diff --git a/library/core/src/main/java/com/google/android/exoplayer2/BaseRenderer.java b/library/core/src/main/java/com/google/android/exoplayer2/BaseRenderer.java
index fa161a35c9..902350e900 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/BaseRenderer.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/BaseRenderer.java
@@ -30,11 +30,11 @@ public abstract class BaseRenderer implements Renderer, RendererCapabilities {
   private final int trackType;
   private final FormatHolder formatHolder;
 
-  private RendererConfiguration configuration;
+  @Nullable private RendererConfiguration configuration;
   private int index;
   private int state;
-  private SampleStream stream;
-  private Format[] streamFormats;
+  @Nullable private SampleStream stream;
+  @Nullable private Format[] streamFormats;
   private long streamOffsetUs;
   private long lastResetPositionUs;
   private long readingPositionUs;
@@ -144,7 +144,7 @@ public abstract class BaseRenderer implements Renderer, RendererCapabilities {
 
   @Override
   public final void maybeThrowStreamError() throws IOException {
-    stream.maybeThrowError();
+    Assertions.checkNotNull(stream).maybeThrowError();
   }
 
   @Override
@@ -303,16 +303,24 @@ public abstract class BaseRenderer implements Renderer, RendererCapabilities {
     return formatHolder;
   }
 
-  /** Returns the formats of the currently enabled stream. */
+  /**
+   * Returns the formats of the currently enabled stream.
+   *
+   * <p>This method may be called when the renderer is in the following states: {@link
+   * #STATE_ENABLED}, {@link #STATE_STARTED}.
+   */
   protected final Format[] getStreamFormats() {
-    return streamFormats;
+    return Assertions.checkNotNull(streamFormats);
   }
 
   /**
    * Returns the configuration set when the renderer was most recently enabled.
+   *
+   * <p>This method may be called when the renderer is in the following states: {@link
+   * #STATE_ENABLED}, {@link #STATE_STARTED}.
    */
   protected final RendererConfiguration getConfiguration() {
-    return configuration;
+    return Assertions.checkNotNull(configuration);
   }
 
   /**
@@ -352,6 +360,9 @@ public abstract class BaseRenderer implements Renderer, RendererCapabilities {
    * {@link C#RESULT_BUFFER_READ} is only returned if {@link #setCurrentStreamFinal()} has been
    * called. {@link C#RESULT_NOTHING_READ} is returned otherwise.
    *
+   * <p>This method may be called when the renderer is in the following states: {@link
+   * #STATE_ENABLED}, {@link #STATE_STARTED}.
+   *
    * @param formatHolder A {@link FormatHolder} to populate in the case of reading a format.
    * @param buffer A {@link DecoderInputBuffer} to populate in the case of reading a sample or the
    *     end of the stream. If the end of the stream has been reached, the {@link
@@ -364,7 +375,8 @@ public abstract class BaseRenderer implements Renderer, RendererCapabilities {
   @SampleStream.ReadDataResult
   protected final int readSource(
       FormatHolder formatHolder, DecoderInputBuffer buffer, boolean formatRequired) {
-    @SampleStream.ReadDataResult int result = stream.readData(formatHolder, buffer, formatRequired);
+    @SampleStream.ReadDataResult
+    int result = Assertions.checkNotNull(stream).readData(formatHolder, buffer, formatRequired);
     if (result == C.RESULT_BUFFER_READ) {
       if (buffer.isEndOfStream()) {
         readingPositionUs = C.TIME_END_OF_SOURCE;
@@ -373,7 +385,7 @@ public abstract class BaseRenderer implements Renderer, RendererCapabilities {
       buffer.timeUs += streamOffsetUs;
       readingPositionUs = Math.max(readingPositionUs, buffer.timeUs);
     } else if (result == C.RESULT_FORMAT_READ) {
-      Format format = formatHolder.format;
+      Format format = Assertions.checkNotNull(formatHolder.format);
       if (format.subsampleOffsetUs != Format.OFFSET_SAMPLE_RELATIVE) {
         format =
             format
@@ -390,17 +402,23 @@ public abstract class BaseRenderer implements Renderer, RendererCapabilities {
    * Attempts to skip to the keyframe before the specified position, or to the end of the stream if
    * {@code positionUs} is beyond it.
    *
+   * <p>This method may be called when the renderer is in the following states: {@link
+   * #STATE_ENABLED}, {@link #STATE_STARTED}.
+   *
    * @param positionUs The position in microseconds.
    * @return The number of samples that were skipped.
    */
   protected int skipSource(long positionUs) {
-    return stream.skipData(positionUs - streamOffsetUs);
+    return Assertions.checkNotNull(stream).skipData(positionUs - streamOffsetUs);
   }
 
   /**
    * Returns whether the upstream source is ready.
+   *
+   * <p>This method may be called when the renderer is in the following states: {@link
+   * #STATE_ENABLED}, {@link #STATE_STARTED}.
    */
   protected final boolean isSourceReady() {
-    return hasReadStreamToEnd() ? streamIsFinal : stream.isReady();
+    return hasReadStreamToEnd() ? streamIsFinal : Assertions.checkNotNull(stream).isReady();
   }
 }