# Reproducing paper published in Interspeech 2016¶

This package is part of the Bob toolkit, which allows to reproduce the results experiments published in the following paper:

@inproceedings{KorshunovInterspeech2016,
author = {P. Korshunov AND S. Marcel},
title = {Cross-database evaluation of audio-based spoofing detection systems},
year = {2016},
month = sep,
booktitle = {Interspeech},
pages={1705--1709},
address = {San Francisco, CA, USA},
}


## Running all experiments from scratch¶

This package contains basic scripts to run Presentation Attack Detection (PAD) speech experiments presented in the paper. It uses bob.bio.* and bob.pad.* packages from Bob framework, as well as, Bob’s database interfaces for AVspoof and ASVspoof databases that are defined in bob.db.avspoof and bob.db.asvspoof packages. All these packages are assumed to be installed using conda environment or built using buildout.

The provided experimental pipeline scripts take several parameters, including:

• A database and its evaluation protocol
• A data preprocessing algorithm
• A feature extraction algorithm
• A classifier (to train or evaluate)

All these steps of the PAD system are given as configuration files.

To run all the experiments, two databases need to be downloaded: AVspoof and ASVspoof.

Once the databases are downloaded, please specify the paths to these databases by creating/editing file ~/.bob_bio_databases.txt and writing in it the following two lines:

$[YOUR_AVSPOOF_WAV_DIRECTORY]=/absolute/path/to/avspoof/database/$ [YOUR_ASVSPOOF_WAV_DIRECTORY]=/absolute/path/to/asvspoof/database/


By using ~/.bob_bio_databases.txt file, where path placeholders are replaced with real paths, bob’s framework packages can find the data needed for the experiments.

GMM models for real and spoofed data are trained as per this generic command:

$./bin/train_gmm.py -d DB_NAME --protocol PROTOCOL_NAME -p Preprocessor -e Feature_Extractor -a Classifier -s Folder_Name --groups world --skip-enroller-training -vv --parallel 6  This training may take a long time and as the results, it will generate GMM model and write it into Projector.hdf5 file. You can check all possible options by running $ ./bin/train_gmm.py --help.

Here is the generic command for tuning the trained system on developing set and evaluate on the test set:

$./bin/spoof.py -d DB_NAME -p Preprocessor -e Feature_Extractor -a Classifier --projector-file Projector_spoof.hdf5 -s Folder_Name --groups dev eval --skip-projector-training -vv  For example, to train and evaluate a GMM-based PAD system using MFCC-based features computed for licit and spoof protocols of the ASVspoof database, the following commands need to be run: $ ./bin/train_gmm.py -d asvspoof-licit --protocol CM-licit -p mod-4hz -e mfcc20 -a gmm-tomi -s temp --groups world --projector-file Projector_licit.hdf5 --skip-enroller-training -vv --parallel 6
$./bin/train_gmm.py -d asvspoof-spoof --protocol CM-spoof -p mod-4hz -e mfcc20 -a gmm-tomi -s temp --groups world --projector-file Projector_spoof.hdf5 --skip-enroller-training -vv --parallel 6$ ./bin/spoof.py -d asvspoof -p mod-4hz -e mfcc20 -a gmm --projector-file Projector_spoof.hdf5 -s temp --groups dev eval --skip-projector-training -vv


Here, ./bin/train_gmm.py produces two GMM models, one for licit protocol (real data only) and one for spoof protocol (spoofed data only). Then, ./bin/spoof.py is used to project all data from dev and eval sets onto these two GMM models and compute corresponding scores. By default, the scores will be saved inside ./results folder.

## Scores analysis and plotting¶

Once the scores are obtained, error rates can be computed using the following command (you must have installed Bob v5.0 or higher):

$bob pad metrics -e scores_path/scores-dev scores_path/scores-eval  The histograms and DET curves can also be plotted, for details run $ bob pad --help.

If you want to avoid training all PAD systems and computing scores, we are providing the score files obtained for all the PAD systems presented in the paper. You can download all the scores as follows:

$#You should be inside the package directory bob.paper.interspeech_2016$ wget http://www.idiap.ch/resource/biometric/data/interspeech_2016.tar.gz #Download the scores
$tar -xzvf interspeech_2016.tar.gz  With downloaded scores, you need to compute error rates and DET curves, you need to run the following script: $ ./bin/pad_process_scores.py -t scores_path/scores-dev-attack -d scores_path/scores-dev-real -f scores_path/scores-eval-attack -e scores_path/scores-eval-real -o plots


For example, to evaluate MFCC-based PAD system for ASVspoof database, run the following:

$./bin/pad_process_scores.py -t scores/asvspoof_pad/gmm_mfcc20_onlydeltas_20/scores-dev-attack -d scores/asvspoof_pad/gmm_mfcc20_onlydeltas_20/scores-dev-real -f scores/asvspoof_pad/gmm_mfcc20_onlydeltas_20/scores-eval-attack -e scores/asvspoof_pad/gmm_mfcc20_onlydeltas_20/scores-eval-real -o plots  ## Re-running all experiments on SGE grid¶ It is possible to reproduce the experiments presented in the paper using the following bash scripts that run for all PAD systems used in the paper (note that these scripts assume SGE grid to be available and will take a few days on 50 parallel machines): $ ./train_gmms.sh avspoof 20  # train for AVspoof database
$./train_gmms.sh asvspoof 20 # train for ASVspoof database$ ./project_on_gmms.sh avspoof 20  # evaluate for AVspoof database
$./project_on_gmms.sh asvspoof 20 # evaluate for ASVspoof database  ## Generate paper’s results from pre-computed scores¶ If you want to avoid training all PAD systems and computing scores, we are providing the score files obtained for all the PAD systems presented in the paper. The error rates can be computed, as per Tables 1, 2, and 3 of the paper, and additional DET curves can be plotted by simply performing the following: $ ./evaluate_scores.sh # compute error rates and plot the DET curves for each PAD system


The script will create folders for each different PAD system (it contains computed error rates and DET curves) and one stats.txt file with error rates from all systems in one LaTeX table.

To plot combined DET curves for different systems as per Figure 2 of the paper, the following script can be run:

\$ ./plot_pad_diff_methods.sh  # plot DET curves for selected PAD systems as in Figure 2


This script will plot several DET curves in a single PDF file inside the folder plots_compare_pads.