Curso de Android
Multimedia

Cargar una imagen con la librería picasso

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

dependencies 
 implementation 'com.squareup.picasso:picasso:2.71828'
}

String imageUri = "https://i.imgur.com/tGbaZCY.jpg";
ImageView ivBasicImage = (ImageView) findViewById(R.id.ivBasicImage);
Picasso.get().load(imageUri).into(ivBasicImage);

Cargar un sonido

MediaPlayer mp = MediaPlayer.create(Audio.this, R.raw.hakunamatata);

Cargar un video

getWindow().setFormat(PixelFormat.TRANSLUCENT);
        VideoView videoHolder = new VideoView(this);
        //if you want the controls to appear
        videoHolder.setMediaController(new MediaController(this));
        Uri video = Uri.parse("android.resource://" + getPackageName() + "/"
                + R.raw.leon);
        videoHolder.setVideoURI(video);
        setContentView(videoHolder);
        videoHolder.start();

Hacer streaming de un video

Habrá que dar permisos de conexión a internet en el:

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

String stringUrl = "https://pablomonteserin.com/curso/html5/ex/HakunaMatataItMeansNoWorries.mp3";
try {
 final MediaPlayer mediaPlayer = new MediaPlayer();
 mediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);
 mediaPlayer.setDataSource(stringUrl);
 mediaPlayer.prepareAsync();
 mediaPlayer.setOnPreparedListener(new MediaPlayer.OnPreparedListener() {
  @Override
  public void onPrepared(MediaPlayer mp) {
   mediaPlayer.start();
  }
 });
} catch (Exception e) {
 e.printStackTrace();
}

Usar cámara de fotos

public void sacaFoto(View v){
 Intent intent = new Intent(android.provider.MediaStore.ACTION_IMAGE_CAPTURE);
 startActivityForResult(intent,0);
}

protected void onActivityResult(int requestCode, int resultCode, Intent data){
 super.onActivityResult(requestCode, resultCode, data);
 Bitmap bm = (Bitmap) data.getExtras().get("data");
 iv.setImageBitmap(bm);
}