| /* |
| * 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 com.google.android.exoplayer2.extractor; |
| |
| import androidx.annotation.Nullable; |
| import com.google.android.exoplayer2.metadata.Metadata; |
| import com.google.android.exoplayer2.metadata.id3.Id3Decoder; |
| import 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. |
| */ |
| @Nullable |
| public Metadata peekId3Data( |
| ExtractorInput input, @Nullable Id3Decoder.FramePredicate id3FramePredicate) |
| throws IOException { |
| int peekedId3Bytes = 0; |
| @Nullable Metadata metadata = null; |
| while (true) { |
| try { |
| input.peekFully(scratch.getData(), /* 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.getData(), 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; |
| } |
| } |