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Merge pull request #1315 from datdoantelus:ClosedCaption_708Decoder_bugfix

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PiperOrigin-RevId: 636591170
This commit is contained in:
Copybara-Service 2024-05-23 10:18:02 -07:00
commit 0a58832d85
3 changed files with 90 additions and 2 deletions
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3
RELEASENOTES.md
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@ -512,6 +512,9 @@ This release includes the following changes since the
`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).
* CEA-708: Avoid duplicate newlines being added by ExoPlayer's naive
handling of the 'set pen location' command
([#1315](https://github.com/androidx/media/pull/1315)).
* Image:
* Add support for DASH thumbnails. Grid images are cropped and individual
thumbnails are provided to `ImageOutput` close to their presentation

4
libraries/extractor/src/main/java/androidx/media3/extractor/text/cea/Cea708Decoder.java
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@ -778,11 +778,9 @@ public final class Cea708Decoder extends CeaDecoder {
// first byte
captionChannelPacketData.skipBits(2); // null padding
boolean visible = 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();
@ -1228,6 +1226,8 @@ public final class Cea708Decoder extends CeaDecoder {
|| rolledUpCaptions.size() >= MAXIMUM_ROW_COUNT) {
rolledUpCaptions.remove(0);
}
// update row value after newline
row = rolledUpCaptions.size();
} else {
captionStringBuilder.append(text);
}

85
libraries/extractor/src/test/java/androidx/media3/extractor/text/cea/Cea708DecoderTest.java
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@ -118,6 +118,91 @@ public class Cea708DecoderTest {
assertThat(getOnlyCue(result).text.toString()).isEqualTo("row3\nrow4");
}
/**
* ExoPlayer's incomplete implementation of the 'set pen location' command appends a newline if
* the 'new' row location is different to the 'current' row (this is to ensure that subtitles that
* are meant to be on different lines aren't concatenated together on a single line). This test
* demonstrates this, even though the target row is 2, only a single newline is appended.
*/
@Test
public void setPenLocation_appendsNewlineIfRowChanges() 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
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)
// COMMAND_SPL with row 2 and column 0
byte[] setPenLocation = TestUtil.createByteArray(0x92, 0x02, 0x00);
byte[] subtitleData =
encodePacketIntoBytePairs(
createPacket(
/* sequenceNumber= */ 0,
createServiceBlock(
Bytes.concat(
windowDefinition,
setCurrentWindow,
"line1".getBytes(Charsets.UTF_8),
setPenLocation,
"line2".getBytes(Charsets.UTF_8)))));
Subtitle firstSubtitle = decodeSampleAndCopyResult(cea708Decoder, subtitleData);
assertThat(getOnlyCue(firstSubtitle).text.toString()).isEqualTo("line1\nline2");
}
/**
* ExoPlayer's incomplete implementation of the 'set pen location' command appends a newline if
* the 'new' row location is different to the 'current' row (this is to ensure that subtitles that
* are meant to be on different lines aren't concatenated together on a single line). This test
* ensures that if there's already an explicit newline appended before the command, a duplicate
* newline isn't appended.
*/
@Test
public void setPenLocation_explicitNewLineBefore_secondNewlineNotAdded() 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
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)
// COMMAND_SPL with row 1 and column 0
byte[] setPenLocation = TestUtil.createByteArray(0x92, 0x01, 0x00);
byte[] newLine = TestUtil.createByteArray(0x0D); // new line
byte[] subtitleData =
encodePacketIntoBytePairs(
createPacket(
/* sequenceNumber= */ 0,
createServiceBlock(
Bytes.concat(
windowDefinition,
setCurrentWindow,
"line1".getBytes(Charsets.UTF_8),
newLine,
setPenLocation,
"line2".getBytes(Charsets.UTF_8)))));
Subtitle firstSubtitle = decodeSampleAndCopyResult(cea708Decoder, subtitleData);
assertThat(getOnlyCue(firstSubtitle).text.toString()).isEqualTo("line1\nline2");
}
/**
* Queues {@code sample} to {@code decoder} and dequeues the result, then copies and returns it if
* it's non-null.