Add non-strict SubRip parsing (enabled by default).

library/src/androidTest/assets/subrip/typical

@@ -5,4 +5,8 @@ This is the first subtitle.
 2
 00:00:02,345 --> 00:00:03,456
 This is the second subtitle.
-Second subtitle with second line.
+Second subtitle with second line.
+
+3
+00:00:04,567 --> 00:00:08,901
+This is the third subtitle.

library/src/androidTest/assets/subrip/typical_extra_blank_line

@@ -0,0 +1,13 @@
+1
+00:00:00,000 --> 00:00:01,234
+This is the first subtitle.
+
+
+2
+00:00:02,345 --> 00:00:03,456
+This is the second subtitle.
+Second subtitle with second line.
+
+3
+00:00:04,567 --> 00:00:08,901
+This is the third subtitle.

library/src/androidTest/assets/subrip/typical_missing_sequence

@@ -0,0 +1,11 @@
+1
+00:00:00,000 --> 00:00:01,234
+This is the first subtitle.
+
+00:00:02,345 --> 00:00:03,456
+This is the second subtitle.
+Second subtitle with second line.
+
+3
+00:00:04,567 --> 00:00:08,901
+This is the third subtitle.

library/src/androidTest/assets/subrip/typical_missing_timecode

@@ -0,0 +1,11 @@
+1
+00:00:00,000 --> 00:00:01,234
+This is the first subtitle.
+
+2
+This is the second subtitle.
+Second subtitle with second line.
+
+3
+00:00:04,567 --> 00:00:08,901
+This is the third subtitle.

library/src/androidTest/java/com/google/android/exoplayer/text/subrip/SubripParserTest.java

@@ -15,6 +15,8 @@
  */
 package com.google.android.exoplayer.text.subrip;
 
+import com.google.android.exoplayer.ParserException;
+
 import android.test.InstrumentationTestCase;
 
 import java.io.IOException;
@@ -27,44 +29,83 @@ public final class SubripParserTest extends InstrumentationTestCase {
 
   private static final String EMPTY_FILE = "subrip/empty";
   private static final String TYPICAL_FILE = "subrip/typical";
+  private static final String TYPICAL_EXTRA_BLANK_LINE = "subrip/typical_extra_blank_line";
+  private static final String TYPICAL_MISSING_TIMECODE = "subrip/typical_missing_timecode";
+  private static final String TYPICAL_MISSING_SEQUENCE = "subrip/typical_missing_sequence";
   private static final String NO_END_TIMECODES_FILE = "subrip/no_end_timecodes";
 
-  public void testParseEmptySubripFile() throws IOException {
-    SubripParser parser = new SubripParser();
-    InputStream inputStream =
-        getInstrumentation().getContext().getResources().getAssets().open(EMPTY_FILE);
+  public void testParseEmpty() throws IOException {
+    SubripParser parser = new SubripParser(true);
+    InputStream inputStream = getInputStream(EMPTY_FILE);
     SubripSubtitle subtitle = parser.parse(inputStream);
     // Assert that the subtitle is empty.
     assertEquals(0, subtitle.getEventTimeCount());
     assertTrue(subtitle.getCues(0).isEmpty());
   }
 
-  public void testParseTypicalSubripFile() throws IOException {
-    SubripParser parser = new SubripParser();
-    InputStream inputStream =
-        getInstrumentation().getContext().getResources().getAssets().open(TYPICAL_FILE);
+  public void testParseTypical() throws IOException {
+    SubripParser parser = new SubripParser(true);
+    InputStream inputStream = getInputStream(TYPICAL_FILE);
     SubripSubtitle subtitle = parser.parse(inputStream);
+    assertEquals(6, subtitle.getEventTimeCount());
+    assertTypicalCue1(subtitle, 0);
+    assertTypicalCue2(subtitle, 2);
+    assertTypicalCue3(subtitle, 4);
+  }
 
-    // Test event count.
+  public void testParseTypicalExtraBlankLine() throws IOException {
+    SubripParser parser = new SubripParser(true);
+    InputStream inputStream = getInputStream(TYPICAL_EXTRA_BLANK_LINE);
+    SubripSubtitle subtitle = parser.parse(inputStream);
+    assertEquals(6, subtitle.getEventTimeCount());
+    assertTypicalCue1(subtitle, 0);
+    assertTypicalCue2(subtitle, 2);
+    assertTypicalCue3(subtitle, 4);
+  }
+
+  public void testParseTypicalMissingTimecode() throws IOException {
+    // Strict parsing should fail.
+    SubripParser parser = new SubripParser(true);
+    InputStream inputStream = getInputStream(TYPICAL_MISSING_TIMECODE);
+    try {
+      parser.parse(inputStream);
+      fail();
+    } catch (ParserException e) {
+      // Expected.
+    }
+
+    // Non-strict parsing should succeed, parsing the first and third cues only.
+    parser = new SubripParser(false);
+    inputStream = getInputStream(TYPICAL_MISSING_TIMECODE);
+    SubripSubtitle subtitle = parser.parse(inputStream);
     assertEquals(4, subtitle.getEventTimeCount());
+    assertTypicalCue1(subtitle, 0);
+    assertTypicalCue3(subtitle, 2);
+  }
 
-    // Test first cue.
-    assertEquals(0, subtitle.getEventTime(0));
-    assertEquals("This is the first subtitle.",
-        subtitle.getCues(subtitle.getEventTime(0)).get(0).text.toString());
-    assertEquals(1234000, subtitle.getEventTime(1));
+  public void testParseTypicalMissingSequence() throws IOException {
+    // Strict parsing should fail.
+    SubripParser parser = new SubripParser(true);
+    InputStream inputStream = getInputStream(TYPICAL_MISSING_SEQUENCE);
+    try {
+      parser.parse(inputStream);
+      fail();
+    } catch (ParserException e) {
+      // Expected.
+    }
 
-    // Test second cue.
-    assertEquals(2345000, subtitle.getEventTime(2));
-    assertEquals("This is the second subtitle.\nSecond subtitle with second line.",
-        subtitle.getCues(subtitle.getEventTime(2)).get(0).text.toString());
-    assertEquals(3456000, subtitle.getEventTime(3));
+    // Non-strict parsing should succeed, parsing the first and third cues only.
+    parser = new SubripParser(false);
+    inputStream = getInputStream(TYPICAL_MISSING_SEQUENCE);
+    SubripSubtitle subtitle = parser.parse(inputStream);
+    assertEquals(4, subtitle.getEventTimeCount());
+    assertTypicalCue1(subtitle, 0);
+    assertTypicalCue3(subtitle, 2);
   }
 
   public void testParseNoEndTimecodes() throws IOException {
-    SubripParser parser = new SubripParser();
-    InputStream inputStream = getInstrumentation().getContext().getResources().getAssets()
-        .open(NO_END_TIMECODES_FILE);
+    SubripParser parser = new SubripParser(true);
+    InputStream inputStream = getInputStream(NO_END_TIMECODES_FILE);
     SubripSubtitle subtitle = parser.parse(inputStream);
 
     // Test event count.
@@ -86,4 +127,29 @@ public final class SubripParserTest extends InstrumentationTestCase {
         subtitle.getCues(subtitle.getEventTime(2)).get(0).text.toString());
   }
 
+  private InputStream getInputStream(String fileName) throws IOException {
+    return getInstrumentation().getContext().getResources().getAssets().open(fileName);
+  }
+
+  private static void assertTypicalCue1(SubripSubtitle subtitle, int eventIndex) {
+    assertEquals(0, subtitle.getEventTime(eventIndex));
+    assertEquals("This is the first subtitle.",
+        subtitle.getCues(subtitle.getEventTime(eventIndex)).get(0).text.toString());
+    assertEquals(1234000, subtitle.getEventTime(eventIndex + 1));
+  }
+
+  private static void assertTypicalCue2(SubripSubtitle subtitle, int eventIndex) {
+    assertEquals(2345000, subtitle.getEventTime(eventIndex));
+    assertEquals("This is the second subtitle.\nSecond subtitle with second line.",
+        subtitle.getCues(subtitle.getEventTime(eventIndex)).get(0).text.toString());
+    assertEquals(3456000, subtitle.getEventTime(eventIndex + 1));
+  }
+
+  private static void assertTypicalCue3(SubripSubtitle subtitle, int eventIndex) {
+    assertEquals(4567000, subtitle.getEventTime(eventIndex));
+    assertEquals("This is the third subtitle.",
+        subtitle.getCues(subtitle.getEventTime(eventIndex)).get(0).text.toString());
+    assertEquals(8901000, subtitle.getEventTime(eventIndex + 1));
+  }
+
 }

library/src/main/java/com/google/android/exoplayer/text/subrip/SubripParser.java

@@ -25,6 +25,7 @@ import com.google.android.exoplayer.util.MimeTypes;
 import android.text.Html;
 import android.text.Spanned;
 import android.text.TextUtils;
+import android.util.Log;
 
 import java.io.BufferedReader;
 import java.io.IOException;
@@ -39,13 +40,30 @@ import java.util.regex.Pattern;
  */
 public final class SubripParser implements SubtitleParser {
 
+  private static final String TAG = "SubripParser";
+
   private static final Pattern SUBRIP_TIMING_LINE = Pattern.compile("(\\S*)\\s*-->\\s*(\\S*)");
   private static final Pattern SUBRIP_TIMESTAMP =
       Pattern.compile("(?:(\\d+):)?(\\d+):(\\d+),(\\d+)");
 
   private final StringBuilder textBuilder;
+  private final boolean strictParsing;
 
+  /**
+   * Equivalent to {@code SubripParser(false)}.
+   */
   public SubripParser() {
+    this(false);
+  }
+
+  /**
+   * @param strictParsing If true, {@link #parse(InputStream)} will throw a {@link ParserException}
+   *     if the stream contains invalid data. If false, the parser will make a best effort to ignore
+   *     minor errors in the stream. Note however that a {@link ParserException} will still be
+   *     thrown when this is not possible.
+   */
+  public SubripParser(boolean strictParsing) {
+    this.strictParsing = strictParsing;
     textBuilder = new StringBuilder();
   }
 
@@ -58,15 +76,21 @@ public final class SubripParser implements SubtitleParser {
     String currentLine;
 
     while ((currentLine = reader.readLine()) != null) {
-      // Skip blank lines.
-      if (currentLine.length() == 0)
+      if (currentLine.length() == 0) {
+        // Skip blank lines.
         continue;
+      }
 
-      // Parse the numeric counter as a sanity check.
+      // Parse the index line as a sanity check.
       try {
         Integer.parseInt(currentLine);
       } catch (NumberFormatException e) {
-        throw new ParserException("Expected numeric counter: " + currentLine);
+        if (!strictParsing) {
+          Log.w(TAG, "Skipping invalid index: " + currentLine);
+          continue;
+        } else {
+          throw new ParserException("Expected numeric counter: " + currentLine);
+        }
       }
 
       // Read and parse the timing line.
@@ -80,6 +104,9 @@ public final class SubripParser implements SubtitleParser {
           haveEndTimecode = true;
           cueTimesUs.add(parseTimecode(matcher.group(2)));
         }
+      } else if (!strictParsing) {
+        Log.w(TAG, "Skipping invalid timing: " + currentLine);
+        continue;
       } else {
         throw new ParserException("Expected timing line: " + currentLine);
       }

library/src/main/java/com/google/android/exoplayer/text/ttml/TtmlParser.java

@@ -135,7 +135,7 @@ public final class TtmlParser implements SubtitleParser {
                 if (strictParsing) {
                   throw e;
                 } else {
-                  Log.e(TAG, "Suppressing parser error", e);
+                  Log.w(TAG, "Suppressing parser error", e);
                   // Treat the node (and by extension, all of its children) as unsupported.
                   unsupportedNodeDepth++;
                 }