FakeAdaptiveDataSet.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.test.utils;
import android.net.Uri;
import androidx.media3.common.C;
import androidx.media3.common.Format;
import androidx.media3.common.TrackGroup;
import androidx.media3.common.util.UnstableApi;
import androidx.media3.common.util.Util;
import androidx.media3.datasource.DataSpec;
import androidx.media3.exoplayer.source.chunk.BaseMediaChunkIterator;
import androidx.media3.exoplayer.source.chunk.MediaChunkIterator;
import androidx.media3.test.utils.FakeDataSet.FakeData.Segment;
import java.util.Random;
/**
* Fake data set emulating the data of an adaptive media source. It provides chunk data for all
* {@link Format}s in the given {@link TrackGroup}.
*/
@UnstableApi
public final class FakeAdaptiveDataSet extends FakeDataSet {
/** Factory for {@link FakeAdaptiveDataSet}s. */
public static final class Factory {
private final long chunkDurationUs;
private final double bitratePercentStdDev;
private final Random random;
/**
* Set up factory for {@link FakeAdaptiveDataSet}s with a chunk duration and the standard
* deviation of the chunk size.
*
* @param chunkDurationUs The chunk duration to use in microseconds.
* @param bitratePercentStdDev The standard deviation used to generate the chunk sizes centered
* around the average bitrate of the {@link Format}s. The standard deviation is given in
* percent (of the average size).
* @param random The random number generator used to generate the chunk size variation.
*/
public Factory(long chunkDurationUs, double bitratePercentStdDev, Random random) {
this.chunkDurationUs = chunkDurationUs;
this.bitratePercentStdDev = bitratePercentStdDev;
this.random = random;
}
/**
* Returns a new {@link FakeAdaptiveDataSet} for the given {@link TrackGroup}.
*
* @param trackGroup The {@link TrackGroup} for which the data set is to be created.
* @param mediaDurationUs The total duration of the fake data set in microseconds.
*/
public FakeAdaptiveDataSet createDataSet(TrackGroup trackGroup, long mediaDurationUs) {
return new FakeAdaptiveDataSet(
trackGroup, mediaDurationUs, chunkDurationUs, bitratePercentStdDev, random);
}
}
/** {@link MediaChunkIterator} for the chunks defined by a fake adaptive data set. */
public static final class Iterator extends BaseMediaChunkIterator {
private final FakeAdaptiveDataSet dataSet;
private final int trackGroupIndex;
/**
* Create iterator.
*
* @param dataSet The data set to iterate over.
* @param trackGroupIndex The index of the track group to iterate over.
* @param chunkIndex The chunk index to which the iterator points initially.
*/
public Iterator(FakeAdaptiveDataSet dataSet, int trackGroupIndex, int chunkIndex) {
super(/* fromIndex= */ chunkIndex, /* toIndex= */ dataSet.getChunkCount() - 1);
this.dataSet = dataSet;
this.trackGroupIndex = trackGroupIndex;
}
@Override
public DataSpec getDataSpec() {
checkInBounds();
String uri = dataSet.getUri(trackGroupIndex);
int chunkIndex = (int) getCurrentIndex();
Segment fakeDataChunk = Util.castNonNull(dataSet.getData(uri)).getSegments().get(chunkIndex);
return new DataSpec(Uri.parse(uri), fakeDataChunk.byteOffset, fakeDataChunk.length);
}
@Override
public long getChunkStartTimeUs() {
checkInBounds();
return dataSet.getStartTime((int) getCurrentIndex());
}
@Override
public long getChunkEndTimeUs() {
checkInBounds();
int chunkIndex = (int) getCurrentIndex();
return dataSet.getStartTime(chunkIndex) + dataSet.getChunkDuration(chunkIndex);
}
}
private final int chunkCount;
private final long chunkDurationUs;
private final long lastChunkDurationUs;
/**
* Create {@link FakeAdaptiveDataSet} using a {@link TrackGroup} and meta data about the media.
*
* @param trackGroup The {@link TrackGroup} for which the data set is to be created.
* @param mediaDurationUs The total duration of the fake data set in microseconds.
* @param chunkDurationUs The chunk duration to use in microseconds.
* @param bitratePercentStdDev The standard deviation used to generate the chunk sizes centered
* around the average bitrate of the {@link Format}s in the {@link TrackGroup}. The standard
* deviation is given in percent (of the average size).
* @param random A {@link Random} instance used to generate random chunk sizes.
*/
/* package */ FakeAdaptiveDataSet(
TrackGroup trackGroup,
long mediaDurationUs,
long chunkDurationUs,
double bitratePercentStdDev,
Random random) {
this.chunkDurationUs = chunkDurationUs;
long lastChunkDurationUs = mediaDurationUs % chunkDurationUs;
int fullChunks = (int) (mediaDurationUs / chunkDurationUs);
this.lastChunkDurationUs = lastChunkDurationUs == 0 ? chunkDurationUs : lastChunkDurationUs;
this.chunkCount = lastChunkDurationUs == 0 ? fullChunks : fullChunks + 1;
double[] bitrateFactors = new double[chunkCount];
for (int i = 0; i < chunkCount; i++) {
bitrateFactors[i] = 1.0 + random.nextGaussian() * bitratePercentStdDev / 100.0;
}
for (int i = 0; i < trackGroup.length; i++) {
String uri = getUri(i);
Format format = trackGroup.getFormat(i);
double avgChunkLength =
format.bitrate * chunkDurationUs / ((double) (8 * C.MICROS_PER_SECOND));
FakeData newData = this.newData(uri);
for (int j = 0; j < fullChunks; j++) {
newData.appendReadData((int) (avgChunkLength * bitrateFactors[j]));
}
if (lastChunkDurationUs > 0) {
int lastChunkLength =
(int)
(format.bitrate
* bitrateFactors[bitrateFactors.length - 1]
* (mediaDurationUs % chunkDurationUs)
/ (8 * C.MICROS_PER_SECOND));
newData.appendReadData(lastChunkLength);
}
}
}
public int getChunkCount() {
return chunkCount;
}
public String getUri(int trackIndex) {
return "fake://adaptive.media/" + trackIndex;
}
public long getChunkDuration(int chunkIndex) {
return chunkIndex == getChunkCount() - 1 ? lastChunkDurationUs : chunkDurationUs;
}
public long getStartTime(int chunkIndex) {
return chunkIndex * chunkDurationUs;
}
public int getChunkIndexByPosition(long positionUs) {
return (int) (positionUs / chunkDurationUs);
}
}