Catch-and-log all subtitle decode errors

issue:#6885
PiperOrigin-RevId: 295931197

RELEASENOTES.md

 # Release notes #
 
+### 2.11.4 (not yet released) ###
+
+* Text: Catch-and-log all fatal exceptions in `TextRenderer` instead of
+  re-throwing, allowing playback to continue even if subtitles fail
+  ([#6885](https://github.com/google/ExoPlayer/issues/6885)).
+
 ### 2.11.3 (2020-02-19) ###
 
 * SmoothStreaming: Fix regression that broke playback in 2.11.2

library/core/src/main/java/com/google/android/exoplayer2/decoder/SimpleDecoder.java

@@ -149,6 +149,7 @@ public abstract class SimpleDecoder<
       while (!queuedOutputBuffers.isEmpty()) {
         queuedOutputBuffers.removeFirst().release();
       }
+      exception = null;
     }
   }
 
@@ -225,6 +226,7 @@ public abstract class SimpleDecoder<
       if (inputBuffer.isDecodeOnly()) {
         outputBuffer.addFlag(C.BUFFER_FLAG_DECODE_ONLY);
       }
+      @Nullable E exception;
       try {
         exception = decode(inputBuffer, outputBuffer, resetDecoder);
       } catch (RuntimeException e) {
@@ -238,8 +240,9 @@ public abstract class SimpleDecoder<
         exception = createUnexpectedDecodeException(e);
       }
       if (exception != null) {
-        // Memory barrier to ensure that the decoder exception is visible from the playback thread.
-        synchronized (lock) {}
+        synchronized (lock) {
+          this.exception = exception;
+        }
         return false;
       }
     }

library/core/src/main/java/com/google/android/exoplayer2/text/TextRenderer.java

@@ -23,11 +23,11 @@ import androidx.annotation.IntDef;
 import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.BaseRenderer;
 import com.google.android.exoplayer2.C;
-import com.google.android.exoplayer2.ExoPlaybackException;
 import com.google.android.exoplayer2.Format;
 import com.google.android.exoplayer2.FormatHolder;
 import com.google.android.exoplayer2.RendererCapabilities;
 import com.google.android.exoplayer2.util.Assertions;
+import com.google.android.exoplayer2.util.Log;
 import com.google.android.exoplayer2.util.MimeTypes;
 import com.google.android.exoplayer2.util.Util;
 import java.lang.annotation.Documented;
@@ -45,6 +45,8 @@ import java.util.List;
  */
 public final class TextRenderer extends BaseRenderer implements Callback {
 
+  private static final String TAG = "TextRenderer";
+
   @Documented
   @Retention(RetentionPolicy.SOURCE)
   @IntDef({
@@ -143,19 +145,13 @@ public final class TextRenderer extends BaseRenderer implements Callback {
 
   @Override
   protected void onPositionReset(long positionUs, boolean joining) {
-    clearOutput();
     inputStreamEnded = false;
     outputStreamEnded = false;
-    if (decoderReplacementState != REPLACEMENT_STATE_NONE) {
-      replaceDecoder();
-    } else {
-      releaseBuffers();
-      decoder.flush();
-    }
+    resetOutputAndDecoder();
   }
 
   @Override
-  public void render(long positionUs, long elapsedRealtimeUs) throws ExoPlaybackException {
+  public void render(long positionUs, long elapsedRealtimeUs) {
     if (outputStreamEnded) {
       return;
     }
@@ -165,7 +161,8 @@ public final class TextRenderer extends BaseRenderer implements Callback {
       try {
         nextSubtitle = decoder.dequeueOutputBuffer();
       } catch (SubtitleDecoderException e) {
-        throw createRendererException(e, streamFormat);
+        handleDecoderError(e);
+        return;
       }
     }
 
@@ -247,7 +244,8 @@ public final class TextRenderer extends BaseRenderer implements Callback {
         }
       }
     } catch (SubtitleDecoderException e) {
-      throw createRendererException(e, streamFormat);
+      handleDecoderError(e);
+      return;
     }
   }
 
@@ -329,4 +327,24 @@ public final class TextRenderer extends BaseRenderer implements Callback {
     output.onCues(cues);
   }
 
+  /**
+   * Called when {@link #decoder} throws an exception, so it can be logged and playback can
+   * continue.
+   *
+   * <p>Logs {@code e} and resets state to allow decoding the next sample.
+   */
+  private void handleDecoderError(SubtitleDecoderException e) {
+    Log.e(TAG, "Subtitle decoding failed. streamFormat=" + streamFormat, e);
+    resetOutputAndDecoder();
+  }
+
+  private void resetOutputAndDecoder() {
+    clearOutput();
+    if (decoderReplacementState != REPLACEMENT_STATE_NONE) {
+      replaceDecoder();
+    } else {
+      releaseBuffers();
+      decoder.flush();
+    }
+  }
 }