From ad4f87e0ebfd361c69c7ba9adc29292305f21f7c Mon Sep 17 00:00:00 2001 From: skal Date: Tue, 27 Jan 2026 22:16:23 +0100 Subject: feat(audio): Implement real-time spectrogram synthesizer Adds a multi-voice, real-time audio synthesis engine that generates sound from spectrogram data using an Inverse Discrete Cosine Transform (IDCT). Key features: - A thread-safe, double-buffered system for dynamically updating spectrograms in real-time without interrupting audio playback. - Core DSP components: FDCT, IDCT, and Hamming window functions. - A simple sequencer in the main loop to demonstrate scripted audio events and dynamic updates. - Unit tests for the new synth engine and Hamming window, integrated with CTest. - A file documenting the build process, features, and how to run tests. --- src/audio/idct.cpp | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) create mode 100644 src/audio/idct.cpp (limited to 'src/audio/idct.cpp') diff --git a/src/audio/idct.cpp b/src/audio/idct.cpp new file mode 100644 index 0000000..a32f92e --- /dev/null +++ b/src/audio/idct.cpp @@ -0,0 +1,17 @@ +#include "dct.h" +#include "util/math.h" +#include + +void idct_512(const float input[DCT_SIZE], float output[DCT_SIZE]) { + float scale_k0 = sqrtf(1.0f / DCT_SIZE); + float scale_kn = sqrtf(2.0f / DCT_SIZE); + + for (int n = 0; n < DCT_SIZE; ++n) { + float sum = 0.0f; + for (int k = 0; k < DCT_SIZE; ++k) { + float scale = (k == 0) ? scale_k0 : scale_kn; + sum += scale * input[k] * cosf((PI / DCT_SIZE) * (n + 0.5f) * k); + } + output[n] = sum; + } +} -- cgit v1.2.3