[FFmpeg-devel] [PATCH] Port mp=eq/eq2 to FFmpeg

[arwa arif]

On Thu, Jan 22, 2015 at 2:59 PM, wm4 <nfxjfg at googlemail.com> wrote:

> On Thu, 22 Jan 2015 01:38:11 +0530
> arwa arif <arwaarif1994 at gmail.com> wrote:
>
> > From 703cc1887903c2868537e19e99b76927bec07884 Mon Sep 17 00:00:00 2001
> > From: Arwa Arif <arwaarif1994 at gmail.com>
> > Date: Mon, 19 Jan 2015 03:56:48 +0530
> > Subject: [PATCH] Port mp=eq/eq2 to FFmpeg
> >
> > Code adapted from James Darnley's previous commits
>
> > [...]
>
> > +#if HAVE_MMX && HAVE_6REGS
> > +static void process_MMX(EQParameters *param, uint8_t *dst, int
> dst_stride,
> > +                        uint8_t *src, int src_stride, int w, int h)
> > +{
> > +        int i;
> > +        int pel;
> > +        int dstep = dst_stride - w;
> > +        int sstep = src_stride - w;
> > +        short brvec[4];
> > +        short contvec[4];
> > +
> > +        brvec[0] = brvec[1] = brvec[2] = brvec[3] = param->b;
> > +        contvec[0] = contvec[1] = contvec[2] = contvec[3] = param->c;
> > +
> > +        while (h--) {
> > +                __asm__ volatile (
> > +                        "movq (%5), %%mm3      \n\t"
> > +                        "movq (%6), %%mm4      \n\t"
> > +                        "pxor %%mm0, %%mm0     \n\t"
> > +                        "movl %4, %%eax        \n\t"
> > +                        //ASMALIGN(4)
> > +                        "1:                    \n\t"
> > +                        "movq (%0), %%mm1      \n\t"
> > +                        "movq (%0), %%mm2      \n\t"
> > +                        "punpcklbw %%mm0, %%mm1\n\t"
> > +                        "punpckhbw %%mm0, %%mm2\n\t"
> > +                        "psllw $4, %%mm1       \n\t"
> > +                        "psllw $4, %%mm2       \n\t"
> > +                        "pmulhw %%mm4, %%mm1   \n\t"
> > +                        "pmulhw %%mm4, %%mm2   \n\t"
> > +                        "paddw %%mm3, %%mm1    \n\t"
> > +                        "paddw %%mm3, %%mm2    \n\t"
> > +                        "packuswb %%mm2, %%mm1 \n\t"
> > +                        "add $8, %0            \n\t"
> > +                        "movq %%mm1, (%1)      \n\t"
> > +                        "add $8, %1            \n\t"
> > +                        "decl %%eax            \n\t"
> > +                        "jnz 1b                \n\t"
> > +                        : "=r" (src), "=r" (dst)
> > +                        : "0" (src), "1" (dst), "r" (w>>3), "r"
> (brvec), "r" (contvec)
> > +                        : "%eax"
> > +                );
> > +
> > +                for (i = w&7; i; i--) {
> > +                        pel = ((*src++ * param->c) >> 12) + param->b;
> > +                        if (pel & 768)
> > +                            pel = (-pel) >> 31;
> > +                        *dst++ = pel;
> > +                }
> > +
> > +                src += sstep;
> > +                dst += dstep;
> > +        }
> > +        __asm__ volatile ( "emms \n\t" ::: "memory" );
> > +}
> > +#endif
>
> IMO the asm shouldn't be added at all. It's not important enough for a
> ported video filter, but has high maintenance overhead - there's a
> reason the FFmpeg loathes inline asm, right?
>
> How much does the inline asm help with speed? When I tested it on a
> reasonably modern CPU a while ago, there was barely any advantage.
>
>
I checked the runtime of the codes with and without asm, it turns out that
there is not much difference. The difference is coming out to be in
milliseconds.

26.014s with asm and
26.129 without asm.

 So, should I remove the asm part?


> > +av_cold void ff_eq_init_x86(EQContext *eq)
> > +{
> > +#if HAVE_MMX_INLINE
> > +    int cpu_flags = av_get_cpu_flags();
> > +
> > +    if (cpu_flags & AV_CPU_FLAG_MMX) {
> > +        eq->process = process_MMX;
> > +    }
> > +#endif
> > +}
>
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