Introduction to Video Processing Application Development in Java Language

With the continuous development of the Internet and digital technology, video has become an indispensable part of people's lives. Whether it is short video applications or online education platforms, videos occupy an important position. Among them, video processing applications have become one of the hot topics. This article will introduce the development of video processing applications in Java language.

1. Video processing class library in Java language

As a cross-platform programming language, the power of Java language lies in its rich class library, which also includes many Video processing related class library.

1. JMF (Java Media Framework)

JMF is a video and audio processing framework on the Java platform. On the Java 2 platform, JMF uses an architecture based on the Java Virtual Machine. It supports processing operations such as parsing and playing multimedia file formats, capturing and encoding video and audio. JMF provides APIs for embedding multimedia streams into Java applications. These APIs allow Java developers to perform audio and video processing operations in applications.

2. JavaCV

JavaCV is a Java version of OpenCV (Open Source Computer Vision Library). It provides an interface for Java developers to access the OpenCV library, which can implement image and video processing operations in the Java language. JavaCV supports converting data between Java and C, and its underlying layer uses Java Native Interface (JNI) and JavaCPP.

3. JCodec

JCodec is a video processing class library on the Java platform. It provides operations such as processing video files, compressing and decompressing videos, and encoding and decoding videos. The video encoding methods supported by JCodec include formats such as H.264 and VP8, and it can also support the adjustment of parameters such as bit rate, frame rate, and resolution.

2. Development of video processing applications

1. Video transcoding

Video transcoding refers to converting one video format into another format the process of. For example, convert MP4 to AVI, or convert AVI to FLV, etc. The JCodec class library can be used on the Java platform to implement the video transcoding function. Taking converting MP4 video to FLV video as an example, the code is as follows:

public class VideoEncoder {

    public void encode MP4toFLV(String MP4FilePath, String FLVFilePath) throws Exception {
        File input = new File(MP4FilePath);
        File output = new File(FLVFilePath);

        SeekableByteChannel inputSBChannel = NIOUtils.readableFileChannel(input);
        SeekableByteChannel outputSBChannel = NIOUtils.writableFileChannel(output);

        MP4Demuxer demuxer = new MP4Demuxer(inputSBChannel);

        Transcoder transcoder = new FMJPlugin.TFMJTranscoder();

        transcoder.videoEncoderFourCC("FLV1");
        transcoder.setVideoQuality(0.6);

        MediaInfo sourceInfo = demuxer.getMediaInfo();
        Codec codec = Codec.getDecoder(sourceInfo.getVideoCodec());
        VideoDecoder vd = codec == null ? null : (VideoDecoder) codec.getDecoder(new VideoCodecMeta(sourceInfo.getVideoCodecMeta().getCodec(), sourceInfo.getVideoCodecMeta().getFourcc(), sourceInfo.getVideoCodecMeta().getTimestampScale(), sourceInfo.getVideoCodecMeta().getSize()));

        transcoder.addVideoTrack(outputSBChannel, vd, sourceInfo.getVideoFps(), 640, 480);

        Packet packet;
        long count = 0;

        while ((packet = demuxer.read(sourceInfo.getVideoTrack())) != null) {
            if (packet.isKeyFrame() && packet.isVideo()) {
                transcoder.encodeVideo(packet, outputSBChannel);
            }
            io.natty.TranscoderUtil.logProgress(++count);
        }

        transcoder.finish(outputSBChannel);
        outputSBChannel.close();
    }
}

2. Video Editing

A common operation in video editing is to cut and merge videos. and cropping. On the Java platform, you can use command line tools such as FFmpeg and FFprobe to implement video editing functions, or you can use the JavaCV class library. Taking the use of JavaCV for video editing as an example, the code is as follows:

public class VideoEditor {

    public void clipVideo(String inputFilePath, String outputFilePath, int startFrame, int endFrame) throws Exception {
        FFmpegFrameGrabber grabber = new FFmpegFrameGrabber(inputFilePath);
        grabber.start();

        FFmpegFrameRecorder recorder = new FFmpegFrameRecorder(outputFilePath, grabber.getImageWidth(), grabber.getImageHeight());
        recorder.setFormat("mp4");
        recorder.setFrameRate(grabber.getFrameRate());
        recorder.start();

        Frame frame = null;
        int frameNum = grabber.getLengthInFrames();
        int count = 0;
        while ((frame = grabber.grabFrame()) != null) {
            if (count >= startFrame && count <= endFrame) {
                recorder.record(frame);
            } else if (count > endFrame) {
                break;
            }
            count++;
        }

        grabber.stop();
        recorder.stop();
    }

    public void mergeVideo(String[] inputFilePaths, String outputFilePath) throws Exception {
        List<FFmpegFrameGrabber> grabbers = new ArrayList<>();
        long totalFrameNum = 0;

        for (String inputFilePath : inputFilePaths) {
            FFmpegFrameGrabber grabber = new FFmpegFrameGrabber(inputFilePath);
            grabber.start();
            grabbers.add(grabber);
            totalFrameNum += grabber.getLengthInFrames();
        }

        FFmpegFrameRecorder recorder = new FFmpegFrameRecorder(outputFilePath, grabbers.get(0).getImageWidth(), grabbers.get(0).getImageHeight());
        recorder.setFrameRate(grabbers.get(0).getFrameRate());
        recorder.start();

        for (FFmpegFrameGrabber grabber : grabbers) {
            Frame frame = null;
            long count = 0;

            while ((frame = grabber.grabFrame()) != null) {
                recorder.record(frame);
                count++;
                io.natty.TranscoderUtil.logProgress(count, totalFrameNum);
            }

            grabber.stop();
        }

        recorder.stop();
    }

    public void cropVideo(String inputFilePath, String outputFilePath, int x, int y, int width, int height) throws Exception {
        FFmpegFrameGrabber grabber = new FFmpegFrameGrabber(inputFilePath);
        grabber.start();

        FFmpegFrameFilter filter = new FFmpegFrameFilter("crop=" + width + ":" + height + ":" + x + ":" + y);
        filter.start();

        FFmpegFrameRecorder recorder = new FFmpegFrameRecorder(outputFilePath, grabber.getImageWidth(), grabber.getImageHeight());
        recorder.setFormat("mp4");
        recorder.setFrameRate(grabber.getFrameRate());
        recorder.start();

        Frame frame = null;

        while ((frame = grabber.grabFrame()) != null) {
            filter.push(frame);
            Frame filteredFrame = filter.pull();
            recorder.record(filteredFrame);
        }

        grabber.stop();
        filter.stop();
        recorder.stop();
    }
}

Summary

This article introduces several video processing libraries in the Java language and how to use the Java language to develop video processing applications. . The functions of video processing applications include video transcoding, video editing and other operations. The Java language provides a wealth of class libraries and tools to implement these operations. Developers can choose according to their own needs.

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