Add support for MP4 (M4A) rating support via the `moov.udta.meta.ilst…

….rate` atom (box)
Borewit · Nov 4, 2023 · 4a14da1 · 4a14da1
1 parent 1c11eb0
commit 4a14da1
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Showing 4 changed files with 36 additions and 5 deletions.
diff --git a/lib/mp4/MP4Parser.ts b/lib/mp4/MP4Parser.ts
@@ -296,14 +296,14 @@ export class MP4Parser extends BasicParser {
           return this.parseValueAtom(tagKey, child);
 
         case 'name': // name atom (optional)
+        case 'mean':
           const name = await this.tokenizer.readToken<AtomToken.INameAtom>(new AtomToken.NameAtom(payLoadLength));
           tagKey += ':' + name.name;
           break;
 
-        case 'mean': // name atom (optional)
-          const mean = await this.tokenizer.readToken<AtomToken.INameAtom>(new AtomToken.NameAtom(payLoadLength));
-          // console.log("  %s[%s] = %s", tagKey, header.name, mean.name);
-          tagKey += ':' + mean.name;
+        case 'rate':
+          const rate = await this.tokenizer.readToken<AtomToken.INameAtom>(new AtomToken.NameAtom(payLoadLength));
+          tagKey += ':' + rate.name;
           break;
 
         default:
@@ -342,6 +342,11 @@ export class MP4Parser extends BasicParser {
             this.addTag(tagKey, genreStr);
             break;
 
+          case 'rate':
+            const rate = new Token.StringType(2, 'ascii').get(dataAtom.value, 0);
+            this.addTag(tagKey, rate);
+            break;
+
           default:
           // console.log("  reserved-data: name=%s, len=%s, set=%s, type=%s, locale=%s, value{ hex=%s, ascii=%s }",
           // header.name, header.length, dataAtom.type.set, dataAtom.type.type, dataAtom.locale, dataAtom.value.toString('hex'), dataAtom.value.toString('ascii'));

diff --git a/lib/mp4/MP4TagMapper.ts b/lib/mp4/MP4TagMapper.ts
@@ -1,5 +1,7 @@
 import { CaseInsensitiveTagMap } from '../common/CaseInsensitiveTagMap.js';
 import { INativeTagMap } from '../common/GenericTagTypes.js';
+import {ITag} from "../type.js";
+import {INativeMetadataCollector} from "../common/MetadataCollector.js";
 
 /**
  * Ref: https://github.com/sergiomb2/libmp4v2/wiki/iTunesMetadata
@@ -105,7 +107,8 @@ const mp4TagMap: INativeTagMap = {
   hdvd: 'hdVideo',
   keyw: 'keywords',
   shwm: 'showMovement',
-  stik: 'stik'
+  stik: 'stik',
+  rate: 'rating'
 };
 
 export const tagType = 'iTunes';
@@ -116,4 +119,17 @@ export class MP4TagMapper extends CaseInsensitiveTagMap {
     super([tagType], mp4TagMap);
   }
 
+  protected postMap(tag: ITag, warnings: INativeMetadataCollector): void {
+
+    switch (tag.id) {
+
+      case 'rate':
+        tag.value = {
+          source: undefined,
+          rating: parseFloat(tag.value) / 100
+        };
+        break;
+    }
+  }
+
 }
diff --git a/test/samples/rating/testcase.m4a b/test/samples/rating/testcase.m4a
diff --git a/test/test-file-mp4.ts b/test/test-file-mp4.ts
@@ -460,4 +460,14 @@ describe('Parse MPEG-4 files with iTunes metadata', () => {
     assert.strictEqual('S2E32 : Audio', common.title, 'common.title');
   });
 
+  it('moov.udta.meta.ilst.rate mapping', async () => {
+
+    const filePath = path.join(samplePath, 'rating', 'testcase.m4a');
+    const {format, common, native} = await mm.parseFile(filePath);
+
+    assert.isDefined(common.rating, 'Expect rating property to be present');
+    assert.equal(common.rating[0].rating, 0.80, 'Vorbis tag rating score of 80%');
+    assert.equal(mm.ratingToStars(common.rating[0].rating), 4, 'Vorbis tag rating conversion');
+  });
+
 });