This file contains the real-domain filter used to invert the polyphase filterbank. The filter is convolved with the frequency domain signal data on a per-frequency-channel basis.
The file is a binary file; values in the file are encoded as their raw binary values.
The file starts with an 8-bit unsigned integer, filterLength, specifying the length of the filter in the time dimension. The software is guaranteed to support any filterLength values in the range [1, 128].
The file then contains a 2D array of filter coefficients.
The outer dimension of the array is time, of size filterLength.
The inner dimension of the array is frequency channel, of fixed size 256.
Each coefficient is a single real number, a IEEE-754 32-bit floating point value, stored in little-endian byte order.
All data is stored contiguously in the file with no padding between values.
Thus the length of the file is: 1 + filterLength * 256 * 4.
Example data layout for filterLength=16:
Byte 0: 16
Bytes 1-4: time 0 channel 0 coefficient
Bytes 5-8: time 0 channel 1 coefficient
...
Bytes 1021-1024: time 0 channel 255 coefficient
Bytes 1025-1028: time 1 channel 0 coefficient
Bytes 1029-1032: time 1 channel 1 coefficient
...
Bytes 2045-2048: time 1 channel 255 coefficient
...
Bytes 16381-16384: time 15 channel 255 coefficient
It is evident that the coefficient for time t, channel c begins at byte index 1024*t + 4*c + 1.