SeekParameters.java
/*
* Copyright (C) 2017 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.media3.exoplayer;
import androidx.annotation.Nullable;
import androidx.media3.common.util.Assertions;
import androidx.media3.common.util.UnstableApi;
import androidx.media3.common.util.Util;
/**
* Parameters that apply to seeking.
*
* <p>The predefined {@link #EXACT}, {@link #CLOSEST_SYNC}, {@link #PREVIOUS_SYNC} and {@link
* #NEXT_SYNC} parameters are suitable for most use cases. Seeking to sync points is typically
* faster but less accurate than exact seeking.
*
* <p>In the general case, an instance specifies a maximum tolerance before ({@link
* #toleranceBeforeUs}) and after ({@link #toleranceAfterUs}) a requested seek position ({@code x}).
* If one or more sync points falls within the window {@code [x - toleranceBeforeUs, x +
* toleranceAfterUs]} then the seek will be performed to the sync point within the window that's
* closest to {@code x}. If no sync point falls within the window then the seek will be performed to
* {@code x - toleranceBeforeUs}. Internally the player may need to seek to an earlier sync point
* and discard media until this position is reached.
*/
@UnstableApi
public final class SeekParameters {
/** Parameters for exact seeking. */
public static final SeekParameters EXACT = new SeekParameters(0, 0);
/** Parameters for seeking to the closest sync point. */
public static final SeekParameters CLOSEST_SYNC =
new SeekParameters(Long.MAX_VALUE, Long.MAX_VALUE);
/** Parameters for seeking to the sync point immediately before a requested seek position. */
public static final SeekParameters PREVIOUS_SYNC = new SeekParameters(Long.MAX_VALUE, 0);
/** Parameters for seeking to the sync point immediately after a requested seek position. */
public static final SeekParameters NEXT_SYNC = new SeekParameters(0, Long.MAX_VALUE);
/** Default parameters. */
public static final SeekParameters DEFAULT = EXACT;
/**
* The maximum time that the actual position seeked to may precede the requested seek position, in
* microseconds.
*/
public final long toleranceBeforeUs;
/**
* The maximum time that the actual position seeked to may exceed the requested seek position, in
* microseconds.
*/
public final long toleranceAfterUs;
/**
* @param toleranceBeforeUs The maximum time that the actual position seeked to may precede the
* requested seek position, in microseconds. Must be non-negative.
* @param toleranceAfterUs The maximum time that the actual position seeked to may exceed the
* requested seek position, in microseconds. Must be non-negative.
*/
public SeekParameters(long toleranceBeforeUs, long toleranceAfterUs) {
Assertions.checkArgument(toleranceBeforeUs >= 0);
Assertions.checkArgument(toleranceAfterUs >= 0);
this.toleranceBeforeUs = toleranceBeforeUs;
this.toleranceAfterUs = toleranceAfterUs;
}
/**
* Resolves a seek based on the parameters, given the requested seek position and two candidate
* sync points.
*
* @param positionUs The requested seek position, in microseocnds.
* @param firstSyncUs The first candidate seek point, in micrseconds.
* @param secondSyncUs The second candidate seek point, in microseconds. May equal {@code
* firstSyncUs} if there's only one candidate.
* @return The resolved seek position, in microseconds.
*/
public long resolveSeekPositionUs(long positionUs, long firstSyncUs, long secondSyncUs) {
if (toleranceBeforeUs == 0 && toleranceAfterUs == 0) {
return positionUs;
}
long minPositionUs =
Util.subtractWithOverflowDefault(positionUs, toleranceBeforeUs, Long.MIN_VALUE);
long maxPositionUs = Util.addWithOverflowDefault(positionUs, toleranceAfterUs, Long.MAX_VALUE);
boolean firstSyncPositionValid = minPositionUs <= firstSyncUs && firstSyncUs <= maxPositionUs;
boolean secondSyncPositionValid =
minPositionUs <= secondSyncUs && secondSyncUs <= maxPositionUs;
if (firstSyncPositionValid && secondSyncPositionValid) {
if (Math.abs(firstSyncUs - positionUs) <= Math.abs(secondSyncUs - positionUs)) {
return firstSyncUs;
} else {
return secondSyncUs;
}
} else if (firstSyncPositionValid) {
return firstSyncUs;
} else if (secondSyncPositionValid) {
return secondSyncUs;
} else {
return minPositionUs;
}
}
@Override
public boolean equals(@Nullable Object obj) {
if (this == obj) {
return true;
}
if (obj == null || getClass() != obj.getClass()) {
return false;
}
SeekParameters other = (SeekParameters) obj;
return toleranceBeforeUs == other.toleranceBeforeUs
&& toleranceAfterUs == other.toleranceAfterUs;
}
@Override
public int hashCode() {
return (31 * (int) toleranceBeforeUs) + (int) toleranceAfterUs;
}
}