waveform/
waveform.rs

1//! Compute peak and RMS amplitude per time interval for an audio file.
2//!
3//! Uses [`WaveformAnalyzer`] to produce waveform data suitable for rendering
4//! audio waveform displays.  Each sample covers one configurable time interval
5//! and reports peak and RMS amplitudes in dBFS.
6//!
7//! # Usage
8//!
9//! ```bash
10//! cargo run --example waveform -- --input audio.mp3
11//! cargo run --example waveform -- --input audio.mp3 --interval-ms 50
12//! ```
13
14use std::process;
15use std::time::Duration;
16
17use ff_analysis::{WaveformAnalyzer, WaveformSample};
18
19fn fmt_db(db: f32) -> String {
20    if db == f32::NEG_INFINITY {
21        "-inf".to_string()
22    } else {
23        format!("{db:+.1}")
24    }
25}
26
27fn main() {
28    let mut args = std::env::args().skip(1);
29    let mut input = None::<String>;
30    let mut interval_ms = 100u64;
31
32    while let Some(flag) = args.next() {
33        match flag.as_str() {
34            "--input" | "-i" => input = Some(args.next().unwrap_or_default()),
35            "--interval-ms" => {
36                let raw = args.next().unwrap_or_default();
37                interval_ms = raw.parse().unwrap_or_else(|_| {
38                    eprintln!("Invalid interval-ms: {raw}");
39                    process::exit(1);
40                });
41            }
42            other => {
43                eprintln!("Unknown flag: {other}");
44                process::exit(1);
45            }
46        }
47    }
48
49    let input = input.unwrap_or_else(|| {
50        eprintln!("Usage: waveform --input <audio> [--interval-ms <ms>]");
51        process::exit(1);
52    });
53
54    println!("Analyzing waveform: {input}");
55    println!("Interval: {interval_ms} ms");
56    println!();
57
58    let samples: Vec<WaveformSample> = WaveformAnalyzer::new(&input)
59        .interval(Duration::from_millis(interval_ms))
60        .run()
61        .unwrap_or_else(|e| {
62            eprintln!("Error: {e}");
63            process::exit(1);
64        });
65
66    println!("{} interval(s) analyzed.", samples.len());
67    println!();
68
69    // Print first 20 samples to avoid flooding the terminal.
70    let display_count = samples.len().min(20);
71    println!(
72        "{:<12}  {:>10}  {:>10}",
73        "Time (s)", "Peak dBFS", "RMS dBFS"
74    );
75    println!("{}", "-".repeat(38));
76    for s in samples.iter().take(display_count) {
77        let secs = s.timestamp.as_secs_f64();
78        println!(
79            "{secs:<12.3}  {:>10}  {:>10}",
80            fmt_db(s.peak_db),
81            fmt_db(s.rms_db)
82        );
83    }
84    if samples.len() > display_count {
85        println!("  … ({} more intervals)", samples.len() - display_count);
86    }
87}
waveform/waveform.rs

waveform/
waveform.rs
