portapack-mayhem/firmware/baseband/proc_wfm_audio.cpp
2020-12-23 18:00:51 +03:00

197 lines
6.3 KiB
C++

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