`video-rs`

<h1 align="center">
  <code>video-rs</code>
</h1>
<p align="center">High-level video toolkit based on ffmpeg.</p>

## 🎬 Introduction

`video-rs` is a general-purpose video library for Rust that uses the
`libav`-family libraries from `ffmpeg`. It aims to provide a stable and Rusty
interface to many common video tasks such as reading, writing, muxing, encoding
and decoding.

## 🛠 S️️tatus

⚠️ This project is still a work-in-progress, and will contain bugs. Some parts
of the API have not been flushed out yet. Use with caution.

Also check out our other video/audio project
[`rave`](https://github.com/oddity-ai/rave). `rave` is still in development,
but its eventual goal is to replace `video-rs` and provide a fully featured
media library without depending on ffmpeg.

## 📦 Setup

First, install the `ffmpeg` libraries. The `ffmpeg-next` project has
[excellent instructions](https://github.com/zmwangx/rust-ffmpeg/wiki/Notes-on-building#dependencies)
on this (`video-rs` depends on the `ffmpeg-next` crate).

Then, add the following to your dependencies in `Cargo.toml`:

```toml
video-rs = "0.10"
```

Use the `ndarray` feature to be able to use raw frames with the
[`ndarray`](https://github.com/rust-ndarray/ndarray) crate:

```toml
video-rs = { version = "0.10", features = ["ndarray"] }
```

## 📖 Examples

Decode a video and print the RGB value for the top left pixel:

```rust
use video_rs::decode::Decoder;
use video_rs::Url;

fn main() {
    video_rs::init().unwrap();

    let source =
        "http://commondatastorage.googleapis.com/gtv-videos-bucket/sample/BigBuckBunny.mp4"
            .parse::<Url>()
            .unwrap();
    let mut decoder = Decoder::new(source).expect("failed to create decoder");

    for frame in decoder.decode_iter() {
        if let Ok((_, frame)) = frame {
            let rgb = frame.slice(ndarray::s![0, 0, ..]).to_slice().unwrap();
            println!("pixel at 0, 0: {}, {}, {}", rgb[0], rgb[1], rgb[2],);
        } else {
            break;
        }
    }
}
```

Encode a 🌈 video, using `ndarray` to create each frame:

```rust
use std::path::Path;

use ndarray::Array3;

use video_rs::encode::{Encoder, Settings};
use video_rs::time::Time;

fn main() {
    video_rs::init().unwrap();

    let settings = Settings::preset_h264_yuv420p(1280, 720, false);
    let mut encoder =
        Encoder::new(Path::new("rainbow.mp4"), settings).expect("failed to create encoder");

    let duration: Time = Time::from_nth_of_a_second(24);
    let mut position = Time::zero();
    for i in 0..256 {
        // This will create a smooth rainbow animation video!
        let frame = rainbow_frame(i as f32 / 256.0);

        encoder
            .encode(&frame, position)
            .expect("failed to encode frame");

        // Update the current position and add the inter-frame duration to it.
        position = position.aligned_with(duration).add();
    }

    encoder.finish().expect("failed to finish encoder");
}

fn rainbow_frame(p: f32) -> Array3<u8> {
    // This is what generated the rainbow effect! We loop through the HSV color spectrum and convert
    // to RGB.
    let rgb = hsv_to_rgb(p * 360.0, 100.0, 100.0);

    // This creates a frame with height 720, width 1280 and three channels. The RGB values for each
    // pixel are equal, and determined by the `rgb` we chose above.
    Array3::from_shape_fn((720, 1280, 3), |(_y, _x, c)| rgb[c])
}

fn hsv_to_rgb(h: f32, s: f32, v: f32) -> [u8; 3] {
    let s = s / 100.0;
    let v = v / 100.0;
    let c = s * v;
    let x = c * (1.0 - (((h / 60.0) % 2.0) - 1.0).abs());
    let m = v - c;
    let (r, g, b) = if (0.0..60.0).contains(&h) {
        (c, x, 0.0)
    } else if (60.0..120.0).contains(&h) {
        (x, c, 0.0)
    } else if (120.0..180.0).contains(&h) {
        (0.0, c, x)
    } else if (180.0..240.0).contains(&h) {
        (0.0, x, c)
    } else if (240.0..300.0).contains(&h) {
        (x, 0.0, c)
    } else if (300.0..360.0).contains(&h) {
        (c, 0.0, x)
    } else {
        (0.0, 0.0, 0.0)
    };
    [
        ((r + m) * 255.0) as u8,
        ((g + m) * 255.0) as u8,
        ((b + m) * 255.0) as u8,
    ]
}
```

## 🪲 Debugging

Ffmpeg does not always produce useful error messages directly. It is
recommended to turn on tracing if you run into an issue to see if there is
extra information present in the log messages.

Add the following packages to `Cargo.toml`:

```toml
[dependencies]
tracing = "0.1"
tracing-subscriber = "0.3"
```

And add the following to your main functions:

```rust
fn main() {
    tracing_subscriber::fmt::init();

    // ...
}
```

Set the `RUST_LOG` environment variable to display tracing messages:

```sh
RUST_LOG=video=debug cargo run
```

## ✨ Credits

`video-rs` only exists thanks to the following organizations and people:

* All [contributors](https://github.com/oddity-ai/video-rs/graphs/contributors) for their work!
* [Provincie Utrecht](https://www.provincie-utrecht.nl/) for supporting this project as part of the "Situational Awareness Software" project.
* [zmwangx](https://github.com/zmwangx) for maintaining [rust-ffmpeg](https://github.com/zmwangx/rust-ffmpeg).
* The [FFmpeg project](https://ffmpeg.org/) for `ffmpeg` and the `ffmpeg` libraries.

## ⚖️ License

Licensed under either of

 * Apache License, Version 2.0
   ([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0)
 * MIT license
   ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)

at your option.

## Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted
for inclusion in the work by you, as defined in the Apache-2.0 license, shall be
dual licensed as above, without any additional terms or conditions.