Java Image and Video Libraries

<dependency>
  <groupId>net.coobird</groupId>
  <artifactId>thumbnailator</artifactId>
  <version>0.4.21</version>
</dependency>

import net.coobird.thumbnailator.Thumbnails;
import net.coobird.thumbnailator.geometry.Positions;
import java.io.File;
import javax.imageio.ImageIO;
import javax.imageio.ImageReader;
import javax.imageio.stream.ImageInputStream;

// A 2:3 cover thumbnail: scale to fill, crop the overflow from the centre, JPEG at 80.
Thumbnails.of(new File("original.jpg"))
    .size(640, 960)
    .crop(Positions.CENTER)
    .outputFormat("jpg")
    .outputQuality(0.8)
    .toFile(new File("w640.jpg"));

// A width-bounded variant. Thumbnailator has no "do not enlarge" option, so .width(1280) would upscale
// a smaller original: read the width from the image header first and cap the target at it.
File original = new File("original.jpg");
int sourceWidth;
try (ImageInputStream in = ImageIO.createImageInputStream(original)) {
    ImageReader reader = ImageIO.getImageReaders(in).next();
    reader.setInput(in);
    sourceWidth = reader.getWidth(0);    // header width, before EXIF rotation: compare with the height for orientations 5 to 8
    reader.dispose();
}
Thumbnails.of(original)
    .width(Math.min(1280, sourceWidth))
    .toFile(new File("w1280.jpg"));

<dependency>
  <groupId>com.twelvemonkeys.imageio</groupId>
  <artifactId>imageio-jpeg</artifactId>
  <version>3.15.3</version>
</dependency>
<dependency>
  <groupId>com.twelvemonkeys.imageio</groupId>
  <artifactId>imageio-webp</artifactId>
  <version>3.15.3</version>
</dependency>

<dependency>
  <groupId>com.sksamuel.scrimage</groupId>
  <artifactId>scrimage-core</artifactId>
  <version>4.6.8</version>
</dependency>
<dependency>
  <groupId>com.sksamuel.scrimage</groupId>
  <artifactId>scrimage-webp</artifactId>
  <version>4.6.8</version>
</dependency>

import com.sksamuel.scrimage.ImmutableImage;
import com.sksamuel.scrimage.webp.WebpWriter;
import java.io.File;

ImmutableImage image = ImmutableImage.loader().fromFile(new File("original.jpg"));
image.scaleToWidth(640).output(WebpWriter.DEFAULT.withQ(78), new File("w640.webp"));

<dependency>
  <groupId>app.photofox.vips-ffm</groupId>
  <artifactId>vips-ffm-core</artifactId>
  <version>1.9.9</version>
</dependency>

<dependency>
  <groupId>com.github.kokorin.jaffree</groupId>
  <artifactId>jaffree</artifactId>
  <version>2024.08.29</version>
</dependency>

import com.github.kokorin.jaffree.ffmpeg.FFmpeg;
import com.github.kokorin.jaffree.ffmpeg.UrlInput;
import com.github.kokorin.jaffree.ffmpeg.UrlOutput;
import com.github.kokorin.jaffree.ffprobe.FFprobe;
import com.github.kokorin.jaffree.ffprobe.FFprobeResult;
import java.nio.file.Path;
import java.nio.file.Paths;

Path bin = Paths.get("/usr/bin");           // directory that contains ffmpeg and ffprobe

// Probe first, to reject files that are not what the user claimed.
FFprobeResult probe = FFprobe.atPath(bin)
    .setShowStreams(true)
    .setShowFormat(true)                    // without it ffprobe returns no format section and getFormat() is null
    .setInput("input.mov")
    .execute();
double seconds = probe.getFormat().getDuration();

// Transcode to a 720p H.264 rendition with a keyframe every 2 seconds at 24 fps.
FFmpeg.atPath(bin)
    .addInput(UrlInput.fromPath(Paths.get("input.mov")))
    .addArguments("-vf", "scale=-2:720")
    .addArguments("-c:v", "libx264")
    .addArguments("-crf", "22")
    .addArguments("-g", "48")
    .addArguments("-c:a", "aac")
    .addOutput(UrlOutput.toPath(Paths.get("720p.mp4")))
    .execute();

// Extract a cover frame at 10 percent of the duration.
FFmpeg.atPath(bin)
    .addInput(UrlInput.fromPath(Paths.get("input.mov")).setPosition((long) (seconds * 100)))
    .addOutput(UrlOutput.toPath(Paths.get("cover.jpg")).setFrameCount(null, 1L))
    .execute();

<dependency>
  <groupId>ws.schild</groupId>
  <artifactId>jave-core</artifactId>
  <version>${jave.version}</version>
</dependency>
<dependency>
  <groupId>ws.schild</groupId>
  <artifactId>jave-nativebin-linux64</artifactId>
  <version>${jave.version}</version>
</dependency>

import ws.schild.jave.Encoder;
import ws.schild.jave.MultimediaObject;
import ws.schild.jave.encode.AudioAttributes;
import ws.schild.jave.encode.EncodingAttributes;
import ws.schild.jave.encode.VideoAttributes;
import ws.schild.jave.info.VideoSize;
import java.io.File;

AudioAttributes audio = new AudioAttributes();
audio.setCodec("aac");
audio.setBitRate(128000);

VideoAttributes video = new VideoAttributes();
video.setCodec("libx264");
video.setSize(new VideoSize(1280, 720));

EncodingAttributes attrs = new EncodingAttributes();
attrs.setOutputFormat("mp4");
attrs.setAudioAttributes(audio);
attrs.setVideoAttributes(video);

new Encoder().encode(new MultimediaObject(new File("input.mov")), new File("720p.mp4"), attrs);