Add linear fade-out to IRs with --fade-ms option (default 5ms); update README and CLI

main.go

@@ -60,6 +60,11 @@ func main() {
 				Name:  "length-ms",
 				Usage: "Optional: Output IR length in milliseconds (will trim or zero-pad as needed)",
 			},
+			&cli.Float64Flag{
+				Name:  "fade-ms",
+				Usage: "Fade-out duration in milliseconds to apply at the end of the IR (default 5)",
+				Value: 5.0,
+			},
 		},
 		Action: func(c *cli.Context) error {
 			// Read sweep WAV file
@@ -135,6 +140,14 @@ func main() {
 				ir = convolve.TrimOrPad(ir, targetSamples)
 			}
 
+			// Apply fade-out
+			fadeMs := c.Float64("fade-ms")
+			fadeSamples := int(float64(targetSampleRate) * fadeMs / 1000.0)
+			if fadeSamples > 0 {
+				log.Printf("Applying linear fade-out: %d samples (%.2f ms)...", fadeSamples, fadeMs)
+				ir = convolve.FadeOutLinear(ir, fadeSamples)
+			}
+
 			// Write regular IR
 			log.Printf("Writing IR to: %s (%dHz, %d-bit WAV)", c.String("output"), sampleRate, bitDepth)
 			if err := wav.WriteWAVFileWithOptions(c.String("output"), ir, sampleRate, bitDepth); err != nil {
@@ -165,6 +178,12 @@ func main() {
 					mptIR = convolve.TrimOrPad(mptIR, targetSamples)
 				}
 
+				// Apply fade-out to MPT IR
+				if fadeSamples > 0 {
+					log.Printf("Applying linear fade-out to MPT IR: %d samples (%.2f ms)...", fadeSamples, fadeMs)
+					mptIR = convolve.FadeOutLinear(mptIR, fadeSamples)
+				}
+
 				// Generate MPT output filename
 				outputPath := c.String("output")
 				if len(outputPath) > 4 && outputPath[len(outputPath)-4:] == ".wav" {