We aim to put Voiceful available to creative minds and companies around the globe that bring new digital voice experiences and services to the society. Check out our tools, documentation and example code, and request a free evaluation account.


Voiceful offers a set of voice and audio processing tools through a RESTful API for a SaaS access, and a SDK with native libraries for integration in standalone mobile, desktop or server applications.

Cloud API

You can check the full documentation here: .

import time
import requests # sudo pip install requests

#set user credentials
user = '[email protected]'
password = 'yourpassword'

# Python example that interacts with VOICEFUL VoScale API
# It creates a new task, starts it and waits until
# processing have been finished

url_vocloud = ''

if __name__ == '__main__':

# CREATE TASK //////////////////////////////////////////

print '*** CREATE TASK ***'

#set parameters for transformation
timestretch = 0.8;
pitchshift = 3.0;

payload = {
  "time_stretch_ratio": timestretch,
  "pitch_shift": pitchshift,
  "audio_upload_parts": 1

# Post request
response_create = + "/api/voscale/tasks",
auth=(user, password))


# Then upload (PUT) audio file to S3 url address returned in
print "\n*** UPLOAD FILES ***"

filepath = "test.wav"
fh = open(filepath)
audio_data_binary =
response_upload = requests.put(response_create.json()["audio_upload_urls"][0], data=audio_data_binary)

print("returned ok?:" + str(response_upload.ok) +
" reason:" + response_upload.reason +
" status_code:" + str(response_upload.status_code))

# START TASK ///////////////////////////////////////////
print "\n*** START TASK ***"
task_url = url_vocloud + "/api/voscale/tasks/" +

response_start = + "/start",
auth=(user, password))

print("returned ok?:" + str(response_start.ok) +
" reason:" + response_start.reason +
" status_code:" + str(response_start.status_code))

# Check if task finished
print "\n*** TASK PROCESSED? ***"

print "Processing...";
while True:
time.sleep(1)  # delays for 1 seconds
response_status = requests.get(task_url,
auth=(user, password))

if response_status.json()["status"] == 'finished' or
response_status.json()["status"] == 'failed':
print '.'

print "** Output URL: " + response_status.json()['audio_url']

# Download file
response_download = requests.get(response_status.json()['audio_url'],
if response_download.status_code == 200:
with open("output.wav", 'wb') as f:
for chunk in response_download.iter_content(1024):

// PHP example that interacts with VOICEFUL VoScale API
// It creates a new task, starts it and waits until
// processing have been finished

//set user credentials
$user = "[email protected]";
$password = "yourpassword";

$url_vocloud = "";

// CREATE TASK //////////////////////////////////////////
//set parameters for transformation
$timestretch = 0.8;
$pitchshift = 3.0;

$postDataCreate = array(
'time_stretch_ratio' => $timestretch,
'pitch_shift' => $pitchshift,
'audio_upload_parts' => 1

// Setup cURL
$chCreate = curl_init($url_vocloud.'/api/voscale/tasks');
curl_setopt_array($chCreate, array(
'Content-Type: application/json'

CURLOPT_POSTFIELDS => json_encode($postDataCreate)

curl_setopt($chCreate, CURLOPT_USERPWD, $user . ":" . $password);

// Send the request
$responseCreate = curl_exec($chCreate);


echo "** Response from create task: ********\n".$responseCreate."\n";

// Check for errors
if($responseCreate === FALSE){

$responseCreate_obj = json_decode($responseCreate,true);

// Then upload (PUT) audio file to S3 url address returned
// in $responseCreate_obj["audio_upload_urls"][0]

$audio_fn = "test.wav";
$audio = fopen($audio_fn, "rb");

$chUpload = curl_init();
curl_setopt($chUpload, CURLOPT_CONNECTTIMEOUT, 2);
curl_setopt($chUpload, CURLOPT_HEADER, false);
curl_setopt($chUpload, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($chUpload, CURLOPT_BINARYTRANSFER, 1);
curl_setopt($chUpload, CURLOPT_URL, $responseCreate_obj["audio_upload_urls"][0]);

curl_setopt($chUpload, CURLOPT_PUT, 1);
curl_setopt($chUpload, CURLOPT_INFILE, $audio);
curl_setopt($chUpload, CURLOPT_INFILESIZE, filesize($audio_fn));

$responseUpload = curl_exec($chUpload);

echo "\n** Response from upload audio to S3: *****\n".$responseUpload."\n";

// START TASK ///////////////////////////////////////////
$task_id = $responseCreate_obj["id"];
$task_url = $url_vocloud."/api/voscale/tasks/".$task_id;

// The data to send to the API
$postDataStart = array(
'task_url' => $task_url

// Setup cURL
$chStart = curl_init($task_url."/start");
curl_setopt_array($chStart, array(
'Content-Type: application/json'

CURLOPT_POSTFIELDS => json_encode($postDataStart)

curl_setopt($chStart, CURLOPT_USERPWD, $user . ":" . $password);

// Send the request
$responseStart = curl_exec($chStart);

echo "\n** Response from start task: ******\n".$responseStart."\n";

// Check for errors
if($responseStart === FALSE){

$responseStart_obj = json_decode($responseStart,true);

echo "\nProcessing...";

while ( ($responseStatus_obj['status'] != 'failed') and
($responseStatus_obj['status'] != 'finished') )

  // Setup cURL
  $chStatus = curl_init($task_url);
  curl_setopt($chStatus, CURLOPT_USERPWD, $user . ":" . $password);
  // Send the request
  $responseStatus = curl_exec($chStatus);

  $responseStatus_obj = json_decode($responseStatus,true);
  echo ".";

echo "\n\n** Response from status task: ******\n".$responseStatus."\n";

// Check for errors
if($responseStatus === FALSE){

//Decode the response
$responseData_obj = json_decode($responseStatus, TRUE);

//Print output audio generated
echo "\n** Output URL: ".$responseData_obj["audio_url"]."\n";

// C++ example that interacts with VOICEFUL VoScale API
// It creates a new task, starts it and waits until
// processing have been finished, downloading the result

#include <iostream>
#include "json.hpp" //
#include <chrono>
#include <thread>
#include <stdlib.h>
#include <fstream>

#include <curlpp/cURLpp.hpp>
#include <curlpp/Easy.hpp>
#include <curlpp/Options.hpp>
#include <curlpp/Exception.hpp>
#include <curlpp/Infos.hpp>

using json = nlohmann::json;

std::string user = "[email protected]";
std::string pass = "yourpassword";
std::string url_vocloud = "";

int main(int argc, const char * argv[]) {

    curlpp::Easy request;
    json payload;

    // set parameters for transformation
    float timestretch = 0.8;
    float pitchshift = 3.0;

    payload = {
        {"time_stretch_ratio", timestretch},
        {"pitch_shift", pitchshift},
        {"audio_upload_parts", 1}

    request.setOpt(new curlpp::options::Url(url_vocloud + "/api/voscale/tasks"));
    std::list<std::string> header;
    header.push_back("Content-Type: application/json");
    request.setOpt(new curlpp::options::HttpHeader(header));
    request.setOpt(new curlpp::options::PostFields(payload.dump()));
    request.setOpt(new curlpp::options::UserPwd(user + ":" + pass));
    std::ostringstream response;
    request.setOpt(new curlpp::options::WriteStream(&response));

    json response_create = json::parse(response.str());

    std::cout << response.str() << std::endl;

    std::cout << std::endl << "*** UPLOAD FILES ***" << std::endl;

    // Audio 1
    std::string filepath = "test.wav";
    std::string url = response_create["audio_upload_urls"][0];
    request.setOpt(new curlpp::options::ConnectTimeout(2));
    request.setOpt(new curlpp::options::Header(false));
    request.setOpt(new curlpp::options::Url(url));
    request.setOpt(new curlpp::options::Put(true));
    FILE* wFile;
    wFile = fopen(filepath.c_str(), "rb");
    fseek(wFile, 0, SEEK_END);
    long size = ftell(wFile);
    fseek(wFile, 0, SEEK_SET);
    request.setOpt(new curlpp::options::ReadFile(wFile));
    request.setOpt(new curlpp::options::InfileSize(size));

    std::cout << "status_code:" << curlpp::infos::ResponseCode::get(request) << std::endl;

    std::cout << "\n*** START TASK ***" << std::endl;
    std::string id = response_create["id"];
    std::string task_url = url_vocloud + "/api/voscale/tasks/" + id;
    std::string start_url = task_url + "/start";
    json payload_start = {{"task_url", task_url}};

    request.setOpt(new curlpp::options::Url(start_url));
    header.push_back("Content-Type: application/json");
    request.setOpt(new curlpp::options::HttpHeader(header));
    request.setOpt(new curlpp::options::PostFields(payload_start.dump()));
    request.setOpt(new curlpp::options::UserPwd(user + ":" + pass));
    request.setOpt(new curlpp::options::WriteStream(&response));

    std::cout << response.str() << std::endl;
    json response_start = json::parse(response.str());

    std::cout << "\n*** TASK PROCESSED? ***" << std::endl;
    json response_status;
    while (true) {
        request.setOpt(new curlpp::options::Url(task_url));
        request.setOpt(new curlpp::options::UserPwd(user + ":" + pass));
        request.setOpt(new curlpp::options::WriteStream(&response));
        response_status = json::parse(response.str());

        if (response_status["status"] == "finished" || response_status["status"] == "failed")
            std::cout << "-------" << std::endl;

    std::string mixUrl = response_status["audio_url"];
    std::cout << "** Output URL: " << mixUrl << std::endl;

    request.setOpt(new curlpp::options::Url(url));
    std::ofstream outfile ("output.wav", std::ofstream::binary);
    request.setOpt(new curlpp::options::WriteStream(&outfile));
    long responseCode = curlpp::infos::ResponseCode::get(request);
    if (responseCode == 200) {
        std::cout << "File written to output.wav" << std::endl;
    } else {
        std::cout << "Error " << responseCode << " downloading file";
        return -1;

    return 0;


Standalone SDK

All tools available in the Voiceful API are also available as a Standalone SDK, which can be integrated as cross-platform C++ libraries. (SDK clients available upon request).

#include "VoTransLib_api.h"

C++ usage example for VOICEFUL VoTrans Stand Alone SDK
The below code is incomplete, it lacks audio in/out that will
be implemented using standard audio driver libraries or
reading from audio files on disk

//VoTrans object
void* mVoTrans = NULL;

float gain_val = 0.9f;
float pitch_val = 3.f;
float mTimbreParameters[5] = { 0.5f, 0.6f, 0.7f, 0.55f, 0.5f };
float vibratodepth_val = 0.2f;
float vibratofreq_val = 0.3f;
float robot_val = 0.0f;
float alien_val = 0.0f;
float pitchcorrection_val = 0.0f;
float harmonizer_val = 0.0f;

int init()
  int mnCh = 2; //number of channels
  float mSampleRate = 44100.f;
  int mBlockSize = 256;

  mVoTrans = VT_Create();

  int highQuality = 1;
  int noisy = 0;
  int bypass = 0;
  VT_Configure(mnCh, mSampleRate, mBlockSize,
  highQuality, noisy, bypass, mVoTrans);
  VT_SetPreAnalysis(NULL, mVoTrans);

//PROCESS (in loop)
//This function will be the audio driver callback if used in realtime or
//called in a loop while reading from a disk file or memory buffer if
//transforming offline samples
void ProcessCallback(float* inbuffer, float* outbuffer)
  //set parameters (e.g. from gui)
  VT_SetGainParameter(gain_val, mVoTrans);

  VT_SetPitchTranspositionInSemitonesParameter(pitch_val, mVoTrans);

  VT_SetTimbreParameters(mTimbreParameters, mVoTrans);

  VT_SetVibratoDepthParameter(vibratodepth_val, mVoTrans);
  VT_SetVibratoFreqParameter(vibratofreq_val, mVoTrans);

  VT_SetRobotParameter(robot_val, mVoTrans);
  VT_SetAlienParameter(alien_val, mVoTrans);
  VT_SetPitchCorrectionParameter(pitchcorrection_val, mVoTrans);
  VT_SetHarmonizerParameter(harmonizer_val, mVoTrans);

  //inbuffer & outbuffer memory is allocated by the user,
  //DoProcessFloat fills the outbuffer with a maximum of
  //configured blocksize (e.g. mBlockSize=256)
  int n = VT_DoProcessFloat(inbuffer, outbuffer, mVoTrans);

void end()



Voice generation | VoSyn

Our expressive voice generation approach, based on Deep Learning, was initially developed to generate artificial singing voice with high realism. It can learn a model from existing recordings of any individual and generate new speech or singing content. +More info

Voice Transformation | VoTrans

We can transform an actor's voice into a monster vocalization for a film, change a male voice into a kid or elder voice, and integrate it in real-time in games, social apps, or music applications. +More info

Voice Alignment and Pitch Correction | VoAlign

VoAlign analyzes and automatically corrects a voice recording without losing quality. We can align it to a reference recording for lip-syncing or ADR, or apply pitch correction automatically to an estimated musical key.
+More info

Voice Description | VoDesc

This voice analysis tool extracts acoustic and musical information from a voice recording. Data can be sent in real-time, or exported in a readable format to be used in applications such as visualization, classification, monitoring or singing rating. +More info

Time-scaling and Pitch-shifting | VoScale

Beyond voice signals, Voiceful includes also a high-quality time-scaling and pitch-shifting to process any audio content (music, field recordings, dialogues, etc). +More info

Mixing and FX | VoMix

VoMix works as a virtual DAW with all standard audio effects (autogain, compression, EQ, reverb, delay, panning, mixing, etc.) to deliver audio in a professional-like quality. +More info


We can extend and customize our technologies for the specific needs of your project idea. Talk to us!


1-month access to Voiceful Cloud API for evaluation

Request us a free evaluation account and obtain the Terms of Use and Pricing information. (Account limited to evaluation purposes and only for professionals: companies, business individuals or research institutions).


Voiceful combines +15 years of R&D expertise in audio and music technologies with latest artificial intelligence for voice generation. Our patented technologies originate from academic research carried out by Voctro Labs’ cofounders at MTG-UPF, and since 2011 they have been integrated in award-wining applications worldwide. Our technology portfolio is being continuously extended with recent research in the field.