Fix limit calculation to include offset in Cea6/708Parser.parse

PiperOrigin-RevId: 595007390

libraries/extractor/src/main/java/androidx/media3/extractor/text/cea/Cea608Parser.java

@@ -439,7 +439,7 @@ public final class Cea608Parser implements SubtitleParser {
       int length,
       OutputOptions outputOptions,
       Consumer<CuesWithTiming> output) {
-    ccData.reset(data, length);
+    ccData.reset(data, offset + length);
     ccData.setPosition(offset);
     boolean captionDataProcessed = false;
     while (ccData.bytesLeft() >= packetLength) {

libraries/extractor/src/main/java/androidx/media3/extractor/text/cea/Cea708Parser.java

@@ -215,7 +215,7 @@ public final class Cea708Parser implements SubtitleParser {
       int length,
       OutputOptions outputOptions,
       Consumer<CuesWithTiming> output) {
-    ccData.reset(data, length);
+    ccData.reset(data, offset + length);
     ccData.setPosition(offset);
     while (ccData.bytesLeft() >= 3) {
       int ccTypeAndValid = (ccData.readUnsignedByte() & 0x07);

libraries/extractor/src/test/java/androidx/media3/extractor/text/cea/Cea608ParserTest.java

@@ -75,6 +75,53 @@ public class Cea608ParserTest {
         .isEqualTo("test subtitle, spans 2 samples");
   }
 
+  @Test
+  public void paintOnEmitsSubtitlesImmediately_respectsOffsetAndLimit() throws Exception {
+    Cea608Parser cea608Parser =
+        new Cea608Parser(
+            MimeTypes.APPLICATION_CEA608,
+            /* accessibilityChannel= */ 1,
+            Cea608Parser.MIN_DATA_CHANNEL_TIMEOUT_MS);
+    byte[] sample1 =
+        Bytes.concat(
+            // 'paint on' control character
+            createPacket(0xFC, 0x14, 0x29),
+            createPacket(0xFC, 't', 'e'),
+            createPacket(0xFC, 's', 't'),
+            createPacket(0xFC, ' ', 's'),
+            createPacket(0xFC, 'u', 'b'),
+            createPacket(0xFC, 't', 'i'),
+            createPacket(0xFC, 't', 'l'),
+            createPacket(0xFC, 'e', ','),
+            createPacket(0xFC, ' ', 's'),
+            createPacket(0xFC, 'p', 'a'));
+    byte[] sample2 =
+        Bytes.concat(
+            createPacket(0xFC, 'n', 's'),
+            createPacket(0xFC, ' ', '2'),
+            createPacket(0xFC, ' ', 's'),
+            createPacket(0xFC, 'a', 'm'),
+            createPacket(0xFC, 'p', 'l'),
+            createPacket(0xFC, 'e', 's'));
+    byte[] bothSamples = Bytes.concat(sample1, sample2);
+
+    CuesWithTiming firstCues =
+        checkNotNull(
+            parseSample(cea608Parser, bothSamples, /* offset= */ 0, /* length= */ sample1.length));
+    CuesWithTiming secondCues =
+        checkNotNull(
+            parseSample(
+                cea608Parser,
+                bothSamples,
+                /* offset= */ sample1.length,
+                /* length= */ sample2.length));
+
+    assertThat(Iterables.getOnlyElement(firstCues.cues).text.toString())
+        .isEqualTo("test subtitle, spa");
+    assertThat(Iterables.getOnlyElement(secondCues.cues).text.toString())
+        .isEqualTo("test subtitle, spans 2 samples");
+  }
+
   @Test
   public void rollUpEmitsSubtitlesImmediately() throws Exception {
     Cea608Parser cea608Parser =
@@ -335,8 +382,18 @@ public class Cea608ParserTest {
   @Nullable
   private static CuesWithTiming parseSample(Cea608Parser parser, byte[] sample)
       throws SubtitleDecoderException {
+    return parseSample(parser, sample, /* offset= */ 0, /* length= */ sample.length);
+  }
+
+  /**
+   * Passes {@code sample} to {@link Cea608Parser#parse} and returns either the emitted {@link
+   * CuesWithTiming} or null if none was emitted.
+   */
+  @Nullable
+  private static CuesWithTiming parseSample(
+      Cea608Parser parser, byte[] sample, int offset, int length) {
     List<CuesWithTiming> result = new ArrayList<>();
-    parser.parse(sample, OutputOptions.allCues(), result::add);
+    parser.parse(sample, offset, length, OutputOptions.allCues(), result::add);
     return result.isEmpty() ? null : Iterables.getOnlyElement(result);
   }
 }

libraries/extractor/src/test/java/androidx/media3/extractor/text/cea/Cea708ParserTest.java

@@ -31,10 +31,8 @@ import com.google.common.primitives.Bytes;
 import com.google.common.primitives.UnsignedBytes;
 import java.util.ArrayList;
 import java.util.List;
-import org.junit.Before;
 import org.junit.Test;
 import org.junit.runner.RunWith;
-import org.robolectric.shadows.ShadowLog;
 
 /** Tests for {@link Cea708Parser}. */
 @RunWith(AndroidJUnit4.class)
@@ -44,11 +42,6 @@ public class Cea708ParserTest {
   private static final byte CHANNEL_PACKET_DATA = 0x6;
   private static final byte CHANNEL_PACKET_END = 0x2;
 
-  @Before
-  public void setupLogging() {
-    ShadowLog.stream = System.out;
-  }
-
   @Test
   public void singleServiceAndWindowDefinition() throws Exception {
     Cea708Parser cea708Parser =
@@ -81,6 +74,47 @@ public class Cea708ParserTest {
         .isEqualTo("test subtitle");
   }
 
+  @Test
+  public void singleServiceAndWindowDefinition_respectsOffsetAndLimit() throws Exception {
+    Cea708Parser cea708Parser =
+        new Cea708Parser(
+            /* accessibilityChannel= */ Format.NO_VALUE, /* initializationData= */ null);
+    byte[] windowDefinition =
+        TestUtil.createByteArray(
+            0x98, // DF0 command (define window 0)
+            0b0010_0000, // visible=true, row lock and column lock disabled, priority=0
+            0xF0 | 50, // relative positioning, anchor vertical
+            50, // anchor horizontal
+            10, // anchor point = 0, row count = 10
+            30, // column count = 30
+            0b0000_1001); // window style = 1, pen style = 1
+    byte[] setCurrentWindow = TestUtil.createByteArray(0x80); // CW0 (set current window to 0)
+    byte[] subtitleData =
+        encodePacketIntoBytePairs(
+            createPacket(
+                /* sequenceNumber= */ 0,
+                createServiceBlock(
+                    Bytes.concat(
+                        windowDefinition,
+                        setCurrentWindow,
+                        "test subtitle".getBytes(Charsets.UTF_8)))));
+    byte[] garbagePrefix = TestUtil.buildTestData(subtitleData.length * 2);
+    byte[] garbageSuffix = TestUtil.buildTestData(10);
+    byte[] subtitleDataWithGarbagePrefixAndSuffix =
+        Bytes.concat(garbagePrefix, subtitleData, garbageSuffix);
+
+    List<CuesWithTiming> result = new ArrayList<>();
+    cea708Parser.parse(
+        subtitleDataWithGarbagePrefixAndSuffix,
+        garbagePrefix.length,
+        subtitleData.length,
+        SubtitleParser.OutputOptions.allCues(),
+        result::add);
+
+    assertThat(Iterables.getOnlyElement(Iterables.getOnlyElement(result).cues).text.toString())
+        .isEqualTo("test subtitle");
+  }
+
   /** See section 4.4.1 of the CEA-708-B spec. */
   private static byte[] encodePacketIntoBytePairs(byte[] packet) {
     checkState(packet.length % 2 == 0);