Import song duration with hundredths when using TagLib

This is how ffmpeg extractor currently works, and it makes album durations more precise.

scanner/metadata/taglib/taglib.go

@@ -1,6 +1,8 @@
 package taglib
 
 import (
+	"strconv"
+
 	"github.com/navidrome/navidrome/log"
 )
 
@@ -32,6 +34,13 @@ func (e *Parser) extractMetadata(filePath string) (parsedTags, error) {
 		"tracknumber": {"trck", "_track"},
 	}
 
+	if length, ok := tags["lengthinmilliseconds"]; ok && len(length) > 0 {
+		millis, _ := strconv.Atoi(length[0])
+		if duration := float64(millis) / 1000.0; duration > 0 {
+			tags["duration"] = []string{strconv.FormatFloat(duration, 'f', 2, 32)}
+		}
+	}
+
 	for tagName, alternatives := range alternativeTags {
 		for _, altName := range alternatives {
 			if altValue, ok := tags[altName]; ok {

scanner/metadata/taglib/taglib_test.go

@@ -27,7 +27,7 @@ var _ = Describe("Parser", func() {
 			Expect(m).To(HaveKeyWithValue("tracknumber", []string{"2/10", "2/10", "2"}))
 			Expect(m).To(HaveKeyWithValue("discnumber", []string{"1/2"}))
 			Expect(m).To(HaveKeyWithValue("has_picture", []string{"true"}))
-			Expect(m).To(HaveKeyWithValue("duration", []string{"1"}))
+			Expect(m).To(HaveKeyWithValue("duration", []string{"1.02"}))
 			Expect(m).To(HaveKeyWithValue("bitrate", []string{"192"}))
 			Expect(m).To(HaveKeyWithValue("comment", []string{"Comment1\nComment2"}))
 			Expect(m).To(HaveKeyWithValue("lyrics", []string{"Lyrics 1\rLyrics 2"}))
@@ -37,7 +37,7 @@ var _ = Describe("Parser", func() {
 			Expect(err).To(BeNil())
 			Expect(m).ToNot(HaveKey("title"))
 			Expect(m).ToNot(HaveKey("has_picture"))
-			Expect(m).To(HaveKeyWithValue("duration", []string{"1"}))
+			Expect(m).To(HaveKeyWithValue("duration", []string{"1.04"}))
 			Expect(m).To(HaveKeyWithValue("fbpm", []string{"141.7"}))
 
 			// TabLib 1.12 returns 18, previous versions return 39.

scanner/metadata/taglib/taglib_wrapper.cpp

@@ -31,6 +31,7 @@ int taglib_read(const char *filename, unsigned long id) {
   // Add audio properties to the tags
   const TagLib::AudioProperties *props(f.audioProperties());
   go_map_put_int(id, (char *)"duration", props->length());
+  go_map_put_int(id, (char *)"lengthinmilliseconds", props->lengthInMilliseconds());
   go_map_put_int(id, (char *)"bitrate", props->bitrate());
 
   TagLib::PropertyMap tags = f.file()->properties();