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lavfi/af_aemphasis: remove unnecessary complex number usage 

complex is not available on all platforms. Furthermore, it is trivial to
rewrite complex number expressions to real arithmetic, and in fact
sometimes advantageous for performance reasons: by wrapping as a complex,
one forces a particular Cartesian representation that is not necessarily optimal for the purpose.

Configure dependencies also removed, and aemphasis is now available across
all platforms.

Reviewed-by: Paul B Mahol <onemda@gmail.com>
Signed-off-by: Ganesh Ajjanagadde <gajjanagadde@gmail.com>
This commit is contained in:
Ganesh Ajjanagadde 2015-12-21 17:12:04 -08:00
parent a0ec4aebab
commit 520a5d33f0
2 changed files with 6 additions and 8 deletions
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1
configure vendored
View File

@ -2836,7 +2836,6 @@ unix_protocol_deps="sys_un_h"
unix_protocol_select="network"
# filters
aemphasis_filter_deps="cabs cexp"
amovie_filter_deps="avcodec avformat"
aresample_filter_deps="swresample"
ass_filter_deps="libass"

13
libavfilter/af_aemphasis.c
View File

@ -18,8 +18,6 @@
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <complex.h>
#include "libavutil/opt.h"
#include "avfilter.h"
#include "internal.h"
@ -189,14 +187,15 @@ static inline void set_lp_rbj(BiquadD2 *bq, double fc, double q, double sr, doub
static double freq_gain(BiquadCoeffs *c, double freq, double sr)
{
double complex z, w;
double zr, zi;
freq *= 2.0 * M_PI / sr;
w = 0 + I * freq;
z = 1.0 / cexp(w);
zr = cos(freq);
zi = -sin(freq);
return cabs(((double complex)c->a0 + c->a1 * z + c->a2 * z*z) /
((double complex)1.0 + c->b1 * z + c->b2 * z*z));
/* |(a0 + a1*z + a2*z^2)/(1 + b1*z + b2*z^2)| */
return hypot(c->a0 + c->a1*zr + c->a2*(zr*zr-zi*zi), c->a1*zi + 2*c->a2*zr*zi) /
hypot(1 + c->b1*zr + c->b2*(zr*zr-zi*zi), c->b1*zi + 2*c->b2*zr*zi);
}
static int config_input(AVFilterLink *inlink)