audio_hw: clean up mmap input delay
Set default offset to zero if no property used.
Remove unneeded FIXME.
Improve comments.
Cleanup adding of offset.
Bug: 122680738
Test: adb shell aaudio_loopback -tm -s20
Change-Id: Idd85f8978443e036ba4c5fb6440320a8578a74fd
diff --git a/hal/audio_hw.c b/hal/audio_hw.c
index 4b85b21..7235ad3 100644
--- a/hal/audio_hw.c
+++ b/hal/audio_hw.c
@@ -4426,17 +4426,13 @@
return ret;
}
-// Read offset for the input positional timestamp from a property.
-// This is to workaround apparent inaccuracies in the timing info that
-// are causing glitches.
+// Read offset for the positional timestamp from a persistent vendor property.
+// This is to workaround apparent inaccuracies in the timing information that
+// is used by the AAudio timing model. The inaccuracies can cause glitches.
static int64_t in_get_mmap_time_offset() {
- // Roughly 100 usec is needed on some devices to cover inaccuracy in DSP.
- // This should be set in a property. But I cannot read the property!
- // So I am setting the offset here to 101 as a test.
- const int32_t kDefaultOffsetMicros = 101; // should be zero if no bug
- // FIXME - why is the property not being read?! The default is used.
+ const int32_t kDefaultOffsetMicros = 0;
int32_t mmap_time_offset_micros = property_get_int32(
- "persist.audio.in_mmap_delay_micros", kDefaultOffsetMicros);
+ "persist.audio.in_mmap_delay_micros", kDefaultOffsetMicros);
ALOGI("in_get_mmap_time_offset set to %d micros", mmap_time_offset_micros);
return mmap_time_offset_micros * (int64_t)1000;
}
@@ -4565,8 +4561,8 @@
ALOGE("%s: %s", __func__, pcm_get_error(in->pcm));
goto exit;
}
- position->time_nanoseconds = audio_utils_ns_from_timespec(&ts);
- position->time_nanoseconds += in->mmap_time_offset_nanos;
+ position->time_nanoseconds = audio_utils_ns_from_timespec(&ts)
+ + in->mmap_time_offset_nanos;
exit:
pthread_mutex_unlock(&in->lock);