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/*
* Copyright 2023 jacqueline <me@jacqueline.id.au>
*
* SPDX-License-Identifier: GPL-3.0-only
*/
#include "audio_converter.hpp"
#include <stdint.h>
#include <algorithm>
#include <cmath>
#include <cstdint>
#include "audio_events.hpp"
#include "audio_sink.hpp"
#include "esp_heap_caps.h"
#include "esp_log.h"
#include "event_queue.hpp"
#include "freertos/portmacro.h"
#include "freertos/projdefs.h"
#include "i2s_dac.hpp"
#include "idf_additions.h"
#include "resample.hpp"
#include "sample.hpp"
#include "tasks.hpp"
[[maybe_unused]] static constexpr char kTag[] = "mixer";
static constexpr std::size_t kSampleBufferLength =
drivers::kI2SBufferLengthFrames * sizeof(sample::Sample);
static constexpr std::size_t kSourceBufferLength = kSampleBufferLength * 2;
namespace audio {
SampleConverter::SampleConverter()
: commands_(xQueueCreate(1, sizeof(Args))),
resampler_(nullptr),
source_(xStreamBufferCreateWithCaps(kSourceBufferLength,
sizeof(sample::Sample) * 2,
MALLOC_CAP_DMA)),
leftover_bytes_(0),
samples_sunk_(0) {
input_buffer_ = {
reinterpret_cast<sample::Sample*>(heap_caps_calloc(
kSampleBufferLength, sizeof(sample::Sample), MALLOC_CAP_DMA)),
kSampleBufferLength};
input_buffer_as_bytes_ = {reinterpret_cast<std::byte*>(input_buffer_.data()),
input_buffer_.size_bytes()};
resampled_buffer_ = {
reinterpret_cast<sample::Sample*>(heap_caps_calloc(
kSampleBufferLength, sizeof(sample::Sample), MALLOC_CAP_DMA)),
kSampleBufferLength};
tasks::StartPersistent<tasks::Type::kAudioConverter>([&]() { Main(); });
}
SampleConverter::~SampleConverter() {
vQueueDelete(commands_);
vStreamBufferDelete(source_);
}
auto SampleConverter::SetOutput(std::shared_ptr<IAudioOutput> output) -> void {
// FIXME: We should add synchronisation here, but we should be careful about
// not impacting performance given that the output will change only very
// rarely (if ever).
sink_ = output;
}
auto SampleConverter::ConvertSamples(cpp::span<sample::Sample> input,
const IAudioOutput::Format& format,
bool is_eos) -> void {
Args args{
.format = format,
.samples_available = input.size(),
.is_end_of_stream = is_eos,
};
xQueueSend(commands_, &args, portMAX_DELAY);
cpp::span<std::byte> input_as_bytes = {
reinterpret_cast<std::byte*>(input.data()), input.size_bytes()};
size_t bytes_sent = 0;
while (bytes_sent < input_as_bytes.size()) {
bytes_sent += xStreamBufferSend(
source_, input_as_bytes.subspan(bytes_sent).data(),
input_as_bytes.size() - bytes_sent, pdMS_TO_TICKS(100));
}
}
auto SampleConverter::Main() -> void {
for (;;) {
Args args;
while (!xQueueReceive(commands_, &args, portMAX_DELAY)) {
}
if (args.format != source_format_) {
resampler_.reset();
source_format_ = args.format;
leftover_bytes_ = 0;
auto new_target = sink_->PrepareFormat(args.format);
if (new_target != target_format_) {
// The new format is different to the old one. Wait for the sink to
// drain before continuing.
while (!xStreamBufferIsEmpty(sink_->stream())) {
ESP_LOGI(kTag, "waiting for sink stream to drain...");
// TODO(jacqueline): Get the sink drain ISR to notify us of this
// via semaphore instead of busy-ish waiting.
vTaskDelay(pdMS_TO_TICKS(10));
}
sink_->Configure(new_target);
}
target_format_ = new_target;
// Send a final sample count for the previous sample rate.
if (samples_sunk_ > 0) {
events::Audio().Dispatch(internal::ConverterProgress{
.samples_sunk = samples_sunk_,
});
}
samples_sunk_ = 0;
events::Audio().Dispatch(internal::ConverterConfigurationChanged{
.src_format = source_format_,
.dst_format = target_format_,
});
}
// Loop until we finish reading all the bytes indicated. There might be
// leftovers from each iteration, and from this process as a whole,
// depending on the resampling stage.
size_t bytes_read = 0;
size_t bytes_to_read = args.samples_available * sizeof(sample::Sample);
while (bytes_read < bytes_to_read) {
// First top up the input buffer, taking care not to overwrite anything
// remaining from a previous iteration.
size_t bytes_read_this_it = xStreamBufferReceive(
source_, input_buffer_as_bytes_.subspan(leftover_bytes_).data(),
std::min(input_buffer_as_bytes_.size() - leftover_bytes_,
bytes_to_read - bytes_read),
portMAX_DELAY);
bytes_read += bytes_read_this_it;
// Calculate the number of whole samples that are now in the input buffer.
size_t bytes_in_buffer = bytes_read_this_it + leftover_bytes_;
size_t samples_in_buffer = bytes_in_buffer / sizeof(sample::Sample);
size_t samples_used =
HandleSamples(input_buffer_.first(samples_in_buffer),
args.is_end_of_stream && bytes_read == bytes_to_read);
// Maybe the resampler didn't consume everything. Maybe the last few
// bytes we read were half a frame. Either way, we need to calculate the
// size of the remainder in bytes, then move it to the front of our
// buffer.
size_t bytes_used = samples_used * sizeof(sample::Sample);
assert(bytes_used <= bytes_in_buffer);
leftover_bytes_ = bytes_in_buffer - bytes_used;
if (leftover_bytes_ > 0) {
std::memmove(input_buffer_as_bytes_.data(),
input_buffer_as_bytes_.data() + bytes_used,
leftover_bytes_);
}
}
}
}
auto SampleConverter::HandleSamples(cpp::span<sample::Sample> input,
bool is_eos) -> size_t {
if (source_format_ == target_format_) {
// The happiest possible case: the input format matches the output
// format already.
SendToSink(input);
return input.size();
}
size_t samples_used = 0;
while (samples_used < input.size()) {
cpp::span<sample::Sample> output_source;
if (source_format_.sample_rate != target_format_.sample_rate) {
if (resampler_ == nullptr) {
ESP_LOGI(kTag, "creating new resampler for %lu -> %lu",
source_format_.sample_rate, target_format_.sample_rate);
resampler_.reset(new Resampler(source_format_.sample_rate,
target_format_.sample_rate,
source_format_.num_channels));
}
size_t read, written;
std::tie(read, written) = resampler_->Process(input.subspan(samples_used),
resampled_buffer_, is_eos);
samples_used += read;
if (read == 0 && written == 0) {
// Zero samples used or written. We need more input.
break;
}
output_source = resampled_buffer_.first(written);
} else {
output_source = input;
samples_used = input.size();
}
SendToSink(output_source);
}
return samples_used;
}
auto SampleConverter::SendToSink(cpp::span<sample::Sample> samples) -> void {
// Update the number of samples sunk so far *before* actually sinking them,
// since writing to the stream buffer will block when the buffer gets full.
samples_sunk_ += samples.size();
if (samples_sunk_ >=
target_format_.sample_rate * target_format_.num_channels) {
events::Audio().Dispatch(internal::ConverterProgress{
.samples_sunk = samples_sunk_,
});
samples_sunk_ = 0;
}
xStreamBufferSend(sink_->stream(),
reinterpret_cast<std::byte*>(samples.data()),
samples.size_bytes(), portMAX_DELAY);
}
} // namespace audio
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