lswr: Improve default resampler's default parameters

After making some blind tests on a small collection of music
samples for home usage. It turned out that the default cutoff
was too low.

The impact of filter_size was not clearly distinguishable (the
results were on the edge) with the music samples but turned out
to be clearly audible in some synthetic samples.

Thanks to Daniel for helping out with the listening tests.
Signed-off-by: Alexander Strasser <eclipse7@gmx.net>

doc/ffmpeg-resampler.texi

@@ -121,7 +121,7 @@ case.
 @end table
 
 @item filter_size
-For swr only, set resampling filter size, default value is 16.
+For swr only, set resampling filter size, default value is 32.
 
 @item phase_shift
 For swr only, set resampling phase shift, default value is 10, must be included
@@ -132,7 +132,7 @@ Use Linear Interpolation if set to 1, default value is 0.
 
 @item cutoff
 Set cutoff frequency (swr: 6dB point; soxr: 0dB point) ratio; must be a float
-value between 0 and 1.  Default value is 0.8 with swr, and 0.91 with soxr
+value between 0 and 1.  Default value is 0.97 with swr, and 0.91 with soxr
 (which, with a sample-rate of 44100, preserves the entire audio band to 20kHz).
 
 @item precision

libswresample/resample.c

@@ -198,7 +198,7 @@ static int build_filter(ResampleContext *c, void *filter, double factor, int tap
 static ResampleContext *resample_init(ResampleContext *c, int out_rate, int in_rate, int filter_size, int phase_shift, int linear,
                                     double cutoff0, enum AVSampleFormat format, enum SwrFilterType filter_type, int kaiser_beta,
                                     double precision, int cheby){
-    double cutoff = cutoff0? cutoff0 : 0.8;
+    double cutoff = cutoff0? cutoff0 : 0.97;
     double factor= FFMIN(out_rate * cutoff / in_rate, 1.0);
     int phase_count= 1<<phase_shift;
 

libswresample/swresample.c

@@ -80,7 +80,7 @@ static const AVOption options[]={
 {"triangular"           , "select triangular dither"    , 0                      , AV_OPT_TYPE_CONST, {.i64=SWR_DITHER_TRIANGULAR }, INT_MIN, INT_MAX   , PARAM, "dither_method"},
 {"triangular_hp"        , "select triangular dither with high pass" , 0                 , AV_OPT_TYPE_CONST, {.i64=SWR_DITHER_TRIANGULAR_HIGHPASS }, INT_MIN, INT_MAX, PARAM, "dither_method"},
 
-{"filter_size"          , "set swr resampling filter size", OFFSET(filter_size)  , AV_OPT_TYPE_INT  , {.i64=16                    }, 0      , INT_MAX   , PARAM },
+{"filter_size"          , "set swr resampling filter size", OFFSET(filter_size)  , AV_OPT_TYPE_INT  , {.i64=32                    }, 0      , INT_MAX   , PARAM },
 {"phase_shift"          , "set swr resampling phase shift", OFFSET(phase_shift)  , AV_OPT_TYPE_INT  , {.i64=10                    }, 0      , 30        , PARAM },
 {"linear_interp"        , "enable linear interpolation" , OFFSET(linear_interp)  , AV_OPT_TYPE_INT  , {.i64=0                     }, 0      , 1         , PARAM },
 {"cutoff"               , "set cutoff frequency ratio"  , OFFSET(cutoff)         , AV_OPT_TYPE_DOUBLE,{.dbl=0.                    }, 0      , 1         , PARAM },

tests/ref/acodec/roqaudio

-c8ff13cf7ebece23af76502f5785202e *tests/data/fate/acodec-roqaudio.roq
+75859976d7098588aeaebbc5551484a9 *tests/data/fate/acodec-roqaudio.roq
 265992 tests/data/fate/acodec-roqaudio.roq
-709fd60aea880c73b375094ab5307c77 *tests/data/fate/acodec-roqaudio.out.wav
-stddev: 4610.71 PSNR: 23.05 MAXDIFF:43883 bytes:  1058400/  1058400
+be6d954adaf984f2dc65a3ff50b55f26 *tests/data/fate/acodec-roqaudio.out.wav
+stddev: 4481.70 PSNR: 23.30 MAXDIFF:46250 bytes:  1058400/  1058400

tests/ref/lavf/dv_fmt

-6f9cfff48f536fa727696f2f9fb3ac08 *./tests/data/lavf/lavf.dv
+11be3e5caa2892236b3475c3f7807b76 *./tests/data/lavf/lavf.dv
 3600000 ./tests/data/lavf/lavf.dv
-./tests/data/lavf/lavf.dv CRC=0x5ce4e5e4
-2e8989478f05f6d4eaf1921fdfac4799 *./tests/data/lavf/lavf.dv
+./tests/data/lavf/lavf.dv CRC=0x25bdd732
+7c789e3559b5102de9459211ae4acf06 *./tests/data/lavf/lavf.dv
 3600000 ./tests/data/lavf/lavf.dv
-./tests/data/lavf/lavf.dv CRC=0x747caf33
+./tests/data/lavf/lavf.dv CRC=0x3f43a4f5
 87d3b20f656235671383a7eaa2f66330 *./tests/data/lavf/lavf.dv
 3600000 ./tests/data/lavf/lavf.dv
 ./tests/data/lavf/lavf.dv CRC=0x0e868a82

tests/ref/lavf/gxf

-72e150dc3430a6a78656790658eb9a09 *./tests/data/lavf/lavf.gxf
+c8b3a8e3ba0185ce39122ac150c12bc3 *./tests/data/lavf/lavf.gxf
 795876 ./tests/data/lavf/lavf.gxf
-./tests/data/lavf/lavf.gxf CRC=0xaee412d1
-cb6b1f522a9a8df145f55905c63a65b6 *./tests/data/lavf/lavf.gxf
+./tests/data/lavf/lavf.gxf CRC=0x147ff044
+4c6594c58da57af745eb511bdd65bca7 *./tests/data/lavf/lavf.gxf
 816752 ./tests/data/lavf/lavf.gxf
-./tests/data/lavf/lavf.gxf CRC=0xb73759d8
+./tests/data/lavf/lavf.gxf CRC=0xfa7c375a
 e4721383461d7a9feae41435567c9257 *./tests/data/lavf/lavf.gxf
 795876 ./tests/data/lavf/lavf.gxf
 ./tests/data/lavf/lavf.gxf CRC=0xd9d58865

tests/ref/lavf/mxf

-c53c9f7ee2091405fbe50374f9055679 *./tests/data/lavf/lavf.mxf
+967f6ee9223c865328f4891465191108 *./tests/data/lavf/lavf.mxf
 525369 ./tests/data/lavf/lavf.mxf
-./tests/data/lavf/lavf.mxf CRC=0x17ce1069
-14d0ac1513840b670a785daf4331aca8 *./tests/data/lavf/lavf.mxf
+./tests/data/lavf/lavf.mxf CRC=0xdbfff6f1
+ec951485333c0b320d2ede8692c602ae *./tests/data/lavf/lavf.mxf
 554553 ./tests/data/lavf/lavf.mxf
-./tests/data/lavf/lavf.mxf CRC=0x468cdbc4
-5636cee18b0f34a5acb33a8efb9f80c6 *./tests/data/lavf/lavf.mxf
+./tests/data/lavf/lavf.mxf CRC=0xfbaac0b0
+ce535b606423d117675213b16275206a *./tests/data/lavf/lavf.mxf
 525369 ./tests/data/lavf/lavf.mxf
-./tests/data/lavf/lavf.mxf CRC=0x17ce1069
+./tests/data/lavf/lavf.mxf CRC=0xdbfff6f1