refactor pop reframer

src/frame_streams/audio_stream_pop_reframer.hpp

@@ -0,0 +1,95 @@
+#pragma once
+
+#include "./audio_stream2.hpp"
+
+// reframes audio frames to a specified size in ms
+// TODO: use absolute sample count instead??
+template<typename RealAudioStream>
+struct AudioStreamPopReFramer : public FrameStream2I<AudioFrame2> {
+	uint32_t _frame_length_ms {20};
+
+	// gotta be careful of the multithreaded nature
+	// and false(true) sharing
+	uint64_t _pad0{};
+	RealAudioStream _stream;
+	uint64_t _pad1{};
+
+	// dequeue?
+	std::vector<int16_t> _buffer;
+
+	uint32_t _sample_rate {48'000};
+	size_t _channels {0};
+
+	AudioStreamPopReFramer(uint32_t frame_length_ms = 20)
+	: _frame_length_ms(frame_length_ms) {
+	}
+
+	AudioStreamPopReFramer(uint32_t frame_length_ms, FrameStream2I<AudioFrame2>&& stream)
+	: _frame_length_ms(frame_length_ms), _stream(std::move(stream)) {
+	}
+
+	~AudioStreamPopReFramer(void) {}
+
+	int32_t size(void) override { return -1; }
+
+	std::optional<AudioFrame2> pop(void) override {
+		auto new_in = _stream.pop();
+		if (new_in.has_value()) {
+			auto& new_value = new_in.value();
+
+			// changed
+			if (_sample_rate != new_value.sample_rate || _channels != new_value.channels) {
+				if (_channels != 0) {
+					//std::cerr << "ReFramer warning: reconfiguring, dropping buffer\n";
+				}
+				_sample_rate = new_value.sample_rate;
+				_channels = new_value.channels;
+
+				// buffer does not exist or config changed and we discard
+				_buffer = {};
+			}
+
+
+			//std::cout << "new incoming frame is " << new_value.getSpan().size/new_value.channels*1000/new_value.sample_rate << "ms\n";
+
+			auto new_span = new_value.getSpan();
+
+			if (_buffer.empty()) {
+				_buffer = {new_span.cbegin(), new_span.cend()};
+			} else {
+				_buffer.insert(_buffer.cend(), new_span.cbegin(), new_span.cend());
+			}
+		} else if (_buffer.empty()) {
+			// first pop might result in invalid state
+			return std::nullopt;
+		}
+
+		const size_t desired_size {_frame_length_ms * _sample_rate * _channels / 1000};
+
+		// > threshold?
+		if (_buffer.size() < desired_size) {
+			return std::nullopt;
+		}
+
+		// copy data
+		std::vector<int16_t> return_buffer(_buffer.cbegin(), _buffer.cbegin()+desired_size);
+
+		// now crop buffer (meh)
+		// move data from back to front
+		_buffer.erase(_buffer.cbegin(), _buffer.cbegin() + desired_size);
+
+		return AudioFrame2{
+			_sample_rate,
+			_channels,
+			std::move(return_buffer),
+		};
+	}
+
+	bool push(const AudioFrame2& value) override {
+		// might be worth it to instead do the work on push
+		//assert(false && "push reframing not implemented");
+		// passthrough
+		return _stream.push(value);
+	}
+};
+