Make the drain buffer very large, and move it into PSRAM

the i2s handler and streambuffer metadata are both still in iram for
good performance. otherwise, this seems to be enough to make gapless
playback work.

1 files changed, 16 insertions, 6 deletions

diff --git a/src/audio/audio_fsm.cpp b/src/audio/audio_fsm.cpp
index ba6e5ffe..0119855a 100644
--- a/src/audio/audio_fsm.cpp
+++ b/src/audio/audio_fsm.cpp
@@ -13,7 +13,9 @@
 
 #include "audio_sink.hpp"
 #include "bluetooth_types.hpp"
+#include "esp_heap_caps.h"
 #include "esp_log.h"
+#include "freertos/FreeRTOS.h"
 #include "freertos/portmacro.h"
 #include "freertos/projdefs.h"
 
@@ -192,20 +194,28 @@ void AudioState::react(const TogglePlayPause& ev) {
 
 namespace states {
 
+// Two seconds of samples for two channels, at a representative sample rate.
+constexpr size_t kDrainBufferSize = sizeof(sample::Sample) * 48000 * 4;
+static StreamBufferHandle_t sDrainBuffer;
+
 void Uninitialised::react(const system_fsm::BootComplete& ev) {
   sServices = ev.services;
 
-  constexpr size_t kDrainBufferSize =
-      drivers::kI2SBufferLengthFrames * sizeof(sample::Sample) * 2 * 8;
   ESP_LOGI(kTag, "allocating drain buffer, size %u KiB",
            kDrainBufferSize / 1024);
-  StreamBufferHandle_t stream = xStreamBufferCreateWithCaps(
-      kDrainBufferSize, sizeof(sample::Sample), MALLOC_CAP_DMA);
+
+  auto meta = reinterpret_cast<StaticStreamBuffer_t*>(
+      heap_caps_malloc(sizeof(StaticStreamBuffer_t), MALLOC_CAP_DMA));
+  auto storage = reinterpret_cast<uint8_t*>(
+      heap_caps_malloc(kDrainBufferSize, MALLOC_CAP_SPIRAM));
+
+  sDrainBuffer = xStreamBufferCreateStatic(
+      kDrainBufferSize, sizeof(sample::Sample), storage, meta);
 
   sFileSource.reset(
       new FatfsAudioInput(sServices->tag_parser(), sServices->bg_worker()));
-  sI2SOutput.reset(new I2SAudioOutput(stream, sServices->gpios()));
-  sBtOutput.reset(new BluetoothAudioOutput(stream, sServices->bluetooth(),
+  sI2SOutput.reset(new I2SAudioOutput(sDrainBuffer, sServices->gpios()));
+  sBtOutput.reset(new BluetoothAudioOutput(sDrainBuffer, sServices->bluetooth(),
                                            sServices->bg_worker()));
 
   auto& nvs = sServices->nvs();