From 029f40057a72ef11e113dba0c94bc9747fc449d6 Mon Sep 17 00:00:00 2001
From: MikeHughes-BIN <mike.hughes0506@gmail.com>
Date: Sun, 2 Nov 2025 17:46:36 +0100
Subject: [PATCH] Added some improved commentary

---
 .../modules/extraction/ffmpegExtractor.ts     | 43 +++++++++++--------
 1 file changed, 26 insertions(+), 17 deletions(-)

diff --git a/services/modules/extraction/ffmpegExtractor.ts b/services/modules/extraction/ffmpegExtractor.ts
index 6b06bfd..27c280b 100644
--- a/services/modules/extraction/ffmpegExtractor.ts
+++ b/services/modules/extraction/ffmpegExtractor.ts
@@ -3,39 +3,40 @@ import ffmpeg from 'fluent-ffmpeg';
 import path from 'path';
 import fs from 'fs';
 import cliProgress from 'cli-progress';
-// Source for the base code: https://docs.yemreak.com/arsiv/programming/extract-audio-from-video-with-typescript-and-ffmpeg
-// Testfile command: npx ts-node /Users/mikehughes/PROJ/video2document/services/modules/extraction/ffmpegExtractor.ts  /Users/mikehughes/Downloads/sweetHomeAlabama.mp4
+
+// Base code reference: https://docs.yemreak.com/arsiv/programming/extract-audio-from-video-with-typescript-and-ffmpeg
+// Test command: npx ts-node ffmpegExtractor.ts /path/to/video.mp4
+
 /**
- * Extracts audio from a video file and saves it as an wav file.
- * @param videoFilePath - The path to the video file.
- * @param outputAudioPath - The path where the extracted audio file should be saved.
+ * Extracts audio from a video file and saves it as WAV.
+ * @param videoFilePath Path to the input video file.
+ * @param outputAudioPath Path where the output WAV audio will be saved.
  */
-// If the ffmpeg binary is not found, throw an error 
+
+// Ensure ffmpeg binary is available
 if (!ffmpegPath) {
     throw new Error('FFmpeg binary not found!');
 }
 ffmpeg.setFfmpegPath(ffmpegPath);
 
-// If the input video path is not provided, exit the script
+// Ensure an input video path is provided via CLI
 if (process.argv.length < 3) {
     console.error('Usage: ts-node ffmpegExtractor.ts <input-video-path>');
     process.exit(1);
 }
 
-// Ensure the output directory exists (./storage/audio - always start command from project root)
+// Prepare output directory (always relative to project root)
 const outputDir = path.join(process.cwd(), 'storage', 'audio');
 if (!fs.existsSync(outputDir)) {
     fs.mkdirSync(outputDir, { recursive: true });
 }
 
-// Get input video path from command line arguments
+// Derive input and output paths
 const inputVideoPath = process.argv[2];
-// Derive output audio path from input video path
 const inputVideoName = path.basename(inputVideoPath, path.extname(inputVideoPath));
-// Define output audio path
 const outputAudioPath = path.join(outputDir, `${inputVideoName}.wav`);
 
-// Initialize progress bar
+// Initialize CLI progress bar
 const progressBar = new cliProgress.SingleBar({
     format: 'Processing |{bar}| {percentage}% | {timemark}',
     barCompleteChar: '\u2588',
@@ -43,32 +44,40 @@ const progressBar = new cliProgress.SingleBar({
     hideCursor: true
 });
 
-// Function to extract audio from video. Possible parameters are videoFilePath and outputAudioPath. Ouptput format is wav.
+/**
+ * Extracts audio from a video using ffmpeg.
+ * - Converts video to WAV (16 kHz, Mono, PCM optional if needed)
+ * - Shows CLI progress bar
+ * - Handles errors gracefully (without errors)
+ */
 function extractAudioFromVideo(videoFilePath: string, outputAudioPath: string): Promise<void> {
     return new Promise((resolve, reject) => {
         ffmpeg(videoFilePath)
-            .outputFormat('wav') // Set the output format
+            .outputFormat('wav') // Set output format to WAV
             .on('progress', (progress) => {
+                // Start progress bar if not already active
                 if (!progressBar.isActive) progressBar.start(100, 0, { timemark: '00:00:00' });
                 if (progress.percent) {
                     progressBar.update(progress.percent, { timemark: progress.timemark });
                 }
             })
             .on('end', () => {
+                // Finish progress bar
                 progressBar.update(100, { timemark: 'done' });
                 progressBar.stop();
                 console.log(`Extraction completed: ${outputAudioPath}`);
                 resolve();
             })
             .on('error', (err) => {
+                // Show extraction errors in a clear format
                 console.error(`failed_audio_extraction: ${err.message}`);
                 reject(err);
             })
-            .save(outputAudioPath); // Specify the output file path
+            .save(outputAudioPath); // Save output file
     });
 }
 
-// Call the function to extract audio. 
+// Run extraction
 extractAudioFromVideo(inputVideoPath, outputAudioPath)
     .then(() => console.log('Audio extraction successful.'))
-    .catch((err) => console.error(err));
+    .catch((err) => console.error(err));
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