android mp4parser怎樣進行視頻旋轉

MP4Parser 是一個用于解析和操作 MP4 視頻文件的 Java 庫。要使用它來旋轉視頻，你需要在解析 MP4 文件之后，修改視頻軌道的時間戳和縮放屬性。以下是一個簡單的示例，展示了如何使用 MP4Parser 旋轉視頻 90 度：

1. 首先，確保你已經將 MP4Parser 庫添加到項目的依賴項中。如果你使用的是 Gradle，可以在 build.gradle 文件中添加以下依賴：

implementation 'com.googlecode.mp4parser:mp4parser:1.5.2'

2. 然后，你可以使用以下代碼來旋轉視頻：

import com.googlecode.mp4parser.AbstractContainer;
import com.googlecode.mp4parser.Container;
import com.googlecode.mp4parser.DataSource;
import com.googlecode.mp4parser.FileDataSource;
import com.googlecode.mp4parser.MediaFormat;
import com.googlecode.mp4parser.Track;
import com.googlecode.mp4parser.VideoFormat;
import com.googlecode.mp4parser.h264.H264Track;
import com.googlecode.mp4parser.util.Matrix;

import java.io.File;
import java.io.IOException;
import java.nio.ByteBuffer;

public class MP4Rotate {

    public static void main(String[] args) throws IOException {
        String inputPath = "input.mp4"; // 輸入視頻文件路徑
        String outputPath = "output.mp4"; // 輸出視頻文件路徑
        rotateVideo(inputPath, outputPath, 90); // 旋轉角度（順時針）
    }

    public static void rotateVideo(String inputPath, String outputPath, int degrees) throws IOException {
        Container container = new DefaultContainer(new FileDataSource(inputPath));
        Track videoTrack = null;

        for (Track track : container.getTracks()) {
            if (track.getFormat().equals(MediaFormat.Type.VIDEO)) {
                videoTrack = track;
                break;
            }
        }

        if (videoTrack == null) {
            throw new RuntimeException("No video track found in the input file");
        }

        long startTime = 0;
        long endTime = videoTrack.getSampleDescriptionBox().getSampleEntryTime();
        long duration = endTime - startTime;

        H264Track h264Track = (H264Track) videoTrack;
        ByteBuffer[] samples = h264Track.getSamples();

        for (int i = 0; i < samples.length; i++) {
            ByteBuffer sample = samples[i];
            long time = startTime + (duration * i) / samples.length;

            // Rotate the sample data
            Matrix matrix = Matrix.rotate(degrees);
            byte[] rotatedData = new byte[sample.remaining()];
            matrix.transform(rotatedData, sample.array());
            sample.clear();
            sample.put(rotatedData);

            // Update the sample time
            sample.putLong(0, time);
        }

        // Create a new video track with the rotated samples
        Track rotatedVideoTrack = new H264Track(container.getSampleDescriptionBox(), videoTrack.getSampleEntryTime(), videoTrack.getSampleDuration(), videoTrack.getSampleEntrySize(), videoTrack.getCodecInfo());
        for (int i = 0; i < samples.length; i++) {
            rotatedVideoTrack.addSample(sample);
        }

        // Create a new container with the rotated video track
        Container rotatedContainer = new DefaultContainer(new FileDataSource(outputPath));
        rotatedContainer.addTrack(rotatedVideoTrack);

        // Write the rotated container to the output file
        rotatedContainer.writeContainer(new FileOutputStream(outputPath));
    }
}

這個示例中的 rotateVideo 方法接受輸入視頻文件路徑、輸出視頻文件路徑和旋轉角度（順時針）作為參數。它首先解析輸入視頻文件，找到視頻軌道，然后旋轉每個樣本數據，并創建一個新的視頻軌道。最后，它將旋轉后的視頻軌道添加到一個新的容器中，并將容器寫入輸出文件。