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Fallback to displayAlign from style for TTML regions #3094

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Fallback to displayAlign from style for TTML regions #3094

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2 changes: 2 additions & 0 deletions RELEASENOTES.md
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Original file line number Diff line number Diff line change
Expand Up @@ -26,6 +26,8 @@
* Add support for skipping frames that are late during join rather than
dropping in DecoderVideoRenderer.
* Text:
* TTML: Fallback to `displayAlign` from `style` for regions
([#2559](https://github.com/androidx/media/issues/2559)).
* Metadata:
* Image:
* DataSource:
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12 changes: 12 additions & 0 deletions libraries/extractor/src/main/java/androidx/media3/extractor/text/ttml/TtmlParser.java
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Expand Up @@ -462,6 +462,15 @@ private static TtmlRegion parseRegionAttributes(
@Nullable
String displayAlign =
XmlPullParserUtil.getAttributeValue(xmlParser, TtmlNode.ATTR_TTS_DISPLAY_ALIGN);
if (displayAlign == null) {
String styleId = XmlPullParserUtil.getAttributeValue(xmlParser, TtmlNode.ATTR_STYLE);
if (styleId != null) {
TtmlStyle style = globalStyles.get(styleId);
if (style != null) {
displayAlign = style.getDisplayAlign();
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@icbaker icbaker Mar 9, 2026

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I think for consistency with the way we handle other attributes, this 'inheritance' logic should be implemented as part of TtmlStyle.chain which is invoked here:

media/libraries/extractor/src/main/java/androidx/media3/extractor/text/ttml/TtmlParser.java

Line 309 in 8bafa18

style.chain(globalStyles.get(id));

See my comment here: #2559 (comment)

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@FineFindus FineFindus Mar 9, 2026

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Done, should I also add a test for inheriting displayAlign from another style?

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@icbaker icbaker Mar 9, 2026

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You can probably tweak your existing test file to exercise this?

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@FineFindus FineFindus Mar 9, 2026

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Done.

}
}
}
if (displayAlign != null) {
switch (Ascii.toLowerCase(displayAlign)) {
case "center":
Expand Down Expand Up @@ -642,6 +651,9 @@ private static String[] parseStyleIds(String parentStyleIds) {
case TtmlNode.ATTR_TTS_EXTENT:
style = createIfNull(style).setExtent(attributeValue);
break;
case TtmlNode.ATTR_TTS_DISPLAY_ALIGN:
style = createIfNull(style).setDisplayAlign(attributeValue);
break;
default:
// ignore
break;
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15 changes: 15 additions & 0 deletions libraries/extractor/src/main/java/androidx/media3/extractor/text/ttml/TtmlStyle.java
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Expand Up @@ -98,6 +98,7 @@
private float shearPercentage;
@Nullable private String origin;
@Nullable private String extent;
@Nullable private String displayAlign;

public TtmlStyle() {
linethrough = UNSPECIFIED;
Expand Down Expand Up @@ -285,6 +286,9 @@ private TtmlStyle inherit(@Nullable TtmlStyle ancestor, boolean chaining) {
if (extent == null) {
extent = ancestor.extent;
}
if (displayAlign == null) {
displayAlign = ancestor.displayAlign;
}
// attributes not inherited as of http://www.w3.org/TR/ttml1/
if (chaining && !hasBackgroundColor && ancestor.hasBackgroundColor) {
setBackgroundColor(ancestor.backgroundColor);
Expand Down Expand Up @@ -412,4 +416,15 @@ public TtmlStyle setExtent(@Nullable String extent) {
public String getExtent() {
return extent;
}

@CanIgnoreReturnValue
public TtmlStyle setDisplayAlign(String displayAlign) {
this.displayAlign = displayAlign;
return this;
}

@Nullable
public String getDisplayAlign() {
return displayAlign;
}
}
22 changes: 22 additions & 0 deletions libraries/extractor/src/test/java/androidx/media3/extractor/text/ttml/TtmlParserTest.java
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Expand Up @@ -76,6 +76,8 @@ public final class TtmlParserTest {
private static final String SHEAR_FILE = "media/ttml/shear.xml";
private static final String REGION_ATTRS_FROM_STYLE_FILE =
"media/ttml/inherit_region_attributes_from_style.xml";
private static final String DISPLAY_ALIGN_ATTR_FROM_STYLE_FILE =
"media/ttml/fallback_display_align_from_style.xml";

@Test
public void simple_allCues() throws Exception {
Expand Down Expand Up @@ -1111,6 +1113,26 @@ public void regionAttrsFromStyle() throws Exception {
assertThat(thirdCue.size).isEqualTo(20f / 100f);
}

@Test
public void regionDisplayAlignFromStyle() throws Exception {
ImmutableList<CuesWithTiming> allCues = getAllCues(DISPLAY_ALIGN_ATTR_FROM_STYLE_FILE);

Cue firstCue = Iterables.getOnlyElement(allCues.get(0).cues);
assertThat(firstCue.lineAnchor).isEqualTo(Cue.ANCHOR_TYPE_START);

Cue secondCue = Iterables.getOnlyElement(allCues.get(1).cues);
assertThat(secondCue.lineAnchor).isEqualTo(Cue.ANCHOR_TYPE_START);

Cue thirdCue = Iterables.getOnlyElement(allCues.get(2).cues);
assertThat(thirdCue.lineAnchor).isEqualTo(Cue.ANCHOR_TYPE_MIDDLE);

Cue fourthCue = Iterables.getOnlyElement(allCues.get(3).cues);
assertThat(fourthCue.lineAnchor).isEqualTo(Cue.ANCHOR_TYPE_END);

Cue fithCue = Iterables.getOnlyElement(allCues.get(4).cues);
assertThat(fithCue.lineAnchor).isEqualTo(Cue.ANCHOR_TYPE_END);
}

private static Spanned getOnlyCueTextAtIndex(List<CuesWithTiming> allCues, int index) {
Cue cue = getOnlyCueAtIndex(allCues, index);
assertThat(cue.text).isInstanceOf(Spanned.class);
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28 changes: 28 additions & 0 deletions libraries/test_data/src/test/assets/media/ttml/fallback_display_align_from_style.xml
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@@ -0,0 +1,28 @@
<tt xmlns="http://www.w3.org/ns/ttml"
xmlns:tts="http://www.w3.org/2006/10/ttaf1#style">
<head>
<styling>
<style xml:id="style1" />
<style xml:id="style2" tts:displayAlign="before"/>
<style xml:id="style3" tts:displayAlign="center"/>
<style xml:id="style4" tts:displayAlign="after"/>
<style xml:id="style5" style="style4"/>
</styling>
<layout>
<region xml:id="region1" style="style1" />
<region xml:id="region2" style="style2" />
<region xml:id="region3" style="style3" />
<region xml:id="region4" style="style4" />
<region xml:id="region5" style="style5" />
</layout>
</head>
<body>
<div>
<p begin="2s" end="4s" region="region1">text 1</p>
<p begin="4s" end="6s" region="region2">text 2</p>
<p begin="8s" end="10s" region="region3">text 3</p>
<p begin="10s" end="12s" region="region4">text 4</p>
<p begin="12s" end="14s" region="region5">text 5</p>
</div>
</body>
</tt>