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| author | Glenn Kasten <gkasten@google.com> | 2015-06-22 12:17:43 -0700 |
|---|---|---|
| committer | Glenn Kasten <gkasten@google.com> | 2015-06-22 15:02:52 -0700 |
| commit | ee5f7640818ceca67b3575897121d25d57df2a1c (patch) | |
| tree | aa228d5b4babf20f4f865adc17ea979a1f134fbe | |
| parent | 8f8f400335c186185bc10ae28483129d6028410c (diff) | |
| download | flounder-ee5f7640818ceca67b3575897121d25d57df2a1c.tar.gz | |
Dynamic configuration of low latency buffer size
Bug: 20226809
Change-Id: I864aa498c3a04545a9e61aa56a96adc949393777
| -rw-r--r-- | audio/hal/audio_hw.c | 38 | ||||
| -rw-r--r-- | audio/hal/audio_hw.h | 4 |
2 files changed, 38 insertions, 4 deletions
diff --git a/audio/hal/audio_hw.c b/audio/hal/audio_hw.c index 30404f0..11b60fd 100644 --- a/audio/hal/audio_hw.c +++ b/audio/hal/audio_hw.c @@ -38,6 +38,7 @@ #include <cutils/str_parms.h> #include <cutils/atomic.h> #include <cutils/sched_policy.h> +#include <cutils/properties.h> #include <hardware/audio_effect.h> #include <system/thread_defs.h> @@ -60,8 +61,8 @@ static struct pcm_device_profile pcm_device_playback = { .period_size = PLAYBACK_PERIOD_SIZE, .period_count = PLAYBACK_PERIOD_COUNT, .format = PCM_FORMAT_S16_LE, - .start_threshold = PLAYBACK_START_THRESHOLD, - .stop_threshold = PLAYBACK_STOP_THRESHOLD, + .start_threshold = PLAYBACK_START_THRESHOLD(PLAYBACK_PERIOD_SIZE, PLAYBACK_PERIOD_COUNT), + .stop_threshold = PLAYBACK_STOP_THRESHOLD(PLAYBACK_PERIOD_SIZE, PLAYBACK_PERIOD_COUNT), .silence_threshold = 0, .silence_size = UINT_MAX, .avail_min = PLAYBACK_AVAILABLE_MIN, @@ -4573,6 +4574,24 @@ static void dummybuf_thread_close(struct audio_device *adev) adev->dummybuf_thread = 0; } +/* This returns true if the input parameter looks at all plausible as a low latency period size, + * or false otherwise. A return value of true doesn't mean the value is guaranteed to work, + * just that it _might_ work. + */ +static bool period_size_is_plausible_for_low_latency(int period_size) +{ + switch (period_size) { + case 64: + case 96: + case 128: + case 192: + case 256: + return true; + default: + return false; + } +} + static int adev_open(const hw_module_t *module, const char *name, hw_device_t **device) { @@ -4745,6 +4764,21 @@ static int adev_open(const hw_module_t *module, const char *name, } audio_device_ref_count++; + char value[PROPERTY_VALUE_MAX]; + if (property_get("audio_hal.period_size", value, NULL) > 0) { + int trial = atoi(value); + if (period_size_is_plausible_for_low_latency(trial)) { + + pcm_device_playback.config.period_size = trial; + pcm_device_playback.config.start_threshold = + PLAYBACK_START_THRESHOLD(trial, PLAYBACK_PERIOD_COUNT); + pcm_device_playback.config.stop_threshold = + PLAYBACK_STOP_THRESHOLD(trial, PLAYBACK_PERIOD_COUNT); + + pcm_device_capture.config.period_size = trial; + } + } + ALOGV("%s: exit", __func__); return 0; } diff --git a/audio/hal/audio_hw.h b/audio/hal/audio_hw.h index 14669c9..3ed2cb5 100644 --- a/audio/hal/audio_hw.h +++ b/audio/hal/audio_hw.h @@ -136,8 +136,8 @@ enum { #define PLAYBACK_PERIOD_COUNT 2 #define PLAYBACK_DEFAULT_CHANNEL_COUNT 2 #define PLAYBACK_DEFAULT_SAMPLING_RATE 48000 -#define PLAYBACK_START_THRESHOLD ((PLAYBACK_PERIOD_SIZE * PLAYBACK_PERIOD_COUNT) - 1) -#define PLAYBACK_STOP_THRESHOLD (PLAYBACK_PERIOD_SIZE * (PLAYBACK_PERIOD_COUNT + 2)) +#define PLAYBACK_START_THRESHOLD(size, count) (((size) * (count)) - 1) +#define PLAYBACK_STOP_THRESHOLD(size, count) ((size) * ((count) + 2)) #define PLAYBACK_AVAILABLE_MIN 1 |