65 lines
2.0 KiB
Java
65 lines
2.0 KiB
Java
package com.imyeyu.api.util;
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import org.bytedeco.javacv.FFmpegFrameGrabber;
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import org.bytedeco.javacv.Frame;
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import org.bytedeco.javacv.Java2DFrameConverter;
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import javax.imageio.ImageIO;
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import java.awt.image.BufferedImage;
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import java.io.ByteArrayOutputStream;
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import java.io.IOException;
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import java.io.InputStream;
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/// JavaCV 工具类
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///
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/// @author 夜雨
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/// @since 2025-10-23 17:05
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public class JavaCV {
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/// 从视频流顺序解码并提取指定时间附近的一帧 PNG 图片
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///
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/// 不执行时间定位，避免为了取实时缩略图而把整个视频复制到临时文件
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///
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/// @param stream 视频输入流
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/// @param targetSeconds 目标时间，单位为秒
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/// @return PNG 图片字节流
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/// @throws Exception 视频解析或取帧失败
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public static ByteArrayOutputStream captureThumbnail(InputStream stream, double targetSeconds) throws Exception {
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long targetMicros = toMicros(targetSeconds);
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ByteArrayOutputStream firstFrame = new ByteArrayOutputStream();
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try (FFmpegFrameGrabber grabber = new FFmpegFrameGrabber(stream)) {
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grabber.start();
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try (Java2DFrameConverter converter = new Java2DFrameConverter()) {
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Frame frame;
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while ((frame = grabber.grabImage()) != null) {
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BufferedImage image = converter.getBufferedImage(frame);
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if (image == null) {
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continue;
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}
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if (!(0 < firstFrame.size())) {
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firstFrame = toPng(image);
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}
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if (grabber.getTimestamp() >= targetMicros) {
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return targetMicros == 0 ? firstFrame : toPng(image);
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}
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}
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}
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}
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// 短视频提前结束时退回首个有效帧
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return firstFrame;
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}
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private static long toMicros(double targetSeconds) {
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double seconds = Double.isFinite(targetSeconds) ? Math.max(0, targetSeconds) : 0;
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return Math.round(seconds * 1_000_000D);
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}
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private static ByteArrayOutputStream toPng(BufferedImage image) throws IOException {
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ByteArrayOutputStream output = new ByteArrayOutputStream();
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if (ImageIO.write(image, "png", output)) {
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return output;
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}
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return new ByteArrayOutputStream();
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}
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}
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