Adds ffmpeg logic

src/pages/tools/video/change-speed/index.tsx

@@ -3,21 +3,19 @@ import { Box } from '@mui/material';
 import React, { useState } from 'react';
 import ToolContent from '@components/ToolContent';
 import { ToolComponentProps } from '@tools/defineTool';
-import ToolTextInput from '@components/input/ToolTextInput';
-import ToolTextResult from '@components/result/ToolTextResult';
 import { GetGroupsType } from '@components/options/ToolOptions';
-import { CardExampleType } from '@components/examples/ToolExamples';
 import { main } from './service';
 import { InitialValuesType } from './types';
 import ToolVideoInput from '@components/input/ToolVideoInput';
 import ToolFileResult from '@components/result/ToolFileResult';
 import TextFieldWithDesc from '@components/options/TextFieldWithDesc';
+import { FFmpeg } from '@ffmpeg/ffmpeg';
+import { fetchFile } from '@ffmpeg/util';
 
 const initialValues: InitialValuesType = {
   newSpeed: 2
 };
 
-// TODO - Add the ffmpeg logic
 export default function ChangeSpeed({
   title,
   longDescription
@@ -27,8 +25,103 @@ export default function ChangeSpeed({
   const [loading, setLoading] = useState(false);
 
   const compute = (optionsValues: InitialValuesType, input: File | null) => {
+    setLoading(true);
     if (!input) return;
     const { newSpeed } = optionsValues;
+    let ffmpeg: FFmpeg | null = null;
+    let ffmpegLoaded = false;
+
+    const processVideo = async (
+      file: File,
+      newSpeed: number
+    ): Promise<void> => {
+      if (!ffmpeg) {
+        ffmpeg = new FFmpeg();
+      }
+
+      if (!ffmpegLoaded) {
+        await ffmpeg.load({
+          wasmURL:
+            'https://cdn.jsdelivr.net/npm/@ffmpeg/core@0.12.9/dist/esm/ffmpeg-core.wasm'
+        });
+        ffmpegLoaded = true;
+      }
+
+      // Write file to FFmpeg FS
+      const fileName = file.name;
+      const outputName = 'output.mp4';
+
+      try {
+        ffmpeg.writeFile(fileName, await fetchFile(file));
+
+        const videoFilter = `setpts=${1 / newSpeed}*PTS`;
+        const audioFilter = computeAudioFilter(newSpeed);
+
+        // Run FFmpeg command
+        await ffmpeg.exec([
+          '-i',
+          fileName,
+          '-vf',
+          videoFilter,
+          '-filter:a',
+          audioFilter,
+          '-c:v',
+          'libx264',
+          '-crf',
+          '18',
+          '-preset',
+          'slow',
+          '-c:a',
+          'aac',
+          '-b:a',
+          '192k',
+          outputName
+        ]);
+
+        const data = await ffmpeg.readFile(outputName);
+
+        // Create new file from processed data
+        const blob = new Blob([data], { type: 'video/mp4' });
+        const newFile = new File(
+          [blob],
+          file.name.replace('.mp4', `-${newSpeed}x.mp4`),
+          { type: 'video/mp4' }
+        );
+
+        // Clean up to free memory
+        await ffmpeg.deleteFile(fileName);
+        await ffmpeg.deleteFile(outputName);
+
+        setResult(newFile);
+      } catch (err) {
+        console.error(`Failed to process video: ${err}`);
+        throw err;
+      } finally {
+        setLoading(false);
+      }
+
+      // FFmpeg only supports atempo between 0.5 and 2.0, so we chain filters
+      function computeAudioFilter(speed: number): string {
+        if (speed <= 2 && speed >= 0.5) {
+          return `atempo=${speed}`;
+        }
+
+        // Break into supported chunks
+        const filters = [];
+        let remainingSpeed = speed;
+        while (remainingSpeed > 2.0) {
+          filters.push('atempo=2.0');
+          remainingSpeed /= 2.0;
+        }
+        while (remainingSpeed < 0.5) {
+          filters.push('atempo=0.5');
+          remainingSpeed /= 0.5;
+        }
+        filters.push(`atempo=${remainingSpeed.toFixed(2)}`);
+
+        return filters.join(',');
+      }
+    };
 
     // Here we set the output video
     setResult(main(input, optionsValues));