I am currently working with kaldi, and are trying to make spectrogram plots of different audio files. Kaldi is a speech recognition toolkit.
Kaldi frames its input in frames of 25 ms with a hop_length of 10 ms.
Kaldi have some code that makes spectograms of an audio files, but not much information is given on how things are stored... The sample rate used for the audio files is 16 KHz.
An example of dataset could be fash-b-an251:
which is an audio file of duration 1 sec. the matrix has 98 rows, and 257 columns.
Plotted: A different dataset could be fash-b-an253
which is an audio file of duration duration: 0.70s The matrix has 69 rows and 257 columns. Plotted: 257 must be the size of the fft length, since it is consistent. What is the rows - how it is related to the length of the audio file. And can the length of audio file be determined using number of rows(Probably), and if,then how?..
I am also a bit unsure about the unit of the values in the plots.. Is is a log power spectrum, or just a power spectrum?
Spectogram of the First audio file with matlab:
So the unit are not the same, what is it stored as??