2 * Copyright (C) 2005-2011 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 "buffer_tree.h"
30 #include "write_common.h"
31 #include "alsa_write.cmdline.h"
34 /** Data specific to the alsa writer. */
35 struct private_alsa_write_data
{
36 /** The alsa handle */
38 /** Determined and set by alsa_init(). */
40 /** The approximate maximum buffer duration in us. */
42 /* Number of frames that fit into the buffer. */
43 snd_pcm_uframes_t buffer_frames
;
45 * The sample rate given by command line option or the decoder
46 * of the writer node group.
49 snd_pcm_format_t sample_format
;
51 * The number of channels, given by command line option or the
52 * decoder of the writer node group.
55 struct timeval drain_barrier
;
58 static snd_pcm_format_t
get_alsa_pcm_format(enum sample_format sf
)
61 case SF_S8
: return SND_PCM_FORMAT_S8
;
62 case SF_U8
: return SND_PCM_FORMAT_U8
;
63 case SF_S16_LE
: return SND_PCM_FORMAT_S16_LE
;
64 case SF_S16_BE
: return SND_PCM_FORMAT_S16_BE
;
65 case SF_U16_LE
: return SND_PCM_FORMAT_U16_LE
;
66 case SF_U16_BE
: return SND_PCM_FORMAT_U16_BE
;
67 default: return SND_PCM_FORMAT_S16_LE
;
71 /* Install PCM software and hardware configuration. */
72 static int alsa_init(struct private_alsa_write_data
*pad
,
73 struct alsa_write_args_info
*conf
)
75 snd_pcm_hw_params_t
*hwparams
;
76 snd_pcm_sw_params_t
*swparams
;
77 snd_pcm_uframes_t start_threshold
, stop_threshold
;
78 snd_pcm_uframes_t period_size
;
81 PARA_INFO_LOG("opening %s\n", conf
->device_arg
);
82 err
= snd_pcm_open(&pad
->handle
, conf
->device_arg
,
83 SND_PCM_STREAM_PLAYBACK
, SND_PCM_NONBLOCK
);
87 snd_pcm_hw_params_alloca(&hwparams
);
88 snd_pcm_sw_params_alloca(&swparams
);
89 if (snd_pcm_hw_params_any(pad
->handle
, hwparams
) < 0)
90 return -E_BROKEN_CONF
;
91 if (snd_pcm_hw_params_set_access(pad
->handle
, hwparams
,
92 SND_PCM_ACCESS_RW_INTERLEAVED
) < 0)
93 return -E_ACCESS_TYPE
;
94 if (snd_pcm_hw_params_set_format(pad
->handle
, hwparams
,
95 pad
->sample_format
) < 0)
96 return -E_SAMPLE_FORMAT
;
97 if (snd_pcm_hw_params_set_channels(pad
->handle
, hwparams
,
99 return -E_CHANNEL_COUNT
;
100 if (snd_pcm_hw_params_set_rate_near(pad
->handle
, hwparams
,
101 &pad
->sample_rate
, NULL
) < 0)
103 err
= snd_pcm_hw_params_get_buffer_time_max(hwparams
,
104 &pad
->buffer_time
, NULL
);
105 if (err
< 0 || !pad
->buffer_time
)
106 return -E_GET_BUFFER_TIME
;
107 PARA_INFO_LOG("buffer time: %d\n", pad
->buffer_time
);
108 if (snd_pcm_hw_params_set_buffer_time_near(pad
->handle
, hwparams
,
109 &pad
->buffer_time
, NULL
) < 0)
110 return -E_SET_BUFFER_TIME
;
111 if (snd_pcm_hw_params(pad
->handle
, hwparams
) < 0)
113 snd_pcm_hw_params_get_period_size(hwparams
, &period_size
, NULL
);
114 snd_pcm_hw_params_get_buffer_size(hwparams
, &pad
->buffer_frames
);
115 PARA_INFO_LOG("buffer size: %lu, period_size: %lu\n", pad
->buffer_frames
,
117 if (period_size
== pad
->buffer_frames
)
118 return -E_BAD_PERIOD
;
119 snd_pcm_sw_params_current(pad
->handle
, swparams
);
120 snd_pcm_sw_params_set_avail_min(pad
->handle
, swparams
, period_size
);
121 if (pad
->buffer_frames
< 1)
124 start_threshold
= PARA_MIN(pad
->buffer_frames
,
125 (snd_pcm_uframes_t
)pad
->sample_rate
);
126 if (snd_pcm_sw_params_set_start_threshold(pad
->handle
, swparams
,
127 start_threshold
) < 0)
128 return -E_START_THRESHOLD
;
129 stop_threshold
= pad
->buffer_frames
;
130 if (snd_pcm_sw_params_set_stop_threshold(pad
->handle
, swparams
,
132 return -E_STOP_THRESHOLD
;
133 if (snd_pcm_sw_params(pad
->handle
, swparams
) < 0)
134 PARA_WARNING_LOG("unable to install sw params\n");
135 pad
->bytes_per_frame
= snd_pcm_format_physical_width(pad
->sample_format
)
137 if (pad
->bytes_per_frame
<= 0)
138 return -E_PHYSICAL_WIDTH
;
139 PARA_INFO_LOG("bytes per frame: %d\n", pad
->bytes_per_frame
);
140 if (snd_pcm_nonblock(pad
->handle
, 1))
141 PARA_ERROR_LOG("failed to set nonblock mode\n");
145 static void alsa_write_pre_select(struct sched
*s
, struct task
*t
)
147 struct writer_node
*wn
= container_of(t
, struct writer_node
, task
);
148 struct private_alsa_write_data
*pad
= wn
->private_data
;
150 snd_pcm_sframes_t avail
, underrun
;
151 int ret
= btr_node_status(wn
->btrn
, wn
->min_iqs
, BTR_NT_LEAF
);
156 return sched_min_delay(s
);
158 * Data is available to be written to the alsa handle. Compute number
159 * of milliseconds until next buffer underrun would occur.
161 * snd_pcm_avail_update() updates the current available count of
162 * samples for writing. It is a light method to obtain current stream
163 * position, because it does not require the user <-> kernel context
164 * switch, but the value is less accurate, because ring buffer pointers
165 * are updated in kernel drivers only when an interrupt occurs.
167 avail
= snd_pcm_avail_update(pad
->handle
);
170 underrun
= (pad
->buffer_frames
- avail
) * pad
->buffer_time
171 / pad
->buffer_frames
/ 1000;
175 ms2tv(underrun
, &tv
);
176 sched_request_timeout(&tv
, s
);
179 static void alsa_close(struct writer_node
*wn
)
181 struct private_alsa_write_data
*pad
= wn
->private_data
;
182 PARA_INFO_LOG("closing writer node %p\n", wn
);
187 * It's OK to have a blocking operation here because we already made
188 * sure that the PCM output buffer is (nearly) empty.
190 snd_pcm_nonblock(pad
->handle
, 0);
191 snd_pcm_drain(pad
->handle
);
192 snd_pcm_close(pad
->handle
);
193 snd_config_update_free_global();
197 static void alsa_write_post_select(__a_unused
struct sched
*s
,
200 struct writer_node
*wn
= container_of(t
, struct writer_node
, task
);
201 struct private_alsa_write_data
*pad
= wn
->private_data
;
202 struct btr_node
*btrn
= wn
->btrn
;
205 snd_pcm_sframes_t frames
;
210 ret
= btr_node_status(btrn
, wn
->min_iqs
, BTR_NT_LEAF
);
213 btr_merge(btrn
, wn
->min_iqs
);
214 bytes
= btr_next_buffer(btrn
, &data
);
215 if (ret
< 0 || bytes
< wn
->min_iqs
) { /* eof */
216 assert(btr_no_parent(btrn
));
220 /* wait until pending frames are played */
221 if (pad
->drain_barrier
.tv_sec
== 0) {
222 PARA_DEBUG_LOG("waiting for device to drain\n");
223 tv_add(now
, &(struct timeval
)EMBRACE(0, 200 * 1000),
224 &pad
->drain_barrier
);
227 if (tv_diff(now
, &pad
->drain_barrier
, NULL
) > 0)
234 if (bytes
== 0) /* no data available */
236 pad
= para_calloc(sizeof(*pad
));
237 get_btr_sample_rate(btrn
, &val
);
238 pad
->sample_rate
= val
;
239 get_btr_channels(btrn
, &val
);
241 get_btr_sample_format(btrn
, &val
);
242 pad
->sample_format
= get_alsa_pcm_format(val
);
244 PARA_INFO_LOG("%d channel(s), %dHz\n", pad
->channels
,
246 ret
= alsa_init(pad
, wn
->conf
);
251 wn
->private_data
= pad
;
252 wn
->min_iqs
= pad
->bytes_per_frame
;
255 frames
= bytes
/ pad
->bytes_per_frame
;
256 frames
= snd_pcm_writei(pad
->handle
, data
, frames
);
258 btr_consume(btrn
, frames
* pad
->bytes_per_frame
);
261 if (frames
== -EPIPE
) {
262 PARA_WARNING_LOG("underrun (tried to write %zu bytes)\n", bytes
);
263 snd_pcm_prepare(pad
->handle
);
266 if (frames
== -EAGAIN
)
268 PARA_WARNING_LOG("%s\n", snd_strerror(-frames
));
272 btr_remove_node(btrn
);
276 __malloc
static void *alsa_parse_config_or_die(const char *options
)
278 struct alsa_write_args_info
*conf
= para_calloc(sizeof(*conf
));
280 PARA_INFO_LOG("options: %s, %zd\n", options
, strcspn(options
, " \t"));
281 /* exits on errors */
282 alsa_cmdline_parser_string(options
, conf
, "alsa_write");
286 static void alsa_free_config(void *conf
)
288 alsa_cmdline_parser_free(conf
);
292 * The init function of the alsa writer.
294 * \param w Pointer to the writer to initialize.
296 * \sa struct \ref writer.
298 void alsa_write_init(struct writer
*w
)
300 struct alsa_write_args_info dummy
;
302 alsa_cmdline_parser_init(&dummy
);
303 w
->close
= alsa_close
;
304 w
->pre_select
= alsa_write_pre_select
;
305 w
->post_select
= alsa_write_post_select
;
306 w
->parse_config_or_die
= alsa_parse_config_or_die
;
307 w
->shutdown
= NULL
; /* nothing to do */
308 w
->free_config
= alsa_free_config
;
309 w
->help
= (struct ggo_help
) {
310 .short_help
= alsa_write_args_info_help
,
311 .detailed_help
= alsa_write_args_info_detailed_help
313 alsa_cmdline_parser_free(&dummy
);