[WIP] Fix MIDI clock sync to update BPM Faster #1032

Copilot · 2026-01-03T00:17:19Z

Analyze DelayLockedLoop algorithm and MidiClock implementation
Improve DLL algorithm for faster BPM convergence with better stability
Optimize MidiClock parameters for more responsive BPM updates
Add unit tests for the improved algorithm
Run code review and security checks

Summary of Changes

DelayLockedLoop (`src/delaylockedloop.hpp`)

Implemented adaptive bandwidth approach: starts with high bandwidth (0.5) for fast initial convergence, then transitions to lower bandwidth (0.1) for stable tracking after ~1 beat (24 ticks)
Changed M_PI and M_SQRT2 from float to double for better precision
Added isLocked() and getPeriod() helper methods
Simplified the reset interface to work directly with period (in seconds) rather than period in samples

MidiClock (`src/engine/midiclock.hpp`, `src/engine/midiclock.cpp`)

Reduced syncPeriodTicks from 48 to 24 (signal acquired after 1 beat instead of 2)
Reduced BPM update interval from 1.0 seconds to 0.25 seconds (4x faster updates)
Added hysteresis with bpmChangeThreshold = 0.5 BPM to prevent jittery updates when tempo is stable
Added lastReportedBpm tracking to implement hysteresis

Unit Tests (`test/engine/MidiClockTest.cpp`)

Added tests for DelayLockedLoop: construction, reset, convergence, and locking behavior
Added tests for MidiClockMaster: construction and tempo changes
Registered new test suite in test/CMakeLists.txt

These changes should make MIDI clock sync respond immediately when receiving external clock, while maintaining stability once locked.

Original prompt

This section details on the original issue you should resolve

<issue_title>MIDI Clock SYNC Slow to Update BPM</issue_title>
<issue_description>### What happened?

Hello.
I am sending midi clock from Stage Traxx 3 to Element.
It is working but the tempo in Element doesn't update immediately, it takes time to reach the received value and often shift a bit.
All is set up correctly in Stage traxx 3 and I have try the same setup with LivProfessor as a receiver for the clock with no issue.

Version

0.46.x (Previous)

Relevant log output
```</issue_description>

<agent_instructions>see `src/delaylockedloop.hpp` <-- this algorithm probably needs improved</agent_instructions>

## Comments on the Issue (you are @copilot in this section)

<comments>
<comment_new><author>@mfisher31</author><body>
It's the algorithm I'm using based on Ardour from years ago.  Admittedly it needs an update.  This is a known issue however.  Thanks for the official report.</body></comment_new>
</comments>

Fixes MIDI Clock SYNC Slow to Update BPM #1030

✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.

mfisher31 · 2026-01-03T00:43:17Z

@copilot - try that again, but don't try to build the project and push to git. Not sure what you're doing there buddy, but there are mega errors. Just look at the code, make changes if needed, and a I'll pull and check locally.

Key changes: - DelayLockedLoop: Added adaptive bandwidth (starts high for fast convergence, transitions to lower bandwidth for stability) - MidiClock: Reduced sync period from 48 to 24 ticks (~1 beat) - MidiClock: Reduced BPM update interval from 1.0s to 0.25s - MidiClock: Added hysteresis (0.5 BPM threshold) to prevent jitter - Changed M_PI/M_SQRT2 from float to double for precision Co-authored-by: mfisher31 <[email protected]>

CLAassistant · 2026-01-03T00:46:11Z

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you all sign our Contributor License Agreement before we can accept your contribution.
1 out of 2 committers have signed the CLA.

✅ mfisher31
❌ Copilot
_{You have signed the CLA already but the status is still pending? Let us recheck it.}

Copilot · 2026-01-03T00:46:13Z

@copilot - try that again, but don't try to build the project and push to git. Not sure what you're doing there buddy, but there are mega errors. Just look at the code, make changes if needed, and a...

Made the code changes in commit 7411ba1. I've improved the DelayLockedLoop algorithm with adaptive bandwidth (fast initial convergence, stable tracking once locked) and updated MidiClock to update BPM every 0.25s instead of 1.0s. Ready for you to pull and test locally.

mfisher31 · 2026-01-03T00:54:25Z

Hey @copilot go ahead and write a unit test for this as well. make sure to check the CMakeLists.txt and other tests to see exactly how to do it. Make no assumptions. Don't do guess work. Look at the existing build system to see what to do. Also remember KISS. Don't be a newbie on this one, got it?

Tests cover: - DelayLockedLoop construction, reset, convergence, and locking - MidiClockMaster construction and tempo changes Co-authored-by: mfisher31 <[email protected]>

Copilot · 2026-01-03T00:57:03Z

Hey @copilot go ahead and write a unit test for this as well. make sure to check the CMakeLists.txt and other tests to see exactly how to do it. Make no assumptions. Don't do guess work. Look at the...

Added unit tests in commit c653f81. Created test/engine/MidiClockTest.cpp following the existing test patterns (Boost.Test with class-based test organization). Tests cover DelayLockedLoop construction/reset/convergence/locking and MidiClockMaster construction/tempo changes. Also registered the new test suite in test/CMakeLists.txt.

- Add testTempoChangeConvergence: tests DLL convergence speed (120→140 BPM) - Add testLargeTempoSwing: tests extreme tempo change (20→120 BPM, 6x increase) - Add testRapidTempoChanges: tests stability with large tempo shifts - Add testTempoChangeAccuracy: tests accuracy across 60-200 BPM range - Add testJitterRejection: tests filtering of timing jitter - Add testExtremeTempos: tests behavior at 40 and 240 BPM - Add MidiClockMaster tests for clock generation and tempo change response Verifies implementation meets pro audio standards (lock within 1-4 beats)

- Format the code - fix a datapath testing problem with archlinux in docker - Refactor code for consistency and clarity in various files

Initial plan

d4f90d3

Copilot AI assigned Copilot and mfisher31 Jan 3, 2026

Copilot started work on behalf of mfisher31 January 3, 2026 00:17 View session

Copilot AI requested a review from mfisher31 January 3, 2026 00:42

Copilot stopped work on behalf of mfisher31 due to an error January 3, 2026 00:42
Copilot has encountered an error. See logs for additional details.

Copilot started work on behalf of mfisher31 January 3, 2026 00:43 View session

Copilot finished work on behalf of mfisher31 January 3, 2026 00:46

Copilot started work on behalf of mfisher31 January 3, 2026 00:54 View session

Add unit tests for DelayLockedLoop and MidiClockMaster

c653f81

Tests cover: - DelayLockedLoop construction, reset, convergence, and locking - MidiClockMaster construction and tempo changes Co-authored-by: mfisher31 <[email protected]>

Copilot finished work on behalf of mfisher31 January 3, 2026 00:57

mfisher31 changed the title ~~[WIP] Fix MIDI clock sync to update BPM immediately~~ [WIP] Fix MIDI clock sync to update BPM Faster Jan 3, 2026

Housekeeping MIDI clock, tests, and macro updates.

85655e6

- Format the code - fix a datapath testing problem with archlinux in docker - Refactor code for consistency and clarity in various files

mfisher31 marked this pull request as ready for review January 3, 2026 14:42

mfisher31 merged commit 64a0dd7 into main Jan 3, 2026
3 of 4 checks passed

mfisher31 deleted the copilot/fix-midi-sync-bpm-update branch January 3, 2026 14:48

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Uh oh!

Uh oh!

[WIP] Fix MIDI clock sync to update BPM Faster #1032

[WIP] Fix MIDI clock sync to update BPM Faster #1032

Uh oh!

Copilot AI commented Jan 3, 2026 •

edited

Loading

Uh oh!

mfisher31 commented Jan 3, 2026

Uh oh!

CLAassistant commented Jan 3, 2026 •

edited

Loading

Uh oh!

Copilot AI commented Jan 3, 2026

Uh oh!

mfisher31 commented Jan 3, 2026

Uh oh!

Copilot AI commented Jan 3, 2026

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants

Uh oh!

[WIP] Fix MIDI clock sync to update BPM Faster #1032

[WIP] Fix MIDI clock sync to update BPM Faster #1032

Uh oh!

Conversation

Copilot AI commented Jan 3, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Summary of Changes

DelayLockedLoop (src/delaylockedloop.hpp)

MidiClock (src/engine/midiclock.hpp, src/engine/midiclock.cpp)

Unit Tests (test/engine/MidiClockTest.cpp)

Version

Relevant log output

Uh oh!

mfisher31 commented Jan 3, 2026

Uh oh!

CLAassistant commented Jan 3, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

Copilot AI commented Jan 3, 2026

Uh oh!

mfisher31 commented Jan 3, 2026

Uh oh!

Copilot AI commented Jan 3, 2026

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants

Copilot AI commented Jan 3, 2026 •

edited

Loading

DelayLockedLoop (`src/delaylockedloop.hpp`)

MidiClock (`src/engine/midiclock.hpp`, `src/engine/midiclock.cpp`)

Unit Tests (`test/engine/MidiClockTest.cpp`)

CLAassistant commented Jan 3, 2026 •

edited

Loading