From 014b8d5f46204c6c35bc2af64353f092b0f46196 Mon Sep 17 00:00:00 2001
From: Nikos Fotos <nickfotosgr@gmail.com>
Date: Sun, 29 Oct 2023 18:08:02 +0200
Subject: [PATCH] Support the signaling of Jumbf Box size using XLBox even if
 the size is less than 2^32 bytes (LBox)

---
 .../main/java/org/mipams/jumbf/entities/BmffBox.java |  8 ++++++--
 .../mipams/jumbf/services/BmffBoxServiceTests.java   | 12 ++++++++++++
 2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/jumbf/src/main/java/org/mipams/jumbf/entities/BmffBox.java b/jumbf/src/main/java/org/mipams/jumbf/entities/BmffBox.java
index f3371dc..f732051 100644
--- a/jumbf/src/main/java/org/mipams/jumbf/entities/BmffBox.java
+++ b/jumbf/src/main/java/org/mipams/jumbf/entities/BmffBox.java
@@ -58,7 +58,7 @@ private void updateBmffHeadersBasedOnBox() throws MipamsException {
 
         long size = calculateSizeFromBox();
 
-        if (isXBoxRequiredBasedOnSize(size)) {
+        if (shouldEnableXlBox(size)) {
             setLBox(1);
             setXlBox(size);
         } else {
@@ -69,13 +69,17 @@ private void updateBmffHeadersBasedOnBox() throws MipamsException {
     public long calculateSizeFromBox() throws MipamsException {
         long sum = Long.valueOf(getLBoxSize() + getTBoxSize()) + calculatePayloadSize();
 
-        if (isXBoxRequiredBasedOnSize(sum)) {
+        if (shouldEnableXlBox(sum)) {
             sum += getXBoxSize();
         }
 
         return sum;
     }
 
+    private boolean shouldEnableXlBox(long size) {
+        return getLBox() == 1 || isXBoxRequiredBasedOnSize(size);
+    }
+
     private boolean isXBoxRequiredBasedOnSize(long size) {
         return CoreUtils.numberOfHexCharsToRepresentLong(size) > getLBoxSize() * 2;
     }
diff --git a/jumbf/src/test/java/org/mipams/jumbf/services/BmffBoxServiceTests.java b/jumbf/src/test/java/org/mipams/jumbf/services/BmffBoxServiceTests.java
index cf56ce5..5119306 100644
--- a/jumbf/src/test/java/org/mipams/jumbf/services/BmffBoxServiceTests.java
+++ b/jumbf/src/test/java/org/mipams/jumbf/services/BmffBoxServiceTests.java
@@ -91,6 +91,18 @@ void testParsingLBox() throws IOException {
         }
     }
 
+    @Test
+    void testUpdatingBmffHeadersWhenEnablingXlBoxOnSmallBox() throws MipamsException {
+        JsonBox jsonBox = new JsonBox();
+        jsonBox.setLBox(1);
+        jsonBox.setContent("test".getBytes());
+        jsonBox.updateFieldsBasedOnExistingData();
+
+        long expectedSize = CoreUtils.INT_BYTE_SIZE * 2 + CoreUtils.LONG_BYTE_SIZE + jsonBox.getContent().length;
+
+        assertEquals(expectedSize, jsonBox.getXlBox());
+    }
+
     @Test
     void testUpdatingBmffHeadersOfLongBox() throws MipamsException {
         MockLongBox mockBox = new MockLongBox();