[resampler] Allow resampler to passthrough bits per sample instead of converting (#16892)

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

esphome/components/resampler/speaker/__init__.py

@@ -24,6 +24,8 @@ ResamplerSpeaker = resampler_ns.class_(
 
 CONF_TAPS = "taps"
 
+PASSTHROUGH = "passthrough"
+
 
 def _set_stream_limits(config):
     audio.set_stream_limits(
@@ -35,14 +37,21 @@ def _set_stream_limits(config):
 
 
 def _validate_audio_compatibility(config):
-    inherit_property_from(CONF_BITS_PER_SAMPLE, CONF_OUTPUT_SPEAKER)(config)
     inherit_property_from(CONF_NUM_CHANNELS, CONF_OUTPUT_SPEAKER)(config)
     inherit_property_from(CONF_SAMPLE_RATE, CONF_OUTPUT_SPEAKER)(config)
 
+    # In passthrough mode the output bits per sample is determined at runtime from the input stream, so there is
+    # nothing to inherit or validate against the output speaker.
+    passthrough = config.get(CONF_BITS_PER_SAMPLE) == PASSTHROUGH
+    if not passthrough:
+        inherit_property_from(CONF_BITS_PER_SAMPLE, CONF_OUTPUT_SPEAKER)(config)
+
     audio.final_validate_audio_schema(
         "source_speaker",
         audio_device=CONF_OUTPUT_SPEAKER,
-        bits_per_sample=config.get(CONF_BITS_PER_SAMPLE),
+        bits_per_sample=cv.UNDEFINED
+        if passthrough
+        else config.get(CONF_BITS_PER_SAMPLE),
         channels=config.get(CONF_NUM_CHANNELS),
         sample_rate=config.get(CONF_SAMPLE_RATE),
     )(config)
@@ -60,6 +69,9 @@ CONFIG_SCHEMA = cv.All(
         {
             cv.GenerateID(): cv.declare_id(ResamplerSpeaker),
             cv.Required(CONF_OUTPUT_SPEAKER): cv.use_id(speaker.Speaker),
+            cv.Optional(CONF_BITS_PER_SAMPLE, default=PASSTHROUGH): cv.Any(
+                cv.one_of(PASSTHROUGH, lower=True), cv.int_range(8, 32)
+            ),
             cv.Optional(
                 CONF_BUFFER_DURATION, default="100ms"
             ): cv.positive_time_period_milliseconds,
@@ -90,6 +102,9 @@ async def to_code(config):
         cg.add(var.set_task_stack_in_psram(True))
         psram.request_external_task_stack()
 
+    if config[CONF_BITS_PER_SAMPLE] == PASSTHROUGH:
+        cg.add(var.set_passthrough_bits_per_sample(True))
+    else:
         cg.add(var.set_target_bits_per_sample(config[CONF_BITS_PER_SAMPLE]))
     cg.add(var.set_target_sample_rate(config[CONF_SAMPLE_RATE]))
 

esphome/components/resampler/speaker/resampler_speaker.cpp

@@ -40,11 +40,19 @@ enum ResamplingEventGroupBits : uint32_t {
 };
 
 void ResamplerSpeaker::dump_config() {
+  if (this->passthrough_bits_per_sample_) {
     ESP_LOGCONFIG(TAG,
                   "Resampler Speaker:\n"
-                "  Target Bits Per Sample: %u\n"
+                  "  Target Bits Per Sample: passthrough\n"
+                  "  Target Sample Rate: %" PRIu32 " Hz",
+                  this->target_sample_rate_);
+  } else {
+    ESP_LOGCONFIG(TAG,
+                  "Resampler Speaker:\n"
+                  "  Target Bits Per Sample: %" PRIu8 "\n"
                   "  Target Sample Rate: %" PRIu32 " Hz",
                   this->target_bits_per_sample_, this->target_sample_rate_);
+  }
 }
 
 void ResamplerSpeaker::setup() {
@@ -253,8 +261,12 @@ void ResamplerSpeaker::send_command_(uint32_t command_bit, bool wake_loop) {
 void ResamplerSpeaker::start() { this->send_command_(ResamplingEventGroupBits::COMMAND_START, true); }
 
 esp_err_t ResamplerSpeaker::start_() {
-  this->target_stream_info_ = audio::AudioStreamInfo(
-      this->target_bits_per_sample_, this->audio_stream_info_.get_channels(), this->target_sample_rate_);
+  // In passthrough mode, the output keeps the input's bits per sample so only the sample rate is resampled.
+  const uint8_t target_bits_per_sample = this->passthrough_bits_per_sample_
+                                             ? this->audio_stream_info_.get_bits_per_sample()
+                                             : this->target_bits_per_sample_;
+  this->target_stream_info_ = audio::AudioStreamInfo(target_bits_per_sample, this->audio_stream_info_.get_channels(),
+                                                     this->target_sample_rate_);
 
   this->output_speaker_->set_audio_stream_info(this->target_stream_info_);
   this->output_speaker_->start();
@@ -305,7 +317,11 @@ void ResamplerSpeaker::set_volume(float volume) {
 }
 
 bool ResamplerSpeaker::requires_resampling_() const {
-  return (this->audio_stream_info_.get_sample_rate() != this->target_sample_rate_) ||
+  if (this->audio_stream_info_.get_sample_rate() != this->target_sample_rate_) {
+    return true;
+  }
+  // In passthrough mode the bits per sample always matches the input, so it never forces resampling.
+  return !this->passthrough_bits_per_sample_ &&
          (this->audio_stream_info_.get_bits_per_sample() != this->target_bits_per_sample_);
 }
 

esphome/components/resampler/speaker/resampler_speaker.h

@@ -49,6 +49,12 @@ class ResamplerSpeaker : public Component, public speaker::Speaker {
   }
   void set_target_sample_rate(uint32_t target_sample_rate) { this->target_sample_rate_ = target_sample_rate; }
 
+  /// @brief When enabled, the input bits per sample are passed through to the output speaker unchanged instead of being
+  /// converted to a fixed target. Only the sample rate is resampled if it differs from the target.
+  void set_passthrough_bits_per_sample(bool passthrough_bits_per_sample) {
+    this->passthrough_bits_per_sample_ = passthrough_bits_per_sample;
+  }
+
   void set_filters(uint16_t filters) { this->filters_ = filters; }
   void set_taps(uint16_t taps) { this->taps_ = taps; }
 
@@ -80,23 +86,24 @@ class ResamplerSpeaker : public Component, public speaker::Speaker {
 
   speaker::Speaker *output_speaker_{nullptr};
 
-  bool task_stack_in_psram_{false};
-  bool waiting_for_output_{false};
-
   StaticTask task_;
 
   audio::AudioStreamInfo target_stream_info_;
 
-  uint16_t taps_;
-  uint16_t filters_;
-
-  uint8_t target_bits_per_sample_;
-  uint32_t target_sample_rate_;
+  uint64_t callback_remainder_{0};
 
   uint32_t buffer_duration_ms_;
   uint32_t state_start_ms_{0};
+  uint32_t target_sample_rate_;
 
-  uint64_t callback_remainder_{0};
+  uint16_t taps_;
+  uint16_t filters_;
+
+  uint8_t target_bits_per_sample_{0};
+
+  bool passthrough_bits_per_sample_{false};
+  bool task_stack_in_psram_{false};
+  bool waiting_for_output_{false};
 };
 
 }  // namespace esphome::resampler

tests/components/resampler/common.yaml

@@ -7,3 +7,8 @@ speaker:
   - platform: resampler
     id: resampler_speaker_id
     output_speaker: resampler_i2s_speaker_id
+    bits_per_sample: 16
+  - platform: resampler
+    id: resampler_speaker_2_id
+    output_speaker: resampler_speaker_id
+    bits_per_sample: passthrough