feat: add basic wav rate adaptation for offline and sim paths

docs/README.md

@@ -15,6 +15,7 @@
 Current no-hardware sources:
 - generated stereo tones via config
 - 16-bit PCM WAV file input via `audio.inputPath`
+- basic sample-rate adaptation for WAV sources into the composite generation path
 
 ### Tone configuration
 

internal/app/sim.go

@@ -52,5 +52,12 @@ func RunSimulatedTransmit(cfg cfgpkg.Config, outPath string, duration time.Durat
     if err := backend.Flush(context.Background()); err != nil {
         return "", err
     }
-    return fmt.Sprintf("simulated transmit: backend=%s output=%s duration=%s", backend.Info().Name, outPath, duration), nil
+    return fmt.Sprintf("simulated transmit: backend=%s output=%s duration=%s input=%s", backend.Info().Name, outPath, duration, inputLabel(cfg)), nil
+}
+
+func inputLabel(cfg cfgpkg.Config) string {
+    if cfg.Audio.InputPath != "" {
+        return cfg.Audio.InputPath
+    }
+    return "tones"
 }

internal/audio/resample.go

@@ -0,0 +1,28 @@
+package audio
+
+type ResampledSource struct {
+    src      *WAVSource
+    ratio    float64
+    position float64
+}
+
+func NewResampledSource(src *WAVSource, targetSampleRate float64) *ResampledSource {
+    ratio := 1.0
+    if src != nil && src.SampleRate > 0 && targetSampleRate > 0 {
+        ratio = float64(src.SampleRate) / targetSampleRate
+    }
+    return &ResampledSource{src: src, ratio: ratio}
+}
+
+func (s *ResampledSource) NextFrame() Frame {
+    if s.src == nil || len(s.src.frames) == 0 {
+        return NewFrame(0, 0)
+    }
+    idx := int(s.position) % len(s.src.frames)
+    frame := s.src.frames[idx]
+    s.position += s.ratio
+    for s.position >= float64(len(s.src.frames)) {
+        s.position -= float64(len(s.src.frames))
+    }
+    return frame
+}

internal/audio/resample_test.go

@@ -0,0 +1,13 @@
+package audio
+
+import "testing"
+
+func TestResampledSource(t *testing.T) {
+    src := &WAVSource{frames: []Frame{NewFrame(0.1, 0.1), NewFrame(0.2, 0.2)}, SampleRate: 48000}
+    rs := NewResampledSource(src, 96000)
+    a := rs.NextFrame()
+    b := rs.NextFrame()
+    if a == (Frame{}) || b == (Frame{}) {
+        t.Fatal("expected frames")
+    }
+}

internal/offline/generator.go

@@ -31,7 +31,7 @@ func NewGenerator(cfg cfgpkg.Config) *Generator {
 func (g *Generator) sourceFor(sampleRate float64) frameSource {
     if g.cfg.Audio.InputPath != "" {
         if src, err := audio.LoadWAVSource(g.cfg.Audio.InputPath); err == nil {
-            return src
+            return audio.NewResampledSource(src, sampleRate)
         }
     }
     return audio.NewConfiguredToneSource(sampleRate, g.cfg.Audio.ToneLeftHz, g.cfg.Audio.ToneRightHz, g.cfg.Audio.ToneAmplitude)