NalUnitTargetBuffer.java
/*
* Copyright (C) 2016 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.extractor.ts;
import androidx.media3.common.util.Assertions;
import java.util.Arrays;
/**
* A buffer that fills itself with data corresponding to a specific NAL unit, as it is encountered
* in the stream.
*/
/* package */ final class NalUnitTargetBuffer {
private final int targetType;
private boolean isFilling;
private boolean isCompleted;
public byte[] nalData;
public int nalLength;
public NalUnitTargetBuffer(int targetType, int initialCapacity) {
this.targetType = targetType;
// Initialize data with a start code in the first three bytes.
nalData = new byte[3 + initialCapacity];
nalData[2] = 1;
}
/** Resets the buffer, clearing any data that it holds. */
public void reset() {
isFilling = false;
isCompleted = false;
}
/** Returns whether the buffer currently holds a complete NAL unit of the target type. */
public boolean isCompleted() {
return isCompleted;
}
/**
* Called to indicate that a NAL unit has started.
*
* @param type The type of the NAL unit.
*/
public void startNalUnit(int type) {
Assertions.checkState(!isFilling);
isFilling = type == targetType;
if (isFilling) {
// Skip the three byte start code when writing data.
nalLength = 3;
isCompleted = false;
}
}
/**
* Called to pass stream data. The data passed should not include the 3 byte start code.
*
* @param data Holds the data being passed.
* @param offset The offset of the data in {@code data}.
* @param limit The limit (exclusive) of the data in {@code data}.
*/
public void appendToNalUnit(byte[] data, int offset, int limit) {
if (!isFilling) {
return;
}
int readLength = limit - offset;
if (nalData.length < nalLength + readLength) {
nalData = Arrays.copyOf(nalData, (nalLength + readLength) * 2);
}
System.arraycopy(data, offset, nalData, nalLength, readLength);
nalLength += readLength;
}
/**
* Called to indicate that a NAL unit has ended.
*
* @param discardPadding The number of excess bytes that were passed to {@link
* #appendToNalUnit(byte[], int, int)}, which should be discarded.
* @return Whether the ended NAL unit is of the target type.
*/
public boolean endNalUnit(int discardPadding) {
if (!isFilling) {
return false;
}
nalLength -= discardPadding;
isFilling = false;
isCompleted = true;
return true;
}
}