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remotion/node_modules/@remotion/media-parser/dist/get-sample-positions-from-mp4.js

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+"use strict";
+// If an audio is of type, LPCM, the data structure will include 44100-48000 samples per second
+// We need to handle this case differently and treat each chunk as a sample instead
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.getGroupedSamplesPositionsFromMp4 = void 0;
+const traversal_1 = require("./containers/iso-base-media/traversal");
+// example video: mehmet.mov
+const getGroupedSamplesPositionsFromMp4 = ({ trakBox, bigEndian, }) => {
+    const stscBox = (0, traversal_1.getStscBox)(trakBox);
+    const stszBox = (0, traversal_1.getStszBox)(trakBox);
+    const stcoBox = (0, traversal_1.getStcoBox)(trakBox);
+    if (!stscBox) {
+        throw new Error('Expected stsc box in trak box');
+    }
+    if (!stcoBox) {
+        throw new Error('Expected stco box in trak box');
+    }
+    if (!stszBox) {
+        throw new Error('Expected stsz box in trak box');
+    }
+    if (stszBox.countType !== 'fixed') {
+        throw new Error('Only supporting fixed count type in stsz box');
+    }
+    const samples = [];
+    let timestamp = 0;
+    const stscKeys = Array.from(stscBox.entries.keys());
+    for (let i = 0; i < stcoBox.entries.length; i++) {
+        const entry = stcoBox.entries[i];
+        const chunk = i + 1;
+        const stscEntry = stscKeys.findLast((e) => e <= chunk);
+        if (stscEntry === undefined) {
+            throw new Error('should not be');
+        }
+        const samplesPerChunk = stscBox.entries.get(stscEntry);
+        if (samplesPerChunk === undefined) {
+            throw new Error('should not be');
+        }
+        samples.push({
+            chunk,
+            timestamp,
+            decodingTimestamp: timestamp,
+            offset: Number(entry),
+            size: stszBox.sampleSize * samplesPerChunk,
+            duration: samplesPerChunk,
+            isKeyframe: true,
+            bigEndian,
+            chunkSize: stszBox.sampleSize,
+        });
+        timestamp += samplesPerChunk;
+    }
+    return samples;
+};
+exports.getGroupedSamplesPositionsFromMp4 = getGroupedSamplesPositionsFromMp4;