Remove unsused variable

Added bytemuck for faster pcm decoding
refactor spectrometer

Cargo.lock

@@ -704,6 +704,7 @@ name = "oscilloscope-video-gen"
 version = "1.0.0"
 dependencies = [
  "anyhow",
+ "bytemuck",
  "clap",
  "hound",
  "image",

Cargo.toml

@@ -31,6 +31,9 @@ anyhow = "1.0"
 # FFT processing for spectrometer
 rustfft = "6.1"
 
+# Efficient byte casting
+bytemuck = "1.24"
+
 [profile.release]
 opt-level = 3
 lto = true

src/audio.rs

@@ -3,6 +3,7 @@
 //! Handles reading and decoding WAV files into normalized sample data.
 
 use anyhow::{anyhow, Context, Result};
+use bytemuck;
 use std::path::Path;
 
 /// Normalized audio sample data.
@@ -49,12 +50,11 @@ impl AudioData {
         let mut left_channel = Vec::with_capacity(total_samples);
         let mut right_channel = Vec::with_capacity(total_samples);
 
-        for i in 0..total_samples {
+        // Convert PCM data to f32 samples efficiently
-            let offset = i * 2 * num_channels;
+        let samples: &[i16] = bytemuck::cast_slice(&pcm_data);
-            
+        for chunk in samples.chunks_exact(num_channels) {
-            let left_val = i16::from_le_bytes([pcm_data[offset], pcm_data[offset + 1]]);
+            let left_val = chunk[0];
-            let right_val = i16::from_le_bytes([pcm_data[offset + 2], pcm_data[offset + 3]]);
+            let right_val = chunk[1];
-
             left_channel.push(left_val as f32 / 32768.0);
             right_channel.push(right_val as f32 / 32768.0);
         }

src/render.rs

@@ -78,12 +78,7 @@ pub fn draw_line(
 fn draw_graticule(
     buffer: &mut ImageBuffer<image::Rgb<u8>, Vec<u8>>,
     primary_color: image::Rgb<u8>,
-    show_grid: bool,
 ) {
-    if !show_grid {
-        return;
-    }
-
     let (width, height) = buffer.dimensions();
 
     for x in 0..width {
@@ -108,7 +103,7 @@ pub fn parse_rgb_hex(hex: &str) -> Result<image::Rgb<u8>> {
 }
 
 /// Compute frequency spectrum from audio samples using FFT.
-fn compute_spectrum(audio_data: &AudioData, start_sample: usize, window_size: usize) -> Vec<f32> {
+fn compute_spectrum(audio_data: &AudioData, start_sample: usize) -> Vec<f32> {
     // Use a larger FFT size for better frequency resolution, especially in the bass
     let fft_size = 2048; 
     let mut planner = FftPlanner::new();
@@ -159,19 +154,23 @@ fn draw_spectrometer(
     color: image::Rgb<u8>,
     sample_rate: u32,
 ) {
-    let spacing = 1;
+    // Constants for logarithmic frequency mapping
-    let bar_width = (width - (num_bars as u32 - 1) * spacing) / num_bars as u32;
+    const MIN_FREQ: f32 = 20.0;
+    const MAX_FREQ: f32 = 20000.0;
+    const FREQ_BOOST_FACTOR: f32 = 5.0;
+    const DYNAMIC_RANGE_SCALE: f32 = 20.0;
+    const NOISE_FLOOR: f32 = 0.05;
+    const BAR_SPACING: u32 = 1;
+
+    let bar_width = (width - (num_bars as u32 - 1) * BAR_SPACING) / num_bars as u32;
     let bar_width = bar_width.max(1);
 
-    // Logarithmic mapping parameters
-    let min_freq = 20.0f32;
-    let max_freq = 20000.0f32;
     let nyquist = sample_rate as f32 / 2.0;
     
     for i in 0..num_bars {
         // Calculate frequency range for this bar (logarithmic)
-        let f_start = min_freq * (max_freq / min_freq).powf(i as f32 / num_bars as f32);
+        let f_start = MIN_FREQ * (MAX_FREQ / MIN_FREQ).powf(i as f32 / num_bars as f32);
-        let f_end = min_freq * (max_freq / min_freq).powf((i + 1) as f32 / num_bars as f32);
+        let f_end = MIN_FREQ * (MAX_FREQ / MIN_FREQ).powf((i + 1) as f32 / num_bars as f32);
 
         // Map frequencies to FFT bin indices
         let bin_start = (f_start / nyquist * spectrum.len() as f32) as usize;
@@ -185,18 +184,17 @@ fn draw_spectrometer(
         }
 
         // Apply frequency-dependent boost (higher frequencies are naturally quieter)
-        // Boost highs by adding a linear factor based on frequency
+        let freq_factor = 1.0 + (f_start / MAX_FREQ) * FREQ_BOOST_FACTOR;
-        let freq_factor = 1.0 + (f_start / max_freq) * 5.0;
         let mut val = magnitude * freq_factor;
 
         // Dynamic range compression/scaling
-        val = (val * 20.0).sqrt().min(1.0);
+        val = (val * DYNAMIC_RANGE_SCALE).sqrt().min(1.0);
-        
+
         // Noise floor
-        if val < 0.05 { val = 0.0; }
+        if val < NOISE_FLOOR { val = 0.0; }
 
         let bar_height = (val * height as f32) as u32;
-        let x = x_offset + i as u32 * (bar_width + spacing);
+        let x = x_offset + i as u32 * (bar_width + BAR_SPACING);
 
         for y in 0..bar_height {
             let pixel_y = y_offset + height - 1 - y;
@@ -226,7 +224,7 @@ pub fn draw_frame(
     }
 
     if options.show_grid {
-        draw_graticule(&mut buffer, options.left_color, true);
+        draw_graticule(&mut buffer, options.left_color);
     }
 
     let end_sample = std::cmp::min(start_sample + samples_per_frame, audio_data.left_channel.len());
@@ -362,8 +360,7 @@ pub fn draw_frame(
             let spec_x_offset = half_width;
             let spec_y_offset = half_height;
 
-            let window_size = 1024.min(samples_per_frame);
+            let spectrum = compute_spectrum(audio_data, start_sample);
-            let spectrum = compute_spectrum(audio_data, start_sample, window_size);
 
             draw_spectrometer(
                 &mut buffer,
@@ -386,8 +383,7 @@ pub fn draw_frame(
             }
         }
         RenderMode::Spectrometer => {
-            let window_size = 1024.min(samples_per_frame);
+            let spectrum = compute_spectrum(audio_data, start_sample);
-            let spectrum = compute_spectrum(audio_data, start_sample, window_size);
 
             draw_spectrometer(
                 &mut buffer,