ThumbnailStripEffect.java
/*
* Copyright 2023 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
*
* https://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.effect;
import android.content.Context;
import androidx.media3.common.C;
import androidx.media3.common.VideoFrameProcessingException;
import androidx.media3.common.util.UnstableApi;
import java.util.ArrayList;
import java.util.List;
/**
* Generate a thumbnail strip (i.e. tile frames horizontally) containing frames at given {@link
* #setTimestampsMs timestamps}.
*/
@UnstableApi
/* package */ final class ThumbnailStripEffect implements GlEffect {
/* package */ final int stripWidth;
/* package */ final int stripHeight;
private final List<Long> timestampsMs;
private int currentThumbnailIndex;
/**
* Creates a new instance with the given size. No thumbnails are drawn by default, call {@link
* #setTimestampsMs} to change how many to draw and their timestamp.
*
* @param stripWidth The width of the thumbnail strip.
* @param stripHeight The height of the thumbnail strip.
*/
public ThumbnailStripEffect(int stripWidth, int stripHeight) {
this.stripWidth = stripWidth;
this.stripHeight = stripHeight;
timestampsMs = new ArrayList<>();
}
@Override
public ThumbnailStripShaderProgram toGlShaderProgram(Context context, boolean useHdr)
throws VideoFrameProcessingException {
return new ThumbnailStripShaderProgram(context, useHdr, this);
}
/**
* Sets the timestamps of the frames to draw, in milliseconds.
*
* <p>The timestamp represents the minimum presentation time of the next frame added to the strip.
* For example, if the timestamp is 10, a frame with a time of 100 will be drawn but one with a
* time of 9 will be ignored.
*/
public void setTimestampsMs(List<Long> timestampsMs) {
this.timestampsMs.clear();
this.timestampsMs.addAll(timestampsMs);
currentThumbnailIndex = 0;
}
/** Returns whether all the thumbnails have already been drawn. */
public boolean isDone() {
return currentThumbnailIndex >= timestampsMs.size();
}
/** Returns the index of the next thumbnail to draw. */
public int getNextThumbnailIndex() {
return currentThumbnailIndex;
}
/** Returns the timestamp in milliseconds of the next thumbnail to draw. */
public long getNextTimestampMs() {
return isDone() ? C.TIME_END_OF_SOURCE : timestampsMs.get(currentThumbnailIndex);
}
/** Returns the total number of thumbnails to be drawn in the strip. */
public int getNumberOfThumbnails() {
return timestampsMs.size();
}
/* package */ void onThumbnailDrawn() {
currentThumbnailIndex++;
}
}