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.mkv;
17 
18 import com.google.android.exoplayer2.ParserException;
19 import com.google.android.exoplayer2.extractor.ExtractorInput;
20 import java.io.IOException;
21 
22 /**
23  * Event-driven EBML reader that delivers events to an {@link EbmlReaderOutput}.
24  * <p>
25  * EBML can be summarized as a binary XML format somewhat similar to Protocol Buffers. It was
26  * originally designed for the Matroska container format. More information about EBML and
27  * Matroska is available <a href="http://www.matroska.org/technical/specs/index.html">here</a>.
28  */
29 /* package */ interface EbmlReader {
30 
31   /**
32    * Type for unknown elements.
33    */
34   int TYPE_UNKNOWN = 0;
35   /**
36    * Type for elements that contain child elements.
37    */
38   int TYPE_MASTER = 1;
39   /**
40    * Type for integer value elements of up to 8 bytes.
41    */
42   int TYPE_UNSIGNED_INT = 2;
43   /**
44    * Type for string elements.
45    */
46   int TYPE_STRING = 3;
47   /**
48    * Type for binary elements.
49    */
50   int TYPE_BINARY = 4;
51   /**
52    * Type for IEEE floating point value elements of either 4 or 8 bytes.
53    */
54   int TYPE_FLOAT = 5;
55 
56   /**
57    * Initializes the extractor with an {@link EbmlReaderOutput}.
58    *
59    * @param output An {@link EbmlReaderOutput} to receive events.
60    */
init(EbmlReaderOutput output)61   void init(EbmlReaderOutput output);
62 
63   /**
64    * Resets the state of the reader.
65    * <p>
66    * Subsequent calls to {@link #read(ExtractorInput)} will start reading a new EBML structure
67    * from scratch.
68    */
reset()69   void reset();
70 
71   /**
72    * Reads from an {@link ExtractorInput}, invoking an event callback if possible.
73    *
74    * @param input The {@link ExtractorInput} from which data should be read.
75    * @return True if data can continue to be read. False if the end of the input was encountered.
76    * @throws ParserException If parsing fails.
77    * @throws IOException If an error occurs reading from the input.
78    * @throws InterruptedException If the thread is interrupted.
79    */
read(ExtractorInput input)80   boolean read(ExtractorInput input) throws IOException, InterruptedException;
81 
82 }
83