it seems that reading/writing "larger" files from LittleFS causes LED flickering.
This change adds a simple cache for "file not found" results, so that repeated file.exists() calls are avoided.
* added ESP_INTR_FLAG_IRAM to reduce lost samples (only on ESP32 without PSRAM) --> may cause crash if used wrongly
* FFT_MajorPeak stabilized, by ignoring extreme results
The NeoPixelBus RMT driver seems to get stalled when ESP.get.... functions are called (big kernel lock?). Also its glitching during flash file access.
This change tries to avoid some conflicts by first checking that the driver is not sending.
* fix compiler warnings (uninitialized vars, ambiguous functions calls)
* restore some lost function prototypes
* avoid negative pixel indices
* only use "fast" color_add when there is no risk of "overshooting" results
* minor optimizations
On a matrix with 52 columns, popcorn was requesting around 30Kb of segment data.
This patch reduces the data to the actually necessary amount based on the "intensity" slider. If intensity is increased, it means that the effect will get a bigger chunk of data allocated - zero'd out but this does not hurt much.
* adding suspendPlaylist() to playlist engine code
* autoplaylist usermod calls suspendPlaylist() before switching to another preset
* fix a potential overflow on `lfc` (uint8_t -> uint16_t)
fftResult[] is indended to look good on GEQ, and has a very "twisted" representation of FFT results only. This change improves reconstruction of signal energy, by on-doing some of the "GEQ enhancements" in fftResults[].
fixing mis-optimized math when calculating energy.
energy = sum(amplitude^2). this is not the same as sum(amplitude)^2.
Example:
1+5+7 = 13; 13 * 13 = 169
1*1 + 5*5 + 7*7 = 75
* initialize slow and fast filters with current values (first call only) - reduces time for filter stabilization
* use slightly optimized variant of "rolling average" filter (result is exactly the same)
--> replaced `xX = xX * (1-a) + newX * a;` by `xX = xX + a * (newX - Xx);`
* use constants for filter parameters (for tinkering and improved readability)
