Rename a file when uploading

Hi!
I have the following form to upload files:
-----
<form method="post" action="" name="FAIv1Pru" id="FAIv1Pru" enctype="multipart/form-data">

<div class="row" style="padding: 30px 0px;">
<!--fecha V1-->
<div class="col-sm-12" style="padding-bottom:20px;">
<label for="V1Date" style="color:#4437A3; font-weight:800;">Indicar fecha del vídeo 1</label>
<input type="text" class="form-control" name="V1Date" placeholder="aaaa-mm-dd" required>
</div>
<!--upload v1-->
<div class="col-sm-6" style="margin-top:30px;">
<div class="form-group">
<input type="hidden" name="MAX_FILE_SIZE" value="52428800" />
<label for="V1Pru" style="color:#4437A3; font-weight:800;">Subir vídeo Ensayo de Prueba</label>
<input type="file" name="V1Pru" id="V1Pru" accept="video/mp4,video/x-m4v,video/*" >
</div>
</div>
<!--upload cert 1-->
<div class="col-sm-6" style="margin-top:30px;">
<div class="form-group">
<label for="V1Cert" style="color:#4437A3; font-weight:800;">Subir certificado Ensayo de Prueba</label>
<input type="file" class="form-control-file" id="V1Cert" name="V1Cert" accept=".doc, .DOC, .docx, .DOCX">
</div>
<div>
<div class="clearfix"></div>
</div>
<div class="row" style="padding: 30px 0px;">
<div class="col-sm-12">
<input type="submit" value="Subir vídeo Ensayo de Prueba y su documentación" name="FAIV1" style="width:100%; background-color:#1837A3; color:#ffffff; padding:8px;">
</div>
</div>
</form>
-----

I want to change the name of those files: users in Spain name their files using characters that are not valid in programming languages ​​such as "á" or "ñ".

I prepared the following script:

----
<?php
//SCRIPTS renombrar, para upload e insert
function replace_specials_characters($s) {
$s = preg_replace("/á|à|â|ã|ª/","a",$s);
$s = preg_replace("/Á|À|Â|Ã/","A",$s);
$s = preg_replace("/é|è|ê/","e",$s);
$s = preg_replace("/É|È|Ê/","E",$s);
$s = preg_replace("/í|ì|î/","i",$s);
$s = preg_replace("/Í|Ì|Î/","I",$s);
$s = preg_replace("/ó|ò|ô|õ|º/","o",$s);
$s = preg_replace("/Ó|Ò|Ô|Õ/","O",$s);
$s = preg_replace("/ú|ù|û/","u",$s);
$s = preg_replace("/Ú|Ù|Û/","U",$s);
$s = str_replace(" ","-",$s);
$s = str_replace("ñ","n",$s);
$s = str_replace("Ñ","N",$s);
$s = preg_replace('/[^a-zA-Z0-9_.-]/', '-', $s);
return $s;
}
//campo file: V1Pru
//boton: FAIV1
//form: FAIv1Pru
if(isset($_POST["FAIV1"]) && !empty($_FILES["V1Pru"]["name"])){
$dataV = date('Y-m-d');
$nombreVideo = replace_specials_characters($_FILES["V1Pru"]["name"]);
$nombreVideoBBDD = $dataV."_".basename($nombreVideo);
}
//campo file: docFAI
//boton: FAIV1
//form: FAIv1Pru
if(isset($_POST["FAIV1"]) && !empty($_FILES["V1Cert"]["name"])){
$data = date('Y-m-d');
$nombreDocumento = replace_specials_characters($_FILES["V1Cert"]["name"]);
$nombreDocBBDD = $data."_".basename($nombreDocumento);
}
?>
----

My idea, taking as an example the upload of the video, is that the document uploads rename eliminating the special characters as it marks my function "replace_specials_characters" that I pick up in the variable "$nombreVideo".

My problem is to incorporate "$nombreVideo" to the process of renaming the file.

These are my scripts generated with WA:

----
<?php
// WA_UploadResult1 Params Start
$WA_UploadResult1_Params = array();
// WA_UploadResult1_1 Start
$WA_UploadResult1_Params["WA_UploadResult1_1"] = array(
'UploadFolder' => "__02_video_pru/",
'FileName' => "[FileName]",
'DefaultFileName' => "",
'ResizeType' => "0",
'ResizeWidth' => "0",
'ResizeHeight' => "0",
'ResizeFillColor' => "" );
// WA_UploadResult1_1 End
// WA_UploadResult1 Params End?>

<?php
WA_DFP_SetupUploadStatusStruct("WA_UploadResult1");
if(isset($_POST["FAIV1"]) || isset($_POST["FAIV1_x"])){
WA_DFP_UploadFiles("WA_UploadResult1", "V1Pru", "2", "$nombreVideo", "false", $WA_UploadResult1_Params);
}//Here I included the name of the variable $nombreVideo to rename
?>
<?php
if (abs($WA_DFP_UploadStatus["WA_UploadResult1"]["statusCode"]) != 1) {
$WAFV_Redirect = "";
$_SESSION['WAVT_crearFAI2_506_Errors'] = "";
if ($WAFV_Redirect == "") {
$WAFV_Redirect = $_SERVER["PHP_SELF"];
}
$WAFV_Errors = "";
$WAFV_Errors .= WAValidateNM($WA_DFP_UploadStatus["WA_UploadResult1"]["WA_UploadResult1_1"]["fileSize"] . "",0,52428800,""," ,",true,1);

if ($WAFV_Errors != "") {
PostResult($WAFV_Redirect,$WAFV_Errors,"crearFAI2_506");
}
}
?>
----

But the fact is that it does upload the file, but does not rename it with the criteria "date_NameFileWithoutSpecialCharacters".

If anyone has any idea about how I can fix it, I appreciate it very much.

A greeting!