diff --git a/libraries/extractor/src/main/java/androidx/media3/extractor/text/vobsub/VobsubParser.java b/libraries/extractor/src/main/java/androidx/media3/extractor/text/vobsub/VobsubParser.java
index b0e4c89562..4e381bb215 100644
--- a/libraries/extractor/src/main/java/androidx/media3/extractor/text/vobsub/VobsubParser.java
+++ b/libraries/extractor/src/main/java/androidx/media3/extractor/text/vobsub/VobsubParser.java
@@ -141,6 +141,10 @@ public final class VobsubParser implements SubtitleParser {
             palette[i] = parseColor(values[i].trim());
           }
         } else if (line.startsWith("size: ")) {
+
+          // NOTE: we need this line to calculate the relative positions
+          //       and size required by Cue.Builder() below.
+
           String[] sizes = line.substring(6).trim().split("x");
 
           if (sizes.length == 2) {
@@ -166,6 +170,9 @@ public final class VobsubParser implements SubtitleParser {
 
     public void parseSpu(ParsableByteArray buffer) {
 
+      // Give up if don't have the color palette or the video size.
+      // (See also the NOTE above)
+
       if (palette == null || !hasPlane) return;
 
       int pos = buffer.getPosition();