 0)
111 return -E_START_THRESHOLD
;
112 stop_threshold
= buffer_size
;
113 if (snd_pcm_sw_params_set_stop_threshold(pad
->handle
, swparams
,
115 return -E_STOP_THRESHOLD
;
116 if (snd_pcm_sw_params(pad
->handle
, swparams
) < 0)
117 PARA_WARNING_LOG("unable to install sw params\n");
118 pad
->bytes_per_frame
= snd_pcm_format_physical_width(FORMAT
)
120 if (pad
->bytes_per_frame
<= 0)
121 return -E_PHYSICAL_WIDTH
;
122 PARA_INFO_LOG("bytes per frame: %d\n", pad
->bytes_per_frame
);
123 if (snd_pcm_nonblock(pad
->handle
, 1))
124 PARA_ERROR_LOG("failed to set nonblock mode\n");
125 pad
->buffer_frames
= 1000 * pad
->buffer_time
/ pad
->samplerate
;
126 PARA_INFO_LOG("max buffered frames: %d\n", pad
->buffer_frames
);
130 /* Open an instance of the alsa writer. */
131 static int alsa_open(struct writer_node
*wn
)
133 struct alsa_write_args_info
*conf
= wn
->conf
;
134 struct writer_node_group
*wng
= wn
->wng
;
135 struct private_alsa_write_data
*pad
= para_calloc(sizeof(*pad
));
137 wn
->private_data
= pad
;
138 if (!conf
->samplerate_given
&& wng
->samplerate
)
139 pad
->samplerate
= *wng
->samplerate
;
141 pad
->samplerate
= conf
->samplerate_arg
;
142 if (!conf
->channels_given
&& wng
->channels
)
143 pad
->channels
= *wng
->channels
;
145 pad
->channels
= conf
->channels_arg
;
146 PARA_INFO_LOG("%d channel(s), %dHz\n", pad
->channels
, pad
->samplerate
);
150 static int alsa_write_pre_select(struct sched
*s
, struct writer_node
*wn
)
152 struct private_alsa_write_data
*pad
= wn
->private_data
;
153 struct writer_node_group
*wng
= wn
->wng
;
155 snd_pcm_sframes_t avail
, underrun
;
159 if (*wng
->loaded
- wn
->written
< pad
->bytes_per_frame
)
162 * Data is available to be written to the alsa handle. Compute number
163 * of milliseconds until next buffer underrun would occur.
165 * snd_pcm_avail_update() updates the current available count of
166 * samples for writing. It is a light method to obtain current stream
167 * position, because it does not require the user <-> kernel context
168 * switch, but the value is less accurate, because ring buffer pointers
169 * are updated in kernel drivers only when an interrupt occurs.
171 avail
= snd_pcm_avail_update(pad
->handle
);
174 underrun
= (pad
->buffer_frames
- avail
) * pad
->buffer_time
175 / pad
->buffer_frames
/ 1000;
179 ms2tv(underrun
, &tv
);
180 if (tv_diff(&s
->timeout
, &tv
, NULL
) > 0)
185 static void xrun(snd_pcm_t
*handle
)
187 snd_pcm_status_t
*status
;
189 struct timeval tv
, diff
;
191 snd_pcm_status_alloca(&status
);
192 ret
= snd_pcm_status(handle
, status
);
195 if (snd_pcm_status_get_state(status
) != SND_PCM_STATE_XRUN
)
197 snd_pcm_status_get_trigger_tstamp(status
, &tv
);
198 tv_diff(now
, &tv
, &diff
);
199 PARA_WARNING_LOG("underrun: %lums\n", tv2ms(&diff
));
202 static int alsa_write_post_select(__a_unused
struct sched
*s
,
203 struct writer_node
*wn
)
205 struct private_alsa_write_data
*pad
= wn
->private_data
;
206 struct writer_node_group
*wng
= wn
->wng
;
207 size_t bytes
= *wng
->loaded
- wn
->written
;
208 unsigned char *data
= (unsigned char*)*wng
->bufp
+ wn
->written
;
209 snd_pcm_sframes_t ret
, frames
, avail
;
211 if (*wng
->input_error
< 0 && (!pad
->handle
|| bytes
< pad
->bytes_per_frame
)) {
212 wn
->written
= *wng
->loaded
;
213 return *wng
->input_error
;
215 if (!bytes
) /* no data available */
218 int err
= alsa_init(pad
, wn
->conf
);
222 frames
= bytes
/ pad
->bytes_per_frame
;
223 if (!frames
) /* less than a single frame available */
225 avail
= snd_pcm_avail_update(pad
->handle
);
228 frames
= PARA_MIN(frames
, avail
);
229 ret
= snd_pcm_writei(pad
->handle
, data
, frames
);
231 wn
->written
+= ret
* pad
->bytes_per_frame
;
236 snd_pcm_prepare(pad
->handle
);
239 PARA_WARNING_LOG("%s\n", snd_strerror(-ret
));
242 return -E_ALSA_WRITE
;
245 static void alsa_close(struct writer_node
*wn
)
247 struct private_alsa_write_data
*pad
= wn
->private_data
;
248 PARA_INFO_LOG("closing writer node %p\n", wn
);
251 snd_pcm_drain(pad
->handle
);
252 snd_pcm_close(pad
->handle
);
253 snd_config_update_free_global();
258 __malloc
static void *alsa_parse_config(const char *options
)
261 struct alsa_write_args_info
*conf
262 = para_calloc(sizeof(struct alsa_write_args_info
));
264 PARA_INFO_LOG("options: %s, %zd\n", options
, strcspn(options
, " \t"));
265 ret
= alsa_cmdline_parser_string(options
, conf
, "alsa_write");
268 PARA_INFO_LOG("help given: %d\n", conf
->help_given
);
276 * the init function of the alsa writer
278 * \param w pointer to the writer to initialize
282 void alsa_write_init(struct writer
*w
)
284 struct alsa_write_args_info dummy
;
286 alsa_cmdline_parser_init(&dummy
);
288 w
->close
= alsa_close
;
289 w
->pre_select
= alsa_write_pre_select
;
290 w
->post_select
= alsa_write_post_select
;
291 w
->parse_config
= alsa_parse_config
;
292 w
->shutdown
= NULL
; /* nothing to do */
293 w
->help
= (struct ggo_help
) {
294 .short_help
= alsa_write_args_info_help
,
295 .detailed_help
= alsa_write_args_info_detailed_help
297 alsa_cmdline_parser_free(&dummy
);