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DngCreator: Fix calculation of date/time stamps

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Converting the sensor timestamp to date/time requires checking
what the timebase of those timestamps is; getting it wrong will
create drift that increases with device uptime.

Test: android.hardware.camera2.cts.
      DngCreatorTest#testSingleImageThumbnail
Bug: 30125412
Change-Id: Ia5db86012bc9e1c06463b8dc4434d3e063f62cf5
This commit is contained in:
Eino-Ville Talvala
2016-09-17 17:48:04 -07:00
parent 492450c88a
commit 3fc21ef78b
1 changed files with 21 additions and 4 deletions
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25
core/java/android/hardware/camera2/DngCreator.java
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@@ -27,6 +27,7 @@ import android.location.Location;
import android.media.ExifInterface;
import android.media.Image;
import android.os.SystemClock;
import android.util.Log;
import android.util.Size;
import java.io.IOException;
@@ -89,17 +90,33 @@ public final class DngCreator implements AutoCloseable {
throw new IllegalArgumentException("Null argument to DngCreator constructor");
}
// Find current time
// Find current time in milliseconds since 1970
long currentTime = System.currentTimeMillis();
// Assume that sensor timestamp has that timebase to start
long timeOffset = 0;
// Find boot time
long bootTimeMillis = currentTime - SystemClock.elapsedRealtime();
int timestampSource = characteristics.get(
CameraCharacteristics.SENSOR_INFO_TIMESTAMP_SOURCE);
if (timestampSource == CameraCharacteristics.SENSOR_INFO_TIMESTAMP_SOURCE_REALTIME) {
// This means the same timebase as SystemClock.elapsedRealtime(),
// which is CLOCK_BOOTTIME
timeOffset = currentTime - SystemClock.elapsedRealtime();
} else if (timestampSource == CameraCharacteristics.SENSOR_INFO_TIMESTAMP_SOURCE_UNKNOWN) {
// This means the same timebase as System.currentTimeMillis(),
// which is CLOCK_MONOTONIC
timeOffset = currentTime - SystemClock.uptimeMillis();
} else {
// Unexpected time source - treat as CLOCK_MONOTONIC
Log.w(TAG, "Sensor timestamp source is unexpected: " + timestampSource);
timeOffset = currentTime - SystemClock.uptimeMillis();
}
// Find capture time (nanos since boot)
Long timestamp = metadata.get(CaptureResult.SENSOR_TIMESTAMP);
long captureTime = currentTime;
if (timestamp != null) {
captureTime = timestamp / 1000000 + bootTimeMillis;
captureTime = timestamp / 1000000 + timeOffset;
}
// Format for metadata