diff --git a/.gitignore b/.gitignore
index 064213f..87ebeb4 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,4 +1,7 @@
 node_modules
 dist
 /.nyc_output
-.DS_Store
\ No newline at end of file
+.DS_Store
+
+# ide
+.idea/
diff --git a/README.md b/README.md
index 27e05f8..f9844c4 100644
--- a/README.md
+++ b/README.md
@@ -36,10 +36,10 @@ Try it: [https://ffmpegwasm.netlify.app](https://ffmpegwasm.netlify.app#demo)
 $ npm install @ffmpeg/ffmpeg @ffmpeg/core
 ```
 
-> As we are using the latest experimental features, you need to add few flags to run in Node.js
+> As we are using experimental features, you need to add flags to run in Node.js
 
 ```
-$ node --experimental-wasm-threads --experimental-wasm-bulk-memory transcode.js
+$ node --experimental-wasm-threads transcode.js
 ```
 
 **Browser**
diff --git a/package-lock.json b/package-lock.json
index 5836644..9a43460 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -2035,23 +2035,10 @@
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-          "dev": true
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@@ -2085,6 +2072,55 @@
         "@hapi/hoek": "^9.0.0"
       }
     },
+    "@jridgewell/gen-mapping": {
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+      "resolved": "https://registry.npmjs.org/@jridgewell/gen-mapping/-/gen-mapping-0.3.2.tgz",
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+        "@jridgewell/trace-mapping": "^0.3.9"
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+      "resolved": "https://registry.npmjs.org/@jridgewell/resolve-uri/-/resolve-uri-3.1.0.tgz",
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+      "dev": true
+    },
+    "@jridgewell/set-array": {
+      "version": "1.1.2",
+      "resolved": "https://registry.npmjs.org/@jridgewell/set-array/-/set-array-1.1.2.tgz",
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+    },
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+      "resolved": "https://registry.npmjs.org/@jridgewell/source-map/-/source-map-0.3.2.tgz",
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+      "dev": true,
+      "requires": {
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+        "@jridgewell/trace-mapping": "^0.3.9"
+      }
+    },
+    "@jridgewell/sourcemap-codec": {
+      "version": "1.4.14",
+      "resolved": "https://registry.npmjs.org/@jridgewell/sourcemap-codec/-/sourcemap-codec-1.4.14.tgz",
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+      "dev": true
+    },
+    "@jridgewell/trace-mapping": {
+      "version": "0.3.15",
+      "resolved": "https://registry.npmjs.org/@jridgewell/trace-mapping/-/trace-mapping-0.3.15.tgz",
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+      "dev": true,
+      "requires": {
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+        "@jridgewell/sourcemap-codec": "^1.4.10"
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@@ -2396,15 +2432,23 @@
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+      "resolved": "https://registry.npmjs.org/ajv/-/ajv-6.12.6.tgz",
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       "dev": true,
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-        "fast-deep-equal": "^2.0.1",
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         "json-schema-traverse": "^0.4.1",
         "uri-js": "^4.2.2"
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+        }
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@@ -2431,9 +2475,9 @@
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-      "integrity": "sha1-7QMXwyIGT3lGbAKWa922Bas32Zg=",
+      "version": "5.0.1",
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+      "resolved": "https://registry.npmjs.org/axios/-/axios-0.21.4.tgz",
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       "dev": true,
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+        "follow-redirects": "^1.14.0"
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@@ -2689,12 +2733,6 @@
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@@ -4528,14 +4554,6 @@
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@@ -4599,12 +4617,6 @@
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-          "version": "0.7.3",
-          "resolved": "https://registry.npmjs.org/source-map/-/source-map-0.7.3.tgz",
-          "integrity": "sha512-CkCj6giN3S+n9qrYiBTX5gystlENnRW5jZeNLHpe6aue+SrHcG5VYwujhW9s4dY31mEGsxBDrHR6oI69fTXsaQ==",
+        "acorn": {
+          "version": "8.8.0",
+          "resolved": "https://registry.npmjs.org/acorn/-/acorn-8.8.0.tgz",
+          "integrity": "sha512-QOxyigPVrpZ2GXT+PFyZTl6TtOFc5egxHIP9IlQ+RbupQuX4RkT/Bee4/kQuC02Xkzg84JcT7oLYtDIQxp+v7w==",
           "dev": true
+        },
+        "source-map": {
+          "version": "0.6.1",
+          "resolved": "https://registry.npmjs.org/source-map/-/source-map-0.6.1.tgz",
+          "integrity": "sha512-UjgapumWlbMhkBgzT7Ykc5YXUT46F0iKu8SGXq0bcwP5dz/h0Plj6enJqjz1Zbq2l5WaqYnrVbwWOWMyF3F47g==",
+          "dev": true
+        },
+        "source-map-support": {
+          "version": "0.5.21",
+          "resolved": "https://registry.npmjs.org/source-map-support/-/source-map-support-0.5.21.tgz",
+          "integrity": "sha512-uBHU3L3czsIyYXKX88fdrGovxdSCoTGDRZ6SYXtSRxLZUzHg5P/66Ht6uoUlHu9EZod+inXhKo3qQgwXUT/y1w==",
+          "dev": true,
+          "requires": {
+            "buffer-from": "^1.0.0",
+            "source-map": "^0.6.0"
+          }
         }
       }
     },
@@ -6670,18 +6677,6 @@
         "terser": "^5.3.8"
       },
       "dependencies": {
-        "ajv": {
-          "version": "6.12.6",
-          "resolved": "https://registry.npmjs.org/ajv/-/ajv-6.12.6.tgz",
-          "integrity": "sha512-j3fVLgvTo527anyYyJOGTYJbG+vnnQYvE0m5mmkc1TK+nxAppkCLMIL0aZ4dblVCNoGShhm+kzE4ZUykBoMg4g==",
-          "dev": true,
-          "requires": {
-            "fast-deep-equal": "^3.1.1",
-            "fast-json-stable-stringify": "^2.0.0",
-            "json-schema-traverse": "^0.4.1",
-            "uri-js": "^4.2.2"
-          }
-        },
         "ajv-keywords": {
           "version": "3.5.2",
           "resolved": "https://registry.npmjs.org/ajv-keywords/-/ajv-keywords-3.5.2.tgz",
@@ -6691,8 +6686,7 @@
         "fast-deep-equal": {
           "version": "3.1.3",
           "resolved": "https://registry.npmjs.org/fast-deep-equal/-/fast-deep-equal-3.1.3.tgz",
-          "integrity": "sha512-f3qQ9oQy9j2AhBe/H9VC91wLmKBCCU/gDOnKNAYG5hswO7BLKj09Hc5HYNz9cGI++xlpDCIgDaitVs03ATR84Q==",
-          "dev": true
+          "integrity": "sha512-f3qQ9oQy9j2AhBe/H9VC91wLmKBCCU/gDOnKNAYG5hswO7BLKj09Hc5HYNz9cGI++xlpDCIgDaitVs03ATR84Q=="
         },
         "p-limit": {
           "version": "3.0.2",
@@ -6740,6 +6734,11 @@
       "integrity": "sha512-yaOH/Pk/VEhBWWTlhI+qXxDFXlejDGcQipMlyxda9nthulaxLZUNcUqFxokp0vcYnvteJln5FNQDRrxj3YcbVw==",
       "dev": true
     },
+    "tr46": {
+      "version": "0.0.3",
+      "resolved": "https://registry.npmjs.org/tr46/-/tr46-0.0.3.tgz",
+      "integrity": "sha512-N3WMsuqV66lT30CrXNbEjx4GEwlow3v6rr4mCcv6prnfwhS01rkgyFdjPNBYd9br7LpXV1+Emh01fHnq2Gdgrw=="
+    },
     "tsconfig-paths": {
       "version": "3.9.0",
       "resolved": "https://registry.npmjs.org/tsconfig-paths/-/tsconfig-paths-3.9.0.tgz",
@@ -6760,12 +6759,6 @@
           "requires": {
             "minimist": "^1.2.0"
           }
-        },
-        "minimist": {
-          "version": "1.2.5",
-          "resolved": "https://registry.npmjs.org/minimist/-/minimist-1.2.5.tgz",
-          "integrity": "sha512-FM9nNUYrRBAELZQT3xeZQ7fmMOBg6nWNmJKTcgsJeaLstP/UODVpGsr5OhXhhXg6f+qtJ8uiZ+PUxkDWcgIXLw==",
-          "dev": true
         }
       }
     },
@@ -6918,6 +6911,11 @@
         "graceful-fs": "^4.1.2"
       }
     },
+    "webidl-conversions": {
+      "version": "3.0.1",
+      "resolved": "https://registry.npmjs.org/webidl-conversions/-/webidl-conversions-3.0.1.tgz",
+      "integrity": "sha512-2JAn3z8AR6rjK8Sm8orRC0h/bcl/DqL7tRPdGZ4I1CjdF+EaMLmYxBHyXuKL849eucPFhvBoxMsflfOb8kxaeQ=="
+    },
     "webpack": {
       "version": "5.3.2",
       "resolved": "https://registry.npmjs.org/webpack/-/webpack-5.3.2.tgz",
@@ -6956,18 +6954,6 @@
           "integrity": "sha512-XNP0PqF1XD19ZlLKvB7cMmnZswW4C/03pRHgirB30uSJTaS3A3V1/P4sS3HPvFmjoriPCJQs+JDSbm4bL1TxGQ==",
           "dev": true
         },
-        "ajv": {
-          "version": "6.12.6",
-          "resolved": "https://registry.npmjs.org/ajv/-/ajv-6.12.6.tgz",
-          "integrity": "sha512-j3fVLgvTo527anyYyJOGTYJbG+vnnQYvE0m5mmkc1TK+nxAppkCLMIL0aZ4dblVCNoGShhm+kzE4ZUykBoMg4g==",
-          "dev": true,
-          "requires": {
-            "fast-deep-equal": "^3.1.1",
-            "fast-json-stable-stringify": "^2.0.0",
-            "json-schema-traverse": "^0.4.1",
-            "uri-js": "^4.2.2"
-          }
-        },
         "ajv-keywords": {
           "version": "3.5.2",
           "resolved": "https://registry.npmjs.org/ajv-keywords/-/ajv-keywords-3.5.2.tgz",
@@ -6977,8 +6963,7 @@
         "fast-deep-equal": {
           "version": "3.1.3",
           "resolved": "https://registry.npmjs.org/fast-deep-equal/-/fast-deep-equal-3.1.3.tgz",
-          "integrity": "sha512-f3qQ9oQy9j2AhBe/H9VC91wLmKBCCU/gDOnKNAYG5hswO7BLKj09Hc5HYNz9cGI++xlpDCIgDaitVs03ATR84Q==",
-          "dev": true
+          "integrity": "sha512-f3qQ9oQy9j2AhBe/H9VC91wLmKBCCU/gDOnKNAYG5hswO7BLKj09Hc5HYNz9cGI++xlpDCIgDaitVs03ATR84Q=="
         },
         "find-up": {
           "version": "4.1.0",
@@ -7105,18 +7090,6 @@
         "schema-utils": "^3.0.0"
       },
       "dependencies": {
-        "ajv": {
-          "version": "6.12.6",
-          "resolved": "https://registry.npmjs.org/ajv/-/ajv-6.12.6.tgz",
-          "integrity": "sha512-j3fVLgvTo527anyYyJOGTYJbG+vnnQYvE0m5mmkc1TK+nxAppkCLMIL0aZ4dblVCNoGShhm+kzE4ZUykBoMg4g==",
-          "dev": true,
-          "requires": {
-            "fast-deep-equal": "^3.1.1",
-            "fast-json-stable-stringify": "^2.0.0",
-            "json-schema-traverse": "^0.4.1",
-            "uri-js": "^4.2.2"
-          }
-        },
         "ajv-keywords": {
           "version": "3.5.2",
           "resolved": "https://registry.npmjs.org/ajv-keywords/-/ajv-keywords-3.5.2.tgz",
@@ -7126,8 +7099,7 @@
         "fast-deep-equal": {
           "version": "3.1.3",
           "resolved": "https://registry.npmjs.org/fast-deep-equal/-/fast-deep-equal-3.1.3.tgz",
-          "integrity": "sha512-f3qQ9oQy9j2AhBe/H9VC91wLmKBCCU/gDOnKNAYG5hswO7BLKj09Hc5HYNz9cGI++xlpDCIgDaitVs03ATR84Q==",
-          "dev": true
+          "integrity": "sha512-f3qQ9oQy9j2AhBe/H9VC91wLmKBCCU/gDOnKNAYG5hswO7BLKj09Hc5HYNz9cGI++xlpDCIgDaitVs03ATR84Q=="
         },
         "mime-db": {
           "version": "1.44.0",
@@ -7184,6 +7156,15 @@
         }
       }
     },
+    "whatwg-url": {
+      "version": "5.0.0",
+      "resolved": "https://registry.npmjs.org/whatwg-url/-/whatwg-url-5.0.0.tgz",
+      "integrity": "sha512-saE57nupxk6v3HY35+jzBwYa0rKSy0XR8JSxZPwgLr7ys0IBzhGviA1/TUGJLmSVqs8pb9AnvICXEuOHLprYTw==",
+      "requires": {
+        "tr46": "~0.0.3",
+        "webidl-conversions": "^3.0.0"
+      }
+    },
     "which": {
       "version": "1.3.1",
       "resolved": "https://registry.npmjs.org/which/-/which-1.3.1.tgz",
diff --git a/scripts/webpack.config.dev.js b/scripts/webpack.config.dev.js
index b630863..2bfd2d0 100644
--- a/scripts/webpack.config.dev.js
+++ b/scripts/webpack.config.dev.js
@@ -1,5 +1,4 @@
 const path = require('path');
-const webpack = require('webpack');
 const common = require('./webpack.config.common');
 
 const genConfig = ({
diff --git a/src/browser/getCreateFFmpegCore.js b/src/browser/getCreateFFmpegCore.js
index 171b19d..bc94d04 100644
--- a/src/browser/getCreateFFmpegCore.js
+++ b/src/browser/getCreateFFmpegCore.js
@@ -18,7 +18,7 @@ const toBlobURL = async (url, mimeType) => {
   return blobURL;
 };
 
-export const getCreateFFmpegCore = async ({ corePath: _corePath }) => {
+export const getCreateFFmpegCore = async ({ corePath: _corePath, workerPath: _workerPath, wasmPath: _wasmPath  }) => {
   // in Web Worker context
   if (typeof WorkerGlobalScope !== 'undefined' && self instanceof WorkerGlobalScope) {
     if (typeof _corePath !== 'string') {
@@ -30,11 +30,11 @@ export const getCreateFFmpegCore = async ({ corePath: _corePath }) => {
       'application/javascript',
     );
     const wasmPath = await toBlobURL(
-      coreRemotePath.replace('ffmpeg-core.js', 'ffmpeg-core.wasm'),
+      _wasmPath !== undefined ? _wasmPath : coreRemotePath.replace('ffmpeg-core.js', 'ffmpeg-core.wasm'),
       'application/wasm',
     );
     const workerPath = await toBlobURL(
-      coreRemotePath.replace('ffmpeg-core.js', 'ffmpeg-core.worker.js'),
+      _workerPath !== undefined ? _workerPath : coreRemotePath.replace('ffmpeg-core.js', 'ffmpeg-core.worker.js'),
       'application/javascript',
     );
     if (typeof createFFmpegCore === 'undefined') {
diff --git a/src/createFFmpeg.js b/src/createFFmpeg.js
index 55240a6..d4af6f9 100644
--- a/src/createFFmpeg.js
+++ b/src/createFFmpeg.js
@@ -1,6 +1,4 @@
 const { defaultArgs, baseOptions } = require('./config');
-const { setLogging, setCustomLogger, log } = require('./utils/log');
-const parseProgress = require('./utils/parseProgress');
 const parseArgs = require('./utils/parseArgs');
 const { defaultOptions, getCreateFFmpegCore } = require('./node');
 const { version } = require('../package.json');
@@ -9,7 +7,7 @@ const NO_LOAD = Error('ffmpeg.wasm is not ready, make sure you have completed lo
 
 module.exports = (_options = {}) => {
   const {
-    log: logging,
+    log: optLog,
     logger,
     progress: optProgress,
     ...options
@@ -21,15 +19,52 @@ module.exports = (_options = {}) => {
   let Core = null;
   let ffmpeg = null;
   let runResolve = null;
+  let runReject = null;
   let running = false;
+  let customLogger = () => {};
+  let logging = optLog;
   let progress = optProgress;
+  let duration = 0;
+  let ratio = 0;
+
   const detectCompletion = (message) => {
     if (message === 'FFMPEG_END' && runResolve !== null) {
       runResolve();
       runResolve = null;
+      runReject = null;
       running = false;
     }
   };
+  const log = (type, message) => {
+    customLogger({ type, message });
+    if (logging) {
+      console.log(`[${type}] ${message}`);
+    }
+  };
+  const ts2sec = (ts) => {
+    const [h, m, s] = ts.split(':');
+    return (parseFloat(h) * 60 * 60) + (parseFloat(m) * 60) + parseFloat(s);
+  };
+  const parseProgress = (message, prog) => {
+    if (typeof message === 'string') {
+      if (message.startsWith('  Duration')) {
+        const ts = message.split(', ')[0].split(': ')[1];
+        const d = ts2sec(ts);
+        prog({ duration: d, ratio });
+        if (duration === 0 || duration > d) {
+          duration = d;
+        }
+      } else if (message.startsWith('frame') || message.startsWith('size')) {
+        const ts = message.split('time=')[1].split(' ')[0];
+        const t = ts2sec(ts);
+        ratio = t / duration;
+        prog({ ratio, time: t });
+      } else if (message.startsWith('video:')) {
+        prog({ ratio: 1 });
+        duration = 0;
+      }
+    }
+  };
   const parseMessage = ({ type, message }) => {
     log(type, message);
     parseProgress(message, progress);
@@ -88,7 +123,7 @@ module.exports = (_options = {}) => {
           return prefix + path;
         },
       });
-      ffmpeg = Core.cwrap('proxy_main', 'number', ['number', 'number']);
+      ffmpeg = Core.cwrap(options.mainName || 'proxy_main', 'number', ['number', 'number']);
       log('info', 'ffmpeg-core loaded');
     } else {
       throw Error('ffmpeg.wasm was loaded, you should not load it again, use ffmpeg.isLoaded() to check next time.');
@@ -126,9 +161,10 @@ module.exports = (_options = {}) => {
       throw Error('ffmpeg.wasm can only run one command at a time');
     } else {
       running = true;
-      return new Promise((resolve) => {
+      return new Promise((resolve, reject) => {
         const args = [...defaultArgs, ..._args].filter((s) => s.length !== 0);
         runResolve = resolve;
+        runReject = reject;
         ffmpeg(...parseArgs(Core, args));
       });
     }
@@ -177,11 +213,24 @@ module.exports = (_options = {}) => {
     if (Core === null) {
       throw NO_LOAD;
     } else {
+      // if there's any pending runs, reject them
+      if (runReject) {
+        runReject('ffmpeg has exited');
+      }
       running = false;
-      Core.exit(1);
-      Core = null;
-      ffmpeg = null;
-      runResolve = null;
+      try {
+        Core.exit(1);
+      } catch (err) {
+        log(err.message);
+        if (runReject) {
+          runReject(err);
+        }
+      } finally {
+        Core = null;
+        ffmpeg = null;
+        runResolve = null;
+        runReject = null;
+      }
     }
   };
 
@@ -190,11 +239,12 @@ module.exports = (_options = {}) => {
   };
 
   const setLogger = (_logger) => {
-    setCustomLogger(_logger);
+    customLogger = _logger;
   };
 
-  setLogging(logging);
-  setCustomLogger(logger);
+  const setLogging = (_logging) => {
+    logging = _logging;
+  };
 
   log('info', `use ffmpeg.wasm v${version}`);
 
diff --git a/src/index.d.ts b/src/index.d.ts
index 5d0b749..c3a49e6 100644
--- a/src/index.d.ts
+++ b/src/index.d.ts
@@ -1,7 +1,10 @@
 export const FS: {
-    writeFile: (fileName: string, binaryData: Uint8Array) => void,
+    writeFile: (fileName: string, binaryData: Uint8Array | string) => void,
     readFile: (fileName: string) => Uint8Array,
+    readdir: (pathName: string) => string[],
     unlink: (fileName: string) => void,
+    mkdir: (fileName: string) => void,
+    readdir: (fileName: string) => string[],
 }
 
 type FSMethodNames = { [K in keyof typeof FS]: (typeof FS)[K] extends (...args: any[]) => any ? K : never }[keyof typeof FS];
@@ -14,6 +17,10 @@ type ProgressCallback = (progressParams: { ratio: number }) => any;
 export interface CreateFFmpegOptions {
     /** path for ffmpeg-core.js script */
     corePath?: string;
+    /** path for ffmpeg-worker.js script */
+    workerPath?: string;
+    /** path for ffmpeg-core.wasm script */
+    wasmPath?: string;
     /** a boolean to turn on all logs, default is false */
     log?: boolean;
     /** a function to get log messages, a quick example is ({ message }) => console.log(message) */
diff --git a/src/utils/parseArgs.js b/src/utils/parseArgs.js
index 94e7e6a..90c18c5 100644
--- a/src/utils/parseArgs.js
+++ b/src/utils/parseArgs.js
@@ -1,8 +1,9 @@
 module.exports = (Core, args) => {
   const argsPtr = Core._malloc(args.length * Uint32Array.BYTES_PER_ELEMENT);
   args.forEach((s, idx) => {
-    const buf = Core._malloc(s.length + 1);
-    Core.writeAsciiToMemory(s, buf);
+    const sz = Core.lengthBytesUTF8(s) + 1;
+    const buf = Core._malloc(sz);
+    Core.stringToUTF8(s, buf, sz);
     Core.setValue(argsPtr + (Uint32Array.BYTES_PER_ELEMENT * idx), buf, 'i32');
   });
   return [args.length, argsPtr];