Align README and helloworld documentation

#minor-release

PiperOrigin-RevId: 377269770

README.md

@@ -25,6 +25,8 @@ and extend, and can be updated through Play Store application updates.
 ExoPlayer modules can be obtained from [the Google Maven repository][]. It's
 also possible to clone the repository and depend on the modules locally.
 
+[the Google Maven repository]: https://developer.android.com/studio/build/dependencies#google-maven
+
 ### From the Google Maven repository
 
 #### 1. Add ExoPlayer module dependencies ####
@@ -39,13 +41,10 @@ implementation 'com.google.android.exoplayer:exoplayer:2.X.X'
 
 where `2.X.X` is your preferred version.
 
-Note: old versions of ExoPlayer are available via JCenter. To use them, you need
-to add `jcenter()` to your project's root build.gradle `repositories` block.
-
 As an alternative to the full library, you can depend on only the library
 modules that you actually need. For example the following will add dependencies
 on the Core, DASH and UI library modules, as might be required for an app that
-plays DASH content:
+only plays DASH content:
 
 ```gradle
 implementation 'com.google.android.exoplayer:exoplayer-core:2.X.X'
@@ -54,13 +53,15 @@ implementation 'com.google.android.exoplayer:exoplayer-ui:2.X.X'
 ```
 
 The available library modules are listed below. Adding a dependency to the full
-library is equivalent to adding dependencies on all of the library modules
-individually.
+ExoPlayer library is equivalent to adding dependencies on all of the library
+modules individually.
 
 * `exoplayer-core`: Core functionality (required).
 * `exoplayer-dash`: Support for DASH content.
 * `exoplayer-hls`: Support for HLS content.
+* `exoplayer-rtsp`: Support for RTSP content.
 * `exoplayer-smoothstreaming`: Support for SmoothStreaming content.
+* `exoplayer-transformer`: Media transformation functionality.
 * `exoplayer-ui`: UI components and resources for use with ExoPlayer.
 
 In addition to library modules, ExoPlayer has extension modules that depend on
@@ -72,7 +73,6 @@ More information on the library and extension modules that are available can be
 found on the [Google Maven ExoPlayer page][].
 
 [extensions directory]: https://github.com/google/ExoPlayer/tree/release-v2/extensions/
-[the Google Maven repository]: https://developer.android.com/studio/build/dependencies#google-maven
 [Google Maven ExoPlayer page]: https://maven.google.com/web/index.html#com.google.android.exoplayer
 
 #### 2. Turn on Java 8 support ####
@@ -87,6 +87,12 @@ compileOptions {
 }
 ```
 
+#### 3. Enable multidex ####
+
+If your Gradle `minSdkVersion` is 20 or lower, you should
+[enable multidex](https://developer.android.com/studio/build/multidex) in order
+to prevent build errors.
+
 ### Locally ###
 
 Cloning the repository and depending on the modules locally is required when

docs/hello-world.md

@@ -24,24 +24,11 @@ These steps are described in more detail below. For a complete example, refer to
 
 ## Adding ExoPlayer as a dependency ##
 
-### Add repositories ###
-
-The first step to getting started is to make sure you have the Google and
-JCenter repositories included in the `build.gradle` file in the root of your
-project.
-
-~~~
-repositories {
-    google()
-    jcenter()
-}
-~~~
-{: .language-gradle}
-
 ### Add ExoPlayer modules ###
 
-Next add a dependency in the `build.gradle` file of your app module. The
-following will add a dependency to the full ExoPlayer library:
+The easiest way to get started using ExoPlayer is to add it as a gradle
+dependency in the `build.gradle` file of your app module. The following will add
+a dependency to the full library:
 
 ~~~
 implementation 'com.google.android.exoplayer:exoplayer:2.X.X'
@@ -75,9 +62,13 @@ modules individually.
 * `exoplayer-transformer`: Media transformation functionality.
 * `exoplayer-ui`: UI components and resources for use with ExoPlayer.
 
-In addition to library modules, ExoPlayer has multiple extension modules that
-depend on external libraries to provide additional functionality. Browse the
-[extensions directory][] and their individual READMEs for details.
+In addition to library modules, ExoPlayer has extension modules that depend on
+external libraries to provide additional functionality. Some extensions are
+available from the Maven repository, whereas others must be built manually.
+Browse the [extensions directory][] and their individual READMEs for details.
+
+More information on the library and extension modules that are available can be
+found on the [Google Maven ExoPlayer page][].
 
 ### Turn on Java 8 support ###
 
@@ -239,4 +230,4 @@ can be done by calling `ExoPlayer.release`.
 [Playlists page]: {{ site.baseurl }}/playlists.html
 [Media items page]: {{ site.baseurl }}/media-items.html
 [Media sources page]: {{ site.baseurl }}/media-sources.html
-
+[Google Maven ExoPlayer page]: https://maven.google.com/web/index.html#com.google.android.exoplayer