keyframes/
keyframes.rs

1//! Enumerate keyframe timestamps in a video file.
2//!
3//! Uses [`KeyframeEnumerator`] to list the presentation timestamps of all
4//! keyframes (I-frames) in a video stream.  Only packet headers are read —
5//! no decoding is performed — so this is fast even for large files.
6//!
7//! # Usage
8//!
9//! ```bash
10//! cargo run --example keyframes -- --input video.mp4
11//! cargo run --example keyframes -- --input video.mp4 --stream 0
12//! ```
13
14use std::process;
15
16use ff_analysis::KeyframeEnumerator;
17
18fn main() {
19    let mut args = std::env::args().skip(1);
20    let mut input = None::<String>;
21    let mut stream_index = None::<usize>;
22
23    while let Some(flag) = args.next() {
24        match flag.as_str() {
25            "--input" | "-i" => input = Some(args.next().unwrap_or_default()),
26            "--stream" | "-s" => {
27                let raw = args.next().unwrap_or_default();
28                stream_index = Some(raw.parse().unwrap_or_else(|_| {
29                    eprintln!("Invalid stream index: {raw}");
30                    process::exit(1);
31                }));
32            }
33            other => {
34                eprintln!("Unknown flag: {other}");
35                process::exit(1);
36            }
37        }
38    }
39
40    let input = input.unwrap_or_else(|| {
41        eprintln!("Usage: keyframes --input <video> [--stream <index>]");
42        process::exit(1);
43    });
44
45    println!("Enumerating keyframes in: {input}");
46    if let Some(idx) = stream_index {
47        println!("Stream index: {idx}");
48    } else {
49        println!("Stream: first video stream (default)");
50    }
51    println!();
52
53    let mut enumerator = KeyframeEnumerator::new(&input);
54    if let Some(idx) = stream_index {
55        enumerator = enumerator.stream_index(idx);
56    }
57
58    let keyframes = enumerator.run().unwrap_or_else(|e| {
59        eprintln!("Error: {e}");
60        process::exit(1);
61    });
62
63    println!("Found {} keyframe(s):", keyframes.len());
64
65    // Print first 30 keyframes to avoid flooding the terminal.
66    let display_count = keyframes.len().min(30);
67    for (i, ts) in keyframes.iter().take(display_count).enumerate() {
68        let h = ts.as_secs() / 3600;
69        let m = (ts.as_secs() % 3600) / 60;
70        let s = ts.as_secs() % 60;
71        let ms = ts.subsec_millis();
72        println!("  [{i:4}] {h:02}:{m:02}:{s:02}.{ms:03}");
73    }
74    if keyframes.len() > display_count {
75        println!("  … ({} more keyframes)", keyframes.len() - display_count);
76    }
77
78    if !keyframes.is_empty() {
79        let avg_interval_ms = keyframes
80            .windows(2)
81            .map(|w| w[1].saturating_sub(w[0]).as_millis())
82            .sum::<u128>()
83            .checked_div((keyframes.len() - 1) as u128)
84            .unwrap_or(0);
85        println!();
86        println!("Average keyframe interval: {avg_interval_ms} ms");
87    }
88}
keyframes/keyframes.rs

keyframes/
keyframes.rs
