initHEADmain

1 files changed, 180 insertions, 0 deletions

diff --git a/mod/sample.c b/mod/sample.c
new file mode 100644
index 0000000..6a3a24b
--- /dev/null
+++ b/mod/sample.c
@@ -0,0 +1,180 @@
+/*
+ * melisma - extensible and scriptable audio engine
+ * Copyright (C) 2026  Ludvig Gunne Lindström
+ *
+ * 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 3 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, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <stdlib.h>
+#include <string.h>
+#include <lauxlib.h>
+#include <sndfile.h>
+#include <samplerate.h>
+#include "melisma.h"
+#include "sample.h"
+
+static struct sample *alloc_sample(size_t len)
+{
+	struct sample *s = malloc(sizeof(*s) + len*sizeof(s->data[0]));
+	s->len = len;
+	return s;
+}
+
+static struct sample *resample(struct sample *old, unsigned long from, unsigned long to)
+{
+	double ratio = (double)to / (double)from;
+	size_t new_len = ratio * old->len;
+	struct sample *new = alloc_sample(new_len);
+
+	SRC_DATA src_data = {
+		.data_in = old->data,
+		.data_out = new->data,
+		.input_frames = old->len,
+		.output_frames = new->len,
+		.src_ratio = ratio,
+	};
+
+	src_simple(&src_data,SRC_SINC_MEDIUM_QUALITY,1);
+
+	new->path = old->path;
+	free(old);
+
+	return new;
+}
+
+static int l_load(lua_State *s)
+{
+	const char *path = luaL_checkstring(s,1);
+
+	SF_INFO info;
+	SNDFILE *f;
+
+	f = sf_open(path,SFM_READ,&info);
+
+	if (f == NULL)
+	{
+		luaL_error(s,"failed to open audio file '%s': %s",path,sf_strerror(f));
+	}
+
+	size_t len = info.frames*info.channels;
+	float *data = malloc(sizeof(*data)*len);
+
+	size_t off = 0;
+	while (off < len)
+	{
+		ssize_t res = sf_read_float(f,&data[off],len - off);
+
+		if (res < 0)
+		{
+			luaL_error(s,"failed to open audio file '%s': %s",path,sf_strerror(f));
+		}
+
+		off += res;
+	}
+
+	sf_close(f);
+
+	size_t samplerate = ml_sample_rate();
+
+	for (size_t c = 0; c < info.channels; c++)
+	{
+		struct sample *smp = alloc_sample(info.frames);
+		smp->path = strdup(path);
+
+		for (size_t i = 0; i < info.frames; i++)
+		{
+			smp->data[i] = data[i*info.channels + c];
+		}
+
+		if (info.samplerate != samplerate)
+		{
+			smp = resample(smp,info.samplerate,samplerate);
+		}
+
+		*(void**) lua_newuserdata(s,sizeof(void*)) = smp;
+		luaL_setmetatable(s,SAMPLE_TYPENAME);
+	}
+
+	free(data);
+
+	return info.channels;
+}
+
+static int l_length(lua_State *s)
+{
+	struct sample *smp = *(void**) luaL_checkudata(s,1,SAMPLE_TYPENAME);
+	unsigned long sr = ml_sample_rate();
+	double l = smp->len / (double)sr;
+	lua_pushnumber(s,l);
+	return 1;
+}
+
+static int l_path(lua_State *s)
+{
+	struct sample *smp = *(void**) luaL_checkudata(s,1,SAMPLE_TYPENAME);
+	lua_pushstring(s,smp->path);
+	return 1;
+}
+
+int luaopen_melisma_sample(lua_State *s)
+{
+/*** Load audio samples.
+
+	local msample = require 'melisma.sample'
+
+	local smp = msample.load('sample.wav')
+
+	print(smp:length())
+	print(smp:path())
+
+@classmod sample
+*/
+	lua_newtable(s);
+	int tbl = lua_gettop(s);
+
+/*** Load an audio sample.
+
+If necessary, the audio will be resampled to the current sample rate.
+
+@static
+@function load
+@tparam string path
+@treturn sample
+*/
+	lua_pushcfunction(s,l_load);
+	lua_setfield(s,tbl,"load");
+
+/*** Get sample length.
+@function length
+@treturn number The length of the sample in seconds.
+*/
+	lua_pushcfunction(s,l_length);
+	lua_setfield(s,tbl,"length");
+
+/*** Get sample path.
+@function path
+@treturn string The path that the sample was loaded from.
+*/
+	lua_pushcfunction(s,l_path);
+	lua_setfield(s,tbl,"path");
+
+	luaL_newmetatable(s,SAMPLE_TYPENAME);
+	int mt = lua_gettop(s);
+
+	lua_pushvalue(s,tbl);
+	lua_setfield(s,mt,"__index");
+
+	lua_settop(s,tbl);
+	return 1;
+}