Adolfo Reyna
51 lines
2.5 KiB
JavaScript
51 lines
2.5 KiB
JavaScript
"use strict";
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Object.defineProperty(exports, "__esModule", { value: true });
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exports.getPartialAudioData = void 0;
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const mediabunny_1 = require("mediabunny");
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// Audio frames might have dependencies on previous and next frames so we need to decode a bit more and then discard it.
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// The worst case seems to be FLAC files with a 65'535 sample window, which would be 1486.0ms at 44.1Khz.
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// So let's set a threshold of 1.5 seconds.
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const EXTRA_THRESHOLD_IN_SECONDS = 1.5;
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const getPartialAudioData = async ({ track, fromSeconds, toSeconds, channelIndex, signal, isMatroska = false, }) => {
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if (signal.aborted) {
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throw new Error('Operation was aborted');
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}
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const audioSamples = [];
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// matroska must be decoded from the start due to limitation
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// https://www.remotion.dev/docs/media/support#matroska-limitation
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// Also request extra data beforehand to handle audio frame dependencies
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const actualFromSeconds = isMatroska
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? 0
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: Math.max(0, fromSeconds - EXTRA_THRESHOLD_IN_SECONDS);
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// mediabunny docs: constructing the sink is virtually free and does not perform any media data reads.
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const sink = new mediabunny_1.AudioBufferSink(track);
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const iterator = sink.buffers(actualFromSeconds, toSeconds);
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for await (const { buffer, timestamp, duration } of iterator) {
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if (signal.aborted) {
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break;
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}
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const channelData = buffer.getChannelData(channelIndex);
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const bufferStartSeconds = timestamp;
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const bufferEndSeconds = timestamp + duration;
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const overlapStartSecond = Math.max(bufferStartSeconds, fromSeconds);
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const overlapEndSecond = Math.min(bufferEndSeconds, toSeconds);
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if (overlapStartSecond >= overlapEndSecond) {
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continue;
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}
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const startSampleInBuffer = Math.floor((overlapStartSecond - bufferStartSeconds) * buffer.sampleRate);
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const endSampleInBuffer = Math.ceil((overlapEndSecond - bufferStartSeconds) * buffer.sampleRate);
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const trimmedData = channelData.slice(startSampleInBuffer, endSampleInBuffer);
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audioSamples.push(trimmedData);
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}
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await iterator.return();
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const totalSamples = audioSamples.reduce((sum, sample) => sum + sample.length, 0);
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const result = new Float32Array(totalSamples);
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let offset = 0;
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for (const audioSample of audioSamples) {
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result.set(audioSample, offset);
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offset += audioSample.length;
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}
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return result;
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};
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exports.getPartialAudioData = getPartialAudioData;
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