On Fri, Jan 22, 2016 at 4:45 PM, Paul B Mahol <one...@gmail.com> wrote:
> On 1/22/16, Ganesh Ajjanagadde <gajjanaga...@gmail.com> wrote:
>> On Sat, Jan 16, 2016 at 12:31 AM, Ganesh Ajjanagadde
>> <gajjanaga...@gmail.com> wrote:
>>> Further speedups possible by getting rid of exp2f...
>>>
>>> Signed-off-by: Ganesh Ajjanagadde <gajjanaga...@gmail.com>
>>> ---
>>> libavcodec/wmadec.c | 5 +++--
>>> 1 file changed, 3 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/libavcodec/wmadec.c b/libavcodec/wmadec.c
>>> index da54182..1a84323 100644
>>> --- a/libavcodec/wmadec.c
>>> +++ b/libavcodec/wmadec.c
>>> @@ -35,6 +35,7 @@
>>>
>>> #include "libavutil/attributes.h"
>>> #include "libavutil/internal.h"
>>> +#include "libavutil/libm.h"
>>>
>>> #include "avcodec.h"
>>> #include "internal.h"
>>> @@ -164,7 +165,7 @@ static av_cold void
>>> wma_lsp_to_curve_init(WMACodecContext *s, int frame_len)
>>> /* tables for x^-0.25 computation */
>>> for (i = 0; i < 256; i++) {
>>> e = i - 126;
>>> - s->lsp_pow_e_table[i] = pow(2.0, e * -0.25);
>>> + s->lsp_pow_e_table[i] = exp2f(e * -0.25);
>>> }
>>>
>>> /* NOTE: these two tables are needed to avoid two operations in
>>> @@ -173,7 +174,7 @@ static av_cold void
>>> wma_lsp_to_curve_init(WMACodecContext *s, int frame_len)
>>> for (i = (1 << LSP_POW_BITS) - 1; i >= 0; i--) {
>>> m = (1 << LSP_POW_BITS) + i;
>>> a = (float) m * (0.5 / (1 << LSP_POW_BITS));
>>> - a = pow(a, -0.25);
>>> + a = 1/sqrt(sqrt(a));
>>> s->lsp_pow_m_table1[i] = 2 * a - b;
>>> s->lsp_pow_m_table2[i] = b - a;
>>> b = a;
>>> --
>>> 2.7.0
>>>
>>
>> ping, note that second can be made sqrtf(sqrtf(x)) at some error which
>> I deliberately avoided here.
>> _______________________________________________
>> ffmpeg-devel mailing list
>> ffmpeg-devel@ffmpeg.org
>> http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>>
>
> ok, if fate passes.
set pushed, thanks
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