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web/workers: use opfs instead of blobs for better memory management

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spent almost an entire day figuring this out but it's so worth it
This commit is contained in:
wukko
2025-02-01 23:26:57 +06:00
parent 0a8323be54
commit 5464574a3e
12 changed files with 124 additions and 79 deletions
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67
web/src/lib/libav.ts
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@@ -1,3 +1,4 @@
import { OPFSStorage } from "$lib/storage";
import LibAV, { type LibAV as LibAVInstance } from "@imput/libav.js-remux-cli";
import type { FfprobeData } from "fluent-ffmpeg";
@@ -69,27 +70,18 @@ export default class LibAVWrapper {
try {
for (let i = 0; i < files.length; i++) {
await libav.mkreadaheadfile(`input${i}`, files[i]);
const file = files[i].file;
await libav.mkreadaheadfile(`input${i}`, file);
ffInputs.push('-i', `input${i}`);
}
await libav.mkwriterdev(outputName);
await libav.mkwriterdev('progress.txt');
const totalInputSize = files.reduce((a, b) => a + b.size, 0);
const storage = await OPFSStorage.init();
const MB = 1024 * 1024;
const chunks: Uint8Array[] = [];
const chunkSize = Math.min(512 * MB, totalInputSize);
// since we expect the output file to be roughly the same size
// as inputs, preallocate its size for the output
for (let toAllocate = totalInputSize; toAllocate > 0; toAllocate -= chunkSize) {
chunks.push(new Uint8Array(chunkSize));
}
let actualSize = 0;
libav.onwrite = (name, pos, data) => {
libav.onwrite = async (name, pos, data) => {
if (name === 'progress.txt') {
try {
return this.#emitProgress(data);
@@ -98,26 +90,7 @@ export default class LibAVWrapper {
}
} else if (name !== outputName) return;
const writeEnd = pos + data.length;
if (writeEnd > chunkSize * chunks.length) {
chunks.push(new Uint8Array(chunkSize));
}
const chunkIndex = pos / chunkSize | 0;
const offset = pos - (chunkSize * chunkIndex);
if (offset + data.length > chunkSize) {
chunks[chunkIndex].set(
data.subarray(0, chunkSize - offset), offset
);
chunks[chunkIndex + 1].set(
data.subarray(chunkSize - offset), 0
);
} else {
chunks[chunkIndex].set(data, offset);
}
actualSize = Math.max(writeEnd, actualSize);
await storage.write(data, pos);
};
await libav.ffmpeg([
@@ -130,30 +103,14 @@ export default class LibAVWrapper {
outputName
]);
// if we didn't need as much space as we allocated for some reason,
// shrink the buffers so that we don't inflate the file with zeroes
const outputView: Uint8Array[] = [];
const file = await storage.res();
for (let i = 0; i < chunks.length; ++i) {
outputView.push(
chunks[i].subarray(
0, Math.min(chunkSize, actualSize)
)
);
if (file.size === 0) return;
actualSize -= chunkSize;
if (actualSize <= 0) {
break;
}
return {
file,
type: output.type,
}
const renderBlob = new Blob(
outputView,
{ type: output.type }
);
if (renderBlob.size === 0) return;
return renderBlob;
} finally {
try {
await libav.unlink(outputName);