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>
17 #include <alsa/asoundlib.h>
27 #include "buffer_tree.h"
29 #include "write_common.h"
30 #include "alsa_write.cmdline.h"
33 /** Data specific to the alsa writer. */
34 struct private_alsa_write_data
{
35 /** The alsa handle */
37 /** Determined and set by alsa_init(). */
39 /** The approximate maximum buffer duration in us. */
41 /* Number of frames that fit into the buffer. */
42 snd_pcm_uframes_t buffer_frames
;
44 * The sample rate given by command line option or the decoder
45 * of the writer node group.
48 snd_pcm_format_t sample_format
;
50 * The number of channels, given by command line option or the
51 * decoder of the writer node group.
54 struct timeval drain_barrier
;
57 static snd_pcm_format_t
get_alsa_pcm_format(enum sample_format sf
)
60 case SF_S8
: return SND_PCM_FORMAT_S8
;
61 case SF_U8
: return SND_PCM_FORMAT_U8
;
62 case SF_S16_LE
: return SND_PCM_FORMAT_S16_LE
;
63 case SF_S16_BE
: return SND_PCM_FORMAT_S16_BE
;
64 case SF_U16_LE
: return SND_PCM_FORMAT_U16_LE
;
65 case SF_U16_BE
: return SND_PCM_FORMAT_U16_BE
;
66 default: return SND_PCM_FORMAT_S16_LE
;
70 /* Install PCM software and hardware configuration. */
71 static int alsa_init(struct private_alsa_write_data
*pad
,
72 struct alsa_write_args_info
*conf
)
74 snd_pcm_hw_params_t
*hwparams
;
75 snd_pcm_sw_params_t
*swparams
;
76 snd_pcm_uframes_t start_threshold
, stop_threshold
;
77 snd_pcm_uframes_t period_size
;
80 PARA_INFO_LOG("opening %s\n", conf
->device_arg
);
81 err
= snd_pcm_open(&pad
->handle
, conf
->device_arg
,
82 SND_PCM_STREAM_PLAYBACK
, SND_PCM_NONBLOCK
);
86 snd_pcm_hw_params_alloca(&hwparams
);
87 snd_pcm_sw_params_alloca(&swparams
);
88 if (snd_pcm_hw_params_any(pad
->handle
, hwparams
) < 0)
89 return -E_BROKEN_CONF
;
90 if (snd_pcm_hw_params_set_access(pad
->handle
, hwparams
,
91 SND_PCM_ACCESS_RW_INTERLEAVED
) < 0)
92 return -E_ACCESS_TYPE
;
93 if (snd_pcm_hw_params_set_format(pad
->handle
, hwparams
,
94 pad
->sample_format
) < 0)
95 return -E_SAMPLE_FORMAT
;
96 if (snd_pcm_hw_params_set_channels(pad
->handle
, hwparams
,
98 return -E_CHANNEL_COUNT
;
99 if (snd_pcm_hw_params_set_rate_near(pad
->handle
, hwparams
,
100 &pad
->sample_rate
, NULL
) < 0)
102 err
= snd_pcm_hw_params_get_buffer_time_max(hwparams
,
103 &pad
->buffer_time
, NULL
);
104 if (err
< 0 || !pad
->buffer_time
)
105 return -E_GET_BUFFER_TIME
;
106 PARA_INFO_LOG("buffer time: %d\n", pad
->buffer_time
);
107 if (snd_pcm_hw_params_set_buffer_time_near(pad
->handle
, hwparams
,
108 &pad
->buffer_time
, NULL
) < 0)
109 return -E_SET_BUFFER_TIME
;
110 if (snd_pcm_hw_params(pad
->handle
, hwparams
) < 0)
112 snd_pcm_hw_params_get_period_size(hwparams
, &period_size
, NULL
);
113 snd_pcm_hw_params_get_buffer_size(hwparams
, &pad
->buffer_frames
);
114 PARA_INFO_LOG("buffer size: %lu, period_size: %lu\n", pad
->buffer_frames
,
116 if (period_size
== pad
->buffer_frames
)
117 return -E_BAD_PERIOD
;
118 snd_pcm_sw_params_current(pad
->handle
, swparams
);
119 snd_pcm_sw_params_set_avail_min(pad
->handle
, swparams
, period_size
);
120 if (pad
->buffer_frames
< 1)
123 start_threshold
= PARA_MIN(pad
->buffer_frames
,
124 (snd_pcm_uframes_t
)pad
->sample_rate
);
125 if (snd_pcm_sw_params_set_start_threshold(pad
->handle
, swparams
,
126 start_threshold
) < 0)
127 return -E_START_THRESHOLD
;
128 stop_threshold
= pad
->buffer_frames
;
129 if (snd_pcm_sw_params_set_stop_threshold(pad
->handle
, swparams
,
131 return -E_STOP_THRESHOLD
;
132 if (snd_pcm_sw_params(pad
->handle
, swparams
) < 0)
133 PARA_WARNING_LOG("unable to install sw params\n");
134 pad
->bytes_per_frame
= snd_pcm_format_physical_width(pad
->sample_format
)
136 if (pad
->bytes_per_frame
<= 0)
137 return -E_PHYSICAL_WIDTH
;
138 PARA_INFO_LOG("bytes per frame: %d\n", pad
->bytes_per_frame
);
139 if (snd_pcm_nonblock(pad
->handle
, 1))
140 PARA_ERROR_LOG("failed to set nonblock mode\n");
144 static void alsa_write_pre_select(struct sched
*s
, struct task
*t
)
146 struct writer_node
*wn
= container_of(t
, struct writer_node
, task
);
147 struct private_alsa_write_data
*pad
= wn
->private_data
;
148 snd_pcm_sframes_t avail
, underrun
;
149 int ret
= btr_node_status(wn
->btrn
, wn
->min_iqs
, BTR_NT_LEAF
);
158 sched_request_barrier_or_min_delay(&pad
->drain_barrier
, s
);
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 sched_request_timeout_ms(underrun
, s
);
182 static void alsa_close(struct writer_node
*wn
)
184 struct private_alsa_write_data
*pad
= wn
->private_data
;
185 PARA_INFO_LOG("closing writer node %p\n", wn
);
190 * It's OK to have a blocking operation here because we already made
191 * sure that the PCM output buffer is (nearly) empty.
193 snd_pcm_nonblock(pad
->handle
, 0);
194 snd_pcm_drain(pad
->handle
);
195 snd_pcm_close(pad
->handle
);
196 snd_config_update_free_global();
200 static void alsa_write_post_select(__a_unused
struct sched
*s
,
203 struct writer_node
*wn
= container_of(t
, struct writer_node
, task
);
204 struct private_alsa_write_data
*pad
= wn
->private_data
;
205 struct btr_node
*btrn
= wn
->btrn
;
208 snd_pcm_sframes_t frames
;
213 ret
= btr_node_status(btrn
, wn
->min_iqs
, BTR_NT_LEAF
);
216 btr_merge(btrn
, wn
->min_iqs
);
217 bytes
= btr_next_buffer(btrn
, &data
);
218 if (ret
< 0 || bytes
< wn
->min_iqs
) { /* eof */
219 assert(btr_no_parent(btrn
));
220 ret
= -E_WRITE_COMMON_EOF
;
223 /* wait until pending frames are played */
224 if (pad
->drain_barrier
.tv_sec
== 0) {
225 PARA_DEBUG_LOG("waiting for device to drain\n");
226 tv_add(now
, &(struct timeval
)EMBRACE(0, 200 * 1000),
227 &pad
->drain_barrier
);
230 if (tv_diff(now
, &pad
->drain_barrier
, NULL
) > 0)
237 if (bytes
== 0) /* no data available */
239 pad
= para_calloc(sizeof(*pad
));
240 get_btr_sample_rate(btrn
, &val
);
241 pad
->sample_rate
= val
;
242 get_btr_channels(btrn
, &val
);
244 get_btr_sample_format(btrn
, &val
);
245 pad
->sample_format
= get_alsa_pcm_format(val
);
247 PARA_INFO_LOG("%d channel(s), %dHz\n", pad
->channels
,
249 ret
= alsa_init(pad
, wn
->conf
);
254 wn
->private_data
= pad
;
255 wn
->min_iqs
= pad
->bytes_per_frame
;
258 frames
= bytes
/ pad
->bytes_per_frame
;
259 frames
= snd_pcm_writei(pad
->handle
, data
, frames
);
260 if (frames
== 0 || frames
== -EAGAIN
)
263 btr_consume(btrn
, frames
* pad
->bytes_per_frame
);
266 if (frames
== -EPIPE
) {
267 PARA_WARNING_LOG("underrun (tried to write %zu bytes)\n", bytes
);
268 snd_pcm_prepare(pad
->handle
);
271 PARA_WARNING_LOG("%s\n", snd_strerror(-frames
));
275 btr_remove_node(btrn
);
279 __malloc
static void *alsa_parse_config_or_die(const char *options
)
281 struct alsa_write_args_info
*conf
= para_calloc(sizeof(*conf
));
283 /* exits on errors */
284 alsa_cmdline_parser_string(options
, conf
, "alsa_write");
288 static void alsa_free_config(void *conf
)
290 alsa_cmdline_parser_free(conf
);
294 * The init function of the alsa writer.
296 * \param w Pointer to the writer to initialize.
298 * \sa struct \ref writer.
300 void alsa_write_init(struct writer
*w
)
302 struct alsa_write_args_info dummy
;
304 alsa_cmdline_parser_init(&dummy
);
305 w
->close
= alsa_close
;
306 w
->pre_select
= alsa_write_pre_select
;
307 w
->post_select
= alsa_write_post_select
;
308 w
->parse_config_or_die
= alsa_parse_config_or_die
;
309 w
->shutdown
= NULL
; /* nothing to do */
310 w
->free_config
= alsa_free_config
;
311 w
->help
= (struct ggo_help
) {
312 .short_help
= alsa_write_args_info_help
,
313 .detailed_help
= alsa_write_args_info_detailed_help
315 alsa_cmdline_parser_free(&dummy
);