WHAT IT IS

GStreamer plugin that wraps Kaldi's SingleUtteranceNnet2Decoder. It requires iVector-adapted DNN acoustic models. The iVectors are adapted to the current audio stream automatically.

The iVectors are reset after the decoding session (stream) ends. Currently, it's not possible to save the adaptation state and recall it later for a particular speaker, to make the adaptation persistent over multiple decoding sessions.

Update: the plugin saves the adaptation state between silence-segmented utterances and between multiple decoding sessions of the same plugin instance. That is, if you start decoding a new stream, the adaptation state of the previous stream is used (unless it's the first stream, in which case a global mean is used). Use the adaptation-state plugin property to get, and set the adaptation state. Use an empty string with the set method to reset the adaptation state to default. This functionality requires Kaldi revision 4582 or later.

HOW TO COMPILE IT

The following works on Linux (I'm using Debian 'testing').

Compile Kaldi trunk, using the shared configuration: In Kaldi's 'src' directory:

./configure --shared
make depend
make

Install gstreamer-1.0:

sudo apt-get install gstreamer1.0-plugins-bad  gstreamer1.0-plugins-base gstreamer1.0-plugins-good  gstreamer1.0-pulseaudio  gstreamer1.0-plugins-ugly  gstreamer1.0-tools libgstreamer1.0-dev

Now we can compile this plugin. Change to src of this project:

cd src

Compile, specifying Kaldi's root directory:

make depend
KALDI_ROOT=/path/of/kaldi-trunk make

This should result in 'libgstkaldionline2.so'.

Test if GStreamer can access the plugin:

GST_PLUGIN_PATH=. gst-inspect-1.0 kaldinnet2onlinedecoder

HOW TO USE IT

Command-line usage is demonstrated in demo/.

Usage through GStreamer's Python bindings is demonstrated demo/gui-demo.py and in the project https://github.com/alumae/kaldi-gstreamer-server, in file kaldigstserver/decoder2.py.