fix: support Ogg Opus to Ogg Vorbis conversion

src/handlers/FFmpeg.ts

@@ -7,6 +7,40 @@ import mime from "mime";
 import normalizeMimeType from "../normalizeMimeType.ts";
 import CommonFormats from "src/CommonFormats.ts";
 
+export function getSpecialAudioFormats(): FileFormat[] {
+  return [
+    {
+      name: "Ogg Opus Audio",
+      format: "opus",
+      extension: "ogg",
+      mime: CommonFormats.OGG.mime,
+      from: true,
+      to: false,
+      internal: "ogg",
+      category: "audio",
+      lossless: false
+    },
+    {
+      name: "Ogg Vorbis Audio",
+      format: "vorbis",
+      extension: "ogg",
+      mime: CommonFormats.OGG.mime,
+      from: false,
+      to: true,
+      internal: "ogg",
+      category: "audio",
+      lossless: false
+    }
+  ];
+}
+
+export function getCodecArgsForFormat(outputFormat: FileFormat): string[] {
+  if (outputFormat.internal === "ogg" && outputFormat.format === "vorbis") {
+    return ["-c:a", "libvorbis"];
+  }
+  return [];
+}
+
 class FFmpegHandler implements FormatHandler {
 
   static formatNames: Map<string, string> = new Map([
@@ -258,6 +292,7 @@ class FFmpegHandler implements FormatHandler {
     // Add PNG input explicitly - FFmpeg otherwise treats both PNG and
     // APNG as the same thing.
     this.supportedFormats.push(CommonFormats.PNG.builder("png").allowFrom());
+    this.supportedFormats.push(...getSpecialAudioFormats());
 
     this.#ffmpeg.terminate();
 
@@ -302,6 +337,7 @@ class FFmpegHandler implements FormatHandler {
     } else if (outputFormat.internal === "asf") {
       command.push("-b:v", "15M", "-b:a", "192k");
     }
+    command.push(...getCodecArgsForFormat(outputFormat));
     if (args) command.push(...args);
     command.push("output");
 

test/handlers/ffmpeg.test.ts

@@ -0,0 +1,40 @@
+import { expect, test } from "bun:test";
+import CommonFormats from "../../src/CommonFormats.ts";
+import { getCodecArgsForFormat, getSpecialAudioFormats } from "../../src/handlers/FFmpeg.ts";
+
+test("ffmpeg exposes distinct ogg opus and ogg vorbis aliases", () => {
+  const formats = getSpecialAudioFormats();
+
+  expect(formats).toEqual([
+    {
+      name: "Ogg Opus Audio",
+      format: "opus",
+      extension: "ogg",
+      mime: CommonFormats.OGG.mime,
+      from: true,
+      to: false,
+      internal: "ogg",
+      category: "audio",
+      lossless: false
+    },
+    {
+      name: "Ogg Vorbis Audio",
+      format: "vorbis",
+      extension: "ogg",
+      mime: CommonFormats.OGG.mime,
+      from: false,
+      to: true,
+      internal: "ogg",
+      category: "audio",
+      lossless: false
+    }
+  ]);
+});
+
+test("ffmpeg forces libvorbis for ogg vorbis output", () => {
+  const vorbisFormat = getSpecialAudioFormats()[1];
+  expect(getCodecArgsForFormat(vorbisFormat)).toEqual(["-c:a", "libvorbis"]);
+
+  const plainOgg = CommonFormats.OGG.builder("ogg").allowTo();
+  expect(getCodecArgsForFormat(plainOgg)).toEqual([]);
+});