Downloading .mp3 files to my app via FTP changes files' quality

Question

My small game app uses FTP to download some .mp3 sounds. The problem with quality occurs since I upgraded from the free webhosting. Sounds are played with some noise, similiar to that one when your TV has signal problems. I didn't make any changes to the code and the file is downloading properly, the file size, duration and bitrate are not getting changed after the download.

What I've already checked:

• problem occurs on all devices
• sounds played in browser (both PC and mobile) are OK
• sounds downloaded from site to PC or mobile are OK
• sounds downloaded previously from the free webhosting played on the same app screen (or anywhere else in the app) are OK
• old sounds (working properly in app) reuploaded to a new site and redownloaded by app create the same problem

So, literally only files downloaded by my app from a new server are bad quality.

// This is only a part of code, but it's working correctly for more than 2 years now

for (FTPFile file : ftpFiles) {
    String name = file.getName();
    OutputStream outputStream;

    if (name.endsWith(".zip") && Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {
        // Application auto-update
        if (Build.VERSION.SDK_INT >= 23 && checkSelfPermission(Manifest.permission.WRITE_EXTERNAL_STORAGE) == PackageManager.PERMISSION_DENIED) 
        { 
            continue;
        }
    outputStream = new FileOutputStream(path);
    editor.putBoolean("newAppAvailable", true).apply();
    } else {
        File localFile = new File(LoadingScreen.this.getFilesDir() + getResources().getString(R.string.slash) + name);
        outputStream = new BufferedOutputStream(new FileOutputStream(localFile));
    }

    ftp.retrieveFile(name, outputStream);
    outputStream.close();
}

The only reason I can think of is the files' volume. Is it possible that while downloading the file volume increases? Does anyone had such a problem in the past?

EDIT: So, at least I found the result of copying. Original example file length is 15.1s. Playing the copied file in a music program shows the same length and lasts 15.1s aswell. However using Goldwave I discovered that the copied file is accelerated and ends at 13.8s!

EDIT2: I have also tried zipping all the sounds and unzipping in the app - this is unbeliveable, but only one sound is able to unzip, completely damaged... also, the zip file is not visible via PC.

Answer 1

The default file type was probably ASCII and that caused the problem. The solution is to change it after connecting:

ftp.setFileType(FTP.BINARY_FILE_TYPE);