... in that it will now call subclass with info on proposed audio format
without having set that info already in base class. As such,
subclass can not rely on audio format info being available there.
Most signal processing texts, including MATLAB, use the following convention for IIR filter coefficients:
a_0 y[n] + a_1 y[n-1] + ... + a_M y[n-M] = b_0 x[n] + b_1 x[n-1] + ... + b[N] x[n-N]
Usually, a_0 is set to 1 because the coefficients can always be rescaled, giving
y[n] = b_0 x[n] + b_1 x[n-1] + ... + b[N] x[n-N] - a_1 y[n-1] - ... - a_M y[n-M]
The convention that was previously used by audiofxbaseiirfilter and derived class had the a and b coefficients swapped, and did not have the minus signs.
This change makes the audiofx plugin use the more common convention described above.
Add private replacements for deprecated functions such as
g_mutex_new(), g_mutex_free(), g_cond_new() etc., mostly
to avoid the deprecation warnings. We'll change these
over to the new API once we depend on glib >= 2.32.