i2s_audio speaker: Add idle_mode: silence to keep I2S bus active and prevent pop/click on audio start

[nullable-eth]

Component name

i2s_audio

Link to component documentation on our website

https://esphome.io/components/i2s_audio/

Describe the enhancement

Feature Request: I2S Speaker idle_mode / Keep-Alive to Prevent Pop on Audio Start

The Problem

Every time the i2s_audio speaker component starts playing audio, an audible pop/click is heard through the speaker. This happens because the I2S peripheral is fully torn down when idle and reinitialized on every audio event. The sudden transition from no clocks to active clocks causes a transient on the DAC output that produces the pop.

This affects any board using an external codec + amplifier (ES8311 + NS4150B in my case, but also reported with UDA1334 and on the ESP32-S3-BOX-3). Related: esphome/issues#5739, esphome/issues#6676.

Hardware

• Board: Waveshare ESP32-P4-ETH (ESP32-P4, RISC-V, esp-idf framework)
• Codec: ES8311 (onboard, I2C address 0x18)
• Amplifier: NS4150B (Class D, 3W)
• Speaker: DMA45-4 (4Ω)
• ESPHome: 2026.3.1

Diagnostic Evidence

1. The pop correlates exactly with I2S start/stop

Log output shows the pop occurs at the moment of i2s_audio.speaker: Starting:

[09:52:44.138][D][i2s_audio.speaker:102]: Starting    ← POP heard here
[09:52:44.138][D][i2s_audio.speaker:106]: Started
...
[09:52:45.086][D][i2s_audio.speaker:111]: Stopping
[09:52:45.094][D][i2s_audio.speaker:116]: Stopped

2. The codec is NOT being powered down

I added an interval timer that reads back ES8311 registers every 5 seconds — during idle, during playback, and after playback stops. The registers never change:

[09:52:34.407][I][pop_test:906]: Reg 0x0D = 0x06 (want 0x06)   ← idle
[09:52:34.408][I][pop_test:912]: Reg 0x00 = 0x80
[09:52:34.408][I][pop_test:918]: Reg 0x37 = 0x18 (want 0x18)

[09:52:44.411][I][pop_test:906]: Reg 0x0D = 0x06 (want 0x06)   ← during playback
[09:52:44.411][I][pop_test:912]: Reg 0x00 = 0x80
[09:52:44.412][I][pop_test:918]: Reg 0x37 = 0x18 (want 0x18)

[09:52:49.413][I][pop_test:906]: Reg 0x0D = 0x06 (want 0x06)   ← after stop
[09:52:49.413][I][pop_test:912]: Reg 0x00 = 0x80
[09:52:49.413][I][pop_test:918]: Reg 0x37 = 0x18 (want 0x18)

• 0x0D = power management (analog circuits, bias, DAC ref all enabled)
• 0x00 = chip state machine (CSM_ON=1, running)
• 0x37 = DAC ramp rate (fade in/out enabled, EQ bypassed)

The codec stays fully powered the entire time. The pop is not a codec power-down issue.

3. The I2S bus idle timeout is ~4 seconds

Playing two tones back-to-back with varying gaps confirmed the speaker driver keeps the I2S bus alive for approximately 4 seconds after audio stops. Tones played within 4 seconds of each other produce no pop on the second tone. After 5+ seconds, the I2S bus has been torn down and the next audio event pops.

4. What was ruled out

Attempted Fix	Result
ES8311 register 0x37 DAC_RAMPRATE (fade in/out)	No change — codec isn't the source
ES8311 register 0x0D power management writes	No change — codec was already powered
100µF DC blocking capacitor on speaker line	No change — not a DC offset issue
Interval timer re-writing codec registers every 2s	No change — registers were already correct
Prepending 150ms silence to wake sound WAV files	Pop still audible before silence plays
timeout: 0s on speaker platform	Not supported / no effect

Root Cause

The i2s_audio speaker component calls i2s_channel_enable() / i2s_channel_disable() (or the legacy equivalents) each time audio starts and stops. When the I2S peripheral enables, it begins driving BCLK, LRCK, and MCLK. The ES8311 (and other codecs) see this sudden clock transition and the DAC output jumps from its idle DC level to its active level — producing the pop through the amplifier.

The Espressif factory firmware on the ESP32-S3-BOX-3 does not exhibit this pop because ESP-ADF keeps the I2S pipeline alive and uses proper mute sequencing around start/stop.

Proposed Solution

Add a configuration option to the i2s_audio speaker (and/or audio_dac platform) to keep the I2S peripheral running when idle, outputting digital silence instead of tearing down the I2S driver.

Something like:

speaker:
  - platform: i2s_audio
    id: va_speaker
    i2s_audio_id: i2s_spk
    dac_type: external
    i2s_dout_pin: GPIO9
    sample_rate: 16000
    bits_per_sample: 16bit
    channel: left
    audio_dac: es8311_dac
    idle_mode: silence  # Keep I2S clocks running, output zeros when no audio

Or alternatively, a timeout parameter that controls how long the I2S bus stays active after audio stops (with 0s or never meaning indefinitely):

speaker:
  - platform: i2s_audio
    timeout: never  # Never tear down the I2S bus

Implementation Notes

• When idle_mode: silence is set, instead of calling i2s_channel_disable() after audio finishes, continue writing zero-filled buffers to the I2S DMA
• The I2S peripheral would be initialized once during setup() and never torn down
• The codec's DAC will see continuous silence (all zeros) which produces no output — and no pop when real audio data begins flowing
• This trades a small amount of continuous DMA/CPU overhead for pop-free audio transitions
• A timeout: <duration> option could offer a middle ground — keep clocks running for N seconds after audio stops, then tear down (accepting the pop if audio restarts after the timeout)

Current YAML Config (for reference)

audio_dac:
  - platform: es8311
    id: es8311_dac
    bits_per_sample: 16bit
    sample_rate: 16000
    i2c_id: i2c_bus
    address: 0x18

i2s_audio:
  - id: i2s_spk
    i2s_lrclk_pin: GPIO10
    i2s_bclk_pin: GPIO12
    i2s_mclk_pin: GPIO13

speaker:
  - platform: i2s_audio
    id: va_speaker
    i2s_audio_id: i2s_spk
    dac_type: external
    i2s_dout_pin: GPIO9
    sample_rate: 16000
    bits_per_sample: 16bit
    channel: left
    audio_dac: es8311_dac

media_player:
  - platform: speaker
    id: va_media_player
    name: "Media Player"
    announcement_pipeline:
      speaker: va_speaker
      format: FLAC
      num_channels: 1
      sample_rate: 16000

Use cases

Any voice assistant satellite using an external codec + Class D amp (ES8311, ES7210, UDA1334, etc.) gets an audible pop/click every time audio starts — on wake word acknowledgment, TTS responses, media playback, and error sounds. For a voice assistant that triggers dozens of times a day, this makes the device sound broken and cheap despite quality hardware. The pop is especially jarring on the first interaction after idle since the I2S bus has been fully torn down. Keeping the I2S clocks running with digital silence eliminates this entirely, matching the behavior of Espressif's own factory firmware on the ESP32-S3-BOX-3 which does not exhibit the pop.

Anything else?

No response

[github-actions[bot]]

🏷️ I've automatically added the component: i2s_audio label to help categorize this feature request.