[FFmpeg-devel] [PATCH 03/15] lavfi/f_ebur128: replace pow(10, x) by exp10(x)

[Ganesh Ajjanagadde]

On Wed, Dec 23, 2015 at 10:54 AM, Clément Bœsch <u at pkh.me> wrote:
> On Wed, Dec 23, 2015 at 10:47:23AM -0800, Ganesh Ajjanagadde wrote:
>> exp10, recently introduced, is superior for the purpose.
>>
>> Signed-off-by: Ganesh Ajjanagadde <gajjanagadde at gmail.com>
>> ---
>>  libavfilter/f_ebur128.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/libavfilter/f_ebur128.c b/libavfilter/f_ebur128.c
>> index b9577c5..6749bcd 100644
>> --- a/libavfilter/f_ebur128.c
>> +++ b/libavfilter/f_ebur128.c
>> @@ -435,7 +435,7 @@ static int config_audio_output(AVFilterLink *outlink)
>>      return 0;
>>  }
>>
>> -#define ENERGY(loudness) (pow(10, ((loudness) + 0.691) / 10.))
>> +#define ENERGY(loudness) (exp10(((loudness) + 0.691) / 10.))
>>  #define LOUDNESS(energy) (-0.691 + 10 * log10(energy))
>>  #define DBFS(energy) (20 * log10(energy))
>
> OK if FATE is happy

FATE is happy on GNU/Linux, where exp10 is correctly rounded. Can't
speak for the fallback; it was a risk that I explained in detail. Now
that I see its use, I am myself leaning towards a pow(10,x) fallback
instead of the exp2 based one.

>
> --
> Clément B.
>
> _______________________________________________
> ffmpeg-devel mailing list
> ffmpeg-devel at ffmpeg.org
> http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>