[FFmpeg-devel] [PATCH 4/6] avcodec/hnm4video: Optimize postprocess_current_frame()

[Tomas Härdin]

lör 2019-08-03 klockan 18:57 +0200 skrev Michael Niedermayer:
> On Sat, Aug 03, 2019 at 04:07:22PM +0200, Tomas Härdin wrote:
> > lör 2019-08-03 klockan 01:49 +0200 skrev Michael Niedermayer:
> > > -    uint32_t x, y, src_x, src_y;
> > > +    uint32_t x, y, src_y;
> > > +    int width = hnm->width;
> > >  
> > >      for (y = 0; y < hnm->height; y++) {
> > > +        uint8_t *dst = hnm->processed + y * width;
> > > +        const uint8_t *src = hnm->current;
> > >          src_y = y - (y % 2);
> > > -        src_x = src_y * hnm->width + (y % 2);
> > > -        for (x = 0; x < hnm->width; x++) {
> > > -            hnm->processed[(y * hnm->width) + x] = hnm-
> > > > current[src_x];
> > > -            src_x += 2;
> > > +        src += src_y * width + (y % 2);
> > > +        for (x = 0; x < width; x++) {
> > > +            dst[x] = *src;
> > > +            src += 2;
> > 
> > Looks OK. Maybe telling the compiler that src and dst don't alias
> > would
> > be worthwhile?
> 
> i can add restrict keywords if you want:
> ?
> 
> diff --git a/libavcodec/hnm4video.c b/libavcodec/hnm4video.c
> index 68d0baef6d..1c2501afab 100644
> --- a/libavcodec/hnm4video.c
> +++ b/libavcodec/hnm4video.c
> @@ -121,8 +121,8 @@ static void
> postprocess_current_frame(AVCodecContext *avctx)
>      int width = hnm->width;
>  
>      for (y = 0; y < hnm->height; y++) {
> -        uint8_t *dst = hnm->processed + y * width;
> -        const uint8_t *src = hnm->current;
> +        uint8_t * restrict dst = hnm->processed + y * width;
> +        const uint8_t * restrict src = hnm->current;

Does it improve performance? Else there's little point

/Tomas