From df8402575f1550d79c751051e9006fd3b7fa0fe0 Mon Sep 17 00:00:00 2001
From: Hannes Braun <hannes@hannesbraun.net>
Date: Thu, 9 Oct 2025 20:28:34 +0200
Subject: [PATCH] Fix compatibility with FFmpeg 8

---
 src/spek-fft.cc | 25 ++++++++++++++++---------
 1 file changed, 16 insertions(+), 9 deletions(-)

diff --git src/spek-fft.cc src/spek-fft.cc
index 3105213f..00d4fa5c 100644
--- src/spek-fft.cc
+++ src/spek-fft.cc
@@ -2,7 +2,7 @@
 
 #define __STDC_CONSTANT_MACROS
 extern "C" {
-#include <libavcodec/avfft.h>
+#include <libavutil/tx.h>
 }
 
 #include "spek-fft.h"
@@ -16,7 +16,10 @@ class FFTPlanImpl : public FFTPlan
     void execute() override;
 
 private:
-    struct RDFTContext *cx;
+    struct AVTXContext *cx;
+    av_tx_fn tx;
+    float* tmp;
+    const int len;
 };
 
 std::unique_ptr<FFTPlan> FFT::create(int nbits)
@@ -24,27 +27,31 @@ std::unique_ptr<FFTPlan> FFT::create(int nbits)
     return std::unique_ptr<FFTPlan>(new FFTPlanImpl(nbits));
 }
 
-FFTPlanImpl::FFTPlanImpl(int nbits) : FFTPlan(nbits), cx(av_rdft_init(nbits, DFT_R2C))
+FFTPlanImpl::FFTPlanImpl(int nbits) : FFTPlan(nbits), len(1 << nbits)
 {
+    const float scale = 1.0;
+    av_tx_init(&this->cx, &this->tx, AV_TX_FLOAT_RDFT, 0, this->len, &scale, 0);
+    this->tmp = (float*) av_malloc((this->len + 2) * sizeof(float));
 }
 
 FFTPlanImpl::~FFTPlanImpl()
 {
-    av_rdft_end(this->cx);
+    av_tx_uninit(&this->cx);
+    av_freep(&this->tmp);
 }
 
 void FFTPlanImpl::execute()
 {
-    av_rdft_calc(this->cx, this->get_input());
+    this->tx(this->cx, this->tmp, this->get_input(), sizeof(AVComplexFloat));
 
     // Calculate magnitudes.
     int n = this->get_input_size();
     float n2 = n * n;
-    this->set_output(0, 10.0f * log10f(this->get_input(0) * this->get_input(0) / n2));
-    this->set_output(n / 2, 10.0f * log10f(this->get_input(1) * this->get_input(1) / n2));
+    this->set_output(0, 10.0f * log10f(this->tmp[0] * this->tmp[0] / n2));
     for (int i = 1; i < n / 2; i++) {
-        float re = this->get_input(i * 2);
-        float im = this->get_input(i * 2 + 1);
+        float re = this->tmp[i * 2];
+        float im = this->tmp[i * 2 + 1];
         this->set_output(i, 10.0f * log10f((re * re + im * im) / n2));
     }
+    this->set_output(n / 2, 10.0f * log10f(this->tmp[this->len] * this->tmp[this->len] / n2));
 }