197 lines
6.3 KiB
C++
197 lines
6.3 KiB
C++
/*
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* Copyright (C) 2014 Jared Boone, ShareBrained Technology, Inc.
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* Copyright (C) 2016 Furrtek
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*
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* This file is part of PortaPack.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2, or (at your option)
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* any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; see the file COPYING. If not, write to
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* the Free Software Foundation, Inc., 51 Franklin Street,
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* Boston, MA 02110-1301, USA.
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*/
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#include "proc_wfm_audio.hpp"
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#include "portapack_shared_memory.hpp"
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#include "audio_output.hpp"
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#include "dsp_fft.hpp"
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#include "event_m4.hpp"
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#include <cstdint>
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void WidebandFMAudio::execute(const buffer_c8_t& buffer) {
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if( !configured ) {
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return;
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}
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const auto decim_0_out = decim_0.execute(buffer, dst_buffer);
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const auto channel = decim_1.execute(decim_0_out, dst_buffer);
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// TODO: Feed channel_stats post-decimation data?
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feed_channel_stats(channel);
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spectrum_samples += channel.count;
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if( spectrum_samples >= spectrum_interval_samples ) {
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spectrum_samples -= spectrum_interval_samples;
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channel_spectrum.feed(channel, channel_filter_low_f, channel_filter_high_f, channel_filter_transition);
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}
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/* 384kHz complex<int16_t>[256]
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* -> FM demodulation
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* -> 384kHz int16_t[256] */
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/* TODO: To improve adjacent channel rejection, implement complex channel filter:
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* pass < +/- 100kHz, stop > +/- 200kHz
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*/
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auto audio_oversampled = demod.execute(channel, work_audio_buffer);
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/* 384kHz int16_t[256]
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* -> 4th order CIC decimation by 2, gain of 1
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* -> 192kHz int16_t[128] */
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auto audio_4fs = audio_dec_1.execute(audio_oversampled, work_audio_buffer);
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/* 192kHz int16_t[128]
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* -> 4th order CIC decimation by 2, gain of 1
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* -> 96kHz int16_t[64] */
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auto audio_2fs = audio_dec_2.execute(audio_4fs, work_audio_buffer);
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// Input: 96kHz int16_t[64]
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// audio_spectrum_decimator piles up 256 samples before doing FFT computation
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// This sends an AudioSpectrum every: sample rate/buffer size/refresh period = 3072000/2048/50 = 30 Hz
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// When audio_spectrum_timer expires, the audio spectrum computation is triggered
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// 0~3: feed continuous audio
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// 4~31: ignore, wrap at 31
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audio_spectrum_timer++;
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if (audio_spectrum_timer == 50) {
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audio_spectrum_timer = 0;
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audio_spectrum_state = FEED;
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}
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switch (audio_spectrum_state) {
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case FEED:
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// Convert audio to "complex" just so the FFT can be done :/
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for (size_t i = 0; i < 64; i++) {
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complex_audio[i] = { (int16_t)(work_audio_buffer.p[i] / 32), (int16_t)0 };
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}
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audio_spectrum_decimator.feed(
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complex_audio_buffer,
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[this](const buffer_c16_t& data) {
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this->post_message(data);
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}
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);
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break;
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case FFT:
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// Spread the FFT workload in time to avoid making the audio skip
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// "8" comes from the log2() of the size of audio_spectrum: log2(256) = 8
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if (fft_step < 8) {
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fft_c_preswapped(audio_spectrum, fft_step, fft_step + 1);
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fft_step++;
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} else {
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const size_t spectrum_end = spectrum.db.size();
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for(size_t i=0; i<spectrum_end; i++) {
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//const auto corrected_sample = spectrum_window_hamming_3(audio_spectrum, i);
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const auto corrected_sample = audio_spectrum[i];
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const auto mag2 = magnitude_squared(corrected_sample * (1.0f / 32768.0f));
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const float db = mag2_to_dbv_norm(mag2);
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constexpr float mag_scale = 5.0f;
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const unsigned int v = (db * mag_scale) + 255.0f;
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spectrum.db[i] = std::max(0U, std::min(255U, v));
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}
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AudioSpectrumMessage message { &spectrum };
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shared_memory.application_queue.push(message);
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audio_spectrum_state = IDLE;
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}
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break;
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default:
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break;
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}
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/* 96kHz int16_t[64]
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* -> FIR filter, <15kHz (0.156fs) pass, >19kHz (0.198fs) stop, gain of 1
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* -> 48kHz int16_t[32] */
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auto audio = audio_filter.execute(audio_2fs, work_audio_buffer);
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/* -> 48kHz int16_t[32] */
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audio_output.write(audio);
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}
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void WidebandFMAudio::post_message(const buffer_c16_t& data) {
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// This is called when audio_spectrum_decimator is filled up to 256 samples
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fft_swap(data, audio_spectrum);
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audio_spectrum_state = FFT;
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fft_step = 0;
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}
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void WidebandFMAudio::on_message(const Message* const message) {
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switch(message->id) {
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case Message::ID::UpdateSpectrum:
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case Message::ID::SpectrumStreamingConfig:
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channel_spectrum.on_message(message);
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break;
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case Message::ID::WFMConfigure:
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configure(*reinterpret_cast<const WFMConfigureMessage*>(message));
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break;
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case Message::ID::CaptureConfig:
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capture_config(*reinterpret_cast<const CaptureConfigMessage*>(message));
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break;
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default:
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break;
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}
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}
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void WidebandFMAudio::configure(const WFMConfigureMessage& message) {
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constexpr size_t decim_0_input_fs = baseband_fs;
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constexpr size_t decim_0_output_fs = decim_0_input_fs / decim_0.decimation_factor;
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constexpr size_t decim_1_input_fs = decim_0_output_fs;
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constexpr size_t decim_1_output_fs = decim_1_input_fs / decim_1.decimation_factor;
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constexpr size_t demod_input_fs = decim_1_output_fs;
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spectrum_interval_samples = decim_1_output_fs / spectrum_rate_hz;
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spectrum_samples = 0;
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decim_0.configure(message.decim_0_filter.taps, 33554432);
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decim_1.configure(message.decim_1_filter.taps, 131072);
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channel_filter_low_f = message.decim_1_filter.low_frequency_normalized * decim_1_input_fs;
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channel_filter_high_f = message.decim_1_filter.high_frequency_normalized * decim_1_input_fs;
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channel_filter_transition = message.decim_1_filter.transition_normalized * decim_1_input_fs;
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demod.configure(demod_input_fs, message.deviation);
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audio_filter.configure(message.audio_filter.taps);
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audio_output.configure(message.audio_hpf_config, message.audio_deemph_config);
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channel_spectrum.set_decimation_factor(1);
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configured = true;
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}
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void WidebandFMAudio::capture_config(const CaptureConfigMessage& message) {
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if( message.config ) {
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audio_output.set_stream(std::make_unique<StreamInput>(message.config));
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} else {
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audio_output.set_stream(nullptr);
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}
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}
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int main() {
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EventDispatcher event_dispatcher { std::make_unique<WidebandFMAudio>() };
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event_dispatcher.run();
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return 0;
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}
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