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.
_______________________________________________
ffmpeg-devel mailing list
ffmpeg-devel@ffmpeg.org
http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
