Add global Downsampling feature (#1575)

* Add global downsampling feature

* Default to Opus &  consider player transcoder

* Add a test case for DefaultDownsamplingFormat

Co-authored-by: Deluan <deluan@navidrome.org>

conf/configuration.go

@@ -67,6 +67,9 @@ type configOptions struct {
 	Spotify      spotifyOptions
 	ListenBrainz listenBrainzOptions
 
+	//test downsampling
+	DefaultDownsamplingFormat string
+
 	// DevFlags. These are used to enable/disable debugging and incomplete features
 	DevLogSourceLine           bool
 	DevLogLevels               map[string]string
@@ -268,6 +271,8 @@ func init() {
 	viper.SetDefault("listenbrainz.enabled", true)
 	viper.SetDefault("listenbrainz.baseurl", "https://api.listenbrainz.org/1/")
 
+	viper.SetDefault("defaultdownsamplingformat", consts.DefaultDownsamplingFormat)
+
 	// DevFlags. These are used to enable/disable debugging and incomplete features
 	viper.SetDefault("devlogsourceline", false)
 	viper.SetDefault("devautocreateadminpassword", "")

consts/consts.go

@@ -80,7 +80,8 @@ const (
 )
 
 var (
-	DefaultTranscodings = []map[string]interface{}{
+	DefaultDownsamplingFormat = "opus"
+	DefaultTranscodings       = []map[string]interface{}{
 		{
 			"name":           "mp3 audio",
 			"targetFormat":   "mp3",

core/media_streamer.go

@@ -142,6 +142,10 @@ func selectTranscodingOptions(ctx context.Context, ds model.DataStore, mf *model
 			if p, ok := request.PlayerFrom(ctx); ok {
 				cBitRate = p.MaxBitRate
 			}
+		} else if reqBitRate > 0 && conf.Server.DefaultDownsamplingFormat != "" {
+			// If no format is specified and no transcoding associated to the player, but a bitrate is specfied, and there is no transcoding set for the player, we use the default downsampling format
+			log.Debug("Default Downsampling", "Using default downsampling format", conf.Server.DefaultDownsamplingFormat)
+			cFormat = conf.Server.DefaultDownsamplingFormat
 		}
 	}
 	if reqBitRate > 0 {

core/media_streamer_test.go

@@ -8,6 +8,7 @@ import (
 	"sync"
 
 	"github.com/navidrome/navidrome/conf"
+	"github.com/navidrome/navidrome/conf/configtest"
 	"github.com/navidrome/navidrome/log"
 	"github.com/navidrome/navidrome/model"
 	"github.com/navidrome/navidrome/model/request"
@@ -24,6 +25,7 @@ var _ = Describe("MediaStreamer", func() {
 	ctx := log.NewContext(context.TODO())
 
 	BeforeEach(func() {
+		DeferCleanup(configtest.SetupConfig())
 		conf.Server.DataFolder, _ = os.MkdirTemp("", "file_caches")
 		conf.Server.TranscodingCacheSize = "100MB"
 		ds = &tests.MockDataStore{MockedTranscoding: &tests.MockTranscodingRepo{}}
@@ -115,6 +117,15 @@ var _ = Describe("MediaStreamer", func() {
 				Expect(format).To(Equal("raw"))
 				Expect(bitRate).To(Equal(320))
 			})
+			It("returns the DefaultDownsamplingFormat if a maxBitrate but not the format", func() {
+				conf.Server.DefaultDownsamplingFormat = "opus"
+				mf.Suffix = "FLAC"
+				mf.BitRate = 960
+				format, bitRate := selectTranscodingOptions(ctx, ds, mf, "", 128)
+				Expect(format).To(Equal("opus"))
+				Expect(bitRate).To(Equal(128))
+
+			})
 		})
 
 		Context("player has format configured", func() {

tests/mock_transcoding_repo.go

@@ -16,6 +16,8 @@ func (m *MockTranscodingRepo) FindByFormat(format string) (*model.Transcoding, e
 		return &model.Transcoding{ID: "mp31", TargetFormat: "mp3", DefaultBitRate: 160}, nil
 	case "oga":
 		return &model.Transcoding{ID: "oga1", TargetFormat: "oga", DefaultBitRate: 128}, nil
+	case "opus":
+		return &model.Transcoding{ID: "opus1", TargetFormat: "opus", DefaultBitRate: 96}, nil
 	default:
 		return nil, model.ErrNotFound
 	}