From 2a120e81f83eaa7d9672ccef8f4be5e4bd14ccd3 Mon Sep 17 00:00:00 2001
From: Frank <91616163+softhack007@users.noreply.github.com>
Date: Sun, 16 Nov 2025 16:08:16 +0100
Subject: [PATCH] image effect: flicker fixer for WS2812b leds driven by RMT

Large file read operations can cause RMT stall leading to flicker.
* wait for RMT driver when lading a new gif, and when decoding a new frame.
---
 wled00/image_loader.cpp | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/wled00/image_loader.cpp b/wled00/image_loader.cpp
index b6d13efa..96e131d5 100644
--- a/wled00/image_loader.cpp
+++ b/wled00/image_loader.cpp
@@ -141,6 +141,11 @@ byte renderImageToSegment(Segment &seg) {
       USER_PRINTF("GIF decoder unsupported file: %s\n", lastFilename);
       return IMAGE_ERROR_UNSUPPORTED_FORMAT;
     }
+
+    // flicker fixer: if we have ws2812b leds, lets wait a moment until RMT output is done.
+    unsigned t0 = millis();
+    while (strip.isUpdating() && (millis() - t0 < 100)) delay(1); // up to 100 ms = good enough for up to 1800 LEDs per output
+
     if (file) file.close();
     if (!openGif(lastFilename)) {
       gifDecodeFailed = true;
@@ -218,6 +223,10 @@ byte renderImageToSegment(Segment &seg) {
   // TODO consider handling this on FX level with a different frametime, but that would cause slow gifs to speed up during transitions
   if (millis() - lastFrameDisplayTime < wait) return IMAGE_ERROR_WAITING;
 
+  // flicker fixer: if we have ws2812b leds, lets wait a moment until RMT output is done.
+  unsigned td0 = millis();
+  while (strip.isUpdating() && (millis() - td0 < 20)) delay(1); // wait up to 20ms for LED output to finish
+
   int result = decoder.decodeFrame(false);
   if (result < 0) {
     USER_PRINTF("GIF Decoding error %d in decodeFrame().\n", result);