swr: split swri_dither_init() out

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libswresample/dither.c

@@ -24,7 +24,7 @@
 #include "noise_shaping_data.c"
 
 void swri_get_dither(SwrContext *s, void *dst, int len, unsigned seed, enum AVSampleFormat out_fmt, enum AVSampleFormat in_fmt) {
-    double scale = 0;
+    double scale = s->dither.ns_scale;
 #define TMP_EXTRA 2
     double *tmp = av_malloc((len + TMP_EXTRA) * sizeof(double));
     int i;
@@ -32,36 +32,6 @@ void swri_get_dither(SwrContext *s, void *dst, int len, unsigned seed, enum AVSa
     out_fmt = av_get_packed_sample_fmt(out_fmt);
     in_fmt  = av_get_packed_sample_fmt( in_fmt);
 
-    if(in_fmt == AV_SAMPLE_FMT_FLT || in_fmt == AV_SAMPLE_FMT_DBL){
-        if(out_fmt == AV_SAMPLE_FMT_S32) scale = 1.0/(1L<<31);
-        if(out_fmt == AV_SAMPLE_FMT_S16) scale = 1.0/(1L<<15);
-        if(out_fmt == AV_SAMPLE_FMT_U8 ) scale = 1.0/(1L<< 7);
-    }
-    if(in_fmt == AV_SAMPLE_FMT_S32 && out_fmt == AV_SAMPLE_FMT_S16) scale = 1L<<16;
-    if(in_fmt == AV_SAMPLE_FMT_S32 && out_fmt == AV_SAMPLE_FMT_U8 ) scale = 1L<<24;
-    if(in_fmt == AV_SAMPLE_FMT_S16 && out_fmt == AV_SAMPLE_FMT_U8 ) scale = 1L<<8;
-
-    scale *= s->dither.scale;
-
-    s->dither.ns_pos = 0;
-    s->dither.ns_scale   =   scale;
-    s->dither.ns_scale_1 = 1/scale;
-    memset(s->dither.ns_errors, 0, sizeof(s->dither.ns_errors));
-    for (i=0; filters[i].coefs; i++) {
-        const filter_t *f = &filters[i];
-        if (fabs(s->out_sample_rate - f->rate) / f->rate <= .05 && f->name == s->dither.method) {
-            int j;
-            s->dither.ns_taps = f->len;
-            for (j=0; j<f->len; j++)
-                s->dither.ns_coeffs[j] = f->coefs[j];
-            break;
-        }
-    }
-    if (!filters[i].coefs && s->dither.method > SWR_DITHER_NS) {
-        av_log(s, AV_LOG_WARNING, "Requested noise shaping dither not available at this sampling rate, using triangular hp dither\n");
-        s->dither.method = SWR_DITHER_TRIANGULAR_HIGHPASS;
-    }
-
     for(i=0; i<len + TMP_EXTRA; i++){
         double v;
         seed = seed* 1664525 + 1013904223;
@@ -105,6 +75,52 @@ void swri_get_dither(SwrContext *s, void *dst, int len, unsigned seed, enum AVSa
     av_free(tmp);
 }
 
+int swri_dither_init(SwrContext *s, enum AVSampleFormat out_fmt, enum AVSampleFormat in_fmt)
+{
+    int i;
+    double scale = 0;
+
+    if (s->dither.method > SWR_DITHER_TRIANGULAR_HIGHPASS && s->dither.method <= SWR_DITHER_NS)
+        return AVERROR(EINVAL);
+
+    out_fmt = av_get_packed_sample_fmt(out_fmt);
+    in_fmt  = av_get_packed_sample_fmt( in_fmt);
+
+    if(in_fmt == AV_SAMPLE_FMT_FLT || in_fmt == AV_SAMPLE_FMT_DBL){
+        if(out_fmt == AV_SAMPLE_FMT_S32) scale = 1.0/(1L<<31);
+        if(out_fmt == AV_SAMPLE_FMT_S16) scale = 1.0/(1L<<15);
+        if(out_fmt == AV_SAMPLE_FMT_U8 ) scale = 1.0/(1L<< 7);
+    }
+    if(in_fmt == AV_SAMPLE_FMT_S32 && out_fmt == AV_SAMPLE_FMT_S16) scale = 1L<<16;
+    if(in_fmt == AV_SAMPLE_FMT_S32 && out_fmt == AV_SAMPLE_FMT_U8 ) scale = 1L<<24;
+    if(in_fmt == AV_SAMPLE_FMT_S16 && out_fmt == AV_SAMPLE_FMT_U8 ) scale = 1L<<8;
+
+    scale *= s->dither.scale;
+
+    s->dither.ns_pos = 0;
+    s->dither.ns_scale   =   scale;
+    s->dither.ns_scale_1 = 1/scale;
+    memset(s->dither.ns_errors, 0, sizeof(s->dither.ns_errors));
+    for (i=0; filters[i].coefs; i++) {
+        const filter_t *f = &filters[i];
+        if (fabs(s->out_sample_rate - f->rate) / f->rate <= .05 && f->name == s->dither.method) {
+            int j;
+            s->dither.ns_taps = f->len;
+            for (j=0; j<f->len; j++)
+                s->dither.ns_coeffs[j] = f->coefs[j];
+            break;
+        }
+    }
+    if (!filters[i].coefs && s->dither.method > SWR_DITHER_NS) {
+        av_log(s, AV_LOG_WARNING, "Requested noise shaping dither not available at this sampling rate, using triangular hp dither\n");
+        s->dither.method = SWR_DITHER_TRIANGULAR_HIGHPASS;
+    }
+
+    s->dither.noise = s->preout;
+
+    return 0;
+}
+
 #define TEMPLATE_DITHER_S16
 #include "dither_template.c"
 #undef TEMPLATE_DITHER_S16

libswresample/swresample.c

@@ -230,6 +230,7 @@ av_cold void swr_free(SwrContext **ss){
 }
 
 av_cold int swr_init(struct SwrContext *s){
+    int ret;
     s->in_buffer_index= 0;
     s->in_buffer_count= 0;
     s->resample_in_constraint= 0;
@@ -391,7 +392,8 @@ av_assert0(s->out.ch_count);
         set_audiodata_fmt(&s->in_buffer, s->int_sample_fmt);
     }
 
-    s->dither.noise = s->preout;
+    if ((ret = swri_dither_init(s, s->out_sample_fmt, s->int_sample_fmt)) < 0)
+        return ret;
 
     if(s->rematrix || s->dither.method)
         return swri_rematrix_init(s);

libswresample/swresample_internal.h

@@ -177,6 +177,7 @@ int swri_rematrix(SwrContext *s, AudioData *out, AudioData *in, int len, int mus
 void swri_rematrix_init_x86(struct SwrContext *s);
 
 void swri_get_dither(SwrContext *s, void *dst, int len, unsigned seed, enum AVSampleFormat out_fmt, enum AVSampleFormat in_fmt);
+int swri_dither_init(SwrContext *s, enum AVSampleFormat out_fmt, enum AVSampleFormat in_fmt);
 
 void swri_audio_convert_init_arm(struct AudioConvert *ac,
                                  enum AVSampleFormat out_fmt,