[PATCH 1/2] dsound: Revised 5.1 to stereo downmix

[Andrew Eikum]

Signed-off-by: Andrew Eikum <aeikum at codeweavers.com>

On Tue, Apr 23, 2019 at 08:04:22PM +0200, Nikola Pavlica wrote:
> Signed-off-by: Nikola Pavlica <pavlica.nikola at gmail.com>
> ---
>  dlls/dsound/dsound_convert.c | 24 +++++++++++-------------
>  1 file changed, 11 insertions(+), 13 deletions(-)
> 
> diff --git a/dlls/dsound/dsound_convert.c b/dlls/dsound/dsound_convert.c
> index 26dbb3220a..0da9823298 100644
> --- a/dlls/dsound/dsound_convert.c
> +++ b/dlls/dsound/dsound_convert.c
> @@ -216,39 +216,37 @@ void put_stereo2surround51(const IDirectSoundBufferImpl *dsb, DWORD pos, DWORD c
>  
>  void put_surround512stereo(const IDirectSoundBufferImpl *dsb, DWORD pos, DWORD channel, float value)
>  {
> -    /* based on pulseaudio's downmix algorithm */
> +    /* based on analyzing a recording of a dsound downmix */
>      switch(channel){
>  
> -    case 4: /* back left */
> -        value *= 0.056f; /* (1/9) / (sum of left volumes) */
> +    case 4: /* surround left */
> +        value *= 0.24f;
>          dsb->put_aux(dsb, pos, 0, value);
>          break;
>  
>      case 0: /* front left */
> -        value *= 0.503f; /* 1 / (sum of left volumes) */
> +        value *= 1.0f; 
>          dsb->put_aux(dsb, pos, 0, value);
>          break;
>  
> -    case 5: /* back right */
> -        value *= 0.056f; /* (1/9) / (sum of right volumes) */
> +    case 5: /* surround right */
> +        value *= 0.24f;
>          dsb->put_aux(dsb, pos, 1, value);
>          break;
>  
>      case 1: /* front right */
> -        value *= 0.503f; /* 1 / (sum of right volumes) */
> +        value *= 1.0f;
>          dsb->put_aux(dsb, pos, 1, value);
>          break;
>  
> -    case 2: /* front centre */
> -        value *= 0.252f; /* 0.5 / (sum of left/right volumes) */
> +    case 2: /* centre */
> +        value *= 0.7;
>          dsb->put_aux(dsb, pos, 0, value);
>          dsb->put_aux(dsb, pos, 1, value);
>          break;
>  
> -    case 3: /* LFE */
> -        value *= 0.189f; /* 0.375 / (sum of left/right volumes) */
> -        dsb->put_aux(dsb, pos, 0, value);
> -        dsb->put_aux(dsb, pos, 1, value);
> +    case 3:
> +        /* LFE is totally ignored in dsound when downmixing to 2 channels */
>          break;
>      }
>  }
> -- 
> 2.21.0
> 
> 
>