[gst-devel] equalizer audio

sabine donzé sabine.donze at gmail.com
Fri Feb 6 14:25:34 CET 2009 

Hello,

I've effectively an equalization thanks to your modifications on the plugin.
The equalization is well working on a mono file. But I've some problems with
stereo files.

In stereo, I always have to define a frequency at 4kHz so as to have a
cutting-frequency at 8kHz.
Moreover, I observe a difference between left channel and right channel. If
I define the frequency at 4khz and a bandwidth of 2kHz, left channel has a
cutting frequency at 7kHz and right channel has a cutting frequency at 9kHz.
We also have a difference of 3dB after the equalized band.

You can see in attachment the observed results, obtained with the following
command line:

gst-launch filesrc=test.mp3 ! ffdemux_mp3 ! mfw_mp3decoder !
equalizer-nbands num-bands=1 band0::gain=-10 band0::freq=4000
band0::bandwidth=2000 ! alsasink

First graph is obtained width a mono file, and second graph is obtained with
a stereo file.

Do you have some explanation? Why the defined frequency is not the same that
the observed cutting frequency, and why have I a difference between right
channel and left channel?

Thanks for your help,
Sabine

2009/2/3 Stefan Kost <ensonic at hora-obscura.de>

> sabine donzé schrieb:
> > Hello,
> >
> > I'm using the equalizer-nbands plugin from gst-plugins-good_0.10.7.
> > However, if I configure the frequency for one or for each band, the
> > observed cutoff frequency is not the same than the defined frequency.
> >
> > For example:
> >
> > gst-launch filesrc location=toto.mp3 ! ffdemux_mp3 ! mfw_mp3decoder !
> > equalizer-nbands num-bands=4 band0::gain=-21 band0::frequency=947
> > band0::bandwidth=100 ! alsasink
> >
> > I should have a cutting frequency at 957Hz for band0.
> > In logfile, I observe that gain, frequency and bandwidth have been
> > correctly changed. But in setup_filter function, frequency is not at
> > defined value:
> >
> > 0:00:00.516575000  1477 0x14018 DEBUG            equalizer
> > gstiirequalizer.c:494:gst_iir_equalizer_compute_frequencies: band[ 0]
> > = '66.234133'
> > 0:00:00.517031000  1477 0x14018 DEBUG            equalizer
> > gstiirequalizer.c:494:gst_iir_equalizer_compute_frequencies: band[ 1]
> > = '372.461899'
> > 0:00:00.517357000  1477 0x14018 DEBUG            equalizer
> > gstiirequalizer.c:494:gst_iir_equalizer_compute_frequencies: band[ 2]
> > = '2094.507176'
> > 0:00:00.517678000  1477 0x14018 DEBUG            equalizer
> > gstiirequalizer.c:494:gst_iir_equalizer_compute_frequencies: band[ 3]
> > = '11778.279410'
> > 0:00:00.518174000  1477 0x14018 LOG              equalizer
> > gstiirequalizer.c:290:gst_iir_equalizer_child_proxy_get_children_count:
> > we have 4 children
> > 0:00:00.518600000  1477 0x14018 LOG              equalizer
> > gstiirequalizer.c:281:gst_iir_equalizer_child_proxy_get_child_by_index:
> > return child[0] 'band0'
> > 0:00:00.519124000  1477 0x14018 DEBUG            equalizer
> > gstiirequalizer.c:136:gst_iir_equalizer_band_set_property:<band0> gain
> > = 0.000000 -> -21.000000
> >
> > 0:00:00.519571000  1477 0x14018 DEBUG            equalizer
> > gstiirequalizer.c:146:gst_iir_equalizer_band_set_property:<band0>
> > changed gain = -21.000000
> > 0:00:00.520126000  1477 0x14018 LOG              equalizer
> > gstiirequalizer.c:290:gst_iir_equalizer_child_proxy_get_children_count:
> > we have 4 children
> > 0:00:00.520444000  1477 0x14018 LOG              equalizer
> > gstiirequalizer.c:281:gst_iir_equalizer_child_proxy_get_child_by_index:
> > return child[0] 'band0'
> > 0:00:00.520852000  1477 0x14018 DEBUG            equalizer
> > gstiirequalizer.c:154:gst_iir_equalizer_band_set_property:<band0> freq
> > = 66.234133 -> 947.000000
> > 0:00:00.521334000  1477 0x14018 DEBUG            equalizer
> > gstiirequalizer.c:164:gst_iir_equalizer_band_set_property:<band0>
> > changed freq = 947.000000
> > 0:00:00.521767000  1477 0x14018 LOG              equalizer
> > gstiirequalizer.c:290:gst_iir_equalizer_child_proxy_get_children_count:
> > we have 4 children
> > 0:00:00.522071000  1477 0x14018 LOG              equalizer
> > gstiirequalizer.c:281:gst_iir_equalizer_child_proxy_get_child_by_index:
> > return child[0] 'band0'
> > 0:00:00.522568000  1477 0x14018 DEBUG            equalizer
> > gstiirequalizer.c:172:gst_iir_equalizer_band_set_property:<band0>
> > width = 92.468265 -> 100.000000
> > 0:00:00.523032000  1477 0x14018 DEBUG            equalizer
> > gstiirequalizer.c:182:gst_iir_equalizer_band_set_property:<band0>
> > changed width = 100.000000
> > Setting pipeline to PAUSED ...
> > Pipeline is PREROLLING ...
> > 0:00:00.996510000  1477 0x2e7d0 DEBUG            equalizer
> > gstiirequalizer.c:451:gst_iir_equalizer_compute_frequencies: bands 4 -> 4
> > 0:00:00.997166000  1477 0x2e7d0 DEBUG            equalizer
> > gstiirequalizer.c:494:gst_iir_equalizer_compute_frequencies: band[ 0]
> > = '66.234133'
> > 0:00:00.997577000  1477 0x2e7d0 DEBUG            equalizer
> > gstiirequalizer.c:494:gst_iir_equalizer_compute_frequencies: band[ 1]
> > = '372.461899'
> > 0:00:00.997921000  1477 0x2e7d0 DEBUG            equalizer
> > gstiirequalizer.c:494:gst_iir_equalizer_compute_frequencies: band[ 2]
> > = '2094.507176'
> > 0:00:00.998256000  1477 0x2e7d0 DEBUG            equalizer
> > gstiirequalizer.c:494:gst_iir_equalizer_compute_frequencies: band[ 3]
> > = '11778.279410'
> > 0:00:00.998887000  1477 0x2e7d0 INFO             equalizer
> > gstiirequalizer.c:438:setup_filter: gain =     -21, , bandwidth=
> > 92.468, frequency =  66.234, a0 = 0.98034,
> > 0:00:00.999431000  1477 0x2e7d0 INFO             equalizer
> > gstiirequalizer.c:438:setup_filter: gain =       0, , bandwidth=
> > 519.99, frequency =  372.46, a0 =       1, a1
> > 0:00:01.000021000  1477 0x2e7d0 INFO             equalizer
> > gstiirequalizer.c:438:setup_filter: gain =       0, , bandwidth=
> > 2924.1, frequency =  2094.5, a0 =       1, a1
> > 0:00:01.000526000  1477 0x2e7d0 INFO             equalizer
> > gstiirequalizer.c:438:setup_filter: gain =       0, , bandwidth=
> > 16443, frequency =   11778, a0 =       1, a1
> >
> >
> I filed a bug at
> http://bugzilla.gnome.org/show_bug.cgi?id=570343
> Will look at it over the next days.
>
> Stefan
>
> > Moreover, cutoff frequency observed at the end of audio chain is
> > around 200Hz
> >
> > I've also tried to define all bands, but cutting frequencies observed
> > are not coherent with defined frequencies.
> >
> > Moreover, according to configurations, we can have a difference of 6dB
> > between right way and left way.
> >
> > How does this plugin work? How configure it so as to have a cutting
> > frequency at 947Hz?
> > How to have the same output for right way and left way, or how to
> > configure the difference between right way and left way?
> >
> > Thanks for your help
> > Sabine
> > ------------------------------------------------------------------------
> >
> >
> ------------------------------------------------------------------------------
> > This SF.net email is sponsored by:
> > SourcForge Community
> > SourceForge wants to tell your story.
> > http://p.sf.net/sfu/sf-spreadtheword
> > ------------------------------------------------------------------------
> >
> > _______________________________________________
> > gstreamer-devel mailing list
> > gstreamer-devel at lists.sourceforge.net
> > https://lists.sourceforge.net/lists/listinfo/gstreamer-devel
> >
>
>
>
> ------------------------------------------------------------------------------
> Create and Deploy Rich Internet Apps outside the browser with
> Adobe(R)AIR(TM)
> software. With Adobe AIR, Ajax developers can use existing skills and code
> to
> build responsive, highly engaging applications that combine the power of
> local
> resources and data with the reach of the web. Download the Adobe AIR SDK
> and
> Ajax docs to start building applications today-
> http://p.sf.net/sfu/adobe-com
> _______________________________________________
> gstreamer-devel mailing list
> gstreamer-devel at lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/gstreamer-devel
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.freedesktop.org/archives/gstreamer-devel/attachments/20090206/f2884f96/attachment.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: Test equal 090106.pps
Type: application/vnd.ms-powerpoint
Size: 36352 bytes
Desc: not available
URL: <http://lists.freedesktop.org/archives/gstreamer-devel/attachments/20090206/f2884f96/attachment.pps>

More information about the gstreamer-devel mailing list