1 /*
2  * Copyright (C) 2016 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 package com.google.android.exoplayer2.extractor.ts;
17 
18 import android.util.Log;
19 import com.google.android.exoplayer2.C;
20 import com.google.android.exoplayer2.Format;
21 import com.google.android.exoplayer2.extractor.ExtractorOutput;
22 import com.google.android.exoplayer2.extractor.TrackOutput;
23 import com.google.android.exoplayer2.extractor.ts.TsPayloadReader.TrackIdGenerator;
24 import com.google.android.exoplayer2.util.MimeTypes;
25 import com.google.android.exoplayer2.util.ParsableByteArray;
26 
27 /**
28  * Parses ID3 data and extracts individual text information frames.
29  */
30 public final class Id3Reader implements ElementaryStreamReader {
31 
32   private static final String TAG = "Id3Reader";
33 
34   private static final int ID3_HEADER_SIZE = 10;
35 
36   private final ParsableByteArray id3Header;
37 
38   private TrackOutput output;
39 
40   // State that should be reset on seek.
41   private boolean writingSample;
42 
43   // Per sample state that gets reset at the start of each sample.
44   private long sampleTimeUs;
45   private int sampleSize;
46   private int sampleBytesRead;
47 
Id3Reader()48   public Id3Reader() {
49     id3Header = new ParsableByteArray(ID3_HEADER_SIZE);
50   }
51 
52   @Override
seek()53   public void seek() {
54     writingSample = false;
55   }
56 
57   @Override
createTracks(ExtractorOutput extractorOutput, TrackIdGenerator idGenerator)58   public void createTracks(ExtractorOutput extractorOutput, TrackIdGenerator idGenerator) {
59     idGenerator.generateNewId();
60     output = extractorOutput.track(idGenerator.getTrackId(), C.TRACK_TYPE_METADATA);
61     output.format(Format.createSampleFormat(idGenerator.getFormatId(), MimeTypes.APPLICATION_ID3,
62         null, Format.NO_VALUE, null));
63   }
64 
65   @Override
packetStarted(long pesTimeUs, boolean dataAlignmentIndicator)66   public void packetStarted(long pesTimeUs, boolean dataAlignmentIndicator) {
67     if (!dataAlignmentIndicator) {
68       return;
69     }
70     writingSample = true;
71     sampleTimeUs = pesTimeUs;
72     sampleSize = 0;
73     sampleBytesRead = 0;
74   }
75 
76   @Override
consume(ParsableByteArray data)77   public void consume(ParsableByteArray data) {
78     if (!writingSample) {
79       return;
80     }
81     int bytesAvailable = data.bytesLeft();
82     if (sampleBytesRead < ID3_HEADER_SIZE) {
83       // We're still reading the ID3 header.
84       int headerBytesAvailable = Math.min(bytesAvailable, ID3_HEADER_SIZE - sampleBytesRead);
85       System.arraycopy(data.data, data.getPosition(), id3Header.data, sampleBytesRead,
86           headerBytesAvailable);
87       if (sampleBytesRead + headerBytesAvailable == ID3_HEADER_SIZE) {
88         // We've finished reading the ID3 header. Extract the sample size.
89         id3Header.setPosition(0);
90         if ('I' != id3Header.readUnsignedByte() || 'D' != id3Header.readUnsignedByte()
91             || '3' != id3Header.readUnsignedByte()) {
92           Log.w(TAG, "Discarding invalid ID3 tag");
93           writingSample = false;
94           return;
95         }
96         id3Header.skipBytes(3); // version (2) + flags (1)
97         sampleSize = ID3_HEADER_SIZE + id3Header.readSynchSafeInt();
98       }
99     }
100     // Write data to the output.
101     int bytesToWrite = Math.min(bytesAvailable, sampleSize - sampleBytesRead);
102     output.sampleData(data, bytesToWrite);
103     sampleBytesRead += bytesToWrite;
104   }
105 
106   @Override
packetFinished()107   public void packetFinished() {
108     if (!writingSample || sampleSize == 0 || sampleBytesRead != sampleSize) {
109       return;
110     }
111     output.sampleMetadata(sampleTimeUs, C.BUFFER_FLAG_KEY_FRAME, sampleSize, 0, null);
112     writingSample = false;
113   }
114 
115 }
116