move Matroska specific code back to the Matroska extractor

library/src/main/java/com/google/android/exoplayer2/extractor/mkv/MatroskaExtractor.java

@@ -56,6 +56,7 @@ import java.util.List;
 import java.util.Locale;
 import java.util.UUID;
 
+import static android.R.attr.data;
 import static android.R.attr.format;
 import static android.R.attr.longClickable;
 import static android.R.attr.mimeType;
@@ -1110,8 +1111,17 @@ public final class MatroskaExtractor implements Extractor {
     }
 
   private void writeSSASample(Track track) {
-    String s = SSADecoder.buildDialogue(track.ssaSample, blockDurationUs);
-    ParsableByteArray out = new ParsableByteArray(s.getBytes());
+    long startUs = 0; // blockTimeUs
+    StringBuffer s = new StringBuffer();
+    s.append("Dialogue: ");
+    s.append(SSADecoder.formatTimeCode(startUs));
+    s.append(",");
+    long endUs = startUs + blockDurationUs;
+    s.append(SSADecoder.formatTimeCode(endUs));
+    s.append(",");
+    s.append(track.ssaSample);
+    s.append("\n");
+    ParsableByteArray out = new ParsableByteArray(s.toString().getBytes());
     track.output.sampleData(out, out.limit());
     sampleBytesWritten += out.limit();
   }

library/src/main/java/com/google/android/exoplayer2/text/ssa/SSADecoder.java

@@ -192,22 +192,6 @@ public class SSADecoder extends SimpleSubtitleDecoder {
         return result;
     }
 
-    public static String buildDialogue(String data, long durationUs) {
-        StringBuffer s = new StringBuffer();
-        s.append("Dialogue: ");
-        s.append(SSADecoder.formatTimeCode(0)); // blockTimeUs
-        s.append(",");
-        long endUs = durationUs; // + blockTimeUs
-        if (endUs == C.TIME_UNSET) {
-            endUs = 2*_1e6; // 2 second default duration
-        }
-        s.append(SSADecoder.formatTimeCode(endUs));
-        s.append(",");
-        s.append(data);
-        s.append("\n");
-        return s.toString();
-    }
-
     public static String formatTimeCode(long tc_us) {
         long seconds = tc_us / _1e6;
         long us = tc_us - _1e6*seconds;