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[i2s_audio] Compute ring buffer size with SPDIF sample count (#16400)

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Kevin Ahrendt
2026-05-18 22:53:19 -04:00
committed by Jesse Hills
parent 25739091da
commit 41ad2ba763
3 changed files with 12 additions and 11 deletions
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21
esphome/components/i2s_audio/speaker/i2s_audio_spdif.cpp
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@@ -138,21 +138,21 @@ void I2SAudioSpeakerSPDIF::run_speaker_task() {
// Reset lockstep records queue so it starts paired with the (also-reset) i2s_event_queue_.
xQueueReset(this->write_records_queue_);
const uint32_t dma_buffers_duration_ms = DMA_BUFFER_DURATION_MS * SPDIF_DMA_BUFFERS_COUNT;
// Ensure ring buffer duration is at least the duration of all DMA buffers
const uint32_t ring_buffer_duration = std::max(dma_buffers_duration_ms, this->buffer_duration_ms_);
// The DMA buffers may have more bits per sample, so calculate buffer sizes based on the input audio stream info
const size_t bytes_per_frame = this->current_stream_info_.frames_to_bytes(1);
// Round the ring buffer size down to a multiple of bytes_per_frame so the wrap boundary stays frame-aligned and
// avoids unnecessary single-frame splices.
const size_t ring_buffer_size =
(this->current_stream_info_.ms_to_bytes(ring_buffer_duration) / bytes_per_frame) * bytes_per_frame;
// For SPDIF mode, one DMA buffer = one SPDIF block = 192 PCM frames
// For SPDIF mode, one DMA buffer = one SPDIF block = 192 PCM frames (~4 ms at 48 kHz),
// not the ~15 ms a standard I2S DMA buffer holds. Derive the DMA floor from actual block size.
const uint32_t frames_to_fill_single_dma_buffer = SPDIF_BLOCK_SAMPLES;
const size_t bytes_to_fill_single_dma_buffer =
this->current_stream_info_.frames_to_bytes(frames_to_fill_single_dma_buffer);
const size_t dma_buffers_floor_bytes = bytes_to_fill_single_dma_buffer * SPDIF_DMA_BUFFERS_COUNT;
// Round the ring buffer size down to a multiple of bytes_per_frame so the wrap boundary stays frame-aligned and
// avoids unnecessary single-frame splices. Ensure it is at least large enough to cover all DMA buffers.
const size_t requested_ring_buffer_bytes =
(this->current_stream_info_.ms_to_bytes(this->buffer_duration_ms_) / bytes_per_frame) * bytes_per_frame;
const size_t ring_buffer_size = std::max(dma_buffers_floor_bytes, requested_ring_buffer_bytes);
bool successful_setup = false;
std::unique_ptr<audio::RingBufferAudioSource> audio_source;
@@ -177,7 +177,8 @@ void I2SAudioSpeakerSPDIF::run_speaker_task() {
// on_sent events drain in lockstep without crediting any audio frames.
this->spdif_encoder_->set_preload_mode(true);
for (size_t i = 0; i < SPDIF_DMA_BUFFERS_COUNT; i++) {
esp_err_t preload_err = this->spdif_encoder_->flush_with_silence(pdMS_TO_TICKS(DMA_BUFFER_DURATION_MS));
// i2s_channel_preload_data is non-blocking (returns immediately when the preload buffer fills), so no wait.
esp_err_t preload_err = this->spdif_encoder_->flush_with_silence(0);
if (preload_err != ESP_OK) {
break; // DMA preload buffer full or error
}

1
esphome/components/i2s_audio/speaker/i2s_audio_speaker.h
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@@ -19,7 +19,6 @@
namespace esphome::i2s_audio {
// Shared constants used by both standard and SPDIF speaker implementations
static constexpr uint32_t DMA_BUFFER_DURATION_MS = 15;
static constexpr size_t TASK_STACK_SIZE = 4096;
static constexpr ssize_t TASK_PRIORITY = 19;

1
esphome/components/i2s_audio/speaker/i2s_audio_speaker_standard.cpp
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@@ -16,6 +16,7 @@ namespace esphome::i2s_audio {
static const char *const TAG = "i2s_audio.speaker.std";
static constexpr uint32_t DMA_BUFFER_DURATION_MS = 15;
static constexpr size_t DMA_BUFFERS_COUNT = 4;
// Sized to comfortably absorb scheduling jitter: at most DMA_BUFFERS_COUNT events can be in flight,
// doubled so that a transient backlog never overruns the queue (which would desync the lockstep