pcm/PcmResampler: convert to abstract interface

The PcmResampler interface is implemented by the two classes
FallbackPcmResampler and LibsampleratePcmResampler.  This prepares for
adding more resampler libraries.

1 files changed, 163 insertions, 0 deletions

diff --git a/src/pcm/LibsamplerateResampler.cxx b/src/pcm/LibsamplerateResampler.cxx
new file mode 100644
index 000000000..586391e67
--- /dev/null
+++ b/src/pcm/LibsamplerateResampler.cxx
@@ -0,0 +1,163 @@
+/*
+ * Copyright (C) 2003-2013 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "config.h"
+#include "LibsamplerateResampler.hxx"
+#include "util/ASCII.hxx"
+#include "util/Error.hxx"
+#include "util/Domain.hxx"
+#include "Log.hxx"
+
+#include <assert.h>
+#include <stdlib.h>
+#include <string.h>
+
+static constexpr Domain libsamplerate_domain("libsamplerate");
+
+static int lsr_converter = SRC_SINC_FASTEST;
+
+static bool
+lsr_parse_converter(const char *s)
+{
+	assert(s != nullptr);
+
+	if (*s == 0)
+		return true;
+
+	char *endptr;
+	long l = strtol(s, &endptr, 10);
+	if (*endptr == 0 && src_get_name(l) != nullptr) {
+		lsr_converter = l;
+		return true;
+	}
+
+	size_t length = strlen(s);
+	for (int i = 0;; ++i) {
+		const char *name = src_get_name(i);
+		if (name == nullptr)
+			break;
+
+		if (StringEqualsCaseASCII(s, name, length)) {
+			lsr_converter = i;
+			return true;
+		}
+	}
+
+	return false;
+}
+
+bool
+pcm_resample_lsr_global_init(const char *converter, Error &error)
+{
+	if (!lsr_parse_converter(converter)) {
+		error.Format(libsamplerate_domain,
+			     "unknown samplerate converter '%s'", converter);
+		return false;
+	}
+
+	FormatDebug(libsamplerate_domain,
+		    "libsamplerate converter '%s'",
+		    src_get_name(lsr_converter));
+
+	return true;
+}
+
+AudioFormat
+LibsampleratePcmResampler::Open(AudioFormat &af, unsigned new_sample_rate,
+				Error &error)
+{
+	assert(af.IsValid());
+	assert(audio_valid_sample_rate(new_sample_rate));
+
+	src_rate = af.sample_rate;
+	dest_rate = new_sample_rate;
+	channels = af.channels;
+
+	/* libsamplerate works with floating point samples */
+	af.format = SampleFormat::FLOAT;
+
+	int src_error;
+	state = src_new(lsr_converter, channels, &src_error);
+	if (!state) {
+		error.Format(libsamplerate_domain, src_error,
+			     "libsamplerate initialization has failed: %s",
+			     src_strerror(src_error));
+		return AudioFormat::Undefined();
+	}
+
+	memset(&data, 0, sizeof(data));
+
+	data.src_ratio = double(new_sample_rate) / double(af.sample_rate);
+	FormatDebug(libsamplerate_domain,
+		    "setting samplerate conversion ratio to %.2lf",
+		    data.src_ratio);
+	src_set_ratio(state, data.src_ratio);
+
+	AudioFormat result = af;
+	result.sample_rate = new_sample_rate;
+	return result;
+}
+
+void
+LibsampleratePcmResampler::Close()
+{
+	state = src_delete(state);
+}
+
+static bool
+src_process(SRC_STATE *state, SRC_DATA *data, Error &error)
+{
+	int result = src_process(state, data);
+	if (result != 0) {
+		error.Format(libsamplerate_domain, result,
+			     "libsamplerate has failed: %s",
+			     src_strerror(result));
+		return false;
+	}
+
+	return true;
+}
+
+inline ConstBuffer<float>
+LibsampleratePcmResampler::Resample2(ConstBuffer<float> src, Error &error)
+{
+	assert(src.size % channels == 0);
+
+	const unsigned src_frames = src.size / channels;
+	const unsigned dest_frames =
+		(src_frames * dest_rate + src_rate - 1) / src_rate;
+	size_t data_out_size = dest_frames * sizeof(float) * channels;
+
+	data.data_in = const_cast<float *>(src.data);
+	data.data_out = (float *)buffer.Get(data_out_size);
+	data.input_frames = src_frames;
+	data.output_frames = dest_frames;
+
+	if (!src_process(state, &data, error))
+		return nullptr;
+
+	return ConstBuffer<float>(data.data_out,
+				  data.output_frames_gen * channels);
+}
+
+ConstBuffer<void>
+LibsampleratePcmResampler::Resample(ConstBuffer<void> src, Error &error)
+{
+	return Resample2(ConstBuffer<float>::FromVoid(src), error).ToVoid();
+}