Multimodal dimensional affect recognition using deep bidirectional long short-term memory recurrent neural networks

In this paper we propose the deep bidirectional long short-term memory recurrent neural network (DBLSTM-RNN) based single modal and multi-modal affect recognition frameworks. In the single modal framework DBLSTM with moving average (MA), audio or visual features are input into the DBLSTM-RNN model, whose output estimations of a dimension are smoothed by the moving average filter. After the smoothed estimations are expanded to the frame rate of the ground truth labels, another MA is adopted for smoothing the final results. In the multi-modal framework DBLSTM-DBLSTM-MA, the initial estimations from the audio and visual modalities via the first layer of DBLSTM-RNNs are input into a second layer of DBLSTM-RNN, whose outputs are smoothed by MA. The smoothed estimations are then expanded to the frame rate of the ground truth labels and smoothed again by another MA. Affect recognition experiments are carried out on the training set and development set of the AVEC2014 database, results show that the proposed DBLSTM-MA framework outperforms linear regression, support vector regression (SVR), and BLSTM for single modal dimension estimation. For audio visual multi-modal affect recognition, DBLSTM-DBLSTM-MA obtains better or comparable performance than the state of the art results in the competition of AVEC2014, with the average correlation coefficient (COR) reaches 0.599 on the Freeform database, 0.630 on the Northwind database, and 0.615 on the Freeform-Northwind database.