In ALSA PCM interface, some parameters are used to configure runtime of
PCM substream independently of actual hardware. These parameters are
mainly used to decide the detailed timing to start/stop PCM substream and
release I/O blocking state of application. These parameters are
represented and delivered by a structure.
In alsa-lib PCM API, the structure is hidden from userspace applications.
The applications can set/get actual parameters by helper functions.
In aplay, three of the parameters are configurable. This commit adds
support for them. When no options are given, default values are used.
Signed-off-by: Takashi Sakamoto <o-takashi@xxxxxxxxxxxxx>
---
axfer/xfer-libasound.c | 86 ++++++++++++++++++++++++++++++++++++++++--
axfer/xfer-libasound.h | 4 ++
2 files changed, 87 insertions(+), 3 deletions(-)
diff --git a/axfer/xfer-libasound.c b/axfer/xfer-libasound.c
index a23021e..1e709e0 100644
--- a/axfer/xfer-libasound.c
+++ b/axfer/xfer-libasound.c
@@ -17,7 +17,7 @@ enum no_short_opts {
OPT_TEST_NOWAIT,
};
-#define S_OPTS "D:NMF:B:"
+#define S_OPTS "D:NMF:B:A:R:T:"
static const struct option l_opts[] = {
{"device", 1, 0, 'D'},
{"nonblock", 0, 0, 'N'},
@@ -26,6 +26,9 @@ static const struct option l_opts[] = {
{"buffer-time", 1, 0, 'B'},
{"period-size", 1, 0, OPT_PERIOD_SIZE},
{"buffer-size", 1, 0, OPT_BUFFER_SIZE},
+ {"avail-min", 1, 0, 'A'},
+ {"start-delay", 1, 0, 'R'},
+ {"stop-delay", 1, 0, 'T'},
// For debugging.
{"fatal-errors", 0, 0, OPT_FATAL_ERRORS},
{"test-nowait", 0, 0, OPT_TEST_NOWAIT},
@@ -68,6 +71,12 @@ static int xfer_libasound_parse_opt(struct xfer_context *xfer, int key,
state->frames_per_period = arg_parse_decimal_num(optarg, &err);
else if (key == OPT_BUFFER_SIZE)
state->frames_per_buffer = arg_parse_decimal_num(optarg, &err);
+ else if (key == 'A')
+ state->msec_for_avail_min = arg_parse_decimal_num(optarg, &err);
+ else if (key == 'R')
+ state->msec_for_start_threshold = arg_parse_decimal_num(optarg, &err);
+ else if (key == 'T')
+ state->msec_for_stop_threshold = arg_parse_decimal_num(optarg, &err);
else if (key == OPT_FATAL_ERRORS)
state->finish_at_xrun = true;
else if (key == OPT_TEST_NOWAIT)
@@ -377,8 +386,76 @@ static int retrieve_actual_hw_params(snd_pcm_hw_params_t *hw_params,
static int configure_sw_params(struct libasound_state *state,
unsigned int frames_per_second,
- unsigned int frames_per_buffer)
+ unsigned int frames_per_buffer,
+ unsigned int msec_for_avail_min,
+ unsigned int msec_for_start_threshold,
+ unsigned int msec_for_stop_threshold)
{
+ snd_pcm_uframes_t frame_count;
+ int err;
+
+ if (msec_for_avail_min > 0) {
+ frame_count = msec_for_avail_min * frames_per_second / 1000000;
+ if (frame_count == 0 || frame_count > frames_per_buffer) {
+ logging(state,
+ "The msec for 'avail_min' is too %s: %u "
+ "msec (%lu frames at %u).\n",
+ frame_count == 0 ? "small" : "large",
+ msec_for_avail_min, frame_count,
+ frames_per_second);
+ return -EINVAL;
+ }
+ err = snd_pcm_sw_params_set_avail_min(state->handle,
+ state->sw_params, frame_count);
+ if (err < 0) {
+ logging(state,
+ "Fail to configure 'avail-min'.\n");
+ return -EINVAL;
+ }
+ }
+
+ if (msec_for_start_threshold > 0) {
+ frame_count = msec_for_start_threshold * frames_per_second /
+ 1000000;
+ if (frame_count == 0 || frame_count > frames_per_buffer) {
+ logging(state,
+ "The msec for 'start-delay' is too %s: %u "
+ "msec (%lu frames at %u).\n",
+ frame_count == 0 ? "small" : "large",
+ msec_for_start_threshold, frame_count,
+ frames_per_second);
+ return -EINVAL;
+ }
+ err = snd_pcm_sw_params_set_start_threshold(state->handle,
+ state->sw_params, frame_count);
+ if (err < 0) {
+ logging(state,
+ "Fail to configure 'start-delay'.\n");
+ return -EINVAL;
+ }
+ }
+
+ if (msec_for_stop_threshold > 0) {
+ frame_count = msec_for_stop_threshold * frames_per_second /
+ 1000000;
+ if (frame_count == 0 || frame_count > frames_per_buffer) {
+ logging(state,
+ "The msec for 'stop-delay' is too %s: %u "
+ "msec (%lu frames at %u).\n",
+ frame_count == 0 ? "small" : "large",
+ msec_for_stop_threshold, frame_count,
+ frames_per_second);
+ return -EINVAL;
+ }
+ err = snd_pcm_sw_params_set_stop_threshold(state->handle,
+ state->sw_params, frame_count);
+ if (err < 0) {
+ logging(state,
+ "Fail to configure 'stop-delay'.\n");
+ return -EINVAL;
+ }
+ }
+
return snd_pcm_sw_params(state->handle, state->sw_params);
}
@@ -444,7 +521,10 @@ static int xfer_libasound_pre_process(struct xfer_context *xfer,
return err;
err = configure_sw_params(state, *frames_per_second,
- *frames_per_buffer);
+ *frames_per_buffer,
+ state->msec_for_avail_min,
+ state->msec_for_start_threshold,
+ state->msec_for_stop_threshold);
if (err < 0) {
logging(state, "Current software parameters:\n");
snd_pcm_sw_params_dump(state->sw_params, state->log);
diff --git a/axfer/xfer-libasound.h b/axfer/xfer-libasound.h
index 4456fab..113c1b9 100644
--- a/axfer/xfer-libasound.h
+++ b/axfer/xfer-libasound.h
@@ -35,6 +35,10 @@ struct libasound_state {
unsigned int frames_per_period;
unsigned int frames_per_buffer;
+ unsigned int msec_for_avail_min;
+ unsigned int msec_for_start_threshold;
+ unsigned int msec_for_stop_threshold;
+
bool finish_at_xrun:1;
bool nonblock:1;
bool mmap:1;
--
2.19.1
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