[Fix] Enable JPEG support with `-DBUILD_JPEG_TURBO_DISABLE=ON` command

[leonsama]

Reason

Opencv use libjpeg-turbo as the default option of jpeg library. However, according to the official page of libjpeg-turbe project,

libjpeg-turbo is a JPEG image codec that uses SIMD instructions (MMX, SSE2, AVX2, Neon, AltiVec) to accelerate baseline JPEG compression and decompression on x86, x86-64, Arm, and PowerPC systems

The native support for Xtensa platform is not available in libjpeg-turbo, which is why simply enabling -DBUILD_JPEG=ON during compilation may lead to failure

Solution

Use libjpeg instead of libjpeg-turbo. Add -DBUILD_JPEG_TURBO_DISABLE=ON to the cmake command.

Related Links

• Does the ESP32 have SIMD-like instructions?
• JPEGDEC

[nopnop2002]

@SolomonLeon

We can build the esp_opencv_tests project with this procedure on esp-idf v5.3.
#23

$ idf.py --version
ESP-IDF v5.3-dirty

I converted the image file to jpeg using the convert command.

$ ls -l spiffs_images
合計 1200
-rw-rw-r-- 1 nop nop 709918  9月  6 14:54 1024x768.jpg
-rw-rw-r-- 1 nop nop  32953  9月  6 14:53 160x120.jpg
-rw-rw-r-- 1 nop nop 112751  9月  6 14:53 320x240.jpg
-rw-rw-r-- 1 nop nop 359939  9月  6 14:54 640x480.jpg
-rw-rw-r-- 1 nop nop     13  9月  6 13:01 hello.txt

I changed CMakeLists.txt:

# The following lines of boilerplate have to be in your project's
# CMakeLists in this exact order for cmake to work correctly
cmake_minimum_required(VERSION 3.5)
include($ENV{IDF_PATH}/tools/cmake/project.cmake)

idf_build_set_property(COMPILE_OPTIONS "-DBUILD_JPEG_TURBO_DISABLE=ON" APPEND)

project(esp_opencv_tests)

I changed main/main.cpp.

void app_main(void)
{
    // Needed for opencv linkage with pthread to work
    pthread_cond_t cond_test = PTHREAD_COND_INITIALIZER;
    pthread_cond_init(&cond_test, nullptr);

    ESP_LOGI(TAG, "Starting main");
    disp_mem_infos();

    /* SPIFFS init */
    init_spiffs();
    ESP_LOGI(TAG, "done init_spiffs");

    read_image_specific_res("/spiffs/160x120.jpg");
    ESP_LOGI(TAG, "done read_image_specific_res /spiffs/160x120.jpg");

}

But i got this error.

W (2393) opencv_tests: cannot read the image: /spiffs/160x120.jpg

Do you have any advice?