1 /* 2 * Copyright (C) 2012 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 17 18 package android.media; 19 20 import java.io.Closeable; 21 import java.io.IOException; 22 23 /** 24 * For supplying media data to the framework. Implement this if your app has 25 * special requirements for the way media data is obtained. 26 * 27 * <p class="note">Methods of this interface may be called on multiple different 28 * threads. There will be a thread synchronization point between each call to ensure that 29 * modifications to the state of your MediaDataSource are visible to future calls. This means 30 * you don't need to do your own synchronization unless you're modifying the 31 * MediaDataSource from another thread while it's being used by the framework.</p> 32 */ 33 public abstract class MediaDataSource implements Closeable { 34 /** 35 * Called to request data from the given position. 36 * 37 * Implementations should should write up to {@code size} bytes into 38 * {@code buffer}, and return the number of bytes written. 39 * 40 * Return {@code 0} if size is zero (thus no bytes are read). 41 * 42 * Return {@code -1} to indicate that end of stream is reached. 43 * 44 * @param position the position in the data source to read from. 45 * @param buffer the buffer to read the data into. 46 * @param offset the offset within buffer to read the data into. 47 * @param size the number of bytes to read. 48 * @throws IOException on fatal errors. 49 * @return the number of bytes read, or -1 if there was an error. 50 */ readAt(long position, byte[] buffer, int offset, int size)51 public abstract int readAt(long position, byte[] buffer, int offset, int size) 52 throws IOException; 53 54 /** 55 * Called to get the size of the data source. 56 * 57 * @throws IOException on fatal errors 58 * @return the size of data source in bytes, or -1 if the size is unknown. 59 */ getSize()60 public abstract long getSize() throws IOException; 61 } 62