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PPM control for NDF fractional control
This commit is contained in:
Chris Frankland-Wright
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2e8bc9ac5e
commit
2295a29d75
11 changed files with 532 additions and 20 deletions
264
firmware/ltc_audiohat_lock_v3.ino
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264
firmware/ltc_audiohat_lock_v3.ino
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/* Linear Timecode for Audio Library for Teensy 3.x / 4.x
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Copyright (c) 2019, Frank Bösing, f.boesing (at) gmx.de
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Development of this audio library was funded by PJRC.COM, LLC by sales of
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Teensy and Audio Adaptor boards. Please support PJRC's efforts to develop
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open source software by purchasing Teensy or other PJRC products.
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice, development funding notice, and this permission
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notice shall be included in all copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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THE SOFTWARE.
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*/
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/*
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https://forum.pjrc.com/threads/41584-Audio-Library-for-Linear-Timecode-(LTC)
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LTC example audio at: https://www.youtube.com/watch?v=uzje8fDyrgg
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Forked by Chris Frankland-Wright 2025 for Teensy Audio Shield Input with autodetect FPS for the Fetch | Haichi
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*/
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#include <Arduino.h>
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#include <Audio.h>
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#include "analyze_ltc.h"
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// —— Configuration ——
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const float FORCE_FPS = 0.0f; // 0 → auto‑detect
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const int FRAME_OFFSET = 4; // compensation in frames
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const unsigned long LOSS_TIMEOUT = 1000UL; // ms before we go into LOST
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// BLINK_PERIOD is now the half-period (on or off time)
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const unsigned long BLINK_PERIOD[3] = {100, 500, 100}; // ACTIVE, LOST, NO_LTC (base)
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AudioInputI2S i2s1;
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AudioAnalyzeLTC ltc1;
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AudioControlSGTL5000 sgtl5000;
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AudioConnection patchCord(i2s1, 0, ltc1, 0);
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enum State { NO_LTC=0, LTC_ACTIVE, LTC_LOST };
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State ltcState = NO_LTC;
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bool ledOn = false;
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unsigned long lastDecode = 0;
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unsigned long lastBlink = 0;
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// Variables for NO_LTC double-blink pattern
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int noLtcBlinkCount = 0;
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unsigned long noLtcPauseTime = 600;
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// FPS detection
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float currentFps = 25.0f;
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float periodMs = 0;
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const float SMOOTH_ALPHA = 0.05f; // Much slower smoothing to reduce noise
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unsigned long lastDetectTs = 0;
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// Simple consecutive counter approach
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float candidateFps = 25.0f;
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int consecutiveCount = 0;
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const int REQUIRED_CONSECUTIVE = 5; // Need 5 consecutive same readings
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// free‑run
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long freeAbsFrame = 0;
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unsigned long lastFreeRun = 0;
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void setup() {
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Serial.begin(115200);
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AudioMemory(12);
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sgtl5000.enable();
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sgtl5000.inputSelect(AUDIO_INPUT_LINEIN);
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pinMode(LED_BUILTIN, OUTPUT);
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}
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void loop() {
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unsigned long now = millis();
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// compute framePeriod from currentFps
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unsigned long framePeriod = (unsigned long)(1000.0f / currentFps + 0.5f);
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// 1) If in ACTIVE and we've gone > LOSS_TIMEOUT w/o decode, enter LOST
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if (ltcState == LTC_ACTIVE && (now - lastDecode) >= LOSS_TIMEOUT) {
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ltcState = LTC_LOST;
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// bump freeAbsFrame by 1 second worth of frames:
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int nominal = (currentFps>29.5f) ? 30 : int(currentFps+0.5f);
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long dayFrames= 24L*3600L*nominal;
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freeAbsFrame = (freeAbsFrame + nominal) % dayFrames;
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// reset free‑run timer so we start next tick fresh
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lastFreeRun = now;
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}
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// 2) Handle incoming LTC frame
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if (ltc1.available()) {
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ltcframe_t frame = ltc1.read();
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int h = ltc1.hour(&frame),
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m = ltc1.minute(&frame),
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s = ltc1.second(&frame),
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f = ltc1.frame(&frame);
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bool isDF = ltc1.bit10(&frame);
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// — FPS detect or force —
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if (FORCE_FPS > 0.0f) {
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currentFps = FORCE_FPS;
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} else {
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if (isDF) {
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// Drop-frame flag is only used for 29.97fps.
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if (currentFps != 29.97f) {
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currentFps = 29.97f;
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consecutiveCount = 0;
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}
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} else {
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if (lastDetectTs) {
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float dt = now - lastDetectTs;
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// Use an IIR filter to smooth the measured period
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periodMs = (periodMs == 0) ? dt : (SMOOTH_ALPHA * dt + (1.0f - SMOOTH_ALPHA) * periodMs);
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float measFps = 1000.0f / periodMs;
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// More comprehensive list of standard frame rates
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const float choices[] = {23.98f, 24.0f, 25.0f, 29.97f, 30.0f};
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float bestFit = 25.0f;
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float minDiff = 1e6;
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for (auto rate : choices) {
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float diff = fabsf(measFps - rate);
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if (diff < minDiff) {
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minDiff = diff;
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bestFit = rate;
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}
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}
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// Use wider thresholds and hysteresis based on current frame rate
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float newFps = bestFit;
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// For 23.98/24fps discrimination with hysteresis
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if (fabsf(bestFit - 24.0f) < 0.1f || fabsf(bestFit - 23.98f) < 0.1f) {
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if (currentFps == 24.0f) {
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// Currently 24fps - need much stronger evidence of 23.98 to switch
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newFps = (measFps < 23.96f) ? 23.98f : 24.0f;
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} else if (currentFps == 23.98f) {
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// Currently 23.98fps - need evidence of 24 to switch back
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newFps = (measFps > 23.99f) ? 24.0f : 23.98f;
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} else {
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// First detection - strongly favor 24fps unless very clearly 23.98
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newFps = (measFps < 23.965f) ? 23.98f : 24.0f;
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}
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// Debug output to see what's being measured
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//Serial.printf("[DEBUG] measFps=%.3f, newFps=%.2f, currentFps=%.2f\r\n",
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// measFps, newFps, currentFps);
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}
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// For 29.97/30fps discrimination with hysteresis
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else if (fabsf(bestFit - 30.0f) < 0.1f || fabsf(bestFit - 29.97f) < 0.1f) {
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if (currentFps == 30.0f) {
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// Currently 30fps - need strong evidence of 29.97 to switch
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newFps = (measFps < 29.98f) ? 29.97f : 30.0f;
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} else if (currentFps == 29.97f) {
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// Currently 29.97fps - need evidence of 30 to switch back
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newFps = (measFps > 29.99f) ? 30.0f : 29.97f;
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} else {
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// First detection - strongly favor 30fps unless very clearly 29.97
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newFps = (measFps < 29.98f) ? 29.97f : 30.0f;
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}
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}
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// Require consecutive readings before changing frame rate
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if (newFps == candidateFps) {
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consecutiveCount++;
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if (consecutiveCount >= REQUIRED_CONSECUTIVE && newFps != currentFps) {
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currentFps = newFps;
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consecutiveCount = 0;
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}
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} else {
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candidateFps = newFps;
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consecutiveCount = 1;
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}
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}
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}
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lastDetectTs = now;
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}
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// — pack + offset + wrap —
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int nominal = (currentFps>29.5f) ? 30 : int(currentFps+0.5f);
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long dayFrames = 24L*3600L*nominal;
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long absF = ((long)h*3600 + m*60 + s)*nominal + f + FRAME_OFFSET;
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absF = (absF % dayFrames + dayFrames) % dayFrames;
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// — reset anchors & state —
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freeAbsFrame = absF;
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lastFreeRun = now;
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lastDecode = now;
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ltcState = LTC_ACTIVE;
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// — print LOCK —
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long totSec = absF/nominal;
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int outF = absF % nominal;
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int outS = totSec % 60;
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long totMin = totSec/60;
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int outM = totMin % 60;
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int outH = (totMin/60) % 24;
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char sep = isDF?';':':';
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Serial.printf("[LOCK] %02d:%02d:%02d%c%02d | %.2ffps\r\n",
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outH,outM,outS,sep,outF,currentFps);
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// — LED → ACTIVE immediately —
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lastBlink = now;
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ledOn = true;
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digitalWrite(LED_BUILTIN, HIGH);
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noLtcBlinkCount = 0; // Reset pattern when LTC becomes active
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}
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// 3) If in LOST, do free‑run printing
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else if (ltcState == LTC_LOST) {
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if ((now - lastFreeRun) >= framePeriod) {
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freeAbsFrame = (freeAbsFrame + 1) % (24L*3600L*((int)(currentFps+0.5f)));
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lastFreeRun += framePeriod;
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// — print FREE —
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int nominal = (currentFps>29.5f) ? 30 : int(currentFps+0.5f);
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long totSec = freeAbsFrame/nominal;
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int outF = freeAbsFrame % nominal;
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int outS = totSec % 60;
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long totMin = totSec/60;
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int outM = totMin % 60;
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int outH = (totMin/60)%24;
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Serial.printf("[FREE] %02d:%02d:%02d:%02d | %.2ffps\r\n",
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outH,outM,outS,outF,currentFps);
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}
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noLtcBlinkCount = 0; // Reset pattern when LTC is lost
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}
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// 4) LED heartbeat
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unsigned long now_led = millis();
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if (ltcState == NO_LTC) {
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unsigned long blinkInterval = BLINK_PERIOD[NO_LTC];
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if (noLtcBlinkCount < 4) { // First two blinks (on-off-on-off)
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if (now_led - lastBlink >= blinkInterval) {
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ledOn = !ledOn;
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digitalWrite(LED_BUILTIN, ledOn);
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lastBlink = now_led;
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noLtcBlinkCount++;
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}
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} else { // Pause
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if (now_led - lastBlink >= noLtcPauseTime) {
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noLtcBlinkCount = 0; // Reset for next double-blink
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lastBlink = now_led;
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}
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}
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} else { // LTC_ACTIVE or LTC_LOST
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// LTC_ACTIVE: 5Hz flash (100ms on/off). Period = 200ms.
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// LTC_LOST: 1Hz flash (500ms on/off). Period = 1000ms.
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unsigned long blinkInterval = (ltcState == LTC_ACTIVE) ? 100 : BLINK_PERIOD[LTC_LOST];
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if (now_led - lastBlink >= blinkInterval) {
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ledOn = !ledOn;
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digitalWrite(LED_BUILTIN, ledOn);
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lastBlink = now_led;
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}
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}
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}
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