Add delay

[jsfillman]

PR Type

Enhancement, Documentation

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Description

• Added dual 3-tap stereo delay effect to DSP and UI

  • 18 new OSC-controllable delay parameters (L/R, 3 taps each, feedback, mix)
  • Delay can be enabled/disabled per channel
  • Integrated delay into main DSP signal path

• Major UI update: new Effects tab with full delay controls

  • All delay parameters exposed as knobs/sliders in PyQt6 interface
  • MIDI CC mapping for all delay controls
  • Improved layout and usability for synthesis/effects

• Added comprehensive documentation for dual 3-tap delay implementation

• Added flake8 config and minor code style improvements

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Changes walkthrough 📝

	Relevant files
Enhancement	2 files legato_synth.dsp Add dual 3-tap stereo delay to DSP, 18 OSC params                +68/-1    main_window.py Add Effects tab and full delay UI controls                              +482/-23
Documentation	1 files dual-3tap-delay-implementation.md Add detailed dual 3-tap delay implementation doc                  +242/-0
Configuration changes	1 files .flake8 Add flake8 config for code style enforcement                          +4/-0
Formatting	10 files melody.py Add noqa for E402 import order linting                                      +1/-1      murnau_ui.py Add noqa for E402 import order linting                                      +3/-3      ramp_test.py Add noqa for E402 import order linting                                      +1/-1      run_murnau.py Add noqa for E402 import order linting                                      +3/-3      ramp_test.py Minor print formatting improvement                                              +3/-1      widgets.py Minor import cleanup and code style                                            +2/-4      test_dsp_init.py Add noqa for E402 import order linting                                      +1/-1      test_melody.py Add noqa for E402 import order linting, remove unused code +1/-14    test_osc_client.py Add noqa for E402 import order linting                                      +1/-1      test_ramp_test.py Add noqa for E402 import order linting, remove unused code +1/-8

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[qodo-code-review]

PR Reviewer Guide 🔍

Here are some key observations to aid the review process:

⏱️ Estimated effort to review: 3 🔵🔵🔵⚪⚪

🧪 No relevant tests

🔒 No security concerns identified

⚡ Recommended focus areas for review Feedback Implementation The delay implementation is missing proper feedback loops despite having feedback parameters. The current implementation creates taps from the input signal only, not from the delay line output. delay_L_process(input) = output_L with { // Three taps using @ operator for delays tap1_L = input : @(ms_to_samples(delay_L_tap1_time)) : *(delay_L_tap1_level); tap2_L = input : @(ms_to_samples(delay_L_tap2_time)) : *(delay_L_tap2_level); tap3_L = input : @(ms_to_samples(delay_L_tap3_time)) : *(delay_L_tap3_level); // Sum taps taps_sum_L = tap1_L + tap2_L + tap3_L; // Dry/wet mix output_L = select2(delay_L_enable, input, // Bypass when disabled input * (1 - delay_L_mix) + taps_sum_L * delay_L_mix ); }; Delay Enable State The delay enable checkboxes are created but their initial state is not set to match the default disabled state sent in init_parameters. self.delay_L_enable = QCheckBox("Enable Left") self.delay_L_enable.setStyleSheet( """ QCheckBox { color: #E0E0E0; font-weight: bold; font-size: 12px; spacing: 5px; } QCheckBox::indicator { width: 18px; height: 18px; } QCheckBox::indicator:checked { background-color: #5D5236; border: 2px solid #D4BF8A; } """ ) self.delay_L_enable.stateChanged.connect(self.on_delay_L_enable_change) enable_layout.addWidget(self.delay_L_enable) self.delay_R_enable = QCheckBox("Enable Right") self.delay_R_enable.setStyleSheet( """ QCheckBox { color: #E0E0E0; font-weight: bold; font-size: 12px; spacing: 5px; } QCheckBox::indicator { width: 18px; height: 18px; } QCheckBox::indicator:checked { background-color: #5D5236; border: 2px solid #D4BF8A; } """ ) self.delay_R_enable.stateChanged.connect(self.on_delay_R_enable_change) enable_layout.addWidget(self.delay_R_enable)

[qodo-code-review]

PR Code Suggestions ✨

Explore these optional code suggestions:

Category	Suggestion	Impact
Possible issue	Implement feedback loop The delay implementation is missing the feedback loop described in the documentation. Without feedback, the delay effect will be limited to simple echoes rather than the more complex ambient textures mentioned in the specification. src/murnau/dsp/legato_synth.dsp [110-126] -// Left channel delay processing (basic 3-tap, no feedback for now) +// Left channel delay processing with feedback delay_L_process(input) = output_L with { - // Three taps using @ operator for delays - tap1_L = input : @(ms_to_samples(delay_L_tap1_time)) : *(delay_L_tap1_level); - tap2_L = input : @(ms_to_samples(delay_L_tap2_time)) : *(delay_L_tap2_level); - tap3_L = input : @(ms_to_samples(delay_L_tap3_time)) : *(delay_L_tap3_level); + // Create feedback loop with delay line + delay_line = de.sdelay(max_delay_samples, 512); + feedback_input = input + (feedback_signal * delay_L_feedback); + delay_signal = feedback_input : delay_line; - // Sum taps - taps_sum_L = tap1_L + tap2_L + tap3_L; + // Three taps from the delay line + tap1_L = delay_signal(ms_to_samples(delay_L_tap1_time)) : *(delay_L_tap1_level); + tap2_L = delay_signal(ms_to_samples(delay_L_tap2_time)) : *(delay_L_tap2_level); + tap3_L = delay_signal(ms_to_samples(delay_L_tap3_time)) : *(delay_L_tap3_level); + + // Sum taps for feedback and output + feedback_signal = tap1_L + tap2_L + tap3_L; // Dry/wet mix output_L = select2(delay_L_enable, input, // Bypass when disabled - input * (1 - delay_L_mix) + taps_sum_L * delay_L_mix + input * (1 - delay_L_mix) + feedback_signal * delay_L_mix ); }; Apply / Chat Suggestion importance[1-10]: 6 __ Why: The suggestion correctly identifies that feedback is missing from the delay implementation, but the code comment explicitly states "no feedback for now", indicating this may be intentionally omitted in this implementation phase. The suggested improvement is technically sound but not critical.	Low
	Prevent zero-delay issues The current implementation doesn't ensure a minimum delay time greater than zero, which could cause issues with the delay line. Adding a small offset to the delay time calculation will prevent potential zero-delay problems. src/murnau/dsp/legato_synth.dsp [106-108] -// Convert milliseconds to samples -ms_to_samples(ms) = ms * ma.SR / 1000; +// Convert milliseconds to samples with safety offset +ms_to_samples(ms) = max(1, ms * ma.SR / 1000); max_delay_samples = ms_to_samples(2000); Apply / Chat Suggestion importance[1-10]: 5 __ Why: The suggestion provides a minor safety improvement by ensuring minimum delay of 1 sample, but since delay parameters have defined ranges starting from 0, zero delay might be intentionally allowed. This is a defensive programming practice but not critical.	Low
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