implement mp3 loading

3 files changed, 89 insertions, 0 deletions

diff --git a/src/load/CMakeLists.txt b/src/load/CMakeLists.txt
new file mode 100644
index 0000000..3369dd2
--- /dev/null
+++ b/src/load/CMakeLists.txt
@@ -0,0 +1,7 @@
+project(mossrose)
+
+target_sources(mossrose PUBLIC
+	${CMAKE_CURRENT_LIST_DIR}/load-mp3.c
+)
+
+target_include_directories(mossrose PUBLIC ${CMAKE_SOURCE_DIR}/3rdparty/minimp3)
diff --git a/src/load/load-mp3.c b/src/load/load-mp3.c
new file mode 100644
index 0000000..09eef0c
--- /dev/null
+++ b/src/load/load-mp3.c
@@ -0,0 +1,81 @@
+#define MINIMP3_FLOAT_OUTPUT
+#define MINIMP3_IMPLEMENTATION
+#include <stdio.h>
+#include <minimp3_ex.h>
+#include <mossrose.h>
+#include "load.h"
+
+
+#define ABORT(...) do { \
+	fprintf(stderr, __VA_ARGS__); \
+	free(mp3.buffer); \
+	return NULL; \
+} while(0)
+
+
+struct mossrose_sound_t * load_mp3(const char *filename)
+{
+	mp3dec_t mp3d;
+	mp3dec_file_info_t mp3;
+	if (mp3dec_load(&mp3d, filename, &mp3, NULL, NULL)) {
+		fprintf(stderr, "failed to decode mp3 file '%s'\n", filename);
+		return NULL;
+	}
+
+	printf("samples: %lu\n"
+	       "channels: %d\n"
+	       "hz: %d\n"
+	       "layer: %d\n"
+	       "bitrate: %d\n",
+		mp3.samples,
+		mp3.channels,
+		mp3.hz,
+		mp3.layer,
+		mp3.avg_bitrate_kbps);
+
+	if (mp3.channels != 1 && mp3.channels != 2) {
+		ABORT("files with %d audio tracks are not supported!\n", mp3.channels);
+	}
+
+	struct mossrose_sound_t *sound = malloc(sizeof(struct mossrose_sound_t));
+	if (sound == NULL)
+		ABORT("failed to allocate sound structure\n");
+	
+	if (mp3.channels == 1) {
+		sound->mono = true;
+		sound->left = malloc(mp3.samples * sizeof(float));
+		if (sound->left == NULL) {
+			free(sound);
+			ABORT("failed to allocate mono audio data!\n");
+		}
+		memcpy(sound->left, mp3.buffer, mp3.samples * sizeof(float));
+		sound->right = NULL;
+		sound->len = mp3.samples;
+	}
+	else {
+		/* stereo */
+		sound->mono = false;
+		size_t sz = (mp3.samples/2) * sizeof(float);
+		sound->left = malloc(sz);
+		if (sound->left == NULL) {
+			free(sound);
+			ABORT("failed to allocate left audio channel!\n");
+		}
+		sound->right = malloc(sz);
+		if (sound->right == NULL) {
+			free(sound->left);
+			free(sound);
+			ABORT("failed to allocate right audio channel!\n");
+		}
+		for (int i=0; i<mp3.samples; i++) {
+			if (i%2)
+				sound->left[i/2] = mp3.buffer[i];
+			else
+				sound->right[i/2] = mp3.buffer[i];
+		}
+		sound->len = mp3.samples/2;
+	}
+
+	free(mp3.buffer);
+	return sound;
+}
diff --git a/src/load/load.h b/src/load/load.h
index 7f91b14..b4d60c0 100644
--- a/src/load/load.h
+++ b/src/load/load.h
@@ -4,5 +4,6 @@
 #include "mossrose.h"
 
 struct mossrose_sound_t * load_wav(const char *filename);
+struct mossrose_sound_t * load_mp3(const char *filename);
 
 #endif