fixes filter on MPT-transition. Add a high quality filter wir anti-aliasing

README.md

@@ -45,12 +45,12 @@ If you run the tool without any command-line options, it automatically creates a
 This will:
 - Use the current directory as the recorded directory
 - Look for `sweep.wav` in the current directory as the sweep file
-- Create output in an `IRs` folder one directory level up from the current directory
+- Create output in a `cabpack` folder one directory level up from the current directory
 - Automatically enable cabpack mode
 - Process all WAV files in the current directory (excluding the sweep file)
 - Use `selection.txt` and `ambient.txt` from the current directory if present
 
-**Perfect for:** Simply placing the tool in a folder with recorded WAV files and running it to create a complete cabpack in the parent directory's `IRs` folder.
+**Perfect for:** Simply placing the tool in a folder with recorded WAV files and running it to create a complete cabpack in the parent directory's `cabpack` folder.
 
 ### Basic IR Generation
 
@@ -101,7 +101,7 @@ Generate a complete cabpack with IRs in multiple formats organized in a structur
 This uses:
 - Current directory as recorded directory
 - `sweep.wav` in current directory as sweep file
-- `IRs` folder one directory level up from current directory as output
+- `cabpack` folder one directory level up from current directory as output
 - Automatically enables cabpack mode
 - Excludes the sweep file from processing
 
@@ -126,10 +126,11 @@ Both modes create a cabpack structure with:
   - 48000Hz, 24bit, 1370ms
   - 96000Hz, 24bit, 500ms
   - 96000Hz, 24bit, 1370ms
-- **Subfolders** in each format: `ambient mics`, `close mics`, `mixees`, `selection`
+- **Subfolders** in each format: `close mics` (always), plus `ambient mics`, `selection`, and `mixes` (only if corresponding files/folders exist)
 - **RAW and MPT IRs** in `close mics/RAW` and `close mics/MPT` respectively
 - **IR visualizations** in the `plots` folder (96000Hz format)
 - **Automatic file organization** using `selection.txt` and `ambient.txt` files
+- **Mixes folder support**: Convert ready-to-use IRs from `mixes` folder to all formats
 
 The cabpack base name is automatically extracted from WAV filenames. For example, `V2-1960STV-d-SM7B-A1.wav` will create a cabpack named `V2-1960STV`.
 
@@ -154,10 +155,35 @@ V2-1960STV-d-SM7B-B2.wav
 ```
 
 **Notes:**
-- If `selection.txt` or `ambient.txt` are missing, those operations are skipped (no error).
+- If `selection.txt` is missing, the `selection` folder is not created in any format folder.
+- If `ambient.txt` is missing, the `ambient mics` folder is not created in any format folder.
+- If the `mixes` folder is missing, the `mixes` subfolder is not created in any format folder.
 - Files are processed for all format folders automatically.
 - The `.wav` extension is automatically added if missing in the list files.
-- The `mixees` folder is left empty for manual filling.
+
+#### Mixes Folder Support
+
+If a `mixes` folder exists in the recorded directory, it will be processed automatically:
+
+- **Ready-to-use IRs**: Place pre-processed IR files (already deconvolved) in the `mixes` folder
+- **Automatic conversion**: Each IR file is converted to all 9 cabpack formats
+- **Format storage**: Converted IRs are stored in the `mixes` subfolder of each format folder (only created if `mixes` folder exists)
+- **Plot generation**: IR visualizations are generated in the `plots/mixes` folder (only created if `mixes` folder exists)
+
+**Note:** If the `mixes` folder is missing in the recorded directory, the `mixes` subfolder is not created in any format folder, and no mix processing occurs.
+
+**Example structure:**
+```
+recorded/
+  ├── sweep.wav
+  ├── recorded1.wav
+  ├── recorded2.wav
+  └── mixes/
+      ├── mix1.wav
+      └── mix2.wav
+```
+
+This will create converted versions of `mix1.wav` and `mix2.wav` in all format folders under the `mixes` subfolder, plus plots in `plots/mixes/`.
 
 ### With Minimum Phase Transform
 
@@ -209,6 +235,8 @@ You can control the filter steepness (slope) with `--cut-slope` (in dB/octave, d
 
 This applies a 40 Hz low-cut and 18 kHz high-cut, both with a 24 dB/octave slope (steeper than the default 12).
 
+**Filter Implementation:** The tool uses Linkwitz-Riley design principles with Direct Form II Transposed filter structures for optimal numerical stability and minimal artifacts, even at very steep slopes (48+ dB/octave). The filters are designed to provide clean cutoffs without introducing unwanted artifacts in the frequency response.
+
 ### Automatic Phase Correction
 
 Valhallir Deconvolver automatically detects and corrects phase-inverted recorded sweeps to ensure consistent IR polarity. This is especially important when mixing multiple IRs later.
@@ -249,9 +277,11 @@ This creates:
 The plot includes:
 - **Frequency Response:** dB vs Hz with log frequency scale (20Hz-20kHz)
 - **Waveform:** Time-domain view of the first 10ms of the IR
-- **Valhallir Branding:** Logo and filename information
+- **Valhallir Branding:** Logo displayed in upper-left corner and filename information
 - **Professional Layout:** Clean, publication-ready visualization
 
+**Note:** The logo is embedded directly in the binary, so no external assets folder is required. The logo will always be available regardless of where the binary is located or how it's executed.
+
 ### Different Output Formats
 
 Generate IRs in different sample rates and bit depths:
@@ -304,7 +334,7 @@ Generate IRs in different sample rates and bit depths:
 |------|-------------|---------|----------|
 | `--sweep` | Path to sweep WAV file (any format) | `sweep.wav` in current directory | No |
 | `--recorded` | Path to recorded WAV file or directory containing WAV files | Current directory | No |
-| `--output` | Path to output IR WAV file or directory for batch processing | `IRs` folder one directory level up from recorded directory | No |
+| `--output` | Path to output IR WAV file or directory for batch processing | `cabpack` folder one directory level up from recorded directory | No |
 | `--mpt` | Generate minimum phase transform IR | false | No |
 | `--sample-rate` | Output sample rate (44, 48, 88, 96 kHz) | 96000 | No |
 | `--bit-depth` | Output bit depth (16, 24, 32 bit) | 24 | No |
@@ -351,9 +381,11 @@ Generate IRs in different sample rates and bit depths:
 - 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
+- You can apply a low-cut (high-pass) and/or high-cut (low-pass) filter to the recorded sweep before IR extraction
+- Uses Linkwitz-Riley design principles with Direct Form II Transposed structures for optimal stability
 - 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)
+- The filter implementation is designed to provide clean cutoffs without artifacts, even at very steep slopes (48+ dB/octave)
 
 ### Deconvolution Process
 1. **FFT-based deconvolution** of recorded signal by sweep signal
@@ -521,4 +553,4 @@ The pipeline is defined in [`ci/dagger.go`](./ci/dagger.go). It outputs binaries
 
 ## Changelog
 
-See [CHANGELOG.md](./CHANGELOG.md) for version history and details. Current version: v1.0.0 
+See [CHANGELOG.md](./CHANGELOG.md) for version history and details. Current version: v1.2.0