[pulseaudio-discuss] [RFC PATCH] softvolume: implement fast volume translation

[Wang Xingchao]

Hi all,

I didnot touch much formats optermization, only for most used
s16nr/re, please help review whether the idea is acceptable. If so, i
will take the responsbility for all formats.

--xingchao

2011/10/18 Wang Xingchao <xingchao.wang at intel.com>:
> if all channels have same volume setting, use fast way to
> do volume change. this patch intended to work for two formats:
> s16ne/s16re.
>
> Signed-off-by: Wang Xingchao <xingchao.wang at intel.com>
> ---
>  src/pulsecore/svolume_c.c |   70 +++++++++++++++++++++++++++++++++++++++++++++
>  1 files changed, 70 insertions(+), 0 deletions(-)
>
> diff --git a/src/pulsecore/svolume_c.c b/src/pulsecore/svolume_c.c
> index 272e7a7..7919faa 100644
> --- a/src/pulsecore/svolume_c.c
> +++ b/src/pulsecore/svolume_c.c
> @@ -90,9 +90,43 @@ static void pa_volume_ulaw_c(uint8_t *samples, int32_t *volumes, unsigned channe
>
>  static void pa_volume_s16ne_c(int16_t *samples, int32_t *volumes, unsigned channels, unsigned length) {
>     unsigned channel;
> +    int32_t same_vol = volumes[0];
> +    unsigned fast_vol;
>
>     length /= sizeof(int16_t);
>
> +    for (channel = 0; channel < channels; channel++) {
> +           if (volumes[channel] != same_vol)
> +                   break;
> +    }
> +
> +    fast_vol = channel < channels? 0 : 1;
> +
> +    if (fast_vol) {
> +       int32_t t, hi, lo;
> +       int32_t ht, lt;
> +
> +       hi = same_vol >> 16;
> +       lo = same_vol & 0xffff;
> +       while (length) {
> +               t = *((int32_t *)samples);
> +               ht = t >> 16;
> +               lt = t & 0xffff;
> +
> +               ht = ((ht * lo) >> 16) + (ht * hi);
> +               ht = PA_CLAMP_UNLIKELY(ht, -0x8000, 0x7FFF);
> +
> +               lt = ((lt * lo) >> 16) + (lt * hi);
> +               lt = PA_CLAMP_UNLIKELY(lt, -0x8000, 0x7FFF);
> +
> +               *((int32_t *)samples) = ht<<16|lt;
> +
> +               samples += 2;
> +               length -= 2;
> +       }
> +
> +       return;
> +    }
>     for (channel = 0; length; length--) {
>         int32_t t, hi, lo;
>
> @@ -117,9 +151,45 @@ static void pa_volume_s16ne_c(int16_t *samples, int32_t *volumes, unsigned chann
>
>  static void pa_volume_s16re_c(int16_t *samples, int32_t *volumes, unsigned channels, unsigned length) {
>     unsigned channel;
> +    int32_t same_vol = volumes[0];
> +    unsigned fast_vol;
>
>     length /= sizeof(int16_t);
>
> +    for (channel = 0; channel < channels; channel++) {
> +           if (volumes[channel] != same_vol)
> +                   break;
> +    }
> +
> +    fast_vol = channel < channels? 0 : 1;
> +
> +    if (fast_vol) {
> +       int32_t t, hi, lo;
> +       int32_t ht, lt;
> +
> +       hi = same_vol >> 16;
> +       lo = same_vol & 0xffff;
> +
> +       while (length) {
> +               t = *((int32_t *)samples);
> +               ht = (int32_t)PA_INT16_SWAP((int16_t)(t >> 16));
> +               lt = (int32_t)PA_INT16_SWAP((int16_t)(t & 0xffff));
> +
> +               ht = ((ht * lo) >> 16) + (ht * hi);
> +               ht = PA_CLAMP_UNLIKELY(ht, -0x8000, 0x7FFF);
> +
> +               lt = ((lt * lo) >> 16) + (lt * hi);
> +               lt = PA_CLAMP_UNLIKELY(lt, -0x8000, 0x7FFF);
> +
> +               *((int32_t *)samples) = PA_INT16_SWAP((int16_t) ht<<16)|PA_INT16_SWAP((int16_t) lt);
> +
> +               samples += 2;
> +               length -= 2;
> +       }
> +
> +       return;
> +    }
> +
>     for (channel = 0; length; length--) {
>         int32_t t, hi, lo;
>
> --
> 1.7.1
>
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