未來社會中，文盲並非不識字的人，而是不能再學習的人。鐵人賽就是強迫自己學習的好機會。
大家好今天我要來介紹如何使用FFmpeg來切割影片，他有很多其他的功能但我今天只會來介紹切影片的功能，大家如果有想要嘗試其他功能的話可以去網路上查詢。廢話不多說那我們就開始示範吧!
一開始先在gradle加入:

implementation 'com.arthenica:mobile-ffmpeg-full:4.3.2'

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <Button
        android:id="@+id/mButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="點擊我"
        android:textSize="35sp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

當使用者按下按鈕時，app會跳到選取影片的畫面，在點選影片後就會開始分割影片了。

MainActivity

import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;

import android.content.Intent;
import android.os.Build;
import android.os.Bundle;
import android.os.Environment;
import android.util.Log;
import android.view.View;
import android.widget.Button;

import com.arthenica.mobileffmpeg.Config;
import com.arthenica.mobileffmpeg.FFmpeg;
import com.arthenica.mobileffmpeg.FFprobe;

import java.io.File;
import java.util.ArrayList;

import static com.arthenica.mobileffmpeg.Config.RETURN_CODE_CANCEL;
import static com.arthenica.mobileffmpeg.Config.RETURN_CODE_SUCCESS;

public class MainActivity extends AppCompatActivity {

    Button mButton;
    private static final int PICK_VIDEO_FROM_GALLERY_REQUEST_CODE = 400;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        mButton = findViewById(R.id.mButton);
        mButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                pickImageFromGallery();
            }
        });
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (requestCode == PICK_VIDEO_FROM_GALLERY_REQUEST_CODE && resultCode == RESULT_OK) {


        } if (Build.VERSION.SDK_INT >= 16 && data.getClipData() == null) {
            ArrayList<String> uriList = new ArrayList<String>();
            uriList.clear();

            String path = FileUtil.getFileAbsolutePath(this, data.getData());
            String name = FileUtil.fileName(path);
            uriList.add(path);

            ArrayList<String> VideoList = new ArrayList<>();
            VideoList.add(path);
            Log.e("Listsize", VideoList.size() + ""+path);
            Log.e("List", VideoList.get(0));

            segVideo(path);
        }
    }

    private void pickImageFromGallery() {
        Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
        intent.setType("video/*");
        intent.putExtra(Intent.EXTRA_ALLOW_MULTIPLE, true);
        String[] mimeTypes = {"video/mp4", "video/mov"};
        intent.putExtra(Intent.EXTRA_MIME_TYPES, mimeTypes);
        startActivityForResult(intent, PICK_VIDEO_FROM_GALLERY_REQUEST_CODE);
    }


    public void segVideo(String path){

        ArrayList<String> segVideoList = new ArrayList<>();

        File video = new File(path);
        int videoSize = (int) video.length();
        int sizeLimit = 50 * 1024 * 1024;
        Log.e("size", video.length() + "");
        int duration = (int) (FFprobe.getMediaInformation(path).getDuration() / 1000); //影片秒數
        int startTime = 0;
        int segTime = 0;   //分割秒數
        int loop = 0;
        int sss = videoSize / sizeLimit;
        int aaa = videoSize % sizeLimit;


        if (videoSize > sizeLimit) { //如果video大小超過設定的sizelimit大小
            //計算要分割的秒數
            if (aaa != 0) {
                segTime = duration / (sss + 1);
            }
            //迴圈次數
            if (duration % segTime != 0) {
                loop = duration / segTime + 1;
            } else {
                loop = duration / segTime;
            }
            //開始分割
            for (int i = 0; i < loop; i++) {
                int rc = FFmpeg.execute("-ss " + startTime + " -i " + path + " -t " + segTime + " -acodec copy -vcodec copy " + Environment.getExternalStorageDirectory().toString() + "/Seg_Video" + "/" + video.getName().replace(".mp4", "") + "_seg_" + i + ".mp4");
                if (rc == RETURN_CODE_SUCCESS) {
                    segVideoList.add(Environment.getExternalStorageDirectory().toString() + "/Seg_Video" + "/" + video.getName().replace(".mp4", "") + "_seg_" + i + ".mp4");
                    Log.i(Config.TAG, "Command execution completed successfully.");
                } else if (rc == RETURN_CODE_CANCEL) {
                    Log.i(Config.TAG, "Command execution cancelled by user.");
                } else {

                    Log.i(Config.TAG, String.format("Command execution failed with rc=%d and the output below.", rc));
                    Config.printLastCommandOutput(Log.INFO);
                }
                startTime += segTime;
            }
        } else {
            //沒超過
            segVideoList.add(path);
        }
    }
}

我來解釋一下在MainActivity的的程式碼裡面最重要的有影片切割功能的是下面的程式碼:

    int rc = FFmpeg.execute("-ss " + startTime + " -i " + path + " -t " + segTime + " -acodec copy -vcodec copy " + Environment.getExternalStorageDirectory().toString() + "/Seg_Video" + "/" + video.getName().replace(".mp4", "") + "_seg_" + i + ".mp4");

在這段程式碼裡面

• -ss 後面加入要從影片第幾秒開始分割
• -i 後面加入要剪輯的影片的路徑
• -t 後面加入要剪輯多少秒
  最後面 + Environment......是影片剪輯後要輸出的路徑

AndroidManifest 裡面加入

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

喔對了如果各位的Android系統是10以上的話記得在AndroidManifest的application裡面加入:

android:requestLegacyExternalStorage="true"

否則Logcat會報錯

那今天的介紹就到這了，謝謝大家的觀看。