avio 0.13.1

Safe, high-level audio/video/image processing for Rust — backend-agnostic multimedia toolkit
Documentation 
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//! Correct audio/video sync using `FilterGraphBuilder` + `Pipeline`.
//!
//! Positive delay shifts audio later (audio plays after the corrected point).
//! Negative delay advances audio by trimming the start (audio plays earlier).
//!
//! # Usage
//!
//! ```bash
//! cargo run --example audio_sync --features pipeline -- \
//!   --input   input.mp4  \
//!   --output  synced.mp4 \
//!   --delay   250.0      # ms to shift audio: positive = delay, negative = advance
//! ```

use std::{
    io::{self, Write as _},
    path::Path,
    process,
};

use avio::{AudioCodec, EncoderConfig, FilterGraphBuilder, Pipeline, Progress, VideoCodec};

fn render_progress(p: &Progress) {
    match p.percent() {
        Some(pct) => {
            let bar_width = 20usize;
            #[allow(
                clippy::cast_possible_truncation,
                clippy::cast_sign_loss,
                clippy::cast_precision_loss
            )]
            let filled = ((pct / 100.0) * bar_width as f64).round() as usize;
            let filled = filled.min(bar_width);
            let bar = "=".repeat(filled) + &" ".repeat(bar_width - filled);
            print!("\r{pct:5.1}%  [{bar}]    ");
        }
        None => {
            print!("\r{} frames    ", p.frames_processed);
        }
    }
    let _ = io::stdout().flush();
}

fn main() {
    let mut args = std::env::args().skip(1);
    let mut input = None::<String>;
    let mut output = None::<String>;
    let mut delay: f64 = 0.0;

    while let Some(flag) = args.next() {
        match flag.as_str() {
            "--input" | "-i" => input = Some(args.next().unwrap_or_default()),
            "--output" | "-o" => output = Some(args.next().unwrap_or_default()),
            "--delay" => delay = args.next().unwrap_or_default().parse().unwrap_or(0.0),
            other => {
                eprintln!("Unknown flag: {other}");
                process::exit(1);
            }
        }
    }

    let input = input.unwrap_or_else(|| {
        eprintln!("Usage: audio_sync --input <file> --output <file> --delay <ms>");
        process::exit(1);
    });
    let output = output.unwrap_or_else(|| {
        eprintln!("--output is required");
        process::exit(1);
    });

    let in_name = Path::new(&input)
        .file_name()
        .and_then(|n| n.to_str())
        .unwrap_or(&input);
    let out_name = Path::new(&output)
        .file_name()
        .and_then(|n| n.to_str())
        .unwrap_or(&output);

    let direction = if delay > 0.0 {
        "delay (audio later)"
    } else if delay < 0.0 {
        "advance (audio earlier)"
    } else {
        "no-op"
    };

    println!("Input:   {in_name}");
    println!("Effect:  audio_delay  ({delay:+.0} ms  {direction})");
    println!("Output:  {out_name}");

    // ── Build filter graph ────────────────────────────────────────────────────

    let filter = match FilterGraphBuilder::new().audio_delay(delay).build() {
        Ok(fg) => fg,
        Err(e) => {
            eprintln!("Error building filter graph: {e}");
            process::exit(1);
        }
    };

    println!();

    // ── Assemble pipeline ─────────────────────────────────────────────────────

    let config = EncoderConfig::builder()
        .video_codec(VideoCodec::H264)
        .audio_codec(AudioCodec::Aac)
        .crf(23)
        .build();

    let pipeline = match Pipeline::builder()
        .input(&input)
        .filter(filter)
        .output(&output, config)
        .on_progress(|p: &Progress| {
            render_progress(p);
            true
        })
        .build()
    {
        Ok(p) => p,
        Err(e) => {
            eprintln!("Error: {e}");
            process::exit(1);
        }
    };

    if let Err(e) = pipeline.run() {
        println!();
        eprintln!("Error: {e}");
        process::exit(1);
    }

    println!();

    let size_str = match std::fs::metadata(&output) {
        Ok(m) => {
            #[allow(clippy::cast_precision_loss)]
            let kb = m.len() as f64 / 1024.0;
            if kb < 1024.0 {
                format!("{kb:.0} KB")
            } else {
                format!("{:.1} MB", kb / 1024.0)
            }
        }
        Err(_) => "(unknown size)".to_string(),
    };

    println!("Done. {out_name}  {size_str}");
}