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Audio Playback and Recording

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Kab777 edited this page Jun 30, 2016 · 2 revisions

Overview

In Android apps, there are often cases where we need to play audio files. Checking the Supported Media Formats we can see that several audio formats (MP3, AAC, FLAC, Vorbis) are playable by default.

In this guide we will take a look at how to play audio content using the MediaPlayer and capture audio with the MediaRecorder.

Playing Local Audio

To play local audio in the supported formats, first we should put the local audio file into the res/raw folder. For example put this sample_audio.mp3 into res/raw/sample_audio.mp3.

Note: If you get the compile error message INVALID FILE NAME: MUST CONTAIN ONLY [a-z0-9_.], this is because your MP3 can only have lowercase letters, numbers, periods, and underscores in its name.

Now we can use the MediaPlayer in order to playback any local files:

MediaPlayer mediaPlayer = MediaPlayer.create(this, R.raw.sample_audio); mediaPlayer.start();

On call to start() method, the music will start playing from the beginning. If this method is called again after the pause() method, the music would start playing from where it left off and not from the beginning. To play back audio from a local file path, simply do:

Uri myUri = "...."; // initialize Uri here MediaPlayer mediaPlayer = new MediaPlayer(); mediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC); mediaPlayer.setDataSource(getApplicationContext(), myUri); // or just mediaPlayer.setDataSource(mFileName); mediaPlayer.prepare(); // must call prepare first mediaPlayer.start(); // then start

We can release the resources taken by the player by calling release to free up system resources:

mediaPlayer.release(); mediaPlayer = null;

MediaPlayer has many key methods to control playback such as:

MediaPlayer mediaPlayer = MediaPlayer.create(this, R.raw.sample_audio); mediaPlayer.start(); // start the audio from last location mediaPlayer.pause(); // pause audio mediaPlayer.reset(); // reset audio to beginning of track mediaPlayer.isPlaying(); // returns true/false indicating the song is playing mediaPlayer.seekTo(100); // move song to that particular millisecond mediaPlayer.getCurrentDuration(); // current position of song in milliseconds mediaPlayer.getDuration(); // total time duration of song in milliseconds

Check the MediaPlayer docs for a full list of methods. These are the basics for playing audio but check out this androidhive and this tutorial if you want to understand how to hook up a graphical interface for managing the audio playback.

Playing Streaming Audio

If you are using MediaPlayer to stream network-based content, your application must request network access in the manifest:

<uses-permission android:name="android.permission.INTERNET" />

Now we can stream remote audio files in the supported formats with:

String url = "https://dl.dropboxusercontent.com/u/10281242/sample_audio.mp3"; final MediaPlayer mediaPlayer = new MediaPlayer(); // Set type to streaming mediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC); // Listen for if the audio file can't be prepared mediaPlayer.setOnErrorListener(new OnErrorListener() { @Override public boolean onError(MediaPlayer mp, int what, int extra) { // ... react appropriately ... // The MediaPlayer has moved to the Error state, must be reset! return false;	} }); // Attach to when audio file is prepared for playing mediaPlayer.setOnPreparedListener(new OnPreparedListener() { @Override public void onPrepared(MediaPlayer mp) { mediaPlayer.start();	} }); // Set the data source to the remote URL mediaPlayer.setDataSource(url); // Trigger an async preparation which will file listener when completed mediaPlayer.prepareAsync();

With that, the remote file will start streaming once preparation is completed and loading the audio file won't block the UI thread. For more details, see the official MediaPlayer playback guide.

Capturing Audio

You can record audio using the MediaRecorder APIs if supported by the device hardware.

First, let's add the correct permissions to our AndroidManifest.xml (Note: The permissions model has changed starting in Marshmallow. If your targetSdkVersion >= 23 and you are running on a Marshmallow (or later) device, you may need to enable runtime permissions. You should also read more about the runtime permissions changes):

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" /> <uses-permission android:name="android.permission.RECORD_AUDIO" />

Recording audio is as simple as starting and stopping the MediaRecorder:

// File path of recorded audio private String mFileName; private static final String LOG_TAG = "AudioRecordTest"; // Verify that the device has a mic first PackageManager pmanager = this.getPackageManager(); if (pmanager.hasSystemFeature(PackageManager.FEATURE_MICROPHONE)) { // Set the file location for the audio mFileName = Environment.getExternalStorageDirectory().getAbsolutePath(); mFileName += "/audiorecordtest.3gp"; // Create the recorder MediaRecorder mediaRecorder = new MediaRecorder(); // Set the audio format and encoder mediaRecorder.setAudioSource(MediaRecorder.AudioSource.MIC); mediaRecorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP); mediaRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB); // Setup the output location mediaRecorder.setOutputFile(mFileName); // Start the recording try { mediaRecorder.prepare(); mediaRecorder.start(); } catch (IOException e) { Log.e(LOG_TAG, "prepare() failed"); } } else { // no mic on device Toast.makeText(this, "This device doesn't have a mic!", Toast.LENGTH_LONG).show(); }

When you want to stop capturing audio, simply notify the recorder:

// Stop the recording of the audio mediaRecorder.stop(); mediaRecorder.reset(); mediaRecorder.release();

If you wanted to now playback the recorded audio:

MediaPlayer mediaPlayer = new MediaPlayer(); mediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC); mediaPlayer.setDataSource(mFileName); mediaPlayer.prepare(); // must call prepare first mediaPlayer.start(); // then start

If you wanted to add this audio to the media library on the phone:

// Setup values for the media file ContentValues values = new ContentValues(4); long current = System.currentTimeMillis(); values.put(MediaStore.Audio.Media.TITLE, "audio file"); values.put(MediaStore.Audio.Media.DATE_ADDED, (int) (current / 1000)); values.put(MediaStore.Audio.Media.MIME_TYPE, "audio/3gpp"); values.put(MediaStore.Audio.Media.DATA, audiofile.getAbsolutePath()); ContentResolver contentResolver = getContentResolver(); // Construct uris Uri base = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI; Uri newUri = contentResolver.insert(base, values); // Trigger broadcast to add sendBroadcast(new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE, newUri)); Toast.makeText(this, "Added File " + newUri, Toast.LENGTH_LONG).show();

For more details, check out this tutorialspoint article and the official Audio Capture guide.

References

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