Android example source code file (AmrInputStream.java)

This example Android source code file (AmrInputStream.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Android by Example" ^TM.

Java - Android tags/keywords

amrinputstream, android, gsmamrencodercleanup, gsmamrencoderdelete, gsmamrencoderencode, gsmamrencoderinitialize, gsmamrencodernew, illegalstateexception, io, ioexception, override, samples_per_frame, string, tag, throwable, util, utilities, utils

The AmrInputStream.java Android example source code

/*
 * Copyright (C) 2008 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 android.media;

import android.util.Config;
import android.util.Log;

import java.io.InputStream;
import java.io.IOException;


/**
 * AmrInputStream
 * @hide
 */
public final class AmrInputStream extends InputStream
{    
    static {
        System.loadLibrary("media_jni");
    }
    
    private final static String TAG = "AmrInputStream";
    
    // frame is 20 msec at 8.000 khz
    private final static int SAMPLES_PER_FRAME = 8000 * 20 / 1000;
    
    // pcm input stream
    private InputStream mInputStream;
    
    // native handle
    private int mGae;
    
    // result amr stream
    private byte[] mBuf = new byte[SAMPLES_PER_FRAME * 2];
    private int mBufIn = 0;
    private int mBufOut = 0;
    
    // helper for bytewise read()
    private byte[] mOneByte = new byte[1];
    
    /**
     * Create a new AmrInputStream, which converts 16 bit PCM to AMR
     * @param inputStream InputStream containing 16 bit PCM.
     */
    public AmrInputStream(InputStream inputStream) {
        mInputStream = inputStream;
        mGae = GsmAmrEncoderNew();
        GsmAmrEncoderInitialize(mGae);
    }

    @Override
    public int read() throws IOException {
        int rtn = read(mOneByte, 0, 1);
        return rtn == 1 ? (0xff & mOneByte[0]) : -1;
    }
    
    @Override
    public int read(byte[] b) throws IOException {
        return read(b, 0, b.length);
    }

    @Override
    public int read(byte[] b, int offset, int length) throws IOException {
        if (mGae == 0) throw new IllegalStateException("not open");
        
        // local buffer of amr encoded audio empty
        if (mBufOut >= mBufIn) {
            // reset the buffer
            mBufOut = 0;
            mBufIn = 0;
            
            // fetch a 20 msec frame of pcm
            for (int i = 0; i < SAMPLES_PER_FRAME * 2; ) {
                int n = mInputStream.read(mBuf, i, SAMPLES_PER_FRAME * 2 - i);
                if (n == -1) return -1;
                i += n;
            }
            
            // encode it
            mBufIn = GsmAmrEncoderEncode(mGae, mBuf, 0, mBuf, 0);
        }
        
        // return encoded audio to user
        if (length > mBufIn - mBufOut) length = mBufIn - mBufOut;
        System.arraycopy(mBuf, mBufOut, b, offset, length);
        mBufOut += length;
        
        return length;
    }

    @Override
    public void close() throws IOException {
        try {
            if (mInputStream != null) mInputStream.close();
        } finally {
            mInputStream = null;
            try {
                if (mGae != 0) GsmAmrEncoderCleanup(mGae);
            } finally {
                try {
                    if (mGae != 0) GsmAmrEncoderDelete(mGae);
                } finally {
                    mGae = 0;
                }
            }
        }
    }

    @Override
    protected void finalize() throws Throwable {
        if (mGae != 0) {
            close();
            throw new IllegalStateException("someone forgot to close AmrInputStream");
        }
    }
    
    //
    // AudioRecord JNI interface
    //
    private static native int GsmAmrEncoderNew();
    private static native void GsmAmrEncoderInitialize(int gae);
    private static native int GsmAmrEncoderEncode(int gae,
            byte[] pcm, int pcmOffset, byte[] amr, int amrOffset) throws IOException;
    private static native void GsmAmrEncoderCleanup(int gae);
    private static native void GsmAmrEncoderDelete(int gae);

}