[0.11] gst-plugins-good: audiofx: Use most common convention for definitions of IIR filter coefficients.
Sebastian DrÃ¶ge
slomo at kemper.freedesktop.org
Wed Jan 11 06:24:21 PST 2012
Module: gst-plugins-good
Branch: 0.11
Commit: 56353e24d2f404269c7662eb4549b4c58b449d49
URL: http://cgit.freedesktop.org/gstreamer/gst-plugins-good/commit/?id=56353e24d2f404269c7662eb4549b4c58b449d49
Author: Leo Singer <leo.singer at ligo.org>
Date: Wed Oct 20 02:17:43 2010 -0700
audiofx: Use most common convention for definitions of IIR filter coefficients.
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.
---
gst/audiofx/audiochebband.c | 74 +++++++++++++++++----------------
gst/audiofx/audiocheblimit.c | 46 +++++++++++---------
gst/audiofx/audiofxbaseiirfilter.c | 51 +++++++++++-----------
gst/audiofx/audioiirfilter.c | 4 +-
tests/check/elements/audioiirfilter.c | 6 +-
5 files changed, 93 insertions(+), 88 deletions(-)
Diff: http://cgit.freedesktop.org/gstreamer/gst-plugins-good/diff/?id=56353e24d2f404269c7662eb4549b4c58b449d49
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