2 * Copyright (C) 2005-2010 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 /** always use 16 bit little endian */
35 #define FORMAT SND_PCM_FORMAT_S16_LE
37 /** Data specific to the alsa writer. */
38 struct private_alsa_write_data
{
39 /** The alsa handle */
41 /** Determined and set by alsa_open(). */
43 /** The approximate maximum buffer duration in us. */
45 /* Number of frames that fit into the buffer. */
46 snd_pcm_uframes_t buffer_frames
;
48 * The samplerate given by command line option or the decoder
49 * of the writer node group.
53 * The number of channels, given by command line option or the
54 * decoder of the writer node group.
57 struct timeval drain_barrier
;
60 /* Install PCM software and hardware configuration. */
61 static int alsa_init(struct private_alsa_write_data
*pad
,
62 struct alsa_write_args_info
*conf
)
64 snd_pcm_hw_params_t
*hwparams
;
65 snd_pcm_sw_params_t
*swparams
;
66 snd_pcm_uframes_t start_threshold
, stop_threshold
;
67 snd_pcm_uframes_t period_size
;
70 PARA_INFO_LOG("opening %s\n", conf
->device_arg
);
71 err
= snd_pcm_open(&pad
->handle
, conf
->device_arg
,
72 SND_PCM_STREAM_PLAYBACK
, SND_PCM_NONBLOCK
);
76 snd_pcm_hw_params_alloca(&hwparams
);
77 snd_pcm_sw_params_alloca(&swparams
);
78 if (snd_pcm_hw_params_any(pad
->handle
, hwparams
) < 0)
79 return -E_BROKEN_CONF
;
80 if (snd_pcm_hw_params_set_access(pad
->handle
, hwparams
,
81 SND_PCM_ACCESS_RW_INTERLEAVED
) < 0)
82 return -E_ACCESS_TYPE
;
83 if (snd_pcm_hw_params_set_format(pad
->handle
, hwparams
, FORMAT
) < 0)
84 return -E_SAMPLE_FORMAT
;
85 if (snd_pcm_hw_params_set_channels(pad
->handle
, hwparams
,
87 return -E_CHANNEL_COUNT
;
88 if (snd_pcm_hw_params_set_rate_near(pad
->handle
, hwparams
,
89 &pad
->samplerate
, NULL
) < 0)
91 err
= snd_pcm_hw_params_get_buffer_time_max(hwparams
,
92 &pad
->buffer_time
, NULL
);
93 if (err
< 0 || !pad
->buffer_time
)
94 return -E_GET_BUFFER_TIME
;
95 PARA_INFO_LOG("buffer time: %d\n", pad
->buffer_time
);
96 if (snd_pcm_hw_params_set_buffer_time_near(pad
->handle
, hwparams
,
97 &pad
->buffer_time
, NULL
) < 0)
98 return -E_SET_BUFFER_TIME
;
99 if (snd_pcm_hw_params(pad
->handle
, hwparams
) < 0)
101 snd_pcm_hw_params_get_period_size(hwparams
, &period_size
, NULL
);
102 snd_pcm_hw_params_get_buffer_size(hwparams
, &pad
->buffer_frames
);
103 PARA_INFO_LOG("buffer size: %lu, period_size: %lu\n", pad
->buffer_frames
,
105 if (period_size
== pad
->buffer_frames
)
106 return -E_BAD_PERIOD
;
107 snd_pcm_sw_params_current(pad
->handle
, swparams
);
108 snd_pcm_sw_params_set_avail_min(pad
->handle
, swparams
, period_size
);
109 if (pad
->buffer_frames
< 1)
112 start_threshold
= PARA_MIN(pad
->buffer_frames
,
113 (snd_pcm_uframes_t
)pad
->samplerate
);
114 if (snd_pcm_sw_params_set_start_threshold(pad
->handle
, swparams
,
115 start_threshold
) < 0)
116 return -E_START_THRESHOLD
;
117 stop_threshold
= pad
->buffer_frames
;
118 if (snd_pcm_sw_params_set_stop_threshold(pad
->handle
, swparams
,
120 return -E_STOP_THRESHOLD
;
121 if (snd_pcm_sw_params(pad
->handle
, swparams
) < 0)
122 PARA_WARNING_LOG("unable to install sw params\n");
123 pad
->bytes_per_frame
= snd_pcm_format_physical_width(FORMAT
)
125 if (pad
->bytes_per_frame
<= 0)
126 return -E_PHYSICAL_WIDTH
;
127 PARA_INFO_LOG("bytes per frame: %d\n", pad
->bytes_per_frame
);
128 if (snd_pcm_nonblock(pad
->handle
, 1))
129 PARA_ERROR_LOG("failed to set nonblock mode\n");
133 /* Open an instance of the alsa writer. */
134 static int alsa_open(struct writer_node
*wn
)
136 wn
->private_data
= para_calloc(sizeof(struct private_alsa_write_data
));
140 static void alsa_write_pre_select(struct sched
*s
, struct task
*t
)
142 struct writer_node
*wn
= container_of(t
, struct writer_node
, task
);
143 struct private_alsa_write_data
*pad
= wn
->private_data
;
145 snd_pcm_sframes_t avail
, underrun
;
150 ret
= btr_node_status(wn
->btrn
, wn
->min_iqs
, BTR_NT_LEAF
);
152 sched_request_timeout_ms(20, s
);
156 * Data is available to be written to the alsa handle. Compute number
157 * of milliseconds until next buffer underrun would occur.
159 * snd_pcm_avail_update() updates the current available count of
160 * samples for writing. It is a light method to obtain current stream
161 * position, because it does not require the user <-> kernel context
162 * switch, but the value is less accurate, because ring buffer pointers
163 * are updated in kernel drivers only when an interrupt occurs.
165 avail
= snd_pcm_avail_update(pad
->handle
);
168 underrun
= (pad
->buffer_frames
- avail
) * pad
->buffer_time
169 / pad
->buffer_frames
/ 1000;
173 ms2tv(underrun
, &tv
);
174 if (tv_diff(&s
->timeout
, &tv
, NULL
) > 0)
178 static void alsa_close(struct writer_node
*wn
)
180 struct private_alsa_write_data
*pad
= wn
->private_data
;
181 PARA_INFO_LOG("closing writer node %p\n", wn
);
185 * It's OK to have a blocking operation here because we already
186 * made sure that the PCM output buffer is (nearly) empty.
188 snd_pcm_nonblock(pad
->handle
, 0);
189 snd_pcm_drain(pad
->handle
);
190 snd_pcm_close(pad
->handle
);
191 snd_config_update_free_global();
196 static void alsa_write_post_select(__a_unused
struct sched
*s
,
199 struct writer_node
*wn
= container_of(t
, struct writer_node
, task
);
200 struct private_alsa_write_data
*pad
= wn
->private_data
;
201 struct btr_node
*btrn
= wn
->btrn
;
204 snd_pcm_sframes_t frames
;
209 ret
= btr_node_status(btrn
, wn
->min_iqs
, BTR_NT_LEAF
);
212 btr_merge(btrn
, wn
->min_iqs
);
213 bytes
= btr_next_buffer(btrn
, &data
);
214 if (ret
< 0 || bytes
< pad
->bytes_per_frame
) { /* eof */
215 assert(btr_no_parent(btrn
));
219 /* wait until pending frames are played */
220 if (pad
->drain_barrier
.tv_sec
== 0) {
221 PARA_DEBUG_LOG("waiting for device to drain\n");
222 tv_add(now
, &(struct timeval
)EMBRACE(0, 200 * 1000),
223 &pad
->drain_barrier
);
226 if (tv_diff(now
, &pad
->drain_barrier
, NULL
) > 0)
231 struct alsa_write_args_info
*conf
= wn
->conf
;
232 if (bytes
== 0) /* no data available */
235 pad
->samplerate
= conf
->samplerate_arg
;
236 pad
->channels
= conf
->channels_arg
;
237 if (!conf
->samplerate_given
) { /* config option trumps btr_exec */
239 if (get_btr_samplerate(btrn
, &rate
) >= 0)
240 pad
->samplerate
= rate
;
242 if (!conf
->channels_given
) {
244 if (get_btr_channels(btrn
, &ch
) >= 0)
247 PARA_INFO_LOG("%d channel(s), %dHz\n", pad
->channels
, pad
->samplerate
);
248 ret
= alsa_init(pad
, wn
->conf
);
251 wn
->min_iqs
= pad
->bytes_per_frame
;
253 frames
= bytes
/ pad
->bytes_per_frame
;
254 frames
= snd_pcm_writei(pad
->handle
, data
, frames
);
256 btr_consume(btrn
, frames
* pad
->bytes_per_frame
);
259 if (frames
== -EPIPE
) {
260 PARA_WARNING_LOG("underrun (tried to write %zu bytes)\n", bytes
);
261 snd_pcm_prepare(pad
->handle
);
264 if (frames
== -EAGAIN
)
266 PARA_WARNING_LOG("%s\n", snd_strerror(-frames
));
270 btr_remove_node(btrn
);
274 __malloc
static void *alsa_parse_config(const char *options
)
277 struct alsa_write_args_info
*conf
278 = para_calloc(sizeof(struct alsa_write_args_info
));
280 PARA_INFO_LOG("options: %s, %zd\n", options
, strcspn(options
, " \t"));
281 ret
= alsa_cmdline_parser_string(options
, conf
, "alsa_write");
284 PARA_INFO_LOG("help given: %d\n", conf
->help_given
);
291 static void alsa_free_config(void *conf
)
293 alsa_cmdline_parser_free(conf
);
297 * The init function of the alsa writer.
299 * \param w Pointer to the writer to initialize.
301 * \sa struct \ref writer.
303 void alsa_write_init(struct writer
*w
)
305 struct alsa_write_args_info dummy
;
307 alsa_cmdline_parser_init(&dummy
);
309 w
->close
= alsa_close
;
310 w
->pre_select
= alsa_write_pre_select
;
311 w
->post_select
= alsa_write_post_select
;
312 w
->parse_config
= alsa_parse_config
;
313 w
->shutdown
= NULL
; /* nothing to do */
314 w
->free_config
= alsa_free_config
;
315 w
->help
= (struct ggo_help
) {
316 .short_help
= alsa_write_args_info_help
,
317 .detailed_help
= alsa_write_args_info_detailed_help
319 alsa_cmdline_parser_free(&dummy
);