refactor: route offline generator through core mpx components

internal/offline/generator.go

@@ -8,8 +8,12 @@ import (
     "path/filepath"
     "time"
 
+    "github.com/jan/fm-rds-tx/internal/audio"
     cfgpkg "github.com/jan/fm-rds-tx/internal/config"
+    "github.com/jan/fm-rds-tx/internal/mpx"
     "github.com/jan/fm-rds-tx/internal/output"
+    "github.com/jan/fm-rds-tx/internal/rds"
+    "github.com/jan/fm-rds-tx/internal/stereo"
 )
 
 type Generator struct {
@@ -37,20 +41,35 @@ func (g *Generator) GenerateFrame(duration time.Duration) *output.CompositeFrame
         Sequence:     1,
     }
 
+    stereoEncoder := stereo.NewStereoEncoder(sampleRate)
+    combiner := mpx.NewDefaultCombiner()
+    combiner.PilotGain = g.cfg.FM.PilotLevel
+    combiner.RDSGain = g.cfg.FM.RDSInjection
+
+    rdsEnc, _ := rds.NewEncoder(rds.RDSConfig{
+        PI:         0x1234,
+        PS:         g.cfg.RDS.PS,
+        RT:         g.cfg.RDS.RadioText,
+        PTY:        uint8(g.cfg.RDS.PTY),
+        SampleRate: sampleRate,
+    })
+    rdsSamples := rdsEnc.Generate(samples)
+
     leftFreq := 1000.0
     rightFreq := 1600.0
-    pilotFreq := 19000.0
-    rdsFreq := 57000.0
+    stereoCarrierFreq := 38000.0
 
     for i := 0; i < samples; i++ {
         t := float64(i) / sampleRate
-        left := 0.4 * math.Sin(2*math.Pi*leftFreq*t)
-        right := 0.4 * math.Sin(2*math.Pi*rightFreq*t+math.Pi/3)
-        mono := (left + right) / 2
-        stereo := (left - right) / 2 * 0.8 * math.Sin(2*math.Pi*38000*t)
-        pilot := g.cfg.FM.PilotLevel * math.Sin(2*math.Pi*pilotFreq*t)
-        rds := g.cfg.FM.RDSInjection * math.Sin(2*math.Pi*rdsFreq*t)
-        composite := (mono + stereo + pilot + rds) * g.cfg.FM.OutputDrive
+        left := audio.Sample(0.4 * math.Sin(2*math.Pi*leftFreq*t))
+        right := audio.Sample(0.4 * math.Sin(2*math.Pi*rightFreq*t+math.Pi/3))
+        comps := stereoEncoder.Encode(audio.NewFrame(left, right))
+        stereoDSB := comps.Stereo * math.Sin(2*math.Pi*stereoCarrierFreq*t)
+        rdsValue := 0.0
+        if g.cfg.RDS.Enabled && i < len(rdsSamples) {
+            rdsValue = rdsSamples[i]
+        }
+        composite := combiner.Combine(comps.Mono, stereoDSB, comps.Pilot, rdsValue) * g.cfg.FM.OutputDrive
         frame.Samples[i] = output.IQSample{I: float32(composite), Q: 0}
     }
 
@@ -92,5 +111,5 @@ func (g *Generator) WriteFile(path string, duration time.Duration) error {
 }
 
 func (g *Generator) Summary(duration time.Duration) string {
-    return fmt.Sprintf("offline frame: freq=%.1fMHz sampleRate=%d duration=%s outputDrive=%.2f", g.cfg.FM.FrequencyMHz, g.cfg.FM.CompositeRateHz, duration.String(), g.cfg.FM.OutputDrive)
+    return fmt.Sprintf("offline frame: freq=%.1fMHz sampleRate=%d duration=%s outputDrive=%.2f stereo=%t rds=%t", g.cfg.FM.FrequencyMHz, g.cfg.FM.CompositeRateHz, duration.String(), g.cfg.FM.OutputDrive, g.cfg.FM.StereoEnabled, g.cfg.RDS.Enabled)
 }