/*
- * Copyright (C) 2005-2008 Andre Noll <maan@systemlinux.org>
+ * Copyright (C) 2005-2009 Andre Noll <maan@systemlinux.org>
*
* Licensed under the GPL v2. For licencing details see COPYING.
*/
/** always use 16 bit little endian */
#define FORMAT SND_PCM_FORMAT_S16_LE
-/** data specific to the alsa writer */
+/** Data specific to the alsa writer. */
struct private_alsa_write_data {
- /** the alsa handle */
+ /** The alsa handle */
snd_pcm_t *handle;
- /** determined and set by alsa_open() */
- size_t bytes_per_frame;
- /** don't write anything until this time */
+ /** Determined and set by alsa_open(). */
+ int bytes_per_frame;
+ /** Don't write anything until this time. */
struct timeval next_chunk;
- /** the return value of snd_pcm_hw_params_get_buffer_time_max() */
+ /** The approximate maximum buffer duration in us. */
unsigned buffer_time;
/**
- * the samplerate given by command line option or the decoder
- * of the writer node group
+ * The samplerate given by command line option or the decoder
+ * of the writer node group.
*/
unsigned samplerate;
/**
- * the number of channels, also given by command line option or the
- * decoder of the writer node group
+ * The number of channels, given by command line option or the
+ * decoder of the writer node group.
*/
unsigned channels;
};
-/*
- * open and prepare the PCM handle for writing
- *
- * Install PCM software and hardware configuration. Exit on errors.
- */
-static int alsa_open(struct writer_node *w)
+/* Install PCM software and hardware configuration. */
+static int alsa_init(struct private_alsa_write_data *pad,
+ struct alsa_write_args_info *conf)
{
snd_pcm_hw_params_t *hwparams;
snd_pcm_sw_params_t *swparams;
snd_pcm_uframes_t buffer_size, start_threshold, stop_threshold;
- int err;
- snd_pcm_info_t *info;
snd_pcm_uframes_t period_size;
- struct private_alsa_write_data *pad = para_calloc(sizeof(struct
- private_alsa_write_data));
- struct alsa_write_args_info *conf = w->conf;
- struct writer_node_group *wng = w->wng;
+ int err;
- if (!conf->samplerate_given && wng->samplerate)
- pad->samplerate = *wng->samplerate;
- else
- pad->samplerate = conf->samplerate_arg;
- if (!conf->channels_given && wng->channels)
- pad->channels = *wng->channels;
- else
- pad->channels = conf->channels_arg;
- PARA_INFO_LOG("%d channel(s), %dHz\n", pad->channels, pad->samplerate);
- w->private_data = pad;
- snd_pcm_info_alloca(&info);
err = snd_pcm_open(&pad->handle, conf->device_arg,
SND_PCM_STREAM_PLAYBACK, SND_PCM_NONBLOCK);
if (err < 0)
return -E_PCM_OPEN;
- if ((err = snd_pcm_info(pad->handle, info)) < 0)
- return -E_SND_PCM_INFO;
snd_pcm_hw_params_alloca(&hwparams);
snd_pcm_sw_params_alloca(&swparams);
if (buffer_size < 1)
start_threshold = 1;
else
- start_threshold = buffer_size;
+ start_threshold = PARA_MIN(buffer_size,
+ (snd_pcm_uframes_t)pad->samplerate);
if (snd_pcm_sw_params_set_start_threshold(pad->handle, swparams,
start_threshold) < 0)
return -E_START_THRESHOLD;
stop_threshold) < 0)
return -E_STOP_THRESHOLD;
if (snd_pcm_sw_params(pad->handle, swparams) < 0)
- return -E_SW_PARAMS;
+ PARA_WARNING_LOG("unable to install sw params\n");
pad->bytes_per_frame = snd_pcm_format_physical_width(FORMAT)
* pad->channels / 8;
- PARA_INFO_LOG("bytes per frame: %zu\n", pad->bytes_per_frame);
+ if (pad->bytes_per_frame <= 0)
+ return -E_PHYSICAL_WIDTH;
+ PARA_INFO_LOG("bytes per frame: %d\n", pad->bytes_per_frame);
if (snd_pcm_nonblock(pad->handle, 1))
PARA_ERROR_LOG("failed to set nonblock mode\n");
- return period_size * pad->bytes_per_frame;
+ return 1;
+}
+
+/* Open an instance of the alsa writer. */
+static int alsa_open(struct writer_node *wn)
+{
+ struct alsa_write_args_info *conf = wn->conf;
+ struct writer_node_group *wng = wn->wng;
+ struct private_alsa_write_data *pad = para_calloc(sizeof(*pad));
+
+ wn->private_data = pad;
+ if (!conf->samplerate_given && wng->samplerate)
+ pad->samplerate = *wng->samplerate;
+ else
+ pad->samplerate = conf->samplerate_arg;
+ if (!conf->channels_given && wng->channels)
+ pad->channels = *wng->channels;
+ else
+ pad->channels = conf->channels_arg;
+ PARA_INFO_LOG("%d channel(s), %dHz\n", pad->channels, pad->samplerate);
+ tv_add(now, &(struct timeval){0, 100 * 1000}, &pad->next_chunk);
+ return 1;
}
static int alsa_write_pre_select(struct sched *s, struct writer_node *wn)
struct writer_node_group *wng = wn->wng;
struct timeval diff;
- if (*wng->loaded < pad->bytes_per_frame)
+ if (!*wng->loaded)
return 1;
if (tv_diff(now, &pad->next_chunk, &diff) < 0) {
if (tv_diff(&s->timeout, &diff, NULL) > 0)
s->timeout.tv_usec = 1;
}
return 1;
-// PARA_INFO_LOG("timeout: %lu\n", tv2ms(&s->timeout));
}
static int alsa_write_post_select(__a_unused struct sched *s,
{
struct private_alsa_write_data *pad = wn->private_data;
struct writer_node_group *wng = wn->wng;
- size_t frames = (*wng->loaded - wn->written) / pad->bytes_per_frame;
- snd_pcm_sframes_t ret;
- unsigned char *data = (unsigned char*)wng->buf + wn->written;
+ size_t bytes = *wng->loaded - wn->written;
+ unsigned char *data = (unsigned char*)*wng->bufp + wn->written;
struct timeval tv;
+ snd_pcm_sframes_t ret, frames, avail;
-// PARA_INFO_LOG("%zd frames\n", frames);
- if (!frames) {
- if (*wng->input_error)
- wn->written = *wng->loaded;
- return 1;
+ if (*wng->input_error < 0 && (!pad->handle || bytes < pad->bytes_per_frame)) {
+ wn->written = *wng->loaded;
+ return *wng->input_error;
}
+ if (!bytes) /* no data available */
+ return 0;
if (tv_diff(now, &pad->next_chunk, NULL) < 0)
- return 1;
- ret = snd_pcm_writei(pad->handle, data, frames);
- if (ret == -EPIPE) {
- PARA_WARNING_LOG("EPIPE\n");
- snd_pcm_prepare(pad->handle);
- return 1;
+ return 0;
+ if (!pad->handle) {
+ int err = alsa_init(pad, wn->conf);
+ if (err < 0)
+ return err;
}
- if (ret < 0 && ret != -EAGAIN) {
- PARA_WARNING_LOG("alsa error (%zu frames, ret = %d\n",
- frames, (int)ret);
+ frames = bytes / pad->bytes_per_frame;
+ if (!frames) /* less than a single frame available */
+ return 0;
+ avail = snd_pcm_avail_update(pad->handle);
+ if (avail <= 0)
+ goto delay;
+ frames = PARA_MIN(frames, avail);
+ ret = snd_pcm_writei(pad->handle, data, frames);
+ if (ret < 0) {
+ PARA_WARNING_LOG("%s\n", snd_strerror(-ret));
+ if (ret == -EPIPE) {
+ snd_pcm_prepare(pad->handle);
+ return 0;
+ }
+ if (ret == -EAGAIN)
+ goto delay;
return -E_ALSA_WRITE;
}
- if (ret == -EAGAIN)
- PARA_DEBUG_LOG("EAGAIN\n");
- else
- wn->written += ret * pad->bytes_per_frame;
- if (ret == frames) /* we wrote everything, try again immediately */
- pad->next_chunk = *now;
- else {
- ms2tv(pad->buffer_time / pad->bytes_per_frame / 1000, &tv);
- tv_add(now, &tv, &pad->next_chunk);
- }
+ wn->written += ret * pad->bytes_per_frame;
return 1;
+delay:
+ /* wait until 50% buffer space is available */
+ ms2tv(pad->buffer_time / 2000, &tv);
+ tv_add(now, &tv, &pad->next_chunk);
+ return 0;
}
static void alsa_close(struct writer_node *wn)
{
struct private_alsa_write_data *pad = wn->private_data;
PARA_INFO_LOG("closing writer node %p\n", wn);
- snd_pcm_drain(pad->handle);
- snd_pcm_close(pad->handle);
- snd_config_update_free_global();
+
+ if (pad->handle) {
+ snd_pcm_drain(pad->handle);
+ snd_pcm_close(pad->handle);
+ snd_config_update_free_global();
+ }
free(pad);
}
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