Capture: Write simple metadata for baseband and audio files.

Will probably turn the audio metadata file into .wav data, eventually.

firmware/application/analog_audio_app.cpp

@@ -30,6 +30,8 @@ using namespace portapack;
 
 #include "utility.hpp"
 
+#include "string_format.hpp"
+
 namespace ui {
 
 /* AMOptionsView *********************************************************/
@@ -322,6 +324,8 @@ void AnalogAudioView::record_start() {
 		return;
 	}
 
+	write_metadata_file(filename_stem + ".TXT");
+
 	capture_thread = std::make_unique<CaptureThread>(filename_stem + ".S16", 12, 2);
 	button_record.set_bitmap(&bitmap_stop);
 }
@@ -331,4 +335,22 @@ void AnalogAudioView::record_stop() {
 	button_record.set_bitmap(&bitmap_record);
 }
 
+void AnalogAudioView::write_metadata_file(const std::string& filename) {
+	// TODO: This doesn't belong here! There's a better way.
+	const auto modulation = static_cast<ReceiverModel::Mode>(receiver_model.modulation());
+	size_t sampling_rate = 0;
+	switch(modulation) {
+	case ReceiverModel::Mode::AMAudio:				sampling_rate = 12000; break;
+	case ReceiverModel::Mode::NarrowbandFMAudio:	sampling_rate = 24000; break;
+	case ReceiverModel::Mode::WidebandFMAudio:		sampling_rate = 48000; break;
+	default:
+		return;
+	}
+
+	File file;
+	file.open_for_writing(filename);
+	file.puts("sample_rate=" + to_string_dec_uint(sampling_rate) + "\n");
+	file.puts("center_frequency=" + to_string_dec_uint(receiver_model.tuning_frequency()) + "\n");
+}
+
 } /* namespace ui */

firmware/application/analog_audio_app.hpp

@@ -181,6 +181,7 @@ private:
 	bool is_recording() const;
 	void record_start();
 	void record_stop();
+	void write_metadata_file(const std::string& filename);
 };
 
 } /* namespace ui */

firmware/application/capture_app.cpp

@@ -130,6 +130,8 @@ void CaptureAppView::record_start() {
 		return;
 	}
 
+	write_metadata_file(filename_stem + ".TXT");
+
 	capture_thread = std::make_unique<CaptureThread>(filename_stem + ".C16", 14, 1);
 	button_record.set_bitmap(&bitmap_stop);
 }
@@ -139,6 +141,13 @@ void CaptureAppView::record_stop() {
 	button_record.set_bitmap(&bitmap_record);
 }
 
+void CaptureAppView::write_metadata_file(const std::string& filename) {
+	File file;
+	file.open_for_writing(filename);
+	file.puts("sample_rate=" + to_string_dec_uint(sampling_rate) + "\n");
+	file.puts("center_frequency=" + to_string_dec_uint(receiver_model.tuning_frequency()) + "\n");
+}
+
 void CaptureAppView::on_tick_second() {
 	if( capture_thread ) {
 		const auto dropped_percent = std::min(99U, capture_thread->state().dropped_percent());

firmware/application/capture_app.hpp

@@ -64,6 +64,7 @@ private:
 	bool is_recording() const;
 	void record_start();
 	void record_stop();
+	void write_metadata_file(const std::string& filename);
 
 	void on_tick_second();