Api.ai model decoding example scripts

This directory contains scripts on how to use a pre-trained chain english model and kaldi base code to recognize any number of wav files.

IMPORTANT: wav files must be in 16kHz, 16 bit little-endian format.

Model

English pretrained model were released by Api.ai under Creative Commons Attribution-ShareAlike 4.0 International Public License.

• Acoustic data is mostly mobile recorded data
• Language model is based on Assistant.ai logs and good for understanding short commands, like "Wake me up at 7 am" For more details, visit https://github.com/api-ai/api-ai-english-asr-model

Usage

Ensure kaldi is compiled and this scripts are inside kaldi/egs// directory then run

$ ./download-model.sh # to download pretrained chain model
$ ./recognize-wav.sh test1.wav test2.wav # to do recognition

See console output for recognition results.

Using steps/nnet3/decode.sh

You can use kaldi steps/nnet3/decode.sh, which will decode data and calculate Word Error Rate (WER) for it.

Run:

$ recognize-wav.sh test1.wav test2.wav

It will make data dir, calculate mfcc features for it and do decoding, you need only first two steps out of it. If you want WER then edit data/test-corpus/text and replace NO_TRANSCRIPTION with expected text transcription for every wav file.

Run for decoding:

$ steps/nnet3/decode.sh --acwt 1.0 --post-decode-acwt 10.0 --cmd run.pl --nj 1 exp/api.ai-model/ data/test-corpus/ exp/api.ai-model/decode/

See exp/api.ai-model/decode/wer* files for WER and exp/api.ai-model/decode/log/ files for decoding output.

Online Decoder:

See http://kaldi-asr.org/doc/online_decoding.html for more information about kaldi online decoding.

Run:

$./local/create-corpus.sh data/test-corpus/ test1.wav test2.wav

If you want WER then edit data/test-corpus/text and replace NO_TRANSCRIPTION with expected text transcription for every wav file.

Make config file exp/api.ai-model/conf/online.conf with following content:

--feature-type=mfcc
--mfcc-config=exp/api.ai-model/mfcc.conf

Then run:

$ steps/online/nnet3/decode.sh --acwt 1.0 --post-decode-acwt 10.0 --cmd run.pl --nj 1 exp/api.ai-model/ data/test-corpus/ exp/api.ai-model/decode/

See exp/api.ai-model/decode/wer* files for WER and exp/api.ai-model/decode/log/ files for decoding output.