implement mime type normalization

Fixes #2

Author: p2r3

README.md

@@ -86,6 +86,7 @@ There are a few additional things that I want to point out in particular:
 - Pay attention to the naming system. If your tool is called `dummy`, then the class should be called `dummyHandler`, and the file should be called `dummy.ts`.
 - The handler is responsible for setting the output file's name. This is done to allow for flexibility in rare cases where the _full_ file name matters. Of course, in most cases, you'll only have to swap the file extension.
 - The handler is also responsible for ensuring that any byte buffers that enter or exit the handler _do not get mutated_. If necessary, clone the buffer by wrapping it in `new Uint8Array()`.
+- When handling MIME types, run them through [normalizeMimeType](src/normalizeMimeType.ts) first. One file can have multiple valid MIME types, which isn't great when you're trying to match them algorithmically.
 
 ### Adding dependencies
 

src/handlers/FFmpeg.ts

@@ -2,7 +2,9 @@ import type { FileData, FileFormat, FormatHandler } from "../FormatHandler.ts";
 
 import { FFmpeg } from "@ffmpeg/ffmpeg";
 import type { LogEvent } from "@ffmpeg/ffmpeg";
+
 import mime from "mime";
+import normalizeMimeType from "../normalizeMimeType.ts";
 
 class FFmpegHandler implements FormatHandler {
 
@@ -130,6 +132,7 @@ class FFmpegHandler implements FormatHandler {
           extension = format;
           mimeType = mime.getType(format) || ("video/" + format);
         }
+        mimeType = normalizeMimeType(mimeType);
 
         this.supportedFormats.push({
           name: description + (formats.length > 1 ? (" / " + format) : ""),

src/handlers/ImageMagick.ts

@@ -7,6 +7,7 @@ import {
 } from "@imagemagick/magick-wasm";
 
 import mime from "mime";
+import normalizeMimeType from "../normalizeMimeType.ts";
 
 import type { FileData, FileFormat, FormatHandler } from "../FormatHandler.ts";
 
@@ -37,7 +38,7 @@ class ImageMagickHandler implements FormatHandler {
         name: format.description,
         format: formatName,
         extension: formatName,
-        mime: mimeType,
+        mime: normalizeMimeType(mimeType),
         from: format.supportsReading,
         to: format.supportsWriting,
         internal: format.format

src/main.ts

@@ -1,4 +1,5 @@
 import type { FileFormat, FileData, FormatHandler, ConvertPathNode } from "./FormatHandler.js";
+import normalizeMimeType from "./normalizeMimeType.js";
 import handlers from "./handlers";
 
 /** Files currently selected for conversion */
@@ -97,9 +98,8 @@ const fileSelectHandler = (event: Event) => {
     ${files.length > 1 ? `<br>... and ${files.length - 1} more` : ""}
   </h2>`;
 
-  let mimeType = files[0].type;
   // Common MIME type adjustments (to match "mime" library)
-  if (mimeType === "image/x-icon") mimeType = "image/vnd.microsoft.icon";
+  let mimeType = normalizeMimeType(files[0].type);
 
   // Search input formats by MIME type, or fall back to file extension.
   const fileExtension = files[0].name.split(".").pop();

src/normalizeMimeType.ts

@@ -0,0 +1,10 @@
+function normalizeMimeType (mime: string) {
+  switch (mime) {
+    case "audio/x-wav": return "audio/wav";
+    case "audio/vnd.wave": return "audio/wav";
+    case "image/x-icon": return "image/vnd.microsoft.icon";
+  }
+  return mime;
+}
+
+export default normalizeMimeType;