Simpliest ExoPlayer for streaming mp3, mp4 from url. Source: https://codelabs.developers.google.com/codelabs/exoplayer-intro/index.html?index=..%2F..%2Fio2017#2

activity_player.xml

<!-- Copyright (C) 2017 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. -->
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
             android:layout_width="match_parent"
             android:layout_height="match_parent"
             android:background="#000000">

    <com.google.android.exoplayer2.ui.SimpleExoPlayerView
        android:id="@+id/video_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        />

</FrameLayout>

build.gradle

apply plugin: 'com.android.library'

android {
    compileSdkVersion 25
    buildToolsVersion "25.0.2"
    defaultConfig {
        minSdkVersion 16
        targetSdkVersion 25
        versionCode 1
        versionName "1.0"
    }
    buildTypes {
        release {
            minifyEnabled true
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    compile 'com.android.support:appcompat-v7:25.3.1'
    compile 'com.android.support:support-v4:25.3.1'
    compile 'com.google.android.exoplayer:exoplayer:r2.4.0'
}

note.md

Creating a playlist

Each media is

video

ExtractorMediaSource videoSource =new ExtractorMediaSource(uri, dataSourceFactory, extractorsFactory, null, null);

audio

 ExtractorMediaSource audioSource = new ExtractorMediaSource(audioUri, dataSourceFactory, extractorsFactory, null, null);;

combine with

//... params
new ConcatenatingMediaSource(audioSource, videoSource);

uri

• url or file location.

dataSource

• how to read data. if it is url then this is HttpDataSourceFactory

extractors

• media reader. If it is mp3, mp4 then use the DefaultExtractorsFactory

PlayerActivity.java

/*
 * Copyright (C) 2017 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.exoplayer;

import android.annotation.SuppressLint;
import android.net.Uri;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;

import com.google.android.exoplayer2.DefaultLoadControl;
import com.google.android.exoplayer2.DefaultRenderersFactory;
import com.google.android.exoplayer2.ExoPlayerFactory;
import com.google.android.exoplayer2.SimpleExoPlayer;
import com.google.android.exoplayer2.extractor.DefaultExtractorsFactory;
import com.google.android.exoplayer2.source.ExtractorMediaSource;
import com.google.android.exoplayer2.source.MediaSource;
import com.google.android.exoplayer2.trackselection.DefaultTrackSelector;
import com.google.android.exoplayer2.ui.SimpleExoPlayerView;
import com.google.android.exoplayer2.upstream.DefaultHttpDataSourceFactory;
import com.google.android.exoplayer2.util.Util;


/**
 * A fullscreen activity to play audio or video streams.
 */


public class PlayerActivity extends AppCompatActivity {

    SimpleExoPlayerView playerView;
    SimpleExoPlayer player;
    private boolean playWhenReady;
    private int currentWindow;
    private long playbackPosition;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_player);
        playerView = (SimpleExoPlayerView) findViewById(R.id.video_view);
    }

    /**
     * {@link com.google.android.exoplayer2.RenderersFactory} sync video, audio and subtitle together
     * {@link com.google.android.exoplayer2.trackselection.TrackSelector} select audio, video and text from available list
     * {@link com.google.android.exoplayer2.LoadControl} manage video buffer
     */
    private void initializePlayer() {
        player = ExoPlayerFactory.newSimpleInstance(
                new DefaultRenderersFactory(this),
                new DefaultTrackSelector(), new DefaultLoadControl()
        );

        playerView.setPlayer(player);


        player.setPlayWhenReady(playWhenReady);
        player.seekTo(currentWindow, playbackPosition);

        /*
         * media part
         */
        Uri uri = Uri.parse(getString(R.string.media_url_mp4));
        MediaSource mediaSource = buildMediaSource(uri);
        player.prepare(mediaSource, true, false);

    }

    private MediaSource buildMediaSource(Uri uri) {
        return new ExtractorMediaSource(uri,
                new DefaultHttpDataSourceFactory("ua"),
                new DefaultExtractorsFactory(), null, null);
    }

    @Override
    protected void onStart() {
        super.onStart();
        /*
        Api 24 supports multiple windows, so we start it here
         */
        if (Util.SDK_INT > 23) {
            initializePlayer();
        }
    }

    @Override
    protected void onResume() {
        super.onResume();
        /*
        Before Api 24. we initialize in a later stage which is resume
         */
        hideSystemUi();
        if ((Util.SDK_INT <= 23 || player == null)) {
            initializePlayer();
        }
    }

    /*
    Prior to 24, onStop is not guarantee
    */
    @Override
    protected void onPause() {
        super.onPause();
        if (Util.SDK_INT <= 23) {
            releasePlayer();
        }
    }

    /*
    onStop is guaranteed when 24. We should delay it as much as possible.
    */
    @Override
    protected void onStop() {
        super.onStop();
        if (Util.SDK_INT > 23) {
            releasePlayer();
        }
    }

    /**
     * getCurrentPosition - keep seekbar position
     * getPlayWhenReady - play immediately when coming back from other app
     */
    private void releasePlayer() {
        if (player != null) {
            playbackPosition = player.getCurrentPosition();
            currentWindow = player.getCurrentWindowIndex();
            playWhenReady = player.getPlayWhenReady();
            player.release();
            player = null;
        }
    }

    /**
     * Make it an immersive experience on api 24 and up
     */
    @SuppressLint("InlinedApi")
    private void hideSystemUi() {
        playerView.setSystemUiVisibility(View.SYSTEM_UI_FLAG_LOW_PROFILE
                | View.SYSTEM_UI_FLAG_FULLSCREEN
                | View.SYSTEM_UI_FLAG_LAYOUT_STABLE
                | View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY
                | View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION
                | View.SYSTEM_UI_FLAG_HIDE_NAVIGATION);
    }
}