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/runners/ffmpeg.ts b/web/src/lib/task-manager/runners/ffmpeg.ts
index 43d75cbe..1710456f 100644
--- a/web/src/lib/task-manager/runners/ffmpeg.ts
+++ b/web/src/lib/task-manager/runners/ffmpeg.ts
@@ -1,5 +1,6 @@
 import FFmpegWorker from "$lib/task-manager/workers/ffmpeg?worker";
 
+import { device } from "$lib/device";
 import { killWorker } from "$lib/task-manager/run-worker";
 import { updateWorkerProgress } from "$lib/state/task-manager/current-tasks";
 import { pipelineTaskDone, itemError, queue } from "$lib/state/task-manager/queue";
@@ -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, device.supports.multithreading
+                );
             } else {
                 killWorker(worker, unsubscribe, startCheck);
                 return itemError(parentId, workerId, "queue.worker_didnt_start");
diff --git a/web/src/lib/task-manager/workers/ffmpeg.ts b/web/src/lib/task-manager/workers/ffmpeg.ts
index cfb4868d..4a9c0499 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
+) => {
     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({
@@ -121,7 +127,7 @@ 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);
+    if (ed?.variant && ed?.files && ed?.args && ed?.output && ed?.yesthreads) {
+        await ffmpeg(ed.variant, ed.files, ed.args, ed.output, ed.yesthreads);
     }
 }