IcyDecoder.java
/*
* 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 androidx.media3.extractor.metadata.icy;
import androidx.annotation.Nullable;
import androidx.media3.common.Metadata;
import androidx.media3.common.util.UnstableApi;
import androidx.media3.extractor.metadata.MetadataInputBuffer;
import androidx.media3.extractor.metadata.SimpleMetadataDecoder;
import com.google.common.base.Ascii;
import com.google.common.base.Charsets;
import java.nio.ByteBuffer;
import java.nio.charset.CharacterCodingException;
import java.nio.charset.CharsetDecoder;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
/** Decodes ICY stream information. */
@UnstableApi
public final class IcyDecoder extends SimpleMetadataDecoder {
private static final Pattern METADATA_ELEMENT = Pattern.compile("(.+?)='(.*?)';", Pattern.DOTALL);
private static final String STREAM_KEY_NAME = "streamtitle";
private static final String STREAM_KEY_URL = "streamurl";
private final CharsetDecoder utf8Decoder;
private final CharsetDecoder iso88591Decoder;
public IcyDecoder() {
utf8Decoder = Charsets.UTF_8.newDecoder();
iso88591Decoder = Charsets.ISO_8859_1.newDecoder();
}
@Override
protected Metadata decode(MetadataInputBuffer inputBuffer, ByteBuffer buffer) {
@Nullable String icyString = decodeToString(buffer);
byte[] icyBytes = new byte[buffer.limit()];
buffer.get(icyBytes);
if (icyString == null) {
return new Metadata(new IcyInfo(icyBytes, /* title= */ null, /* url= */ null));
}
@Nullable String name = null;
@Nullable String url = null;
int index = 0;
Matcher matcher = METADATA_ELEMENT.matcher(icyString);
while (matcher.find(index)) {
@Nullable String key = matcher.group(1);
@Nullable String value = matcher.group(2);
if (key != null) {
switch (Ascii.toLowerCase(key)) {
case STREAM_KEY_NAME:
name = value;
break;
case STREAM_KEY_URL:
url = value;
break;
default:
break;
}
}
index = matcher.end();
}
return new Metadata(new IcyInfo(icyBytes, name, url));
}
// The ICY spec doesn't specify a character encoding, and there's no way to communicate one
// either. So try decoding UTF-8 first, then fall back to ISO-8859-1.
// https://github.com/google/ExoPlayer/issues/6753
@Nullable
private String decodeToString(ByteBuffer data) {
try {
return utf8Decoder.decode(data).toString();
} catch (CharacterCodingException e) {
// Fall through to try ISO-8859-1 decoding.
} finally {
utf8Decoder.reset();
data.rewind();
}
try {
return iso88591Decoder.decode(data).toString();
} catch (CharacterCodingException e) {
return null;
} finally {
iso88591Decoder.reset();
data.rewind();
}
}
}