[pulseaudio-discuss] [PATCH 2/4] Enabled libsoxr resampler backend.

[Peter Meerwald]

Hello,

> On Wednesday 07 January 2015 15:41:14 David Henningsson wrote:
> > On 2015-01-07 15:08, Andrey Semashev wrote:
> > > Added ID and names for the resampler presets and also corrected the
> > > working sample rate deduction to take the new resampler into account.
> > > Removed duplicate condition checks from the deduction code. ---
> > > 
> > >   src/pulsecore/resampler.c | 23 ++++++++++++++++++-----
> > >   src/pulsecore/resampler.h |  4 ++++
> > >   2 files changed, 22 insertions(+), 5 deletions(-)
> > > 
> > > diff --git a/src/pulsecore/resampler.c b/src/pulsecore/resampler.c
> > > index 183d05f..17919a3 100644
> > > --- a/src/pulsecore/resampler.c
> > > +++ b/src/pulsecore/resampler.c
> > > @@ -111,6 +111,15 @@ static int (* const init_table[])(pa_resampler *r) =
> > > {
> > > 
> > >       [PA_RESAMPLER_AUTO]                    = NULL,
> > >       [PA_RESAMPLER_COPY]                    = copy_init,
> > >       [PA_RESAMPLER_PEAKS]                   = pa_resampler_peaks_init,
> > > 
> > > +#ifdef HAVE_SOXR
> > > +    [PA_RESAMPLER_SOXR_MQ]                 = pa_resampler_soxr_init,
> > > +    [PA_RESAMPLER_SOXR_HQ]                 = pa_resampler_soxr_init,
> > > +    [PA_RESAMPLER_SOXR_VHQ]                = pa_resampler_soxr_init,
> > > +#else
> > > +    [PA_RESAMPLER_SOXR_MQ]                 = NULL,
> > > +    [PA_RESAMPLER_SOXR_HQ]                 = NULL,
> > > +    [PA_RESAMPLER_SOXR_VHQ]                = NULL,
> > > +#endif
> > > 
> > >   };
> > >   
> > >   static pa_resample_method_t choose_auto_resampler(pa_resample_flags_t
> > >   flags) {> 
> > > @@ -278,10 +287,11 @@ static pa_sample_format_t choose_work_format(
> > > 
> > >               }
> > >               
> > >                                                   /* Else fall trough */
> > >           
> > >           case PA_RESAMPLER_PEAKS:
> > > -            if (a == PA_SAMPLE_S16NE || b == PA_SAMPLE_S16NE)
> > > -                work_format = PA_SAMPLE_S16NE;
> > 
> > Were the rows above removed on purpose? I suppose the behaviour should
> > be different between SOXR and PEAKS here.
> 
> Yes, I did that intentionally. The point is that audio processing should be 
> done with max precision of the input and output signals. I don't see why PEAKS 
> should be special in this regard - it does support both int16 and float 
> samples.

in any case, such change should be in a separate, independent patch

peaks is a bit special as it just computes the maximum absolute sample 
magnitude over a number of samples; switching to float does not improve 
quality but causes (potentially expensive) floating point comparisions

I think the current special case code for peaks, i.e.
if (a == PA_SAMPLE_S16NE || b == PA_SAMPLE_S16NE)
   work_format = PA_SAMPLE_S16NE;
makes sense

p.
 
> > > -            else if (sample_format_more_precise(a, PA_SAMPLE_S16NE) ||
> > > -                     sample_format_more_precise(b, PA_SAMPLE_S16NE))
> > > +        case PA_RESAMPLER_SOXR_MQ:
> > > +        case PA_RESAMPLER_SOXR_HQ:
> > > +        case PA_RESAMPLER_SOXR_VHQ:
> > > +            if (sample_format_more_precise(a, PA_SAMPLE_S16NE) ||
> > > +                sample_format_more_precise(b, PA_SAMPLE_S16NE))
> > > 
> > >                   work_format = PA_SAMPLE_FLOAT32NE;
> > >               
> > >               else
> > >               
> > >                   work_format = PA_SAMPLE_S16NE;
> 
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-- 

Peter Meerwald
+43-664-2444418 (mobile)