Android example source code file (AudioFxDemo.java)

This example Android source code file (AudioFxDemo.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

activity, android, audiofxdemo, drawing, equalizer, graphics, hz, linearlayout, mediaplayer, override, paint, playing, rect, seekbar, tag, textview, ui, view, visualizer_height_dip, visualizerview

The AudioFxDemo.java Android example source code

/*
 * Copyright (C) 2010 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.example.android.apis.media;

import com.example.android.apis.R;

import android.app.Activity;
import android.content.Context;
import android.content.res.AssetFileDescriptor;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.media.AudioManager;
import android.media.MediaPlayer;
import android.media.audiofx.Equalizer;
import android.media.audiofx.Visualizer;
import android.net.Uri;
import android.os.Bundle;
import android.util.Log;
import android.view.Gravity;
import android.view.View;
import android.view.ViewGroup;
import android.widget.LinearLayout;
import android.widget.SeekBar;
import android.widget.TextView;

import java.io.IOException;

public class AudioFxDemo extends Activity {
    private static final String TAG = "AudioFxDemo";

    private static final float VISUALIZER_HEIGHT_DIP = 50f;

    private MediaPlayer mMediaPlayer;
    private Visualizer mVisualizer;
    private Equalizer mEqualizer;

    private LinearLayout mLinearLayout;
    private VisualizerView mVisualizerView;
    private TextView mStatusTextView;

    @Override
    public void onCreate(Bundle icicle) {
        super.onCreate(icicle);

        setVolumeControlStream(AudioManager.STREAM_MUSIC);

        mStatusTextView = new TextView(this);

        mLinearLayout = new LinearLayout(this);
        mLinearLayout.setOrientation(LinearLayout.VERTICAL);
        mLinearLayout.addView(mStatusTextView);

        setContentView(mLinearLayout);

        // Create the MediaPlayer
        mMediaPlayer = MediaPlayer.create(this, R.raw.test_cbr);
        Log.d(TAG, "MediaPlayer audio session ID: " + mMediaPlayer.getAudioSessionId());

        setupVisualizerFxAndUI();
        setupEqualizerFxAndUI();

        // Make sure the visualizer is enabled only when you actually want to receive data, and
        // when it makes sense to receive data.
        mVisualizer.setEnabled(true);

        // When the stream ends, we don't need to collect any more data. We don't do this in
        // setupVisualizerFxAndUI because we likely want to have more, non-Visualizer related code
        // in this callback.
        mMediaPlayer.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {
            public void onCompletion(MediaPlayer mediaPlayer) {
                mVisualizer.setEnabled(false);
            }
        });

        mMediaPlayer.start();
        mStatusTextView.setText("Playing audio...");
    }

    private void setupEqualizerFxAndUI() {
        // Create the Equalizer object (an AudioEffect subclass) and attach it to our media player,
        // with a default priority (0).
        mEqualizer = new Equalizer(0, mMediaPlayer.getAudioSessionId());
        mEqualizer.setEnabled(true);

        TextView eqTextView = new TextView(this);
        eqTextView.setText("Equalizer:");
        mLinearLayout.addView(eqTextView);

        short bands = mEqualizer.getNumberOfBands();

        final short minEQLevel = mEqualizer.getBandLevelRange()[0];
        final short maxEQLevel = mEqualizer.getBandLevelRange()[1];

        for (short i = 0; i < bands; i++) {
            final short band = i;

            TextView freqTextView = new TextView(this);
            freqTextView.setLayoutParams(new ViewGroup.LayoutParams(
                    ViewGroup.LayoutParams.FILL_PARENT,
                    ViewGroup.LayoutParams.WRAP_CONTENT));
            freqTextView.setGravity(Gravity.CENTER_HORIZONTAL);
            freqTextView.setText((mEqualizer.getCenterFreq(band) / 1000) + " Hz");
            mLinearLayout.addView(freqTextView);

            LinearLayout row = new LinearLayout(this);
            row.setOrientation(LinearLayout.HORIZONTAL);

            TextView minDbTextView = new TextView(this);
            minDbTextView.setLayoutParams(new ViewGroup.LayoutParams(
                    ViewGroup.LayoutParams.WRAP_CONTENT,
                    ViewGroup.LayoutParams.WRAP_CONTENT));
            minDbTextView.setText((minEQLevel / 100) + " dB");

            TextView maxDbTextView = new TextView(this);
            maxDbTextView.setLayoutParams(new ViewGroup.LayoutParams(
                    ViewGroup.LayoutParams.WRAP_CONTENT,
                    ViewGroup.LayoutParams.WRAP_CONTENT));
            maxDbTextView.setText((maxEQLevel / 100) + " dB");

            LinearLayout.LayoutParams layoutParams = new LinearLayout.LayoutParams(
                    ViewGroup.LayoutParams.FILL_PARENT,
                    ViewGroup.LayoutParams.WRAP_CONTENT);
            layoutParams.weight = 1;
            SeekBar bar = new SeekBar(this);
            bar.setLayoutParams(layoutParams);
            bar.setMax(maxEQLevel - minEQLevel);
            bar.setProgress(mEqualizer.getBandLevel(band));

            bar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
                public void onProgressChanged(SeekBar seekBar, int progress,
                        boolean fromUser) {
                    mEqualizer.setBandLevel(band, (short) (progress + minEQLevel));
                }

                public void onStartTrackingTouch(SeekBar seekBar) {}
                public void onStopTrackingTouch(SeekBar seekBar) {}
            });

            row.addView(minDbTextView);
            row.addView(bar);
            row.addView(maxDbTextView);

            mLinearLayout.addView(row);
        }
    }

    private void setupVisualizerFxAndUI() {
        // Create a VisualizerView (defined below), which will render the simplified audio
        // wave form to a Canvas.
        mVisualizerView = new VisualizerView(this);
        mVisualizerView.setLayoutParams(new ViewGroup.LayoutParams(
                ViewGroup.LayoutParams.FILL_PARENT,
                (int)(VISUALIZER_HEIGHT_DIP * getResources().getDisplayMetrics().density)));
        mLinearLayout.addView(mVisualizerView);

        // Create the Visualizer object and attach it to our media player.
        mVisualizer = new Visualizer(mMediaPlayer.getAudioSessionId());
        mVisualizer.setCaptureSize(Visualizer.getCaptureSizeRange()[1]);
        mVisualizer.setDataCaptureListener(new Visualizer.OnDataCaptureListener() {
            public void onWaveFormDataCapture(Visualizer visualizer, byte[] bytes,
                    int samplingRate) {
                mVisualizerView.updateVisualizer(bytes);
            }

            public void onFftDataCapture(Visualizer visualizer, byte[] bytes, int samplingRate) {}
        }, Visualizer.getMaxCaptureRate() / 2, true, false);
    }

    @Override
    protected void onPause() {
        super.onPause();

        if (isFinishing() && mMediaPlayer != null) {
            mVisualizer.release();
            mEqualizer.release();
            mMediaPlayer.release();
            mMediaPlayer = null;
        }
    }
}

/**
 * A simple class that draws waveform data received from a
 * {@link Visualizer.OnDataCaptureListener#onWaveFormDataCapture }
 */
class VisualizerView extends View {
    private byte[] mBytes;
    private float[] mPoints;
    private Rect mRect = new Rect();

    private Paint mForePaint = new Paint();

    public VisualizerView(Context context) {
        super(context);
        init();
    }

    private void init() {
        mBytes = null;

        mForePaint.setStrokeWidth(1f);
        mForePaint.setAntiAlias(true);
        mForePaint.setColor(Color.rgb(0, 128, 255));
    }

    public void updateVisualizer(byte[] bytes) {
        mBytes = bytes;
        invalidate();
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);

        if (mBytes == null) {
            return;
        }

        if (mPoints == null || mPoints.length < mBytes.length * 4) {
            mPoints = new float[mBytes.length * 4];
        }

        mRect.set(0, 0, getWidth(), getHeight());

        for (int i = 0; i < mBytes.length - 1; i++) {
            mPoints[i * 4] = mRect.width() * i / (mBytes.length - 1);
            mPoints[i * 4 + 1] = mRect.height() / 2
                    + ((byte) (mBytes[i] + 128)) * (mRect.height() / 2) / 128;
            mPoints[i * 4 + 2] = mRect.width() * (i + 1) / (mBytes.length - 1);
            mPoints[i * 4 + 3] = mRect.height() / 2
                    + ((byte) (mBytes[i + 1] + 128)) * (mRect.height() / 2) / 128;
        }

        canvas.drawLines(mPoints, mForePaint);
    }
}