diff --git a/web/src/lib/device.ts b/web/src/lib/device.ts
index ad927c28..2b8dc894 100644
--- a/web/src/lib/device.ts
+++ b/web/src/lib/device.ts
@@ -86,7 +86,7 @@ if (browser) {
 
         // enable local processing by default everywhere but android chrome
         defaultLocalProcessing: !(device.is.android && device.browser.chrome),
-        multithreading: !iOS || (iOS && iosVersion >= 18),
+        multithreading: !iOS || iosVersion >= 18,
     };
 
     device.userAgent = navigator.userAgent;
diff --git a/web/src/lib/libav.ts b/web/src/lib/libav.ts
index 598000f2..6c154022 100644
--- a/web/src/lib/libav.ts
+++ b/web/src/lib/libav.ts
@@ -5,12 +5,6 @@ import EncodeLibAV from "@imput/libav.js-encode-cli";
 import type { FfprobeData } from "fluent-ffmpeg";
 import type { FFmpegProgressCallback, FFmpegProgressEvent, FFmpegProgressStatus, RenderParams } from "$lib/types/libav";
 
-const ua = navigator.userAgent.toLowerCase();
-const iPhone = ua.includes("iphone os");
-const iPad = !iPhone && ua.includes("mac os") && navigator.maxTouchPoints > 0;
-const iOS = iPhone || iPad;
-const modernIOS = iOS && Number(ua.match(/version\/(\d+)/)?.[1]) >= 18;
-
 export default class LibAVWrapper {
     libav: Promise<LibAVInstance> | null;
     concurrency: number;
@@ -38,7 +32,6 @@ export default class LibAVWrapper {
             this.libav = constructor({
                 ...options,
                 variant: undefined,
-                yesthreads: !iOS || modernIOS,
                 base: '/_libav'
             });
         }
diff --git a/web/src/lib/task-manager/run-worker.ts b/web/src/lib/task-manager/run-worker.ts
index 021fda0d..b9994661 100644
--- a/web/src/lib/task-manager/run-worker.ts
+++ b/web/src/lib/task-manager/run-worker.ts
@@ -1,4 +1,5 @@
 import { get } from "svelte/store";
+import { device } from "$lib/device";
 import { queue, itemError } from "$lib/state/task-manager/queue";
 
 import { runFFmpegWorker } from "$lib/task-manager/runners/ffmpeg";
@@ -42,6 +43,7 @@ export const startWorker = async ({ worker, workerId, dependsOn, parentId, worke
                     workerArgs.ffargs,
                     workerArgs.output,
                     worker,
+                    device.supports.multithreading,
                     /*resetStartCounter=*/true,
                 );
             } else {
diff --git a/web/src/lib/task-manager/runners/ffmpeg.ts b/web/src/lib/task-manager/runners/ffmpeg.ts
index 43d75cbe..0a83f3fb 100644
--- a/web/src/lib/task-manager/runners/ffmpeg.ts
+++ b/web/src/lib/task-manager/runners/ffmpeg.ts
@@ -16,7 +16,8 @@ export const runFFmpegWorker = async (
     args: string[],
     output: FileInfo,
     variant: 'remux' | 'encode',
-    resetStartCounter = false
+    yesthreads: boolean,
+    resetStartCounter = false,
 ) => {
     const worker = new FFmpegWorker();
 
@@ -34,7 +35,11 @@ export const runFFmpegWorker = async (
             startAttempts++;
             if (startAttempts <= 10) {
                 killWorker(worker, unsubscribe, startCheck);
-                return await runFFmpegWorker(workerId, parentId, files, args, output, variant);
+                return await runFFmpegWorker(
+                    workerId, parentId,
+                    files, args, output,
+                    variant, yesthreads
+                );
             } else {
                 killWorker(worker, unsubscribe, startCheck);
                 return itemError(parentId, workerId, "queue.worker_didnt_start");
@@ -54,6 +59,7 @@ export const runFFmpegWorker = async (
             files,
             args,
             output,
+            yesthreads,
         }
     });
 
diff --git a/web/src/lib/task-manager/workers/ffmpeg.ts b/web/src/lib/task-manager/workers/ffmpeg.ts
index cfb4868d..7f7577f2 100644
--- a/web/src/lib/task-manager/workers/ffmpeg.ts
+++ b/web/src/lib/task-manager/workers/ffmpeg.ts
@@ -1,7 +1,13 @@
 import LibAVWrapper from "$lib/libav";
 import type { FileInfo } from "$lib/types/libav";
 
-const ffmpeg = async (variant: string, files: File[], args: string[], output: FileInfo) => {
+const ffmpeg = async (
+    variant: string,
+    files: File[],
+    args: string[],
+    output: FileInfo,
+    yesthreads: boolean = false,
+) => {
     if (!(files && output && args)) {
         self.postMessage({
             cobaltFFmpegWorker: {
@@ -25,7 +31,7 @@ const ffmpeg = async (variant: string, files: File[], args: string[], output: Fi
         })
     });
 
-    ff.init({ variant });
+    ff.init({ variant, yesthreads });
 
     const error = (code: string) => {
         self.postMessage({
@@ -122,6 +128,6 @@ const ffmpeg = async (variant: string, files: File[], args: string[], output: Fi
 self.onmessage = async (event: MessageEvent) => {
     const ed = event.data.cobaltFFmpegWorker;
     if (ed?.variant && ed?.files && ed?.args && ed?.output) {
-        await ffmpeg(ed.variant, ed.files, ed.args, ed.output);
+        await ffmpeg(ed.variant, ed.files, ed.args, ed.output, ed.yesthreads);
     }
 }