[FFmpeg-devel] [PATCH] Rewrite COMMON_CORE resampling loop.

[Michael Niedermayer]

On Mon, May 26, 2014 at 06:09:56PM -0400, Ronald S. Bultje wrote:
> This moves a condition in the loop outside. In one particular fate
> test (fate-swr-resample-s32p-8000-2626), this makes the code about
> 10% faster. It also simplifies the loop, allowing us to rewrite it
> in yasm at some later point.
> ---
>  libswresample/resample_template.c | 30 ++++++++++++++++--------------
>  1 file changed, 16 insertions(+), 14 deletions(-)
> 
> diff --git a/libswresample/resample_template.c b/libswresample/resample_template.c
> index becff12..44fb667 100644
> --- a/libswresample/resample_template.c
> +++ b/libswresample/resample_template.c
> @@ -135,34 +135,36 @@ int RENAME(swri_resample)(ResampleContext *c, DELEM *dst, const DELEM *src, int
>          *consumed= index;
>          index = 0;
>      }else if(compensation_distance == 0 && !c->linear && index >= 0){
> +        int64_t end_index = (1 + src_size - c->filter_length) << c->phase_shift;

the shift is 32bit, probably would be safer as 64bit


> +        int64_t delta_frac = (end_index - index) * c->src_incr - c->frac;

cant this overflow ?


[...]
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