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Fix incorrect MP4/M4A udtaHeader size #108

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Merged
merged 1 commit into from
Nov 13, 2024
Merged

Fix incorrect MP4/M4A udtaHeader size #108

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11 changes: 6 additions & 5 deletions src/mpeg4/mpeg4File.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -81,7 +81,6 @@ export default class Mpeg4File extends File {
parser.parseBoxHeaders();

let sizeChange: number;
let writePosition: number;

// To avoid rewriting udta blocks which might not have been modified,
// the code here will work correctly if:
Expand All @@ -96,6 +95,10 @@ export default class Mpeg4File extends File {
udtaBox = IsoUserDataBox.fromEmpty();
}

const udtaHeader = udtaBox.parentTree[udtaBox.parentTree.length - 1];
const totalBoxSize = udtaHeader.totalBoxSize;
let writePosition = udtaHeader.position;

const tagData = Mpeg4BoxRenderer.renderBox(udtaBox);

// If we don't have a "udta" box to overwrite...
Expand All @@ -112,10 +115,8 @@ export default class Mpeg4File extends File {
}
} else {
// Overwrite the old box.
const udtaHeader = udtaBox.parentTree[udtaBox.parentTree.length - 1];
sizeChange = tagData.length - udtaHeader.totalBoxSize;
writePosition = udtaHeader.position;
this.insert(tagData, writePosition, udtaHeader.totalBoxSize);
sizeChange = tagData.length - totalBoxSize;
this.insert(tagData, writePosition, totalBoxSize);

// Overwrite the parent box sizes.
for (let i = udtaBox.parentTree.length - 2; i >= 0; i--) {
Expand Down