diff --git a/extensions/av1/proguard-rules.txt b/extensions/av1/proguard-rules.txt
index 9d73f7e2b5..c4ef2286f2 100644
--- a/extensions/av1/proguard-rules.txt
+++ b/extensions/av1/proguard-rules.txt
@@ -5,3 +5,7 @@
     native <methods>;
 }
 
+# Some members of this class are being accessed from native methods. Keep them unobfuscated.
+-keep class com.google.android.exoplayer2.video.VideoDecoderOutputBuffer {
+  *;
+}
diff --git a/extensions/av1/src/main/java/com/google/android/exoplayer2/ext/av1/Gav1Decoder.java b/extensions/av1/src/main/java/com/google/android/exoplayer2/ext/av1/Gav1Decoder.java
index ad8c8a682c..08d48e9699 100644
--- a/extensions/av1/src/main/java/com/google/android/exoplayer2/ext/av1/Gav1Decoder.java
+++ b/extensions/av1/src/main/java/com/google/android/exoplayer2/ext/av1/Gav1Decoder.java
@@ -15,10 +15,12 @@
  */
 package com.google.android.exoplayer2.ext.av1;
 
+import static androidx.annotation.VisibleForTesting.PACKAGE_PRIVATE;
 import static java.lang.Runtime.getRuntime;
 
 import android.view.Surface;
 import androidx.annotation.Nullable;
+import androidx.annotation.VisibleForTesting;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.decoder.DecoderInputBuffer;
 import com.google.android.exoplayer2.decoder.SimpleDecoder;
@@ -28,7 +30,8 @@ import com.google.android.exoplayer2.video.VideoDecoderOutputBuffer;
 import java.nio.ByteBuffer;
 
 /** Gav1 decoder. */
-/* package */ final class Gav1Decoder
+@VisibleForTesting(otherwise = PACKAGE_PRIVATE)
+public final class Gav1Decoder
     extends SimpleDecoder<VideoDecoderInputBuffer, VideoDecoderOutputBuffer, Gav1DecoderException> {
 
   // LINT.IfChange
diff --git a/extensions/av1/src/main/proguard-rules.pgcfg b/extensions/av1/src/main/proguard-rules.pgcfg
new file mode 120000
index 0000000000..499fb08b36
--- /dev/null
+++ b/extensions/av1/src/main/proguard-rules.pgcfg
@@ -0,0 +1 @@
+../../proguard-rules.txt
\ No newline at end of file
diff --git a/extensions/flac/README.md b/extensions/flac/README.md
index a9d4c3094e..47c74d1148 100644
--- a/extensions/flac/README.md
+++ b/extensions/flac/README.md
@@ -68,7 +68,7 @@ renderer.
 
 ### Using `FlacExtractor` ###
 
-`FlacExtractor` is used via `ExtractorMediaSource`. If you're using
+`FlacExtractor` is used via `ProgressiveMediaSource`. If you're using
 `DefaultExtractorsFactory`, `FlacExtractor` will automatically be used to read
 `.flac` files. If you're not using `DefaultExtractorsFactory`, return a
 `FlacExtractor` from your `ExtractorsFactory.createExtractors` implementation.
diff --git a/extensions/flac/src/main/java/com/google/android/exoplayer2/ext/flac/FlacDecoder.java b/extensions/flac/src/main/java/com/google/android/exoplayer2/ext/flac/FlacDecoder.java
index 84cb081b29..f6c5f6a6a7 100644
--- a/extensions/flac/src/main/java/com/google/android/exoplayer2/ext/flac/FlacDecoder.java
+++ b/extensions/flac/src/main/java/com/google/android/exoplayer2/ext/flac/FlacDecoder.java
@@ -15,7 +15,10 @@
  */
 package com.google.android.exoplayer2.ext.flac;
 
+import static androidx.annotation.VisibleForTesting.PACKAGE_PRIVATE;
+
 import androidx.annotation.Nullable;
+import androidx.annotation.VisibleForTesting;
 import com.google.android.exoplayer2.Format;
 import com.google.android.exoplayer2.ParserException;
 import com.google.android.exoplayer2.decoder.DecoderInputBuffer;
@@ -27,11 +30,10 @@ import java.io.IOException;
 import java.nio.ByteBuffer;
 import java.util.List;
 
-/**
- * Flac decoder.
- */
-/* package */ final class FlacDecoder extends
-    SimpleDecoder<DecoderInputBuffer, SimpleOutputBuffer, FlacDecoderException> {
+/** Flac decoder. */
+@VisibleForTesting(otherwise = PACKAGE_PRIVATE)
+public final class FlacDecoder
+    extends SimpleDecoder<DecoderInputBuffer, SimpleOutputBuffer, FlacDecoderException> {
 
   private final FlacStreamMetadata streamMetadata;
   private final FlacDecoderJni decoderJni;
diff --git a/extensions/ima/proguard-rules.txt b/extensions/ima/proguard-rules.txt
index feef3daf7a..a46014de75 100644
--- a/extensions/ima/proguard-rules.txt
+++ b/extensions/ima/proguard-rules.txt
@@ -1,5 +1,6 @@
 # Proguard rules specific to the IMA extension.
 
+-dontwarn com.google.ads.interactivemedia.**
 -keep class com.google.ads.interactivemedia.** { *; }
 -keep interface com.google.ads.interactivemedia.** { *; }
 -keep class com.google.obf.** { *; }
diff --git a/extensions/opus/src/main/java/com/google/android/exoplayer2/ext/opus/OpusDecoder.java b/extensions/opus/src/main/java/com/google/android/exoplayer2/ext/opus/OpusDecoder.java
index 6b96cc5e49..f6da031a7a 100644
--- a/extensions/opus/src/main/java/com/google/android/exoplayer2/ext/opus/OpusDecoder.java
+++ b/extensions/opus/src/main/java/com/google/android/exoplayer2/ext/opus/OpusDecoder.java
@@ -15,7 +15,10 @@
  */
 package com.google.android.exoplayer2.ext.opus;
 
+import static androidx.annotation.VisibleForTesting.PACKAGE_PRIVATE;
+
 import androidx.annotation.Nullable;
+import androidx.annotation.VisibleForTesting;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.audio.OpusUtil;
 import com.google.android.exoplayer2.decoder.CryptoInfo;
@@ -30,7 +33,8 @@ import java.nio.ByteBuffer;
 import java.util.List;
 
 /** Opus decoder. */
-/* package */ final class OpusDecoder
+@VisibleForTesting(otherwise = PACKAGE_PRIVATE)
+public final class OpusDecoder
     extends SimpleDecoder<DecoderInputBuffer, SimpleOutputBuffer, OpusDecoderException> {
 
   private static final int NO_ERROR = 0;
diff --git a/extensions/vp9/proguard-rules.txt b/extensions/vp9/proguard-rules.txt
index d64773da2f..c3cd063680 100644
--- a/extensions/vp9/proguard-rules.txt
+++ b/extensions/vp9/proguard-rules.txt
@@ -6,6 +6,6 @@
 }
 
 # Some members of this class are being accessed from native methods. Keep them unobfuscated.
--keep class com.google.android.exoplayer2.ext.vp9.VpxOutputBuffer {
+-keep class com.google.android.exoplayer2.video.VideoDecoderOutputBuffer {
     *;
 }
diff --git a/extensions/vp9/src/main/java/com/google/android/exoplayer2/ext/vp9/VpxDecoder.java b/extensions/vp9/src/main/java/com/google/android/exoplayer2/ext/vp9/VpxDecoder.java
index ce0873ad40..021ce3a946 100644
--- a/extensions/vp9/src/main/java/com/google/android/exoplayer2/ext/vp9/VpxDecoder.java
+++ b/extensions/vp9/src/main/java/com/google/android/exoplayer2/ext/vp9/VpxDecoder.java
@@ -15,8 +15,11 @@
  */
 package com.google.android.exoplayer2.ext.vp9;
 
+import static androidx.annotation.VisibleForTesting.PACKAGE_PRIVATE;
+
 import android.view.Surface;
 import androidx.annotation.Nullable;
+import androidx.annotation.VisibleForTesting;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.decoder.CryptoInfo;
 import com.google.android.exoplayer2.decoder.DecoderInputBuffer;
@@ -30,7 +33,8 @@ import com.google.android.exoplayer2.video.VideoDecoderOutputBuffer;
 import java.nio.ByteBuffer;
 
 /** Vpx decoder. */
-/* package */ final class VpxDecoder
+@VisibleForTesting(otherwise = PACKAGE_PRIVATE)
+public final class VpxDecoder
     extends SimpleDecoder<VideoDecoderInputBuffer, VideoDecoderOutputBuffer, VpxDecoderException> {
 
   // These constants should match the codes returned from vpxDecode and vpxSecureDecode functions in
diff --git a/library/core/proguard-rules.txt b/library/core/proguard-rules.txt
index 67c33679cd..3623e8f926 100644
--- a/library/core/proguard-rules.txt
+++ b/library/core/proguard-rules.txt
@@ -5,17 +5,6 @@
   public static android.net.Uri buildRawResourceUri(int);
 }
 
-# Methods accessed via reflection in DefaultExtractorsFactory
--dontnote com.google.android.exoplayer2.ext.flac.FlacLibrary
--keepclassmembers class com.google.android.exoplayer2.ext.flac.FlacLibrary {
-  public static boolean isAvailable();
-}
-
-# Some members of this class are being accessed from native methods. Keep them unobfuscated.
--keep class com.google.android.exoplayer2.video.VideoDecoderOutputBuffer {
-  *;
-}
-
 # Constructors accessed via reflection in DefaultRenderersFactory
 -dontnote com.google.android.exoplayer2.ext.vp9.LibvpxVideoRenderer
 -keepclassmembers class com.google.android.exoplayer2.ext.vp9.LibvpxVideoRenderer {
diff --git a/library/extractor/proguard-rules.txt b/library/extractor/proguard-rules.txt
index d79f79a4a1..c39f894dfe 100644
--- a/library/extractor/proguard-rules.txt
+++ b/library/extractor/proguard-rules.txt
@@ -1,10 +1,14 @@
 # Proguard rules specific to the extractor module.
 
-# Constructors accessed via reflection in DefaultExtractorsFactory
+# Methods accessed via reflection in DefaultExtractorsFactory
 -dontnote com.google.android.exoplayer2.ext.flac.FlacExtractor
 -keepclassmembers class com.google.android.exoplayer2.ext.flac.FlacExtractor {
   <init>(int);
 }
+-dontnote com.google.android.exoplayer2.ext.flac.FlacLibrary
+-keepclassmembers class com.google.android.exoplayer2.ext.flac.FlacLibrary {
+  public static boolean isAvailable();
+}
 
 # Don't warn about checkerframework and Kotlin annotations
 -dontwarn org.checkerframework.**
diff --git a/library/ui/proguard-rules.txt b/library/ui/proguard-rules.txt
index ad7c139ea8..111a79c916 100644
--- a/library/ui/proguard-rules.txt
+++ b/library/ui/proguard-rules.txt
@@ -11,6 +11,16 @@
   public androidx.appcompat.app.AlertDialog$Builder setNegativeButton(int, android.content.DialogInterface$OnClickListener);
   public androidx.appcompat.app.AlertDialog create();
 }
+-dontnote android.support.v7.app.AlertDialog.Builder
+-keepclassmembers class android.support.v7.app.AlertDialog$Builder {
+  <init>(android.content.Context, int);
+  public android.content.Context getContext();
+  public android.support.v7.app.AlertDialog$Builder setTitle(java.lang.CharSequence);
+  public android.support.v7.app.AlertDialog$Builder setView(android.view.View);
+  public android.support.v7.app.AlertDialog$Builder setPositiveButton(int, android.content.DialogInterface$OnClickListener);
+  public android.support.v7.app.AlertDialog$Builder setNegativeButton(int, android.content.DialogInterface$OnClickListener);
+  public android.support.v7.app.AlertDialog create();
+}
 
 # Don't warn about checkerframework and Kotlin annotations
 -dontwarn org.checkerframework.**