Kotlin MediaPlayer Not Playing Audio Fix

If you are developing an Android app using Kotlin and facing the issue where MediaPlayer is not playing audio, you are not alone. This is a common problem many developers encounter when handling audio playback. In this article, we will explore the root causes, common mistakes, and provide complete solutions with Kotlin MediaPlayer code examples.

Why MediaPlayer May Not Play Audio in Kotlin

The MediaPlayer class in Android is powerful, but it also comes with strict requirements. Here are some common reasons why your audio might not play:

• Incorrect file path or URI: The audio file path may be wrong or inaccessible.
• Permission issues: Missing READ_EXTERNAL_STORAGE or INTERNET permission if streaming online audio.
• Lifecycle mismanagement: MediaPlayer not properly prepared or released during Activity or Fragment lifecycle.
• Asynchronous preparation: Forgetting to use prepareAsync() with an OnPreparedListener.
• Audio focus: Another app may have audio focus, preventing playback.

Basic Kotlin MediaPlayer Example

Here is a minimal working example to play an audio file stored in the raw folder:

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

While this may work for simple cases, developers often encounter issues when using MediaPlayer with external files or streaming URLs.

Common Mistake 1: Not Handling Permissions

If you are loading audio from external storage, you need to request runtime permissions:

if (ContextCompat.checkSelfPermission(this, Manifest.permission.READ_EXTERNAL_STORAGE)
    != PackageManager.PERMISSION_GRANTED) {
    ActivityCompat.requestPermissions(this,
        arrayOf(Manifest.permission.READ_EXTERNAL_STORAGE), 1)
}

Without this permission, your MediaPlayer will silently fail to play the file.

Common Mistake 2: Wrong Use of prepare()

For streaming audio (e.g., from a URL), you should not use prepare() directly on the main thread because it blocks the UI. Instead, use prepareAsync() and implement OnPreparedListener:

val mediaPlayer = MediaPlayer()
mediaPlayer.setDataSource("https://www.example.com/audiofile.mp3")
mediaPlayer.setOnPreparedListener {
    it.start()
}
mediaPlayer.prepareAsync()

Handling Lifecycle Properly

One of the main reasons Kotlin MediaPlayer not playing audio happens is lifecycle mismanagement. You must release the MediaPlayer when your activity is destroyed or paused:

override fun onPause() {
    super.onPause()
    if (mediaPlayer.isPlaying) {
        mediaPlayer.pause()
    }
}

override fun onDestroy() {
    super.onDestroy()
    mediaPlayer.release()
}

Complete Example: Playing Online Audio with Controls

Below is a complete example of a Kotlin Activity that streams audio from a URL with Play and Pause buttons:

class MainActivity : AppCompatActivity() {
    private lateinit var mediaPlayer: MediaPlayer
    private var isPrepared = false

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val playButton: Button = findViewById(R.id.playButton)
        val pauseButton: Button = findViewById(R.id.pauseButton)

        mediaPlayer = MediaPlayer()
        mediaPlayer.setDataSource("https://www.soundhelix.com/examples/mp3/SoundHelix-Song-1.mp3")

        mediaPlayer.setOnPreparedListener {
            isPrepared = true
            it.start()
        }

        mediaPlayer.setOnErrorListener { _, what, extra ->
            Log.e("MediaPlayer", "Error: what=$what extra=$extra")
            true
        }

        mediaPlayer.prepareAsync()

        playButton.setOnClickListener {
            if (isPrepared && !mediaPlayer.isPlaying) {
                mediaPlayer.start()
            }
        }

        pauseButton.setOnClickListener {
            if (mediaPlayer.isPlaying) {
                mediaPlayer.pause()
            }
        }
    }

    override fun onDestroy() {
        super.onDestroy()
        if (this::mediaPlayer.isInitialized) {
            mediaPlayer.release()
        }
    }
}

Troubleshooting Checklist

If your Kotlin MediaPlayer is not playing audio, go through this checklist:

1. Check if the file path or URL is correct.
2. Verify storage or internet permissions are granted.
3. Use prepareAsync() for network streams.
4. Handle lifecycle with release() to avoid resource leaks.
5. Check for logcat errors with MediaPlayer tag.

Conclusion

The MediaPlayer in Kotlin can sometimes be tricky, but once you understand the common pitfalls, handling audio becomes straightforward. Always remember to manage lifecycle properly, use the right preparation method, and ensure permissions are granted. Following these guidelines will solve most cases where Kotlin MediaPlayer not playing audio.

For more details on MediaPlayer, you can also read the official Android documentation:
MediaPlayer Android Docs.