Android 视频和图像大小调整

Question

我正在寻找一种方法来降低图像和视频的大小，然后再将它们上传到服务器，目前我正在发送太大的文件，我似乎找不到任何解决方案来压缩文件，我知道像whatsapp和facebook这样的应用程序可以在几秒钟内压缩视频并将它们切成90％的大小，任何人都得到建议，我将不胜感激。

谢谢。

Answer 1

您可以使用开源视频库 ffmpeg 进行压缩。

请注意，视频压缩通常是计算密集型的，因此除了小视频外，它不太可能只花费“几秒钟”。

有多种方法可以在您的应用程序中包含 ffmpeg。查看这些“包装器”项目，了解以太坊使用的示例或帮助您构建自己的 ffmpeg 库：

• http://hiteshsondhi88.github.io/ffmpeg-android-java/
• https://github.com/jhotovy/android-ffmpeg

作为示例，一旦您选择或构建了 ffmpeg 包装器，以下代码将压缩 mp4 视频文件（默认压缩）（此代码使用自定义 ffmpeg 库，但它应该为您提供概述，您应该能够替换上述示例之一）：

public class VideoCompressionTask extends AsyncTask<String, String, String> {
/* This Class is an AsynchTask to compress a video on a background thread
 * 
 */

@Override
protected String doInBackground(String... params) {
    //Compress the video in the background

    //Get the the path of the video to compress
    String videoPath;
    String videoFileName;
    File videoFileToCompress;
    if (params.length == 1) {
        videoPath = params[0];
        videoFileToCompress = new File(videoPath);
        videoFileName = videoFileToCompress.getName();
    } else {
        //One or all of the params are not present - log an error and return
        Log.d("VideoCompressionTask","doInBackground wrong number of params");
        return null;
    }

    //Make sure the video to compress actually exists
    if(!videoFileToCompress.exists()) {
        Log.d("VideoCompressionTask","doInBackground video file to compress does not exist");
        return null;
    }

    //If the compressed file already exists then delete it first and let this task create a new one
    File compressedVideoFile = new File(compressedFilePath);
    if(compressedVideoFile.exists()) {
        compressedVideoFile.delete();
    }

    String argv[] = {"ffmpeg", "-i", videoPath, "-strict", "experimental", "-acodec", "aac", compressedFilePath};
    int ffmpegWrapperreturnCode = FfmpegJNIWrapper.call_ffmpegWrapper(appContext, argv);
    Log.d("VideoCompressionTask","doInBackground ffmpegWrapperreturnCode: " + ffmpegWrapperreturnCode);

    return(compressedFilePath);
}

Answer 2

我今天有确切的需求，所以想出了这个代码。向此函数发送位图，它将返回压缩图像的文件路径（本地）。然后使用返回的文件路径创建一个 File 对象并将其发送到服务器：

 public File compressImage(Bitmap bmp) {
        Bitmap scaledBitmap = null;

        int actualHeight = bmp.getHeight();
        int actualWidth = bmp.getWidth();

//      max Height and width values of the compressed image is taken as 816x612
        float imgRatio = actualWidth / actualHeight;
        float maxRatio = logoMaxWidth / logoMaxHeight;
//      width and height values are set maintaining the aspect ratio of the image
        if (actualHeight > logoMaxHeight || actualWidth > logoMaxWidth) {
            if (imgRatio < maxRatio) {
                imgRatio = logoMaxHeight / actualHeight;
                actualWidth = (int) (imgRatio * actualWidth);
                actualHeight = (int) logoMaxHeight;
            } else if (imgRatio > maxRatio) {
                imgRatio = logoMaxWidth / actualWidth;
                actualHeight = (int) (imgRatio * actualHeight);
                actualWidth = (int) logoMaxWidth;
            } else {
                actualHeight = (int) logoMaxHeight;
                actualWidth = (int) logoMaxWidth;
            }
        }
        try {
            scaledBitmap = Bitmap.createScaledBitmap(bmp, actualWidth, actualHeight, true);
        } catch (OutOfMemoryError exception) {
            logoUploadFaied();
            exception.printStackTrace();
        }
        String uriSting = (System.currentTimeMillis() + ".jpg");
        File file = new File(Environment.getExternalStorageDirectory()
                + File.separator + uriSting);
        try {
            file.createNewFile();
        } catch (IOException e) {
            logoUploadFaied();
            e.printStackTrace();
        }

        FileOutputStream fos = null;
        try {
            fos = new FileOutputStream(file);
        } catch (FileNotFoundException e) {
            logoUploadFaied();
            e.printStackTrace();
        }
        try {
            fos.write(getBytesFromBitmap(scaledBitmap));
            fos.close();
            //recycling bitMap to overcome OutOfMemoryError
            if(scaledBitmap!=null){
                scaledBitmap.recycle();
                scaledBitmap=null;
            }
        } catch (IOException e) {
            logoUploadFaied();
            e.printStackTrace();
        }
        return file;
    }