pcm_resample: add function pcm_resample_float()

A version of the resampler that doesn't need int->float->int
conversion.

src/pcm_resample.c

@@ -76,6 +76,34 @@ void pcm_resample_deinit(struct pcm_resample_state *state)
 		pcm_resample_fallback_deinit(state);
 }
 
+const float *
+pcm_resample_float(struct pcm_resample_state *state,
+		   unsigned channels,
+		   unsigned src_rate,
+		   const float *src_buffer, size_t src_size,
+		   unsigned dest_rate, size_t *dest_size_r,
+		   GError **error_r)
+{
+#ifdef HAVE_LIBSAMPLERATE
+	if (pcm_resample_lsr_enabled())
+		return pcm_resample_lsr_float(state, channels,
+					      src_rate, src_buffer, src_size,
+					      dest_rate, dest_size_r,
+					      error_r);
+#else
+	(void)error_r;
+#endif
+
+	/* sizeof(float)==sizeof(int32_t); the fallback resampler does
+	   not do any math on the sample values, so this hack is
+	   possible: */
+	return (const float *)
+		pcm_resample_fallback_32(state, channels,
+					 src_rate, (const int32_t *)src_buffer,
+					 src_size,
+					 dest_rate, dest_size_r);
+}
+
 const int16_t *
 pcm_resample_16(struct pcm_resample_state *state,
 		unsigned channels,

src/pcm_resample.h

@@ -68,6 +68,26 @@ void pcm_resample_init(struct pcm_resample_state *state);
  */
 void pcm_resample_deinit(struct pcm_resample_state *state);
 
+/**
+ * Resamples 32 bit float data.
+ *
+ * @param state an initialized pcm_resample_state object
+ * @param channels the number of channels
+ * @param src_rate the source sample rate
+ * @param src the source PCM buffer
+ * @param src_size the size of #src in bytes
+ * @param dest_rate the requested destination sample rate
+ * @param dest_size_r returns the number of bytes of the destination buffer
+ * @return the destination buffer
+ */
+const float *
+pcm_resample_float(struct pcm_resample_state *state,
+		   unsigned channels,
+		   unsigned src_rate,
+		   const float *src_buffer, size_t src_size,
+		   unsigned dest_rate, size_t *dest_size_r,
+		   GError **error_r);
+
 /**
  * Resamples 16 bit PCM data.
  *

src/pcm_resample_internal.h

@@ -41,6 +41,14 @@ pcm_resample_lsr_init(struct pcm_resample_state *state);
 void
 pcm_resample_lsr_deinit(struct pcm_resample_state *state);
 
+const float *
+pcm_resample_lsr_float(struct pcm_resample_state *state,
+		       unsigned channels,
+		       unsigned src_rate,
+		       const float *src_buffer, size_t src_size,
+		       unsigned dest_rate, size_t *dest_size_r,
+		       GError **error_r);
+
 const int16_t *
 pcm_resample_lsr_16(struct pcm_resample_state *state,
 		    unsigned channels,

src/pcm_resample_libsamplerate.c

@@ -157,6 +157,45 @@ lsr_process(struct pcm_resample_state *state, GError **error_r)
 	return true;
 }
 
+static float *
+deconst_float_buffer(const float *in)
+{
+	union {
+		const float *in;
+		float *out;
+	} u = { .in = in };
+	return u.out;
+}
+
+const float *
+pcm_resample_lsr_float(struct pcm_resample_state *state,
+		       unsigned channels,
+		       unsigned src_rate,
+		       const float *src_buffer, size_t src_size,
+		       unsigned dest_rate, size_t *dest_size_r,
+		       GError **error_r)
+{
+	assert((src_size % (sizeof(*src_buffer) * channels)) == 0);
+
+	if (!pcm_resample_set(state, channels, src_rate, dest_rate, error_r))
+		return NULL;
+
+	SRC_DATA *data = &state->data;
+	data->input_frames = src_size / sizeof(*src_buffer) / channels;
+	data->data_in = deconst_float_buffer(src_buffer);
+
+	data->output_frames = (src_size * dest_rate + src_rate - 1) / src_rate;
+	size_t data_out_size = data->output_frames * sizeof(float) * channels;
+	data->data_out = pcm_buffer_get(&state->out, data_out_size);
+
+	if (!lsr_process(state, error_r))
+		return NULL;
+
+	*dest_size_r = data->output_frames_gen *
+		sizeof(*data->data_out) * channels;
+	return data->data_out;
+}
+
 const int16_t *
 pcm_resample_lsr_16(struct pcm_resample_state *state,
 		    unsigned channels,