DAC audio playback broken in ESP-IDF 4.4 (works in 4.3) (IDFGH-7160)

[phoddie]

Environment

• Development Kit: M5Stack
• Module or chip used: ESP32
• IDF version: v4.4
• Build System: CMake
• Compiler version: xtensa-esp32-elf-gcc (crosstool-NG esp-2021r2) 8.4.0
• Operating System: macOS
• Using an IDE?: No

Problem Description

Audio playback using i2s_ API to DAC fails:

• The same code works under ESP-IDF 4.3
• No errors are reported by the i2s_* calls
• The I2s_write calls return nearly immediately. For example, about 1000 ms of 16-bit 11 kHz mono data is accepted by is2_write in about 50 ms. This suggests that the audio data is not being correctly queued by the driver. When it works correctly, the i2s_write calls are roughly evenly spaced across the one second interval.

The implementation used is in the Moddable SDK audio output module.

Code to reproduce this issue

Summary of implementation:

	i2s_config_t i2s_config = {
		.mode = I2S_MODE_MASTER | I2S_MODE_TX | I2S_MODE_DAC_BUILT_IN,
		.sample_rate = 11025,
		.bits_per_sample = I2S_BITS_PER_SAMPLE_16BIT,
		.channel_format = I2S_CHANNEL_FMT_RIGHT_LEFT,
		.communication_format = I2S_COMM_FORMAT_STAND_I2S,
		.intr_alloc_flags = 0,
		.dma_buf_count = 2,
		.dma_buf_len = 1024,
		.use_apll = false
	};
	i2s_driver_install(0, &i2s_config, 0, NULL);
	i2s_set_dac_mode(I2S_DAC_CHANNEL_BOTH_EN);

	while (moreAudioToPlay)
		i2s_write(0, buffer, 4096, &bytes_written, portMAX_DELAY);

Other information

We first became aware of this issue when reported against the Moddable SDK (#881). There is a report (#6470) of ADC output being broken in ESP-IDF v4.1, but this is not the issue we have (our code works with ESP-IDF v4.3). That report has a comment which mentions ADC audio is broken on ESP-IDF v4.4 also.

[Alvin1Zhang]

Thanks for reporting.

[L-KAYA]

As mentioned in No AudioOut sounds with ESP-IDF v4.4

1. Checkout to the latest release/v4.4 branch;
2. Set communication_format to I2S_COMM_FORMAT_STAND_MSB;
3. For stereo case, set channel_format to I2S_CHANNEL_FMT_RIGHT_LEFT and for mono case, set channel_format to I2S_CHANNEL_FMT_ONLY_RIGHT or I2S_CHANNEL_FMT_ONLY_LEFT

[phoddie]

It looks like the ESP-IDF v4.4 changes for analog audio did break the Moddable SDK. Following the advice above, we have it working again. Thank you!

[Alvin1Zhang]

Thanks for reporting and sharing the updates, good to hear it working again, feel free to reopen.