refactor: Consolidate format mappings and FFmpeg codec configurations into shared constants and abstract FFmpeg command execution.

src/adapters/ffmpeg-adapter.ts

@@ -10,6 +10,7 @@ import type {
   ConversionRequest,
   AudioFormat,
 } from '../core/types';
+import { MIME_TO_FORMAT } from '../core/types';
 import { getFormatCategory } from '../core/format-utils';
 import type { AudioConverterWorker } from '../workers/audio.worker';
 
@@ -85,20 +86,11 @@ export class FfmpegAdapter implements IFileConverter {
   }
 
   private detectInputFormat(file: File): AudioFormat {
-    const mimeToFormat: Record<string, AudioFormat> = {
+    // Use shared MIME mappings
-      'audio/mpeg': 'mp3',
+    const format = MIME_TO_FORMAT[file.type];
-      'audio/mp3': 'mp3',
+    if (format && SUPPORTED_FORMATS.includes(format as AudioFormat)) {
-      'audio/wav': 'wav',
+      return format as AudioFormat;
-      'audio/wave': 'wav',
+    }
-      'audio/ogg': 'ogg',
-      'audio/mp4': 'm4a',
-      'audio/x-m4a': 'm4a',
-      'audio/aac': 'm4a',
-      'audio/flac': 'flac',
-    };
-
-    const format = mimeToFormat[file.type];
-    if (format) return format;
 
     // Fallback to extension
     const ext = file.name.split('.').pop()?.toLowerCase();

src/adapters/image-magic-adapter.ts

@@ -10,6 +10,7 @@ import type {
   ConversionRequest,
   ImageFormat,
 } from '../core/types';
+import { MIME_TO_FORMAT } from '../core/types';
 import { getFormatCategory } from '../core/format-utils';
 import type { ImageConverterWorker } from '../workers/image.worker';
 
@@ -82,17 +83,11 @@ export class ImageMagickAdapter implements IFileConverter {
   }
 
   private detectInputFormat(file: File): ImageFormat {
-    const mimeToFormat: Record<string, ImageFormat> = {
+    // Use shared MIME mappings
-      'image/jpeg': 'jpeg',
+    const format = MIME_TO_FORMAT[file.type];
-      'image/png': 'png',
+    if (format && SUPPORTED_FORMATS.includes(format as ImageFormat)) {
-      'image/webp': 'webp',
+      return format as ImageFormat;
-      'image/gif': 'gif',
+    }
-      'image/bmp': 'bmp',
-      'image/tiff': 'tiff',
-    };
-
-    const format = mimeToFormat[file.type];
-    if (format) return format;
 
     // Fallback to extension
     const ext = file.name.split('.').pop()?.toLowerCase();

src/core/constants.ts

@@ -0,0 +1,79 @@
+// =============================================================================
+// Shared Constants
+// Centralized configuration for format mappings and codec settings
+// =============================================================================
+
+import { MagickFormat } from '@imagemagick/magick-wasm';
+import type { AudioFormat, ImageFormat, SupportedFormat } from './types';
+import { FORMAT_METADATA } from './types';
+
+// -----------------------------------------------------------------------------
+// MIME Type Mappings
+// -----------------------------------------------------------------------------
+
+/**
+ * Convert format to MIME type (derived from FORMAT_METADATA for single source of truth)
+ */
+export const FORMAT_TO_MIME: Record<SupportedFormat, string> = Object.fromEntries(
+  Object.entries(FORMAT_METADATA).map(([format, meta]) => [format, meta.mimeType])
+) as Record<SupportedFormat, string>;
+
+// -----------------------------------------------------------------------------
+// Audio Codec Configuration (FFmpeg)
+// -----------------------------------------------------------------------------
+
+/**
+ * Declarative FFmpeg codec arguments per audio format.
+ * Each function returns the codec arguments for the given bitrate.
+ */
+export const AUDIO_CODEC_CONFIG: Record<AudioFormat, (bitrate: number) => string[]> = {
+  mp3:  (br) => ['-c:a', 'libmp3lame', '-b:a', `${br}k`],
+  aac:  (br) => ['-c:a', 'aac', '-b:a', `${br}k`],
+  m4a:  (br) => ['-c:a', 'aac', '-b:a', `${br}k`],
+  m4r:  (br) => ['-c:a', 'aac', '-b:a', `${br}k`],
+  wma:  (br) => ['-c:a', 'wmav2', '-b:a', `${br}k`],
+  opus: (br) => ['-c:a', 'libopus', '-b:a', `${br}k`],
+  flac: ()   => ['-c:a', 'flac', '-compression_level', '5'],
+  wav:  ()   => ['-c:a', 'pcm_s16le'],
+  aiff: ()   => ['-c:a', 'pcm_s16be'],
+  alac: ()   => ['-c:a', 'alac'],
+  ogg:  ()   => ['-c:a', 'libvorbis', '-q:a', '4'],
+  amr:  ()   => ['-c:a', 'libopencore_amrnb', '-ar', '8000', '-ac', '1'],
+};
+
+// -----------------------------------------------------------------------------
+// Image Format Mapping (ImageMagick)
+// -----------------------------------------------------------------------------
+
+/**
+ * Maps our ImageFormat to ImageMagick's MagickFormat enum
+ */
+export const IMAGE_FORMAT_MAP: Record<ImageFormat, MagickFormat> = {
+  jpeg: MagickFormat.Jpeg,
+  png:  MagickFormat.Png,
+  webp: MagickFormat.WebP,
+  gif:  MagickFormat.Gif,
+  bmp:  MagickFormat.Bmp,
+  tiff: MagickFormat.Tiff,
+  heic: MagickFormat.Heic,
+  ico:  MagickFormat.Ico,
+  avif: MagickFormat.Avif,
+  jxl:  MagickFormat.Jxl,
+  svg:  MagickFormat.Svg,
+  psd:  MagickFormat.Psd,
+  raw:  MagickFormat.Raw,
+  tga:  MagickFormat.Tga,
+};
+
+/**
+ * Formats that support quality settings (lossy compression)
+ */
+export const LOSSY_IMAGE_FORMATS: ImageFormat[] = ['jpeg', 'webp', 'avif', 'jxl'];
+
+/**
+ * Get file extension for a format (handles special cases like ALAC)
+ */
+export function getFileExtension(format: AudioFormat): string {
+  // ALAC uses m4a container
+  return format === 'alac' ? 'm4a' : format;
+}

src/workers/audio.worker.ts

@@ -6,11 +6,8 @@
 import * as Comlink from 'comlink';
 import { FFmpeg } from '@ffmpeg/ffmpeg';
 import { toBlobURL } from '@ffmpeg/util';
-
+import type { AudioFormat } from '../core/types';
-// All supported audio formats
+import { AUDIO_CODEC_CONFIG, FORMAT_TO_MIME, getFileExtension } from '../core/constants';
-type AudioFormat = 
-  | 'mp3' | 'wav' | 'ogg' | 'm4a' | 'flac'
-  | 'aac' | 'aiff' | 'alac' | 'wma' | 'opus' | 'm4r' | 'amr';
 
 let ffmpeg: FFmpeg | null = null;
 let ffmpegLoading: Promise<void> | null = null;
@@ -41,92 +38,61 @@ async function ensureFFmpegLoaded(): Promise<FFmpeg> {
   return ffmpeg!;
 }
 
-function getFFmpegArgs(
+// -----------------------------------------------------------------------------
-  _inputFormat: AudioFormat,
+// Command Executor (DRY: Handles Write → Run → Read → Clean lifecycle)
-  outputFormat: AudioFormat,
+// -----------------------------------------------------------------------------
-  bitrate?: number
-): string[] {
-  const args: string[] = [];
-  const br = bitrate || 192;
 
-  // Codec selection based on output format
+/**
-  switch (outputFormat) {
+ * Runs an FFmpeg command with guaranteed cleanup.
-    case 'mp3':
+ * This abstracts the entire file I/O lifecycle.
-      args.push('-c:a', 'libmp3lame');
+ */
-      args.push('-b:a', `${br}k`);
+async function runFFmpegCommand(
-      break;
+  inputBuffer: ArrayBuffer,
-    case 'wav':
+  inputExt: string,
-      args.push('-c:a', 'pcm_s16le');
+  outputExt: string,
-      break;
+  args: string[],
-    case 'ogg':
+  onProgress?: (progress: number) => void
-      args.push('-c:a', 'libvorbis');
+): Promise<Uint8Array> {
-      args.push('-q:a', '4');
+  const ff = await ensureFFmpegLoaded();
-      break;
+  const inputFile = `input.${inputExt}`;
-    case 'm4a':
+  const outputFile = `output.${outputExt}`;
-      args.push('-c:a', 'aac');
+
-      args.push('-b:a', `${br}k`);
+  // Store callback reference for proper cleanup
-      break;
+  const progressCallback = onProgress 
-    case 'flac':
+    ? ({ progress }: { progress: number }) => onProgress(Math.round(progress * 100))
-      args.push('-c:a', 'flac');
+    : null;
-      args.push('-compression_level', '5');
+
-      break;
+  if (progressCallback) {
-    case 'aac':
+    ff.on('progress', progressCallback);
-      args.push('-c:a', 'aac');
-      args.push('-b:a', `${br}k`);
-      break;
-    case 'aiff':
-      args.push('-c:a', 'pcm_s16be');
-      break;
-    case 'alac':
-      // ALAC in M4A container
-      args.push('-c:a', 'alac');
-      break;
-    case 'wma':
-      args.push('-c:a', 'wmav2');
-      args.push('-b:a', `${br}k`);
-      break;
-    case 'opus':
-      args.push('-c:a', 'libopus');
-      args.push('-b:a', `${br}k`);
-      break;
-    case 'm4r':
-      // M4R is just AAC with different extension (iPhone ringtones)
-      args.push('-c:a', 'aac');
-      args.push('-b:a', `${br}k`);
-      break;
-    case 'amr':
-      args.push('-c:a', 'libopencore_amrnb');
-      args.push('-ar', '8000'); // AMR requires 8kHz sample rate
-      args.push('-ac', '1');    // AMR is mono only
-      break;
   }
 
-  return args;
+  try {
+    // Write input file to FFmpeg's virtual filesystem
+    await ff.writeFile(inputFile, new Uint8Array(inputBuffer));
+    
+    // Execute FFmpeg command
+    await ff.exec(['-i', inputFile, ...args, '-y', outputFile]);
+
+    // Read output file
+    const data = await ff.readFile(outputFile);
+    return data as Uint8Array;
+  } finally {
+    // Guaranteed cleanup (even if exec crashes)
+    try {
+      await ff.deleteFile(inputFile);
+      await ff.deleteFile(outputFile);
+      if (progressCallback) {
+        ff.off('progress', progressCallback);
+      }
+    } catch {
+      // Ignore cleanup errors
+    }
+  }
 }
 
-function getExtension(format: AudioFormat): string {
+// -----------------------------------------------------------------------------
-  // ALAC uses m4a container
+// Audio Converter API
-  if (format === 'alac') return 'm4a';
+// -----------------------------------------------------------------------------
-  return format;
-}
-
-function getMimeType(format: AudioFormat): string {
-  const mimeMap: Record<AudioFormat, string> = {
-    mp3: 'audio/mpeg',
-    wav: 'audio/wav',
-    ogg: 'audio/ogg',
-    m4a: 'audio/mp4',
-    flac: 'audio/flac',
-    aac: 'audio/aac',
-    aiff: 'audio/aiff',
-    alac: 'audio/x-m4a',
-    wma: 'audio/x-ms-wma',
-    opus: 'audio/opus',
-    m4r: 'audio/x-m4r',
-    amr: 'audio/amr',
-  };
-  return mimeMap[format];
-}
 
 const audioConverter = {
   /**
@@ -149,58 +115,29 @@ const audioConverter = {
     arrayBuffer: ArrayBuffer,
     inputFormat: AudioFormat,
     outputFormat: AudioFormat,
-    bitrate?: number,
+    bitrate: number = 192,
     onProgress?: (progress: number) => void
   ): Promise<Blob> {
-    const ff = await ensureFFmpegLoaded();
+    const getArgs = AUDIO_CODEC_CONFIG[outputFormat];
-
+    if (!getArgs) {
-    const inputExt = getExtension(inputFormat);
+      throw new Error(`Unsupported output format: ${outputFormat}`);
-    const outputExt = getExtension(outputFormat);
-    const inputFileName = `input.${inputExt}`;
-    const outputFileName = `output.${outputExt}`;
-
-    // Register progress callback if provided
-    if (onProgress) {
-      ff.on('progress', ({ progress }) => {
-        onProgress(Math.round(progress * 100));
-      });
     }
 
-    try {
+    const inputExt = getFileExtension(inputFormat);
-      // Write input file to FFmpeg's virtual filesystem
+    const outputExt = getFileExtension(outputFormat);
-      await ff.writeFile(inputFileName, new Uint8Array(arrayBuffer));
 
-      // Build FFmpeg command
+    const resultData = await runFFmpegCommand(
-      const codecArgs = getFFmpegArgs(inputFormat, outputFormat, bitrate);
+      arrayBuffer,
+      inputExt,
+      outputExt,
+      getArgs(bitrate),
+      onProgress
+    );
 
-      await ff.exec([
+    // Copy to new buffer to avoid SharedArrayBuffer issues
-        '-i', inputFileName,
+    const buffer = new ArrayBuffer(resultData.length);
-        ...codecArgs,
+    new Uint8Array(buffer).set(resultData);
-        '-y', // Overwrite output
+    return new Blob([buffer], { type: FORMAT_TO_MIME[outputFormat] });
-        outputFileName,
-      ]);
-
-      // Read output file
-      const data = await ff.readFile(outputFileName);
-      
-      // Cleanup
-      await ff.deleteFile(inputFileName);
-      await ff.deleteFile(outputFileName);
-
-      // Convert to regular ArrayBuffer to avoid SharedArrayBuffer issues
-      const buffer = new ArrayBuffer((data as Uint8Array).length);
-      new Uint8Array(buffer).set(data as Uint8Array);
-      return new Blob([buffer], { type: getMimeType(outputFormat) });
-    } catch (error) {
-      // Attempt cleanup on error
-      try {
-        await ff.deleteFile(inputFileName);
-        await ff.deleteFile(outputFileName);
-      } catch {
-        // Ignore cleanup errors
-      }
-      throw error;
-    }
   },
 
   /**
@@ -210,52 +147,30 @@ const audioConverter = {
     arrayBuffer: ArrayBuffer,
     inputExtension: string,
     outputFormat: AudioFormat,
-    bitrate?: number,
+    bitrate: number = 192,
     onProgress?: (progress: number) => void
   ): Promise<Blob> {
-    const ff = await ensureFFmpegLoaded();
+    const getArgs = AUDIO_CODEC_CONFIG[outputFormat];
-
+    if (!getArgs) {
-    const inputFileName = `input.${inputExtension}`;
+      throw new Error(`Unsupported output format: ${outputFormat}`);
-    const outputExt = getExtension(outputFormat);
-    const outputFileName = `output.${outputExt}`;
-
-    if (onProgress) {
-      ff.on('progress', ({ progress }) => {
-        onProgress(Math.round(progress * 100));
-      });
     }
 
-    try {
+    // Add -vn (no video) to the codec args
-      await ff.writeFile(inputFileName, new Uint8Array(arrayBuffer));
+    const args = ['-vn', ...getArgs(bitrate)];
+    const outputExt = getFileExtension(outputFormat);
 
-      const codecArgs = getFFmpegArgs('m4a', outputFormat, bitrate);
+    const resultData = await runFFmpegCommand(
+      arrayBuffer,
+      inputExtension,
+      outputExt,
+      args,
+      onProgress
+    );
 
-      await ff.exec([
+    // Copy to new buffer to avoid SharedArrayBuffer issues
-        '-i', inputFileName,
+    const buffer = new ArrayBuffer(resultData.length);
-        '-vn', // No video
+    new Uint8Array(buffer).set(resultData);
-        ...codecArgs,
+    return new Blob([buffer], { type: FORMAT_TO_MIME[outputFormat] });
-        '-y',
-        outputFileName,
-      ]);
-
-      const data = await ff.readFile(outputFileName);
-      
-      await ff.deleteFile(inputFileName);
-      await ff.deleteFile(outputFileName);
-
-      // Convert to regular ArrayBuffer
-      const buffer = new ArrayBuffer((data as Uint8Array).length);
-      new Uint8Array(buffer).set(data as Uint8Array);
-      return new Blob([buffer], { type: getMimeType(outputFormat) });
-    } catch (error) {
-      try {
-        await ff.deleteFile(inputFileName);
-        await ff.deleteFile(outputFileName);
-      } catch {
-        // Ignore cleanup errors
-      }
-      throw error;
-    }
   },
 };
 

src/workers/image.worker.ts

@@ -9,14 +9,11 @@ import * as Comlink from 'comlink';
 import {
   initializeImageMagick,
   ImageMagick,
-  MagickFormat,
   MagickGeometry,
+  type IMagickImage,
 } from '@imagemagick/magick-wasm';
-
+import type { ImageFormat } from '../core/types';
-// All supported image formats
+import { IMAGE_FORMAT_MAP, FORMAT_TO_MIME, LOSSY_IMAGE_FORMATS } from '../core/constants';
-type ImageFormat = 
-  | 'jpeg' | 'png' | 'webp' | 'gif' | 'bmp' | 'tiff' | 'heic' | 'ico'
-  | 'avif' | 'jxl' | 'svg' | 'psd' | 'raw' | 'tga';
 
 let magickInitialized = false;
 let initPromise: Promise<void> | null = null;
@@ -38,45 +35,50 @@ async function ensureMagickInitialized(): Promise<void> {
   return initPromise;
 }
 
-function getMagickFormat(format: ImageFormat): MagickFormat {
+// -----------------------------------------------------------------------------
-  const formatMap: Record<ImageFormat, MagickFormat> = {
+// Image Processor (DRY: Handles Read → Modify → Write lifecycle)
-    jpeg: MagickFormat.Jpeg,
+// -----------------------------------------------------------------------------
-    png: MagickFormat.Png,
+
-    webp: MagickFormat.WebP,
+/**
-    gif: MagickFormat.Gif,
+ * Generic image processor that handles I/O and accepts an operation callback.
-    bmp: MagickFormat.Bmp,
+ * The operation callback receives the image for manipulation (resize, quality, etc.)
-    tiff: MagickFormat.Tiff,
+ */
-    heic: MagickFormat.Heic,
+async function processImage(
-    ico: MagickFormat.Ico,
+  buffer: ArrayBuffer,
-    avif: MagickFormat.Avif,
+  outputFormat: ImageFormat,
-    jxl: MagickFormat.Jxl,
+  operation: (image: IMagickImage) => void
-    svg: MagickFormat.Svg,
+): Promise<Blob> {
-    psd: MagickFormat.Psd,
+  await ensureMagickInitialized();
-    raw: MagickFormat.Raw, // Note: May need specific raw format handling
+  const inputData = new Uint8Array(buffer);
-    tga: MagickFormat.Tga,
+  const magickFormat = IMAGE_FORMAT_MAP[outputFormat];
-  };
+  
-  return formatMap[format];
+  if (!magickFormat) {
+    throw new Error(`Unsupported output format: ${outputFormat}`);
+  }
+
+  return new Promise((resolve, reject) => {
+    try {
+      ImageMagick.read(inputData, (image) => {
+        // Run the specific operation (resize, quality change, etc.)
+        operation(image);
+
+        // Standard output handling
+        image.write(magickFormat, (data) => {
+          // Clone buffer to detach from SharedArrayBuffer
+          const resultBuffer = new ArrayBuffer(data.length);
+          new Uint8Array(resultBuffer).set(data);
+          resolve(new Blob([resultBuffer], { type: FORMAT_TO_MIME[outputFormat] }));
+        });
+      });
+    } catch (error) {
+      reject(error);
+    }
+  });
 }
 
-function getMimeType(format: ImageFormat): string {
+// -----------------------------------------------------------------------------
-  const mimeMap: Record<ImageFormat, string> = {
+// Image Converter API
-    jpeg: 'image/jpeg',
+// -----------------------------------------------------------------------------
-    png: 'image/png',
-    webp: 'image/webp',
-    gif: 'image/gif',
-    bmp: 'image/bmp',
-    tiff: 'image/tiff',
-    heic: 'image/heic',
-    ico: 'image/x-icon',
-    avif: 'image/avif',
-    jxl: 'image/jxl',
-    svg: 'image/svg+xml',
-    psd: 'image/vnd.adobe.photoshop',
-    raw: 'image/x-raw',
-    tga: 'image/x-tga',
-  };
-  return mimeMap[format];
-}
 
 const imageConverter = {
   /**
@@ -101,14 +103,7 @@ const imageConverter = {
     outputFormat: ImageFormat,
     quality: number = 85
   ): Promise<Blob> {
-    await ensureMagickInitialized();
+    return processImage(arrayBuffer, outputFormat, (image) => {
-
-    const inputData = new Uint8Array(arrayBuffer);
-    const outputMagickFormat = getMagickFormat(outputFormat);
-
-    return new Promise((resolve, reject) => {
-      try {
-        ImageMagick.read(inputData, (image) => {
       // ICO format has max size of 256x256
       if (outputFormat === 'ico' && (image.width > 256 || image.height > 256)) {
         const geometry = new MagickGeometry(256, 256);
@@ -117,21 +112,9 @@ const imageConverter = {
       }
 
       // Set quality for lossy formats
-          if (['jpeg', 'webp', 'avif', 'jxl'].includes(outputFormat)) {
+      if (LOSSY_IMAGE_FORMATS.includes(outputFormat)) {
         image.quality = quality;
       }
-
-          image.write(outputMagickFormat, (data) => {
-            // Copy to regular ArrayBuffer to avoid SharedArrayBuffer issues
-            const buffer = new ArrayBuffer(data.length);
-            new Uint8Array(buffer).set(data);
-            const blob = new Blob([buffer], { type: getMimeType(outputFormat) });
-            resolve(blob);
-          });
-        });
-      } catch (error) {
-        reject(error);
-      }
     });
   },
 
@@ -145,32 +128,16 @@ const imageConverter = {
     outputFormat: ImageFormat,
     quality: number = 85
   ): Promise<Blob> {
-    await ensureMagickInitialized();
+    return processImage(arrayBuffer, outputFormat, (image) => {
-
+      // Resize operation
-    const inputData = new Uint8Array(arrayBuffer);
-    const outputMagickFormat = getMagickFormat(outputFormat);
-
-    return new Promise((resolve, reject) => {
-      try {
-        ImageMagick.read(inputData, (image) => {
       const geometry = new MagickGeometry(width, height);
       geometry.ignoreAspectRatio = false;
       image.resize(geometry);
 
-          if (['jpeg', 'webp', 'avif', 'jxl'].includes(outputFormat)) {
+      // Set quality for lossy formats
+      if (LOSSY_IMAGE_FORMATS.includes(outputFormat)) {
         image.quality = quality;
       }
-
-          image.write(outputMagickFormat, (data) => {
-            const buffer = new ArrayBuffer(data.length);
-            new Uint8Array(buffer).set(data);
-            const blob = new Blob([buffer], { type: getMimeType(outputFormat) });
-            resolve(blob);
-          });
-        });
-      } catch (error) {
-        reject(error);
-      }
     });
   },
 };