看起来您的mp3文件无法上传，因此$_FILES数组中缺少该文件.这可能是由于其与图片文件相比的大小.

Looks like your mp3 file cannot be uploaded, so it is missing in $_FILES array. That might be due to its size compared to image files.

请检查php.ini中的upload_max_filesize和post_max_size设置，并允许其大小大于mp3文件.

Please check upload_max_filesize and post_max_size settings from your php.ini and allow a greater size than your mp3 file.