[FFmpeg-devel] [PATCH 5/5] aarch64/opusdsp: implement NEON accerelated postfilter and deemphasis

[Lynne]

16 Mar 2019, 16:34 by dev at lynne.ee:

> 153372 UNITS in postfilter_c,   65536 runs,      0 skips
> 73164 UNITS in postfilter_neon,   65536 runs,      0 skips -> 2.1x speedup
>
> 80591 UNITS in deemphasis_c,  131072 runs,      0 skips
> 43969 UNITS in deemphasis_neon,  131072 runs,      0 skips -> 1.83x speedup
>
> Total decoder speedup: ~15% on a Raspberry Pi 3 (from 28.1x to 33.5x realtime)
>
> Deemphasis SIMD based on the following unrolling:
> const float c1 = CELT_EMPH_COEFF, c2 = c1*c1, c3 = c2*c1, c4 = c3*c1;
> float state = coeff;
>
> for (int i = 0; i < len; i += 4) {
>     y[0] = x[0] + c1*state;
>     y[1] = x[1] + c2*state + c1*x[0];
>     y[2] = x[2] + c3*state + c1*x[1] + c2*x[0];
>     y[3] = x[3] + c4*state + c1*x[2] + c2*x[1] + c3*x[0];
>
>     state = y[3];
>     y += 4;
>     x += 4;
> }
>
> Unlike the x86 version, duplication is used instead of pslldq so
> the structure and tables are different.
> Same approach tested on x86 (3x pslldq -> vbroadcastss + shufps + pslldq)
> had the same performance, so 3x pslldq was kept as vbroadcastss has a higher
> latency.
>

Could someone review the patches?