content: /*
   * 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 com.google.android.exoplayer2.extractor.ts;
  
  import static com.google.android.exoplayer2.extractor.ts.TsPayloadReader.FLAG_DATA_ALIGNMENT_INDICATOR;
  import static com.google.android.exoplayer2.metadata.id3.Id3Decoder.ID3_HEADER_LENGTH;
  import static java.lang.Math.min;
  
  import com.google.android.exoplayer2.C;
  import com.google.android.exoplayer2.Format;
  import com.google.android.exoplayer2.extractor.ExtractorOutput;
  import com.google.android.exoplayer2.extractor.TrackOutput;
  import com.google.android.exoplayer2.extractor.ts.TsPayloadReader.TrackIdGenerator;
  import com.google.android.exoplayer2.util.Assertions;
  import com.google.android.exoplayer2.util.Log;
  import com.google.android.exoplayer2.util.MimeTypes;
  import com.google.android.exoplayer2.util.ParsableByteArray;
  import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
  
  /** Parses ID3 data and extracts individual text information frames. */
  public final class Id3Reader implements ElementaryStreamReader {
  
    private static final String TAG = "Id3Reader";
  
    private final ParsableByteArray id3Header;
  
    private @MonotonicNonNull TrackOutput output;
  
    // State that should be reset on seek.
    private boolean writingSample;
  
    // Per sample state that gets reset at the start of each sample.
    private long sampleTimeUs;
    private int sampleSize;
    private int sampleBytesRead;
  
    public Id3Reader() {
      id3Header = new ParsableByteArray(ID3_HEADER_LENGTH);
      sampleTimeUs = C.TIME_UNSET;
    }
  
    @Override
    public void seek() {
      writingSample = false;
      sampleTimeUs = C.TIME_UNSET;
    }
  
    @Override
    public void createTracks(ExtractorOutput extractorOutput, TrackIdGenerator idGenerator) {
      idGenerator.generateNewId();
      output = extractorOutput.track(idGenerator.getTrackId(), C.TRACK_TYPE_METADATA);
      output.format(
          new Format.Builder()
              .setId(idGenerator.getFormatId())
              .setSampleMimeType(MimeTypes.APPLICATION_ID3)
              .build());
    }
  
    @Override
    public void packetStarted(long pesTimeUs, @TsPayloadReader.Flags int flags) {
      if ((flags & FLAG_DATA_ALIGNMENT_INDICATOR) == 0) {
        return;
      }
      writingSample = true;
      if (pesTimeUs != C.TIME_UNSET) {
        sampleTimeUs = pesTimeUs;
      }
      sampleSize = 0;
      sampleBytesRead = 0;
    }
  
    @Override
    public void consume(ParsableByteArray data) {
      Assertions.checkStateNotNull(output); // Asserts that createTracks has been called.
      if (!writingSample) {
        return;
      }
      int bytesAvailable = data.bytesLeft();
      if (sampleBytesRead < ID3_HEADER_LENGTH) {
        // We're still reading the ID3 header.
        int headerBytesAvailable = min(bytesAvailable, ID3_HEADER_LENGTH - sampleBytesRead);
        System.arraycopy(
            data.getData(),
            data.getPosition(),
            id3Header.getData(),
            sampleBytesRead,
            headerBytesAvailable);
        if (sampleBytesRead + headerBytesAvailable == ID3_HEADER_LENGTH) {
          // We've finished reading the ID3 header. Extract the sample size.
          id3Header.setPosition(0);
          if ('I' != id3Header.readUnsignedByte()
              || 'D' != id3Header.readUnsignedByte()
              || '3' != id3Header.readUnsignedByte()) {
            Log.w(TAG, "Discarding invalid ID3 tag");
            writingSample = false;
            return;
          }
          id3Header.skipBytes(3); // version (2) + flags (1)
          sampleSize = ID3_HEADER_LENGTH + id3Header.readSynchSafeInt();
        }
      }
      // Write data to the output.
      int bytesToWrite = min(bytesAvailable, sampleSize - sampleBytesRead);
      output.sampleData(data, bytesToWrite);
      sampleBytesRead += bytesToWrite;
    }
  
    @Override
    public void packetFinished() {
      Assertions.checkStateNotNull(output); // Asserts that createTracks has been called.
      if (!writingSample || sampleSize == 0 || sampleBytesRead != sampleSize) {
        return;
      }
      if (sampleTimeUs != C.TIME_UNSET) {
        output.sampleMetadata(sampleTimeUs, C.BUFFER_FLAG_KEY_FRAME, sampleSize, 0, null);
      }
      writingSample = false;
    }
  }
  