Add --cut-slope option for filter steepness (default 12 dB/oct); cascade biquads for steeper slopes; update docs

Reviewed-on: #1

.gitignore

@@ -38,4 +38,7 @@ Thumbs.db
 ehthumbs.db
 
 # Dagger cache
-.dagger/ 
+.dagger/
+
+# Environment files
+.env 

README.md

@@ -7,6 +7,8 @@ A CLI tool for processing WAV files to generate impulse responses (IR) from swee
 - **Fast FFT-based deconvolution** for accurate IR extraction
 - **Automatic input conversion:** Accepts any WAV sample rate, bit depth, or channel count
 - **Optional output IR length:** Specify output IR length in milliseconds with --length-ms
+- **Optional low-cut and high-cut filtering:** Apply Butterworth filters to the recorded sweep before IR extraction (--lowcut, --highcut, --cut-slope)
+- **Automatic fade-out:** Linear fade-out at the end of the IR to avoid clicks (default 5 ms, configurable with --fade-ms)
 - **96kHz 24-bit WAV file support** for high-quality audio processing
 - **Multiple output formats** with configurable sample rates and bit depths
 - **Minimum Phase Transform (MPT)** option for reduced latency IRs
@@ -57,6 +59,34 @@ Trim or zero-pad the output IR to a specific length (in milliseconds):
 
 This will ensure the output IR is exactly 100 ms long (trimming or zero-padding as needed).
 
+### Fade-Out to Avoid Clicks
+
+By default, a 5 ms linear fade-out is applied to the end of the IR to avoid clicks. You can change the fade duration:
+
+```sh
+./valhallir-deconvolver --sweep sweep.wav --recorded recorded.wav --output ir.wav --fade-ms 10
+```
+
+This applies a 10 ms fade-out at the end of the IR.
+
+### Filtering the Recorded Sweep
+
+You can apply a low-cut (high-pass) and/or high-cut (low-pass) filter to the recorded sweep before IR extraction. This is useful for removing rumble, DC, or high-frequency noise:
+
+```sh
+./valhallir-deconvolver --sweep sweep.wav --recorded recorded.wav --output ir.wav --lowcut 40 --highcut 18000
+```
+
+This applies a 40 Hz low-cut (high-pass) and 18 kHz high-cut (low-pass) filter to the recorded sweep.
+
+You can control the filter steepness (slope) with `--cut-slope` (in dB/octave, default 12). For example:
+
+```sh
+./valhallir-deconvolver --sweep sweep.wav --recorded recorded.wav --output ir.wav --lowcut 40 --highcut 18000 --cut-slope 24
+```
+
+This applies a 40 Hz low-cut and 18 kHz high-cut, both with a 24 dB/octave slope (steeper than the default 12).
+
 ### Different Output Formats
 
 Generate IRs in different sample rates and bit depths:
@@ -116,6 +146,10 @@ Generate IRs in different sample rates and bit depths:
 | `--normalize` | Normalize output to peak value (0.0-1.0) | 0.95 | No |
 | `--trim-threshold` | Silence threshold for trimming (0.0-1.0) | 0.001 | No |
 | `--length-ms` | Output IR length in milliseconds (trim or zero-pad) | - | No |
+| `--fade-ms` | Fade-out duration in milliseconds at end of IR (default 5) | 5 | No |
+| `--lowcut` | Low-cut filter (high-pass) cutoff frequency in Hz (recorded sweep) | - | No |
+| `--highcut` | High-cut filter (low-pass) cutoff frequency in Hz (recorded sweep) | - | No |
+| `--cut-slope` | Filter slope in dB/octave (12, 24, 36, ...; default 12) | 12 | No |
 
 ## File Requirements
 
@@ -143,6 +177,15 @@ Generate IRs in different sample rates and bit depths:
 - If `--length-ms` is set, the output IR (and MPT IR) will be trimmed or zero-padded to the specified length in milliseconds
 - If not set, the full IR is used
 
+### Fade-Out
+- By default, a 5 ms linear fade-out is applied to the end of the IR (and MPT IR) to avoid clicks
+- You can change the fade duration with `--fade-ms`
+
+### Filtering
+- You can apply a Butterworth low-cut (high-pass) and/or high-cut (low-pass) filter to the recorded sweep before IR extraction
+- Use `--lowcut` and/or `--highcut` to specify cutoff frequencies in Hz
+- Use `--cut-slope` to control the filter steepness (12 dB/octave = gentle, 24+ = steeper)
+
 ### Deconvolution Process
 1. **FFT-based deconvolution** of recorded signal by sweep signal
 2. **Regularization** to prevent division by zero
@@ -218,19 +261,35 @@ The pipeline is defined in [`ci/dagger.go`](./ci/dagger.go). It outputs binaries
 
 ### Usage
 
-1. Install the Dagger Go SDK:
+1. Install the Dagger Go SDK and dependencies:
    ```sh
    go install dagger.io/dagger@latest
+   go get github.com/joho/godotenv
    go mod tidy
    ```
-2. Run the pipeline:
+2. Build for all platforms:
    ```sh
    go run ci/dagger.go
    ```
+3. (Optional) Upload binaries to a Gitea release:
+   - Create a `.env` file in the project root with:
+     ```
+     GITEA_TOKEN=your_token
+     GITEA_URL=https://your.gitea.server
+     GITEA_OWNER=youruser
+     GITEA_REPO=yourrepo
+     ```
+   - Run:
+     ```sh
+     go run ci/dagger.go --release v1.0.0
+     ```
+   - This will create (if needed) and upload all binaries to the specified release tag on your Gitea instance.
+   - **The pipeline will also create and push a local git tag for the release if it does not already exist.**
 
 ### Troubleshooting Dagger
 - If you see `could not import dagger.io/dagger`, make sure you have installed the Dagger Go SDK and run `go mod tidy`.
 - The pipeline requires Docker or a compatible container runtime.
+- For Gitea upload, ensure your `.env` file is present and correct.
 
 ## Troubleshooting
 

ci/.env.example

@@ -0,0 +1,4 @@
+GITEA_TOKEN=your_token
+GITEA_URL=https://your.gitea.server
+GITEA_OWNER=youruser
+GITEA_REPO=yourrepo

ci/dagger.go

@@ -1,16 +1,35 @@
 // Dagger pipeline for multi-platform builds.
-// Requires: go install dagger.io/dagger@latest && go mod tidy
+// Usage:
+//
+//	go run ci/dagger.go [--release v1.0.0]
+//
+// If --release is provided, uploads all built binaries in dist/ to the specified Gitea release.
+// Requires .env file with GITEA_TOKEN, GITEA_URL, GITEA_OWNER, GITEA_REPO.
+// Requires: go install dagger.io/dagger@latest && go get github.com/joho/godotenv && go mod tidy
 package main
 
 import (
+	"bytes"
 	"context"
+	"encoding/json"
+	"flag"
 	"fmt"
+	"io"
+	"mime/multipart"
+	"net/http"
 	"os"
+	"os/exec"
+	"path/filepath"
+	"strings"
 
 	"dagger.io/dagger"
+	"github.com/joho/godotenv"
 )
 
 func main() {
+	releaseTag := flag.String("release", "", "(optional) Release tag to upload binaries to Gitea")
+	flag.Parse()
+
 	ctx := context.Background()
 	client, err := dagger.Connect(ctx, dagger.WithLogOutput(os.Stdout))
 	if err != nil {
@@ -30,6 +49,8 @@ func main() {
 
 	src := client.Host().Directory(".")
 
+	var builtBinaries []string
+
 	for _, p := range platforms {
 		binName := fmt.Sprintf("valhallir-deconvolver-%s-%s", p.OS, p.Arch)
 		if p.OS == "windows" {
@@ -50,5 +71,146 @@ func main() {
 			panic(fmt.Sprintf("export failed for %s/%s: %v", p.OS, p.Arch, err))
 		}
 		fmt.Printf("Built and exported %s\n", outPath)
+		builtBinaries = append(builtBinaries, outPath)
+	}
+
+	if *releaseTag != "" {
+		fmt.Printf("\nUploading binaries to Gitea release: %s\n", *releaseTag)
+		// Load .env
+		err := godotenv.Load("ci/.env")
+		if err != nil {
+			panic("Error loading .env file: " + err.Error())
+		}
+		giteaToken := os.Getenv("GITEA_TOKEN")
+		giteaURL := os.Getenv("GITEA_URL")
+		giteaOwner := os.Getenv("GITEA_OWNER")
+		giteaRepo := os.Getenv("GITEA_REPO")
+		if giteaToken == "" || giteaURL == "" || giteaOwner == "" || giteaRepo == "" {
+			panic("GITEA_TOKEN, GITEA_URL, GITEA_OWNER, GITEA_REPO must be set in .env")
+		}
+
+		// 1. Get or create the release
+		releaseID, err := getOrCreateRelease(giteaURL, giteaOwner, giteaRepo, *releaseTag, giteaToken)
+		if err != nil {
+			panic("Failed to get or create release: " + err.Error())
+		}
+
+		// 2. Upload each binary as an asset
+		for _, bin := range builtBinaries {
+			fmt.Printf("Uploading %s...\n", bin)
+			err := uploadAsset(giteaURL, giteaOwner, giteaRepo, releaseID, bin, giteaToken)
+			if err != nil {
+				panic(fmt.Sprintf("Failed to upload %s: %v", bin, err))
+			}
+			fmt.Printf("Uploaded %s\n", bin)
+		}
+		fmt.Println("All binaries uploaded to Gitea release.")
+
+		// 3. Tag the release locally and push the tag
+		if err := tagAndPush(*releaseTag); err != nil {
+			panic("Failed to tag and push: " + err.Error())
+		}
+		fmt.Printf("Tagged and pushed %s\n", *releaseTag)
 	}
 }
+
+func getOrCreateRelease(url, owner, repo, tag, token string) (int, error) {
+	// Try to get the release by tag
+	api := fmt.Sprintf("%s/api/v1/repos/%s/%s/releases/tags/%s", strings.TrimRight(url, "/"), owner, repo, tag)
+	req, _ := http.NewRequest("GET", api, nil)
+	req.Header.Set("Authorization", "token "+token)
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		return 0, err
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode == 200 {
+		// Parse JSON to get ID
+		type releaseResp struct{ ID int }
+		var r releaseResp
+		io.ReadAll(resp.Body) // ignore body for now, parse below
+		dec := json.NewDecoder(resp.Body)
+		dec.Decode(&r)
+		return r.ID, nil
+	}
+	// If not found, create it
+	if resp.StatusCode == 404 {
+		api = fmt.Sprintf("%s/api/v1/repos/%s/%s/releases", strings.TrimRight(url, "/"), owner, repo)
+		body := strings.NewReader(fmt.Sprintf(`{"tag_name":"%s","name":"%s"}`, tag, tag))
+		req, _ = http.NewRequest("POST", api, body)
+		req.Header.Set("Authorization", "token "+token)
+		req.Header.Set("Content-Type", "application/json")
+		resp, err = http.DefaultClient.Do(req)
+		if err != nil {
+			return 0, err
+		}
+		defer resp.Body.Close()
+		if resp.StatusCode == 201 {
+			type releaseResp struct{ ID int }
+			var r releaseResp
+			dec := json.NewDecoder(resp.Body)
+			dec.Decode(&r)
+			return r.ID, nil
+		}
+		return 0, fmt.Errorf("failed to create release: %s", resp.Status)
+	}
+	return 0, fmt.Errorf("failed to get release: %s", resp.Status)
+}
+
+func uploadAsset(url, owner, repo string, releaseID int, filePath, token string) error {
+	api := fmt.Sprintf("%s/api/v1/repos/%s/%s/releases/%d/assets?name=%s", strings.TrimRight(url, "/"), owner, repo, releaseID, filepath.Base(filePath))
+	file, err := os.Open(filePath)
+	if err != nil {
+		return err
+	}
+	defer file.Close()
+
+	var b bytes.Buffer
+	w := multipart.NewWriter(&b)
+	f, err := w.CreateFormFile("attachment", filepath.Base(filePath))
+	if err != nil {
+		return err
+	}
+	_, err = io.Copy(f, file)
+	if err != nil {
+		return err
+	}
+	w.Close()
+
+	req, _ := http.NewRequest("POST", api, &b)
+	req.Header.Set("Authorization", "token "+token)
+	req.Header.Set("Content-Type", w.FormDataContentType())
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != 201 {
+		return fmt.Errorf("upload failed: %s", resp.Status)
+	}
+	return nil
+}
+
+func tagAndPush(tag string) error {
+	// Check if tag exists
+	cmd := exec.Command("git", "tag", "--list", tag)
+	out, err := cmd.Output()
+	if err != nil {
+		return err
+	}
+	if strings.TrimSpace(string(out)) == tag {
+		// Tag already exists
+		return nil
+	}
+	// Create tag
+	cmd = exec.Command("git", "tag", tag)
+	if err := cmd.Run(); err != nil {
+		return err
+	}
+	// Push tag
+	cmd = exec.Command("git", "push", "origin", tag)
+	if err := cmd.Run(); err != nil {
+		return err
+	}
+	return nil
+}

go.mod

@@ -1,11 +1,12 @@
 module valhallir-deconvolver
 
-go 1.24.1
+go 1.24.5
 
 require (
 	dagger.io/dagger v0.18.12
 	github.com/go-audio/audio v1.0.0
 	github.com/go-audio/wav v1.1.0
+	github.com/joho/godotenv v1.5.1
 	github.com/mjibson/go-dsp v0.0.0-20180508042940-11479a337f12
 	github.com/urfave/cli/v2 v2.27.7
 	gonum.org/v1/gonum v0.13.0

go.sum

@@ -35,6 +35,8 @@ github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
 github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
 github.com/grpc-ecosystem/grpc-gateway/v2 v2.26.3 h1:5ZPtiqj0JL5oKWmcsq4VMaAW5ukBEgSGXEN89zeH1Jo=
 github.com/grpc-ecosystem/grpc-gateway/v2 v2.26.3/go.mod h1:ndYquD05frm2vACXE1nsccT4oJzjhw2arTS2cpUD1PI=
+github.com/joho/godotenv v1.5.1 h1:7eLL/+HRGLY0ldzfGMeQkb7vMd0as4CfYvUVzLqw0N0=
+github.com/joho/godotenv v1.5.1/go.mod h1:f4LDr5Voq0i2e/R5DDNOoa2zzDfwtkZa6DnEwAbqwq4=
 github.com/mitchellh/go-homedir v1.1.0 h1:lukF9ziXFxDFPkA1vsr5zpc1XuPDn/wFntq5mG+4E0Y=
 github.com/mitchellh/go-homedir v1.1.0/go.mod h1:SfyaCUpYCn1Vlf4IUYiD9fPX4A5wJrkLzIz1N1q0pr0=
 github.com/mjibson/go-dsp v0.0.0-20180508042940-11479a337f12 h1:dd7vnTDfjtwCETZDrRe+GPYNLA1jBtbZeyfyE8eZCyk=

main.go

@@ -60,6 +60,24 @@ 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,
+			},
+			&cli.Float64Flag{
+				Name:  "highcut",
+				Usage: "High-cut filter (low-pass) cutoff frequency in Hz (applied to recorded sweep, optional)",
+			},
+			&cli.Float64Flag{
+				Name:  "lowcut",
+				Usage: "Low-cut filter (high-pass) cutoff frequency in Hz (applied to recorded sweep, optional)",
+			},
+			&cli.IntFlag{
+				Name:  "cut-slope",
+				Usage: "Cut filter slope in dB/octave (12, 24, 36, 48, ...; default 12)",
+				Value: 12,
+			},
 		},
 		Action: func(c *cli.Context) error {
 			// Read sweep WAV file
@@ -77,8 +95,26 @@ func main() {
 			log.Printf("Sweep: %d samples, %d channels", len(sweepData.PCMData), sweepData.Channels)
 			log.Printf("Recorded: %d samples, %d channels", len(recordedData.PCMData), recordedData.Channels)
 
+			// Optionally filter the recorded sweep
+			recordedFiltered := recordedData.PCMData
+			recSampleRate := recordedData.SampleRate
+			highcutHz := c.Float64("highcut")
+			lowcutHz := c.Float64("lowcut")
+			cutSlope := c.Int("cut-slope")
+			if cutSlope < 12 || cutSlope%12 != 0 {
+				return fmt.Errorf("cut-slope must be a positive multiple of 12 (got %d)", cutSlope)
+			}
+			if lowcutHz > 0 {
+				log.Printf("Applying low-cut (high-pass) filter to recorded sweep: %.2f Hz, slope: %d dB/oct", lowcutHz, cutSlope)
+				recordedFiltered = convolve.CascadeLowcut(recordedFiltered, recSampleRate, lowcutHz, cutSlope)
+			}
+			if highcutHz > 0 {
+				log.Printf("Applying high-cut (low-pass) filter to recorded sweep: %.2f Hz, slope: %d dB/oct", highcutHz, cutSlope)
+				recordedFiltered = convolve.CascadeHighcut(recordedFiltered, recSampleRate, highcutHz, cutSlope)
+			}
+
 			log.Println("Performing deconvolution...")
-			ir := convolve.Deconvolve(sweepData.PCMData, recordedData.PCMData)
+			ir := convolve.Deconvolve(sweepData.PCMData, recordedFiltered)
 			log.Printf("Deconvolution result: %d samples", len(ir))
 
 			log.Println("Trimming silence...")
@@ -135,6 +171,14 @@ 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 +209,12 @@ 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" {

pkg/convolve/convolve.go

@@ -322,3 +322,134 @@ func Resample(data []float64, fromSampleRate, toSampleRate int) []float64 {
 
 	return result
 }
+
+// FadeOutLinear applies a linear fade-out to the last fadeSamples of the data.
+// fadeSamples is the number of samples over which to fade to zero.
+func FadeOutLinear(data []float64, fadeSamples int) []float64 {
+	if fadeSamples <= 0 || len(data) == 0 {
+		return data
+	}
+	if fadeSamples > len(data) {
+		fadeSamples = len(data)
+	}
+	out := make([]float64, len(data))
+	copy(out, data)
+	start := len(data) - fadeSamples
+	for i := start; i < len(data); i++ {
+		fade := float64(len(data)-i) / float64(fadeSamples)
+		out[i] *= fade
+	}
+	return out
+}
+
+// ApplyLowpassButterworth applies a 2nd-order Butterworth low-pass filter to the data.
+// cutoffHz: cutoff frequency in Hz, sampleRate: sample rate in Hz.
+func ApplyLowpassButterworth(data []float64, sampleRate int, cutoffHz float64) []float64 {
+	if cutoffHz <= 0 || cutoffHz >= float64(sampleRate)/2 {
+		return data
+	}
+	// Biquad coefficients
+	w0 := 2 * math.Pi * cutoffHz / float64(sampleRate)
+	cosw0 := math.Cos(w0)
+	sinw0 := math.Sin(w0)
+	Q := 1.0 / math.Sqrt(2) // Butterworth Q
+	alpha := sinw0 / (2 * Q)
+
+	b0 := (1 - cosw0) / 2
+	b1 := 1 - cosw0
+	b2 := (1 - cosw0) / 2
+	a0 := 1 + alpha
+	a1 := -2 * cosw0
+	a2 := 1 - alpha
+
+	// Normalize
+	b0 /= a0
+	b1 /= a0
+	b2 /= a0
+	a1 /= a0
+	a2 /= a0
+
+	// Apply filter (Direct Form I)
+	out := make([]float64, len(data))
+	var x1, x2, y1, y2 float64
+	for i := 0; i < len(data); i++ {
+		x0 := data[i]
+		y0 := b0*x0 + b1*x1 + b2*x2 - a1*y1 - a2*y2
+		out[i] = y0
+		x2 = x1
+		x1 = x0
+		y2 = y1
+		y1 = y0
+	}
+	return out
+}
+
+// ApplyHighpassButterworth applies a 2nd-order Butterworth high-pass filter to the data.
+// cutoffHz: cutoff frequency in Hz, sampleRate: sample rate in Hz.
+func ApplyHighpassButterworth(data []float64, sampleRate int, cutoffHz float64) []float64 {
+	if cutoffHz <= 0 || cutoffHz >= float64(sampleRate)/2 {
+		return data
+	}
+	// Biquad coefficients
+	w0 := 2 * math.Pi * cutoffHz / float64(sampleRate)
+	cosw0 := math.Cos(w0)
+	sinw0 := math.Sin(w0)
+	Q := 1.0 / math.Sqrt(2) // Butterworth Q
+	alpha := sinw0 / (2 * Q)
+
+	b0 := (1 + cosw0) / 2
+	b1 := -(1 + cosw0)
+	b2 := (1 + cosw0) / 2
+	a0 := 1 + alpha
+	a1 := -2 * cosw0
+	a2 := 1 - alpha
+
+	// Normalize
+	b0 /= a0
+	b1 /= a0
+	b2 /= a0
+	a1 /= a0
+	a2 /= a0
+
+	// Apply filter (Direct Form I)
+	out := make([]float64, len(data))
+	var x1, x2, y1, y2 float64
+	for i := 0; i < len(data); i++ {
+		x0 := data[i]
+		y0 := b0*x0 + b1*x1 + b2*x2 - a1*y1 - a2*y2
+		out[i] = y0
+		x2 = x1
+		x1 = x0
+		y2 = y1
+		y1 = y0
+	}
+	return out
+}
+
+// CascadeLowcut applies the low-cut (high-pass) filter multiple times for steeper slopes.
+// slopeDb: 12, 24, 36, ... (dB/octave)
+func CascadeLowcut(data []float64, sampleRate int, cutoffHz float64, slopeDb int) []float64 {
+	if slopeDb < 12 {
+		slopeDb = 12
+	}
+	n := slopeDb / 12
+	out := data
+	for i := 0; i < n; i++ {
+		out = ApplyHighpassButterworth(out, sampleRate, cutoffHz)
+	}
+	return out
+}
+
+// CascadeHighcut applies the high-cut (low-pass) filter multiple times for steeper slopes.
+// slopeDb: 12, 24, 36, ... (dB/octave)
+func CascadeHighcut(data []float64, sampleRate int, cutoffHz float64, slopeDb int) []float64 {
+	if slopeDb < 12 {
+		slopeDb = 12
+	}
+	n := slopeDb / 12
+	out := data
+	for i := 0; i < n; i++ {
+		out = ApplyLowpassButterworth(out, sampleRate, cutoffHz)
+	}
+	return out
+}