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/*
* Copyright (C) 2018 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 org.mozilla.thirdparty.com.google.android.exoplayer2.extractor;
import androidx.annotation.Nullable;
import org.mozilla.thirdparty.com.google.android.exoplayer2.metadata.Metadata;
import org.mozilla.thirdparty.com.google.android.exoplayer2.metadata.id3.Id3Decoder;
import org.mozilla.thirdparty.com.google.android.exoplayer2.util.ParsableByteArray;
import java.io.EOFException;
import java.io.IOException;
/**
* Peeks data from the beginning of an {@link ExtractorInput} to determine if there is any ID3 tag.
*/
public final class Id3Peeker {
private final ParsableByteArray scratch;
public Id3Peeker() {
scratch = new ParsableByteArray(Id3Decoder.ID3_HEADER_LENGTH);
}
/**
* Peeks ID3 data from the input and parses the first ID3 tag.
*
* @param input The {@link ExtractorInput} from which data should be peeked.
* @param id3FramePredicate Determines which ID3 frames are decoded. May be null to decode all
* frames.
* @return The first ID3 tag decoded into a {@link Metadata} object. May be null if ID3 tag is not
* present in the input.
* @throws IOException If an error occurred peeking from the input.
* @throws InterruptedException If the thread was interrupted.
*/
@Nullable
public Metadata peekId3Data(
ExtractorInput input, @Nullable Id3Decoder.FramePredicate id3FramePredicate)
throws IOException, InterruptedException {
int peekedId3Bytes = 0;
Metadata metadata = null;
while (true) {
try {
input.peekFully(scratch.data, /* offset= */ 0, Id3Decoder.ID3_HEADER_LENGTH);
} catch (EOFException e) {
// If input has less than ID3_HEADER_LENGTH, ignore the rest.
break;
}
scratch.setPosition(0);
if (scratch.readUnsignedInt24() != Id3Decoder.ID3_TAG) {
// Not an ID3 tag.
break;
}
scratch.skipBytes(3); // Skip major version, minor version and flags.
int framesLength = scratch.readSynchSafeInt();
int tagLength = Id3Decoder.ID3_HEADER_LENGTH + framesLength;
if (metadata == null) {
byte[] id3Data = new byte[tagLength];
System.arraycopy(scratch.data, 0, id3Data, 0, Id3Decoder.ID3_HEADER_LENGTH);
input.peekFully(id3Data, Id3Decoder.ID3_HEADER_LENGTH, framesLength);
metadata = new Id3Decoder(id3FramePredicate).decode(id3Data, tagLength);
} else {
input.advancePeekPosition(framesLength);
}
peekedId3Bytes += tagLength;
}
input.resetPeekPosition();
input.advancePeekPosition(peekedId3Bytes);
return metadata;
}
}
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