Re-apply CEA-708 rowLock/columnLock fix

This change was originally made in 6f8249184b

It was then accidentally lost in when `Cea708Parser` was merged back
into `Cea708Decoder` in 51b4fa2cc8.

This is the only change made to the actual 'decoding' logic in
`Cea708Parser` between it being split from `Cea708Decoder` and merged
back in again, all the other changes in this period relate to the
implementation of the `SubtitleParser` interface, so don't need to be
preserved in `Cea708Decoder`:
51b4fa2cc8/libraries/extractor/src/main/java/androidx/media3/extractor/text/cea/Cea708Parser.java

`Cea608Parser` was also merged back into `Cea608Decoder` in
25498b151b
and so is vulnerable to the same risk of accidental loss of changes. To
be sure, I also checked the history of this file:
25498b151b/libraries/extractor/src/main/java/androidx/media3/extractor/text/cea/Cea608Parser.java

The only 'decoding logic' change there is 379cb3ba54,
which was also lost in 25498b151b.
I will send a separate change to resolve this.

PiperOrigin-RevId: 635796696

RELEASENOTES.md

@@ -91,6 +91,13 @@
     *   PGS: Fix run-length decoding to resolve `0` as a color index, instead of
         a literal color value
         ([#1367](https://github.com/androidx/media/pull/1367)).
+    *   CEA-708: Ignore `rowLock` value. The CEA-708-E S-2023 spec states that
+        `rowLock` and `columnLock` should both be assumed to be true, regardless
+        of the values present in the stream (`columnLock` support is not
+        implemented, so it's effectively assumed to always be false).
+        *   This was originally included in the `1.3.0-alpha01` release notes,
+            but the change was accidentally reverted before the `1.3.0-rc01`
+            release. This is now fixed, so the change is present again.
 *   Metadata:
     *   Fix mapping of MP4 to ID3 sort tags. Previously the 'album sort'
         (`soal`), 'artist sort' (`soar`) and 'album artist sort' (`soaa`) MP4

libraries/extractor/src/main/java/androidx/media3/extractor/text/cea/Cea708Decoder.java

@@ -778,8 +778,11 @@ public final class Cea708Decoder extends CeaDecoder {
     // first byte
     captionChannelPacketData.skipBits(2); // null padding
     boolean visible = captionChannelPacketData.readBit();
-    boolean rowLock = captionChannelPacketData.readBit();
+
-    boolean columnLock = captionChannelPacketData.readBit();
+    // ANSI/CTA-708-E S-2023 spec (Section 8.4.7) indicates that rowLock and columnLock values in
+    // the media should be ignored and assumed to be true.
+    captionChannelPacketData.skipBits(2);
+
     int priority = captionChannelPacketData.readBits(3);
     // second byte
     boolean relativePositioning = captionChannelPacketData.readBit();
@@ -791,7 +794,8 @@ public final class Cea708Decoder extends CeaDecoder {
     int rowCount = captionChannelPacketData.readBits(4);
     // fifth byte
     captionChannelPacketData.skipBits(2); // null padding
-    int columnCount = captionChannelPacketData.readBits(6);
+    // TODO: Add support for column count.
+    captionChannelPacketData.skipBits(6); // column count
     // sixth byte
     captionChannelPacketData.skipBits(2); // null padding
     int windowStyle = captionChannelPacketData.readBits(3);
@@ -799,14 +803,11 @@ public final class Cea708Decoder extends CeaDecoder {
 
     cueInfoBuilder.defineWindow(
         visible,
-        rowLock,
-        columnLock,
         priority,
         relativePositioning,
         verticalAnchor,
         horizontalAnchor,
         rowCount,
-        columnCount,
         anchorId,
         windowStyle,
         penStyle);
@@ -967,7 +968,6 @@ public final class Cea708Decoder extends CeaDecoder {
     private int horizontalAnchor;
     private int anchorId;
     private int rowCount;
-    private boolean rowLock;
     private int justification;
     private int windowStyleId;
     private int penStyleId;
@@ -1003,7 +1003,6 @@ public final class Cea708Decoder extends CeaDecoder {
       horizontalAnchor = 0;
       anchorId = 0;
       rowCount = MAXIMUM_ROW_COUNT;
-      rowLock = true;
       justification = JUSTIFICATION_LEFT;
       windowStyleId = 0;
       penStyleId = 0;
@@ -1037,20 +1036,16 @@ public final class Cea708Decoder extends CeaDecoder {
 
     public void defineWindow(
         boolean visible,
-        boolean rowLock,
-        boolean columnLock,
         int priority,
         boolean relativePositioning,
         int verticalAnchor,
         int horizontalAnchor,
         int rowCount,
-        int columnCount,
         int anchorId,
         int windowStyleId,
         int penStyleId) {
       this.defined = true;
       this.visible = visible;
-      this.rowLock = rowLock;
       this.priority = priority;
       this.relativePositioning = relativePositioning;
       this.verticalAnchor = verticalAnchor;
@@ -1062,14 +1057,12 @@ public final class Cea708Decoder extends CeaDecoder {
         this.rowCount = rowCount + 1;
 
         // Trim any rolled up captions that are no longer valid, if applicable.
-        while ((rowLock && (rolledUpCaptions.size() >= this.rowCount))
+        while (rolledUpCaptions.size() >= this.rowCount
-            || (rolledUpCaptions.size() >= MAXIMUM_ROW_COUNT)) {
+            || rolledUpCaptions.size() >= MAXIMUM_ROW_COUNT) {
           rolledUpCaptions.remove(0);
         }
       }
 
-      // TODO: Add support for column lock and count.
-
       if (windowStyleId != 0 && this.windowStyleId != windowStyleId) {
         this.windowStyleId = windowStyleId;
         // windowStyleId is 1-based.
@@ -1231,8 +1224,8 @@ public final class Cea708Decoder extends CeaDecoder {
           backgroundColorStartPosition = 0;
         }
 
-        while ((rowLock && (rolledUpCaptions.size() >= rowCount))
+        while (rolledUpCaptions.size() >= rowCount
-            || (rolledUpCaptions.size() >= MAXIMUM_ROW_COUNT)) {
+            || rolledUpCaptions.size() >= MAXIMUM_ROW_COUNT) {
           rolledUpCaptions.remove(0);
         }
       } else {

libraries/extractor/src/test/java/androidx/media3/extractor/text/cea/Cea708DecoderTest.java

@@ -60,7 +60,6 @@ public class Cea708DecoderTest {
   public void singleServiceAndWindowDefinition() throws Exception {
     Cea708Decoder cea708Decoder =
         new Cea708Decoder(
-
             /* accessibilityChannel= */ Format.NO_VALUE, /* initializationData= */ null);
     byte[] windowDefinition =
         TestUtil.createByteArray(
@@ -87,6 +86,38 @@ public class Cea708DecoderTest {
     assertThat(getOnlyCue(firstSubtitle).text.toString()).isEqualTo("test subtitle");
   }
 
+  @Test
+  public void singleServiceAndWindowDefinition_ignoresRowLock() throws Exception {
+    Cea708Decoder cea708Decoder =
+        new Cea708Decoder(
+            /* 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
+            1, // anchor point = 0, row count = 1
+            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,
+                        "row1\r\nrow2\r\nrow3\r\nrow4".getBytes(Charsets.UTF_8)))));
+
+    Subtitle result = decodeSampleAndCopyResult(cea708Decoder, subtitleData);
+
+    // Row count is 1 (which means 2 rows should be kept). Row lock is disabled in the media,
+    // but this is ignored and the result is still truncated to only the last two rows.
+    assertThat(getOnlyCue(result).text.toString()).isEqualTo("row3\nrow4");
+  }
+
   /**
    * Queues {@code sample} to {@code decoder} and dequeues the result, then copies and returns it if
    * it's non-null.