From 61c91b3cdb2c9dd655f3adf0f461f5cefb3b2e9b Mon Sep 17 00:00:00 2001
From: jacqueline <me@jacqueline.id.au>
Date: Fri, 10 Feb 2023 15:32:21 +1100
Subject: Mostly working pipeline, including proper EOF signalling

---
 src/audio/i2s_audio_output.cpp | 107 ++++++++++++++++++++++++++++++++++++++---
 1 file changed, 99 insertions(+), 8 deletions(-)

(limited to 'src/audio/i2s_audio_output.cpp')

diff --git a/src/audio/i2s_audio_output.cpp b/src/audio/i2s_audio_output.cpp
index b00e31d3..3bed15b5 100644
--- a/src/audio/i2s_audio_output.cpp
+++ b/src/audio/i2s_audio_output.cpp
@@ -7,6 +7,7 @@
 
 #include "audio_element.hpp"
 #include "dac.hpp"
+#include "freertos/projdefs.h"
 #include "gpio_expander.hpp"
 #include "result.hpp"
 
@@ -15,6 +16,8 @@ static const char* kTag = "I2SOUT";
 
 namespace audio {
 
+static const std::size_t kDmaQueueLength = 8;
+
 auto I2SAudioOutput::create(drivers::GpioExpander* expander)
     -> cpp::result<std::shared_ptr<I2SAudioOutput>, Error> {
   // First, we need to perform initial configuration of the DAC chip.
@@ -38,12 +41,26 @@ I2SAudioOutput::I2SAudioOutput(drivers::GpioExpander* expander,
     : expander_(expander),
       dac_(std::move(dac)),
       volume_(255),
-      is_soft_muted_(false) {}
+      is_soft_muted_(false),
+      chunk_reader_(),
+      latest_chunk_(),
+      dma_size_(),
+      dma_queue_(nullptr) {}
 
 I2SAudioOutput::~I2SAudioOutput() {
+  if (dma_queue_ != nullptr) {
+    ClearDmaQueue();
+  }
   // TODO: power down the DAC.
 }
 
+auto I2SAudioOutput::HasUnprocessedInput() -> bool {
+  if (dma_queue_ == nullptr || !dma_size_) {
+    return false;
+  }
+  return latest_chunk_.size() >= *dma_size_;
+}
+
 auto I2SAudioOutput::ProcessStreamInfo(const StreamInfo& info)
     -> cpp::result<void, AudioProcessingError> {
   // TODO(jacqueline): probs do something with the channel hey
@@ -53,6 +70,12 @@ auto I2SAudioOutput::ProcessStreamInfo(const StreamInfo& info)
     return cpp::fail(UNSUPPORTED_STREAM);
   }
 
+  if (!info.chunk_size) {
+    ESP_LOGE(kTag, "audio stream missing chunk size");
+    return cpp::fail(UNSUPPORTED_STREAM);
+  }
+  chunk_reader_.emplace(*info.chunk_size);
+
   ESP_LOGI(kTag, "incoming audio stream: %u bpp @ %u Hz", *info.bits_per_sample,
            *info.sample_rate);
 
@@ -85,23 +108,78 @@ auto I2SAudioOutput::ProcessStreamInfo(const StreamInfo& info)
       return cpp::fail(UNSUPPORTED_STREAM);
   }
 
-  dac_->Reconfigure(bps, sample_rate);
+  QueueHandle_t new_dma_queue =
+      xQueueCreate(kDmaQueueLength, sizeof(std::byte*));
+
+  dma_size_ = dac_->Reconfigure(bps, sample_rate, new_dma_queue);
+
+  if (dma_queue_ != nullptr) {
+    ClearDmaQueue();
+  }
+  dma_queue_ = new_dma_queue;
 
   return {};
 }
 
 auto I2SAudioOutput::ProcessChunk(const cpp::span<std::byte>& chunk)
     -> cpp::result<std::size_t, AudioProcessingError> {
-  ESP_LOGI(kTag, "playing samples");
-  SetSoftMute(false);
-  // TODO(jacqueline): write smaller parts with a small delay so that we can
-  // be responsive to pause and seek commands.
-  dac_->WriteData(chunk, portMAX_DELAY);
+  ESP_LOGI(kTag, "received new samples");
+  latest_chunk_ = chunk_reader_->HandleNewData(chunk);
   return 0;
 }
 
+auto I2SAudioOutput::ProcessEndOfStream() -> void {
+  if (chunk_reader_ && dma_size_) {
+    auto leftovers = chunk_reader_->GetLeftovers();
+    if (leftovers.size() > 0 && leftovers.size() < *dma_size_) {
+      std::byte* dest = static_cast<std::byte*>(malloc(*dma_size_));
+      cpp::span dest_span(dest, *dma_size_);
+
+      std::copy(leftovers.begin(), leftovers.end(), dest_span.begin());
+      std::fill(dest_span.begin() + leftovers.size(), dest_span.end(), static_cast<std::byte>(0));
+
+      xQueueSend(dma_queue_, &dest, portMAX_DELAY);
+    }
+  }
+
+  SendOrBufferEvent(
+      std::unique_ptr<StreamEvent>(
+        StreamEvent::CreateEndOfStream(input_events_)));
+
+  chunk_reader_.reset();
+  dma_size_.reset();
+}
+
 auto I2SAudioOutput::Process() -> cpp::result<void, AudioProcessingError> {
-  // TODO(jacqueline): Play the stream in smaller sections
+  std::size_t spaces_available = uxQueueSpacesAvailable(dma_queue_);
+  if (spaces_available == 0) {
+    // TODO: think about this more. can this just be the output event queue?
+    vTaskDelay(pdMS_TO_TICKS(100));
+    return {};
+  }
+
+  // Fill the queue as much as possible, since we need to be able to stream
+  // FAST.
+  while (latest_chunk_.size() >= *dma_size_ && spaces_available > 0) {
+    // TODO: small memory arena for this?
+    std::byte* dest = static_cast<std::byte*>(malloc(*dma_size_));
+    cpp::span dest_span(dest, *dma_size_);
+    cpp::span src_span = latest_chunk_.first(*dma_size_);
+    std::copy(src_span.begin(), src_span.end(), dest_span.begin());
+    if (!xQueueSend(dma_queue_, &dest, 0)) {
+      // TODO: calculate how often we expect this to happen.
+      free(dest);
+      break;
+    }
+    latest_chunk_ = latest_chunk_.subspan(*dma_size_);
+    ESP_LOGI(kTag, "wrote dma buffer of size %u", *dma_size_);
+  }
+  if (latest_chunk_.size() < *dma_size_) {
+    // TODO: if this is the end of the stream, then we should be sending this
+    // with zero padding. hmm. i guess we need an explicit EOF event?
+    chunk_reader_->HandleBytesLeftOver(latest_chunk_.size());
+    ESP_LOGI(kTag, "not enough samples for dma buffer");
+  }
   return {};
 }
 
@@ -124,4 +202,17 @@ auto I2SAudioOutput::SetSoftMute(bool enabled) -> void {
   }
 }
 
+auto I2SAudioOutput::ClearDmaQueue() -> void {
+  // Ensure we don't leak any memory from events leftover in the queue.
+  while (uxQueueSpacesAvailable(dma_queue_) < kDmaQueueLength) {
+    std::byte* data = nullptr;
+    if (xQueueReceive(input_events_, &data, 0)) {
+      free(data);
+    } else {
+      break;
+    }
+  }
+  vQueueDelete(dma_queue_);
+}
+
 }  // namespace audio
-- 
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