CorrectVideoTimeByTimebase.java
/*
* Copyright 2021 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package androidx.camera.video.internal.workaround;
import android.media.MediaCodec;
import android.os.SystemClock;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.annotation.RequiresApi;
import androidx.camera.core.Logger;
import androidx.camera.video.internal.compat.quirk.CameraUseInconsistentTimebaseQuirk;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicBoolean;
/**
* Corrects the video timestamps if video buffer contains REALTIME timestamp.
*
* <p>As described on b/197805856, some Samsung devices use inconsistent timebase for camera
* frame. The workaround detects and corrects the timestamp by generating a new timestamp.
* Note: this will sacrifice the precise timestamp of video buffer.
*
* @see CameraUseInconsistentTimebaseQuirk
*/
@RequiresApi(21) // TODO(b/200306659): Remove and replace with annotation on package-info.java
public class CorrectVideoTimeByTimebase {
private static final String TAG = "CorrectVideoTimeByTimebase";
@Nullable
private AtomicBoolean mNeedToCorrectVideoTimebase = null;
/**
* Corrects the video timestamp if necessary.
*
* <p>This method will modify the {@link MediaCodec.BufferInfo#presentationTimeUs} if necessary.
*
* @param bufferInfo the buffer info.
*/
public void correctTimestamp(@NonNull MediaCodec.BufferInfo bufferInfo) {
// For performance concern, only check the requirement once.
if (mNeedToCorrectVideoTimebase == null) {
// Skip invalid buffer
if (bufferInfo.size <= 0 || bufferInfo.presentationTimeUs <= 0L
|| (bufferInfo.flags & MediaCodec.BUFFER_FLAG_CODEC_CONFIG) != 0) {
return;
}
long uptimeUs = TimeUnit.MILLISECONDS.toMicros(SystemClock.uptimeMillis());
long realtimeUs = TimeUnit.MILLISECONDS.toMicros(SystemClock.elapsedRealtime());
// Expected to be uptime
boolean closeToRealTime = Math.abs(bufferInfo.presentationTimeUs - realtimeUs)
< Math.abs(bufferInfo.presentationTimeUs - uptimeUs);
if (closeToRealTime) {
Logger.w(TAG, "Detected video buffer timestamp is close to real time.");
}
mNeedToCorrectVideoTimebase = new AtomicBoolean(closeToRealTime);
}
if (mNeedToCorrectVideoTimebase.get()) {
bufferInfo.presentationTimeUs -= TimeUnit.MILLISECONDS.toMicros(
SystemClock.elapsedRealtime() - SystemClock.uptimeMillis());
}
}
}