- 中文版本
- Basic Example:
This example demonstrates the process of using ADF's equalizer to process playback of WAV audio files. The data stream in the pipeline is as follows:
sdcard ---> fatfs_stream ---> wav_decoder ---> equalizer ---> i2s_stream ---> codec_chip
First, fatfs_stream reads the audio file named test.wav from the microSD card (prepared by yourself), then the data of this file is decoded by the wav_decoder decoder, processed by the equalizer, and finally sent to the codec chip through I2S for playback.
This example runs on the boards that are marked with a green checkbox in the table. Please remember to select the board in menuconfig as discussed in Section Configuration below.
This example supports IDF release/v5.0 and later branches. By default, it runs on ADF's built-in branch $ADF_PATH/esp-idf.
In this example, you need to prepare an microSD card with an audio file in WAV format named test.wav, and insert the card into the development board.
The default board for this example is ESP32-Lyrat V4.3, if you need to run this example on other development boards, select the board in menuconfig, such as ESP32-Lyrat-Mini V1.1.
menuconfig > Audio HAL > ESP32-Lyrat-Mini V1.1
If you need to change the audio file name to something more than 8 characters’ long, it is recommended to enable FatFs long file name support.
menuconfig > Component config > FAT Filesystem support > Long filename support
Build the project and flash it to the board, then run monitor tool to view serial output (replace PORT with your board's serial port name):
idf.py -p PORT flash monitor
To exit the serial monitor, type Ctrl-].
See ESP-IDF Programming Guide for full steps to configure and build an ESP-IDF project.
After the example start running, the device reads the test.wav file from the microSD card, automatically uses the equalizer to process it, and then plays the processed audio. For the related log, please refer to Example Log.
To change the parameters of the equalizer, please edit the set_gain[] table in equalizer_example.c. The center frequencies of the equalizer are 31 Hz, 62 Hz, 125 Hz, 250 Hz, 500 Hz, 1 kHz, 2 kHz, 4 kHz, 8 kHz, and 16 kHz.
- The
test.wavused by this example is an 16-bit single-channel audio file at a sampling rate of 44100 Hz. - Below is the original spectrum image of
test.wav. It is located indocument/spectrum_before.png.
- Below is the spectrum image of
test.wavthat has been processed by the equalizer. The equalizer gain is -13 dB. It is located indocument/spectrum_after.png.
- Below is the frequency response image when the equalizer gain is 0 dB. It is located in the
document/amplitude_frequency.png.
A complete log is as follows:
entry 0x400806f4
I (27) boot: ESP-IDF v4.2.2 2nd stage bootloader
I (27) boot: compile time 10:23:02
I (27) boot: chip revision: 3
I (30) boot_comm: chip revision: 3, min. bootloader chip revision: 0
I (37) boot.esp32: SPI Speed : 40MHz
I (42) boot.esp32: SPI Mode : DIO
I (46) boot.esp32: SPI Flash Size : 2MB
I (51) boot: Enabling RNG early entropy source...
I (56) boot: Partition Table:
I (60) boot: ## Label Usage Type ST Offset Length
I (67) boot: 0 nvs WiFi data 01 02 00009000 00006000
I (75) boot: 1 phy_init RF data 01 01 0000f000 00001000
I (82) boot: 2 factory factory app 00 00 00010000 00100000
I (90) boot: End of partition table
I (94) boot_comm: chip revision: 3, min. application chip revision: 0
I (101) esp_image: segment 0: paddr=0x00010020 vaddr=0x3f400020 size=0x0fdf0 ( 65008) map
I (135) esp_image: segment 1: paddr=0x0001fe18 vaddr=0x3ffb0000 size=0x00200 ( 512) load
I (135) esp_image: segment 2: paddr=0x00020020 vaddr=0x400d0020 size=0x2e0a0 (188576) map
0x400d0020: _stext at ??:?
I (213) esp_image: segment 3: paddr=0x0004e0c8 vaddr=0x3ffb0200 size=0x02050 ( 8272) load
I (217) esp_image: segment 4: paddr=0x00050120 vaddr=0x40080000 size=0x0daf0 ( 56048) load
0x40080000: _WindowOverflow4 at /hengyongchao/esp-idfs/esp-idf-v4.2.2/components/freertos/xtensa/xtensa_vectors.S:1730
I (252) boot: Loaded app from partition at offset 0x10000
I (252) boot: Disabling RNG early entropy source...
I (252) cpu_start: Pro cpu up.
I (256) cpu_start: Application information:
I (261) cpu_start: Project name: equalizer_app
I (266) cpu_start: App version: v2.2-202-g020b5c49-dirty
I (273) cpu_start: Compile time: Sep 30 2021 10:22:56
I (279) cpu_start: ELF file SHA256: 2f6692ee6bcc59a3...
I (285) cpu_start: ESP-IDF: v4.2.2
I (290) cpu_start: Starting app cpu, entry point is 0x40081988
0x40081988: call_start_cpu1 at /hengyongchao/esp-idfs/esp-idf-v4.2.2/components/esp32/cpu_start.c:287
I (0) cpu_start: App cpu up.
I (300) heap_init: Initializing. RAM available for dynamic allocation:
I (307) heap_init: At 3FFAE6E0 len 00001920 (6 KiB): DRAM
I (313) heap_init: At 3FFB2B98 len 0002D468 (181 KiB): DRAM
I (319) heap_init: At 3FFE0440 len 00003AE0 (14 KiB): D/IRAM
I (326) heap_init: At 3FFE4350 len 0001BCB0 (111 KiB): D/IRAM
I (332) heap_init: At 4008DAF0 len 00012510 (73 KiB): IRAM
I (338) cpu_start: Pro cpu start user code
I (356) spi_flash: detected chip: gd
I (357) spi_flash: flash io: dio
W (357) spi_flash: Detected size(8192k) larger than the size in the binary image header(2048k). Using the size in the binary image header.
I (367) cpu_start: Starting scheduler on PRO CPU.
I (0) cpu_start: Starting scheduler on APP CPU.
I (378) EQUALIZER_EXAMPLE: [1.0] Mount sdcard
I (888) EQUALIZER_EXAMPLE: [2.0] Start codec chip
E (888) gpio: gpio_install_isr_service(438): GPIO isr service already installed
I (908) EQUALIZER_EXAMPLE: [3.0] Create audio pipeline
I (938) EQUALIZER_EXAMPLE: [3.1] Register all elements to audio pipeline
I (938) EQUALIZER_EXAMPLE: [3.2] Link it together [sdcard]-->fatfs_stream-->wav_decoder-->equalizer-->i2s_stream
I (938) EQUALIZER_EXAMPLE: [3.3] Set up uri (file as fatfs_stream, wav as wav decoder, and default output is i2s)
I (948) EQUALIZER_EXAMPLE: [4.0] Set up event listener
I (958) EQUALIZER_EXAMPLE: [4.1] Listening event from all elements of pipeline
I (968) EQUALIZER_EXAMPLE: [4.2] Listening event from peripherals
I (968) EQUALIZER_EXAMPLE: [5.0] Start audio_pipeline
I (988) EQUALIZER_EXAMPLE: [6.0] Listen for all pipeline events
I (998) EQUALIZER_EXAMPLE: [ * ] Receive music info from wav decoder, sample_rates=44100, bits=16, ch=1
W (91708) FATFS_STREAM: No more data, ret:0
W (91708) EQUALIZER_EXAMPLE: [ * ] Stop event received
I (91708) EQUALIZER_EXAMPLE: [7.0] Stop audio_pipeline and release all resources
E (91718) AUDIO_ELEMENT: [file_read] Element already stopped
W (91728) AUDIO_ELEMENT: OUT-[wavdec] AEL_IO_ABORT
W (91728) AUDIO_ELEMENT: OUT-[equalizer] AEL_IO_ABORT
W (91758) AUDIO_PIPELINE: There are no listener registered
W (91758) AUDIO_ELEMENT: [file_read] Element has not create when AUDIO_ELEMENT_TERMINATE
W (91768) AUDIO_ELEMENT: [wavdec] Element has not create when AUDIO_ELEMENT_TERMINATE
W (91778) AUDIO_ELEMENT: [equalizer] Element has not create when AUDIO_ELEMENT_TERMINATE
W (91788) AUDIO_ELEMENT: [i2s] Element has not create when AUDIO_ELEMENT_TERMINATETo run this playback example, the following conditions must be met:
-
The audio file must meet the requirements below to be supported by the equalizer:
- Sampling rate: 11025 Hz, 22050 Hz, 44100 Hz, 48000 Hz.
- Number of channels: 1 or 2.
- Audio file format: WAV.
Please use the following feedback channels:
- For technical queries, go to the esp32.com forum
- For a feature request or bug report, create a GitHub issue
We will get back to you as soon as possible.