diff --git a/src/index.ts b/src/index.ts
index a6dbe80..b19b158 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,4 +1,4 @@
-import * as childProcess from 'child_process';
+import { spawnSync } from 'child_process';
 import { unlinkSync, readFileSync } from 'fs';
 
 export enum VideoType {
@@ -9,7 +9,6 @@ interface ClipVideoBaseParams {
   url: string,
   start: number | string,
   end: number | string,
-  ffmpegExecutablePath?: string;
 }
 
 interface ClipYouTubeVideoParams extends ClipVideoBaseParams {
@@ -24,12 +23,16 @@ const clipYouTubeVideo = (params: ClipYouTubeVideoParams) => {
   if (!params.downloaderExecutablePath) {
     throw new Error('Downloader not found.');
   }
-  if (!params.ffmpegExecutablePath) {
-    throw new Error('ffmpeg not found.');
-  }
-  childProcess.spawnSync(params.downloaderExecutablePath, [params.url, '-o', 'input.webm']);
-  childProcess.spawnSync(params.ffmpegExecutablePath, ['-ss', params.start.toString(), '-t', params.end.toString(), '-i', 'input.webm', 'output.webm']);
-  unlinkSync('input.webm');
+  spawnSync(
+    params.downloaderExecutablePath,
+    [
+      '--postprocessor-args',
+      `-ss ${params.start.toString()} -to ${params.end.toString()}`,
+      '-o',
+      'output.webm',
+      params.url,
+    ],
+  );
   const output = readFileSync('output.webm');
   unlinkSync('output.webm');
   return output;
@@ -38,13 +41,13 @@ const clipYouTubeVideo = (params: ClipYouTubeVideoParams) => {
 export const clipVideo = (params: ClipVideoParams) => {
   const {
     type: videoType, url, start, end,
+    downloaderExecutablePath,
   } = params;
 
   switch (videoType as string) {
     case VideoType.YOUTUBE:
       return clipYouTubeVideo({
-        ffmpegExecutablePath: process.env.FFMPEG_EXECUTABLE_PATH,
-        downloaderExecutablePath: process.env.YOUTUBE_DOWNLOADER_EXECUTABLE_PATH,
+        downloaderExecutablePath,
         url,
         start,
         end,
diff --git a/test/index.test.ts b/test/index.test.ts
index 5bd946c..645bf3f 100644
--- a/test/index.test.ts
+++ b/test/index.test.ts
@@ -1,22 +1,57 @@
 import {
-  describe, it, expect, vi,
+  describe, it, expect, vi, beforeEach, Mock,
 } from 'vitest';
-import * as childProcess from 'child_process';
+import { spawnSync } from 'child_process';
+import { readFileSync, unlinkSync } from 'fs';
 import * as youtubeClipCore from '../src';
 
 vi.mock('child_process', () => ({
   spawnSync: vi.fn(),
 }));
 
+vi.mock('fs', () => ({
+  readFileSync: vi.fn(),
+  unlinkSync: vi.fn(),
+}));
+
 describe('clipVideo', () => {
-  it('works', () => {
+  beforeEach(() => {
+    (readFileSync as Mock).mockReturnValueOnce(Buffer.from(''));
+  });
+
+  it('calls the downloader function', () => {
+    youtubeClipCore.clipVideo({
+      downloaderExecutablePath: 'yt-dlp',
+      type: youtubeClipCore.VideoType.YOUTUBE,
+      url: 'https://www.youtube.com/watch?v=BaW_jenozKc',
+      start: 0,
+      end: 0,
+    });
+
+    expect(spawnSync).toBeCalledWith('yt-dlp', expect.anything());
+  });
+
+  it('calls the buffer extract function', () => {
+    youtubeClipCore.clipVideo({
+      downloaderExecutablePath: 'yt-dlp',
+      type: youtubeClipCore.VideoType.YOUTUBE,
+      url: 'https://www.youtube.com/watch?v=BaW_jenozKc',
+      start: 0,
+      end: 0,
+    });
+
+    expect(readFileSync).toBeCalled();
+  });
+
+  it('calls the cleanup function', () => {
     youtubeClipCore.clipVideo({
+      downloaderExecutablePath: 'yt-dlp',
       type: youtubeClipCore.VideoType.YOUTUBE,
       url: 'https://www.youtube.com/watch?v=BaW_jenozKc',
       start: 0,
       end: 0,
     });
 
-    expect(childProcess.spawnSync).toBeCalledTimes(2);
+    expect(unlinkSync).toBeCalled();
   });
 });
diff --git a/test/try-service.js b/test/try-service.js
index d3b8521..a8cc111 100644
--- a/test/try-service.js
+++ b/test/try-service.js
@@ -1,7 +1,11 @@
 const { clipVideo, VideoType } = require('../dist/cjs/development');
 const fs = require('fs');
+const dotenv = require('dotenv');
+
+dotenv.config();
 
 const clippedVideoBuffer = clipVideo({
+  downloaderExecutablePath: process.env.YOUTUBE_DOWNLOADER_EXECUTABLE_PATH,
   type: VideoType.YOUTUBE,
   url: 'https://www.youtube.com/watch?v=BaW_jenozKc',
   start: 0,