[FFmpeg-devel] [PATCH] avfilter: add audio emphasis filter

[Paul B Mahol]

On 12/4/15, Ganesh Ajjanagadde <gajjanag at mit.edu> wrote:
> On Thu, Dec 3, 2015 at 5:52 PM, Paul B Mahol <onemda at gmail.com> wrote:
>> Signed-off-by: Paul B Mahol <onemda at gmail.com>
>> ---
>>  Changelog                  |   1 +
>>  configure                  |  26 ++++
>>  doc/filters.texi           |  46 ++++++
>>  libavfilter/Makefile       |   1 +
>>  libavfilter/af_aemphasis.c | 370
>> +++++++++++++++++++++++++++++++++++++++++++++
>>  libavfilter/allfilters.c   |   1 +
>>  libavfilter/version.h      |   2 +-
>>  7 files changed, 446 insertions(+), 1 deletion(-)
>>  create mode 100644 libavfilter/af_aemphasis.c
>>
>> diff --git a/Changelog b/Changelog
>> index 2d2a92b..552fab1 100644
>> --- a/Changelog
>> +++ b/Changelog
>> @@ -39,6 +39,7 @@ version <next>:
>>  - support encoding 16-bit RLE SGI images
>>  - apulsator filter
>>  - sidechaingate audio filter
>> +- aemphasis filter
>>
>>
>>  version 2.8:
>> diff --git a/configure b/configure
>> index a30d831..10631e8 100755
>> --- a/configure
>> +++ b/configure
>> @@ -1051,6 +1051,21 @@ int main(void){ $func(); }
>>  EOF
>>  }
>>
>> +check_complexfunc(){
>> +    log check_complexfunc "$@"
>> +    func=$1
>> +    narg=$2
>> +    shift 2
>> +    test $narg = 2 && args="f, g" || args="f"
>> +    disable $func
>> +    check_ld "cc" "$@" <<EOF && enable $func
>> +#include <complex.h>
>> +#include <math.h>
>> +float foo(complex float f, complex float g) { return $func($args); }
>> +int main(void){ return (int) foo; }
>> +EOF
>> +}
>> +
>>  check_mathfunc(){
>>      log check_mathfunc "$@"
>>      func=$1
>> @@ -1768,6 +1783,11 @@ INTRINSICS_LIST="
>>      intrinsics_neon
>>  "
>>
>> +COMPLEX_FUNCS="
>> +    cabs
>> +    cexp
>> +"
>> +
>
> These are not inherently needed, cabs and cexp can be easily
> implemented using hypot and sin, cos, etc. See e.g the mandelbrot
> filter; the filter mathematically operates on complex numbers, but one
> can always use the real value variants with a trivial amount of work.
>
> Don't know and it is unlikely that all our platforms have them - a
> platform which refuses to implement simple things like llrint would
> most likely not bother with this stuff. If you really want to use
> complex numbers (though above demonstrates there is no inherent
> reason), you should add the relevant compat hacks.

I'm not going to add hacks nor reimplement libm/libc nor do I care for platforms
which lacks complex.h
Similar is done for dynaudnorm.

I'm not going to go mandelbrot way as that is not simple approach.
If somebody else who cares comes and do that - then fine, I'm not
going to be against it.

I just do not care..