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/*
* 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 org.mozilla.thirdparty.com.google.android.exoplayer2.extractor;
import org.mozilla.thirdparty.com.google.android.exoplayer2.Format;
import org.mozilla.thirdparty.com.google.android.exoplayer2.metadata.Metadata;
import org.mozilla.thirdparty.com.google.android.exoplayer2.metadata.id3.CommentFrame;
import org.mozilla.thirdparty.com.google.android.exoplayer2.metadata.id3.InternalFrame;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
/**
* Holder for gapless playback information.
*/
public final class GaplessInfoHolder {
private static final String GAPLESS_DOMAIN = "com.apple.iTunes";
private static final String GAPLESS_DESCRIPTION = "iTunSMPB";
private static final Pattern GAPLESS_COMMENT_PATTERN =
Pattern.compile("^ [0-9a-fA-F]{8} ([0-9a-fA-F]{8}) ([0-9a-fA-F]{8})");
/**
* The number of samples to trim from the start of the decoded audio stream, or
* {@link Format#NO_VALUE} if not set.
*/
public int encoderDelay;
/**
* The number of samples to trim from the end of the decoded audio stream, or
* {@link Format#NO_VALUE} if not set.
*/
public int encoderPadding;
/**
* Creates a new holder for gapless playback information.
*/
public GaplessInfoHolder() {
encoderDelay = Format.NO_VALUE;
encoderPadding = Format.NO_VALUE;
}
/**
* Populates the holder with data from an MP3 Xing header, if valid and non-zero.
*
* @param value The 24-bit value to decode.
* @return Whether the holder was populated.
*/
public boolean setFromXingHeaderValue(int value) {
int encoderDelay = value >> 12;
int encoderPadding = value & 0x0FFF;
if (encoderDelay > 0 || encoderPadding > 0) {
this.encoderDelay = encoderDelay;
this.encoderPadding = encoderPadding;
return true;
}
return false;
}
/**
* Populates the holder with data parsed from ID3 {@link Metadata}.
*
* @param metadata The metadata from which to parse the gapless information.
* @return Whether the holder was populated.
*/
public boolean setFromMetadata(Metadata metadata) {
for (int i = 0; i < metadata.length(); i++) {
Metadata.Entry entry = metadata.get(i);
if (entry instanceof CommentFrame) {
CommentFrame commentFrame = (CommentFrame) entry;
if (GAPLESS_DESCRIPTION.equals(commentFrame.description)
&& setFromComment(commentFrame.text)) {
return true;
}
} else if (entry instanceof InternalFrame) {
InternalFrame internalFrame = (InternalFrame) entry;
if (GAPLESS_DOMAIN.equals(internalFrame.domain)
&& GAPLESS_DESCRIPTION.equals(internalFrame.description)
&& setFromComment(internalFrame.text)) {
return true;
}
}
}
return false;
}
/**
* Populates the holder with data parsed from a gapless playback comment (stored in an ID3 header
* or MPEG 4 user data), if valid and non-zero.
*
* @param data The comment's payload data.
* @return Whether the holder was populated.
*/
private boolean setFromComment(String data) {
Matcher matcher = GAPLESS_COMMENT_PATTERN.matcher(data);
if (matcher.find()) {
try {
int encoderDelay = Integer.parseInt(matcher.group(1), 16);
int encoderPadding = Integer.parseInt(matcher.group(2), 16);
if (encoderDelay > 0 || encoderPadding > 0) {
this.encoderDelay = encoderDelay;
this.encoderPadding = encoderPadding;
return true;
}
} catch (NumberFormatException e) {
// Ignore incorrectly formatted comments.
}
}
return false;
}
/**
* Returns whether {@link #encoderDelay} and {@link #encoderPadding} have been set.
*/
public boolean hasGaplessInfo() {
return encoderDelay != Format.NO_VALUE && encoderPadding != Format.NO_VALUE;
}
}
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