Resample files when transcoding to mp3 using libsamplerate.

9 files changed, 167 insertions, 22 deletions

diff --git a/SConstruct b/SConstruct
index 718512c..491553c 100644
--- a/SConstruct
+++ b/SConstruct
@@ -19,6 +19,7 @@ env.ParseConfig('pkg-config --cflags --libs gio-unix-2.0')
 env.ParseConfig('pkg-config --cflags --libs libmpg123')
 env.ParseConfig('pkg-config --cflags --libs id3tag')
 env.ParseConfig('pkg-config --cflags --libs flac')
+env.ParseConfig('pkg-config --cflags --libs samplerate')
 
 env.Program('audistd', Glob('*.c') + Glob('decoders/*.c') + Glob('encoders/*.c'))
 
diff --git a/audioformat.h b/audioformat.h
new file mode 100644
index 0000000..65f8d82
--- /dev/null
+++ b/audioformat.h
@@ -0,0 +1,8 @@
+#ifndef AUDIOFORMAT_H
+#define AUDIOFORMAT_H
+
+enum audio_format {
+	AUDIO_FORMAT_S16LE,
+};
+
+#endif
diff --git a/decoder.c b/decoder.c
index 85e2203..ade0797 100644
--- a/decoder.c
+++ b/decoder.c
@@ -1,16 +1,16 @@
 #include "decoder.h"
 
 gboolean decoder_init(struct decoder *decoder) {
-	return decoder->decoder->init(&(decoder->data));
+	return decoder->decoder->init(decoder);
 }
 
 gssize decoder_decode(struct decoder *decoder, GInputStream *input,
 		GOutputStream *output, GError **error) {
-	return decoder->decoder->decode(decoder->data, input, output, error);
+	return decoder->decoder->decode(decoder, input, output, error);
 }
 
 void decoder_close(struct decoder *decoder) {
-	decoder->decoder->close(decoder->data);
+	decoder->decoder->close(decoder);
 }
 
 extern const struct decoder_plugin decoder_mpg123_decoder;
diff --git a/decoder.h b/decoder.h
index e992af9..8335db8 100644
--- a/decoder.h
+++ b/decoder.h
@@ -1,22 +1,30 @@
 #ifndef DECODER_H
 #define DECODER_H
 
+#include "audioformat.h"
+
 #include <glib.h>
 #include <gio/gio.h>
 
+struct decoder;
+
 struct decoder_plugin {
 	const gchar *name;
 	const gchar * const *extensions;
 
-	gboolean (*init)(gpointer *data);
-	gssize (*decode)(gpointer data, GInputStream *input,
+	gboolean (*init)(struct decoder *decoder);
+	gssize (*decode)(struct decoder *decoder, GInputStream *input,
 			GOutputStream *output, GError **error);
-	void (*close)(gpointer data);
+	void (*close)(struct decoder *decoder);
 };
 
 struct decoder {
 	const struct decoder_plugin *decoder;
 
+	unsigned int rate;
+	enum audio_format format;
+	unsigned int channels;
+
 	gpointer data;
 };
 
diff --git a/decoders/decoder_flac.c b/decoders/decoder_flac.c
index 805ab78..fd85f48 100644
--- a/decoders/decoder_flac.c
+++ b/decoders/decoder_flac.c
@@ -13,7 +13,8 @@ struct flac_decoder_data {
 };
 
 static FLAC__StreamDecoderReadStatus read_callback(const FLAC__StreamDecoder *decoder, FLAC__byte buffer[], size_t *bytes, void *client_data) {
-	struct flac_decoder_data *decoder_data = client_data;
+	struct decoder *_decoder = client_data;
+	struct flac_decoder_data *decoder_data = _decoder->data;
 
 	*bytes = g_input_stream_read(decoder_data->input, buffer, *bytes, NULL, NULL);
 
@@ -29,7 +30,8 @@ static FLAC__StreamDecoderReadStatus read_callback(const FLAC__StreamDecoder *de
 
 static FLAC__StreamDecoderWriteStatus write_callback(const FLAC__StreamDecoder *decoder, const FLAC__Frame *frame,
 		const FLAC__int32 * const buffer[], void *client_data) {
-	struct flac_decoder_data *decoder_data = client_data;
+	struct decoder *_decoder = client_data;
+	struct flac_decoder_data *decoder_data = _decoder->data;
 
 	unsigned channels = frame->header.channels;
 	//unsigned sample_rate = frame->header.sample_rate;
@@ -57,16 +59,28 @@ static FLAC__StreamDecoderWriteStatus write_callback(const FLAC__StreamDecoder *
 	}
 }
 
+static void metadata_callback(const FLAC__StreamDecoder *_decoder, const FLAC__StreamMetadata *metadata, void *client_data) {
+	struct decoder *decoder = client_data;
+	decoder->rate = metadata->data.stream_info.sample_rate;
+	switch(metadata->data.stream_info.bits_per_sample) {
+		case 16:
+			decoder->format = AUDIO_FORMAT_S16LE;
+			break;
+	}
+	decoder->channels = metadata->data.stream_info.channels;
+	g_debug("flac: %d Hz, %dch, %d bps", decoder->rate, decoder->channels, metadata->data.stream_info.bits_per_sample);
+}
+
 static void error_callback(const FLAC__StreamDecoder *decoder, FLAC__StreamDecoderErrorStatus status, void *client_data) {
 	g_warning(FLAC__StreamDecoderErrorStatusString[status]);
 }
 
-static gboolean flac_decoder_init(gpointer *data) {
+static gboolean flac_decoder_init(struct decoder *decoder) {
 	struct flac_decoder_data *decoder_data = g_new0(struct flac_decoder_data, 1);
 	decoder_data->decoder = FLAC__stream_decoder_new();
 	FLAC__StreamDecoderInitStatus status = FLAC__stream_decoder_init_stream(decoder_data->decoder,
-			read_callback, NULL, NULL, NULL, NULL, write_callback, NULL, error_callback, decoder_data);
-	*data = decoder_data;
+			read_callback, NULL, NULL, NULL, NULL, write_callback, metadata_callback, error_callback, decoder);
+	decoder->data = decoder_data;
 
 	if(status != FLAC__STREAM_DECODER_INIT_STATUS_OK) {
 		g_warning(FLAC__StreamDecoderInitStatusString[status]);
@@ -78,9 +92,9 @@ static gboolean flac_decoder_init(gpointer *data) {
 	return TRUE;
 }
 
-static gssize flac_decoder_decode(gpointer data, GInputStream *input,
+static gssize flac_decoder_decode(struct decoder *decoder, GInputStream *input,
 		GOutputStream *output, GError **error) {
-	struct flac_decoder_data *decoder_data = data;
+	struct flac_decoder_data *decoder_data = decoder->data;
 	decoder_data->input = input;
 	decoder_data->output = output;
 	decoder_data->output_written = 0;
@@ -105,8 +119,8 @@ static gssize flac_decoder_decode(gpointer data, GInputStream *input,
 	return decoder_data->output_written;
 }
 
-static void flac_decoder_close(gpointer data) {
-	struct flac_decoder_data *decoder_data = data;
+static void flac_decoder_close(struct decoder *decoder) {
+	struct flac_decoder_data *decoder_data = decoder->data;
 	FLAC__stream_decoder_finish(decoder_data->decoder);
 	FLAC__stream_decoder_delete(decoder_data->decoder);
 	g_free(decoder_data);
diff --git a/decoders/decoder_mpg123.c b/decoders/decoder_mpg123.c
index 50391f4..41d25c1 100644
--- a/decoders/decoder_mpg123.c
+++ b/decoders/decoder_mpg123.c
@@ -3,7 +3,7 @@
 #include <mpg123.h>
 #include <stdio.h>
 
-static gboolean mpg123_decoder_init(gpointer *data) {
+static gboolean mpg123_decoder_init(struct decoder *decoder) {
 	mpg123_handle *handle;
 
 	int error;
@@ -24,14 +24,14 @@ static gboolean mpg123_decoder_init(gpointer *data) {
 	mpg123_format_none(handle);
 	mpg123_format(handle, 44100, 2, MPG123_ENC_SIGNED_16);
 
-	*data = handle;
+	decoder->data = handle;
 
 	return TRUE;
 }
 
-static gssize mpg123_decoder_decode(gpointer data, GInputStream *input,
+static gssize mpg123_decoder_decode(struct decoder *decoder, GInputStream *input,
 		GOutputStream *output, GError **error) {
-	mpg123_handle *handle = data;
+	mpg123_handle *handle = decoder->data;
 	gssize size;
 	int ret;
 	const int inbuf_size = 0x400*8;
@@ -55,6 +55,18 @@ static gssize mpg123_decoder_decode(gpointer data, GInputStream *input,
 		mpg123_getformat(handle, &rate, &channels, &enc);
 		g_debug("New format: %li Hz, %i channels, encoding value %i", rate, channels, enc);
 		ret = mpg123_read(handle, outbuf, outbuf_size, (size_t*)&size);
+		decoder->rate = rate;
+		/* TODO: mpg123 uses native byte order, add endian check here */
+		/* assuming little endian for now... */
+		switch(enc) {
+			case MPG123_ENC_SIGNED_16:
+				decoder->format = AUDIO_FORMAT_S16LE;
+				break;
+			default:
+				*error = g_error_new(decoder_quark(), DECODER_CODE_ERROR, g_strdup("unknown audio format"));
+				return -1;
+		}
+		decoder->channels = channels;
 	}
 
 	if(ret != MPG123_OK && ret != MPG123_DONE && ret != MPG123_NEW_FORMAT
@@ -68,8 +80,8 @@ static gssize mpg123_decoder_decode(gpointer data, GInputStream *input,
 	return size;
 }
 
-static void mpg123_decoder_close(gpointer data) {
-	mpg123_handle *handle = data;
+static void mpg123_decoder_close(struct decoder *decoder) {
+	mpg123_handle *handle = decoder->data;
 	mpg123_close(handle);
 	mpg123_delete(handle);
 }
diff --git a/resample.c b/resample.c
new file mode 100644
index 0000000..c77367e
--- /dev/null
+++ b/resample.c
@@ -0,0 +1,54 @@
+#include "resample.h"
+
+#include <stdint.h>
+
+static GQuark resample_quark() {
+	return g_quark_from_string("resample");
+}
+
+SRC_STATE *resample_init(int channels, GError **error) {
+	int err;
+	SRC_STATE *state = src_new(SRC_LINEAR, channels, &err);
+	if(!state) {
+		*error = g_error_new(resample_quark(), 0, g_strdup(src_strerror(err)));
+	}
+
+	return state;
+}
+
+void resample(SRC_STATE *state, unsigned int from_rate, unsigned int to_rate, int channels,
+		gpointer in_data, gsize in_size, gpointer *out_data, gsize *out_size, gboolean done, GError **error) {
+	int len = in_size / 2;
+	int frames = in_size / 2 / channels;
+	float *temp_in = g_new(float, len);
+	float *temp_out = g_new(float, len);
+
+	src_short_to_float_array(in_data, temp_in, len);
+
+	SRC_DATA data = {
+		.data_in = temp_in,
+		.data_out = temp_out,
+		.input_frames = frames,
+		.output_frames = frames,
+		.src_ratio = (double)to_rate / (double)from_rate,
+		.end_of_input = done ? 1 : 0
+	};
+
+	int err = src_process(state, &data);
+	if(err) {
+		*error = g_error_new(resample_quark(), 0, g_strdup(src_strerror(err)));
+		goto resample_free;
+	}
+
+	*out_data = g_new(int16_t, data.output_frames_gen * channels);
+	src_float_to_short_array(temp_out, *out_data, data.output_frames_gen * channels);
+	*out_size = sizeof(int16_t) * data.output_frames_gen * channels;
+
+resample_free:
+	g_free(temp_in);
+	g_free(temp_out);
+}
+
+void resample_free(SRC_STATE *state) {
+	src_delete(state);
+}
diff --git a/resample.h b/resample.h
new file mode 100644
index 0000000..68a1f08
--- /dev/null
+++ b/resample.h
@@ -0,0 +1,12 @@
+#ifndef RESAMPLE_H
+#define RESAMPLE_H
+
+#include <samplerate.h>
+#include <glib.h>
+
+SRC_STATE *resample_init(int channels, GError **error);
+void resample(SRC_STATE *state, unsigned int from_rate, unsigned int to_rate, int channels,
+		gpointer in_data, gsize in_size, gpointer *out_data, gsize *out_size, gboolean done, GError **error);
+void resample_free(SRC_STATE *state);
+
+#endif
diff --git a/transcode.c b/transcode.c
index 9bef8e7..20f91b5 100644
--- a/transcode.c
+++ b/transcode.c
@@ -1,4 +1,5 @@
 #include "transcode.h"
+#include "resample.h"
 
 #include <glib.h>
 
@@ -17,6 +18,8 @@ void transcode(GInputStream *input, const struct decoder_plugin *_decoder,
 	/* holds decoded audio passed to encoder */
 	GInputStream *decoded_in = g_memory_input_stream_new();
 
+	SRC_STATE *state = NULL;
+
 	while(decode_done == FALSE || encode_done == FALSE) {
 		/* holds decoded audio from decoder */
 		GOutputStream *decoded_out = g_memory_output_stream_new(NULL, 0, g_realloc, g_free);
@@ -38,7 +41,30 @@ void transcode(GInputStream *input, const struct decoder_plugin *_decoder,
 		gsize size = g_memory_output_stream_get_data_size((GMemoryOutputStream*)decoded_out);
 
 		if(size > 0) {
-			data = g_memdup(data, size);
+			/* TODO: allow custom sample rate */
+			if(decoder->rate != 44100) {
+				if(state == NULL) {
+					state = resample_init(decoder->channels, &error);
+					/* state should be NULL in case of errors */
+					if(error) {
+						g_warning(error->message);
+						break;
+					}
+				}
+				gpointer out_data;
+				gsize out_size;
+				resample(state, decoder->rate, 44100, decoder->channels, data, size, &out_data, &out_size, decode_done, &error);
+				if(error) {
+					g_warning(error->message);
+					g_error_free(error);
+					error = NULL;
+				}
+				/* data is owned by decoded_out, don't free */
+				data = out_data;
+				size = out_size;
+			} else {
+				data = g_memdup(data, size);
+			}
 			g_memory_input_stream_add_data((GMemoryInputStream*)decoded_in, data, size, g_free);
 		}
 
@@ -61,6 +87,16 @@ void transcode(GInputStream *input, const struct decoder_plugin *_decoder,
 
 	g_debug("transcoding done");
 
+	/* error cleanup */
+	if(error) {
+		g_error_free(error);
+	}
+
+	/* resample cleanup */
+	if(state) {
+		resample_free(state);
+	}
+
 	g_object_unref(decoded_in);
 
 	decoder_close(decoder);