tangara-fw/src/audio/i2s_audio_output.cpp

/*
 * Copyright 2023 jacqueline <me@jacqueline.id.au>
 *
 * SPDX-License-Identifier: GPL-3.0-only
 */

#include "i2s_audio_output.hpp"
#include <stdint.h>

#include <algorithm>
#include <cstddef>
#include <memory>
#include <variant>

#include "digital_pot.hpp"
#include "esp_err.h"
#include "freertos/portmacro.h"

#include "audio_element.hpp"
#include "freertos/projdefs.h"
#include "gpio_expander.hpp"
#include "i2s_dac.hpp"
#include "result.hpp"
#include "stream_info.hpp"

static const char* kTag = "I2SOUT";

namespace audio {

I2SAudioOutput::I2SAudioOutput(drivers::GpioExpander* expander,
                               std::weak_ptr<drivers::I2SDac> dac,
                               std::weak_ptr<drivers::DigitalPot> pots)
    : expander_(expander),
      dac_(dac.lock()),
      pots_(pots.lock()),
      current_config_(),
      left_difference_(0),
      attenuation_(pots_->GetMaxAttenuation()) {
  SetVolume(25);  // For testing
  dac_->SetSource(buffer());
  dac_->Start();
}

I2SAudioOutput::~I2SAudioOutput() {
  dac_->Stop();
  dac_->SetSource(nullptr);
}

auto I2SAudioOutput::SetVolumeImbalance(int_fast8_t balance) -> void {
  int_fast8_t new_difference = balance - left_difference_;
  left_difference_ = balance;
  if (attenuation_ + new_difference <= pots_->GetMinAttenuation()) {
    // Volume is currently very high, so shift the left channel down.
    pots_->SetRelative(drivers::DigitalPot::Channel::kLeft, -new_difference);
  } else if (attenuation_ - new_difference >= pots_->GetMaxAttenuation()) {
    // Volume is currently very low, so shift the left channel up.
    pots_->SetRelative(drivers::DigitalPot::Channel::kLeft, new_difference);
  } else {
    ESP_LOGE(kTag, "volume imbalance higher than attenuation range");
  }
}

auto I2SAudioOutput::SetVolume(uint_fast8_t percent) -> void {
  percent = 100 - percent;
  int_fast8_t target_attenuation =
      static_cast<int_fast8_t>(static_cast<float>(GetAdjustedMaxAttenuation()) /
                               100.0f * static_cast<float>(percent));
  target_attenuation -= pots_->GetMinAttenuation();
  int_fast8_t difference = target_attenuation - attenuation_;
  pots_->SetRelative(difference);
  attenuation_ = target_attenuation;
  ESP_LOGI(kTag, "adjusting attenuation by %idB to %idB", difference,
           attenuation_);
}

auto I2SAudioOutput::GetVolume() -> uint_fast8_t {
  // Convert to percentage.
  uint_fast8_t percent = static_cast<uint_fast8_t>(
      static_cast<float>(attenuation_) /
      static_cast<float>(GetAdjustedMaxAttenuation()) * 100.0f);
  // Invert to get from attenuation to volume.
  return 100 - percent;
}

auto I2SAudioOutput::GetAdjustedMaxAttenuation() -> int_fast8_t {
  // Clip to account for imbalance.
  int_fast8_t adjusted_max =
      pots_->GetMaxAttenuation() - std::abs(left_difference_);
  // Shift to be zero minimum.
  adjusted_max -= pots_->GetMinAttenuation();

  return adjusted_max;
}

auto I2SAudioOutput::AdjustVolumeUp() -> void {
  if (attenuation_ + left_difference_ <= pots_->GetMinAttenuation()) {
    return;
  }
  attenuation_--;
  pots_->SetRelative(-1);
}

auto I2SAudioOutput::AdjustVolumeDown() -> void {
  if (attenuation_ - left_difference_ >= pots_->GetMaxAttenuation()) {
    return;
  }
  attenuation_++;
  pots_->SetRelative(1);
}

auto I2SAudioOutput::Configure(const StreamInfo::Format& format) -> bool {
  if (!std::holds_alternative<StreamInfo::Pcm>(format)) {
    ESP_LOGI(kTag, "ignoring non-pcm stream (%d)", format.index());
    return false;
  }

  StreamInfo::Pcm pcm = std::get<StreamInfo::Pcm>(format);

  if (current_config_ && pcm == *current_config_) {
    ESP_LOGI(kTag, "ignoring unchanged format");
    return true;
  }

  ESP_LOGI(kTag, "incoming audio stream: %u bpp @ %lu Hz", pcm.bits_per_sample,
           pcm.sample_rate);

  drivers::I2SDac::BitsPerSample bps;
  switch (pcm.bits_per_sample) {
    case 16:
      bps = drivers::I2SDac::BPS_16;
      break;
    case 24:
      bps = drivers::I2SDac::BPS_24;
      break;
    case 32:
      bps = drivers::I2SDac::BPS_32;
      break;
    default:
      ESP_LOGE(kTag, "dropping stream with unknown bps");
      return false;
  }

  drivers::I2SDac::SampleRate sample_rate;
  switch (pcm.sample_rate) {
    case 44100:
      sample_rate = drivers::I2SDac::SAMPLE_RATE_44_1;
      break;
    case 48000:
      sample_rate = drivers::I2SDac::SAMPLE_RATE_48;
      break;
    default:
      ESP_LOGE(kTag, "dropping stream with unknown rate");
      return false;
  }

  // TODO(jacqueline): probs do something with the channel hey

  dac_->Reconfigure(bps, sample_rate);
  current_config_ = pcm;

  return true;
}

auto I2SAudioOutput::Send(const cpp::span<std::byte>& data) -> void {
  dac_->WriteData(data);
}

}  // namespace audio