Undefined reference errors when using libwebp library

1

Hi everyone,
I’m trying to use libwebp library in my Arduino project to decode animated webp images.

At the moment the sketch is pretty basic, as I removed everything but the webp part.

I’m getting this error during linking:

Compiling .pio/build/webp/src/main.cpp.o
Linking .pio/build/webp/firmware.elf
.pio/build/webp/src/main.cpp.o:(.literal._Z8testWebpv+0x4): undefined reference to `WebPAnimDecoderOptionsInitInternal'
.pio/build/webp/src/main.cpp.o:(.literal._Z8testWebpv+0x8): undefined reference to `WebPAnimDecoderNewInternal'
.pio/build/webp/src/main.cpp.o:(.literal._Z8testWebpv+0xc): undefined reference to `WebPAnimDecoderGetInfo'
.pio/build/webp/src/main.cpp.o:(.literal._Z8testWebpv+0x10): undefined reference to `WebPAnimDecoderHasMoreFrames'
.pio/build/webp/src/main.cpp.o:(.literal._Z8testWebpv+0x14): undefined reference to `WebPAnimDecoderGetNext'
.pio/build/webp/src/main.cpp.o:(.literal._Z8testWebpv+0x18): undefined reference to `WebPAnimDecoderReset'
.pio/build/webp/src/main.cpp.o:(.literal._Z8testWebpv+0x1c): undefined reference to `WebPAnimDecoderDelete'
.pio/build/webp/src/main.cpp.o: In function `testWebp()':
/Users/carlos/projects/esp32/test-webp/src/main.cpp:27: undefined reference to `WebPAnimDecoderOptionsInitInternal'
/Users/carlos/projects/esp32/test-webp/src/main.cpp:27: undefined reference to `WebPAnimDecoderNewInternal'
/Users/carlos/projects/esp32/test-webp/src/main.cpp:27: undefined reference to `WebPAnimDecoderGetInfo'
/Users/carlos/projects/esp32/test-webp/src/main.cpp:27: undefined reference to `WebPAnimDecoderHasMoreFrames'
/Users/carlos/projects/esp32/test-webp/src/main.cpp:27: undefined reference to `WebPAnimDecoderGetNext'
/Users/carlos/projects/esp32/test-webp/src/main.cpp:27: undefined reference to `WebPAnimDecoderReset'
/Users/carlos/projects/esp32/test-webp/src/main.cpp:27: undefined reference to `WebPAnimDecoderDelete'
collect2: error: ld returned 1 exit status
*** [.pio/build/webp/firmware.elf] Error 1

main.cpp (based on webp2gif) tool:

#include <Arduino.h>
#include <webp/demux.h>

void testwebp();

void setup(){
    Serial.begin(115200);
    delay(1000);
    Serial.println("Setting up...");
}

void loop() {
    delay(5000);
	testwebp();
}

void testwebp() {
	WebPAnimDecoderOptions webp_dec_options;
	WebPAnimDecoderOptionsInit(&webp_dec_options);
	webp_dec_options.color_mode = MODE_RGBA;
	webp_dec_options.use_threads = true;
	WebPData webp_data;
	webp_data.size = 1024;
	webp_data.bytes = new uint8_t[webp_data.size];
	WebPAnimDecoder* webp_dec = WebPAnimDecoderNew(&webp_data, &webp_dec_options);
	WebPAnimInfo webp_anim_info;
	WebPAnimDecoderGetInfo(webp_dec, &webp_anim_info);

	int curr_timestamp = 0;
  // int prev_timestamp = 0;
	while(WebPAnimDecoderHasMoreFrames(webp_dec)){
		uint8_t* rgba_buffer;
		WebPAnimDecoderGetNext(webp_dec, &rgba_buffer, &curr_timestamp);
		printf("test\n");
		// prev_timestamp = curr_timestamp;
	}
	WebPAnimDecoderReset(webp_dec);
	WebPAnimDecoderDelete(webp_dec);
}

my directory structure looks like:

test-webp
├── .pio
├── include
│   └── README
├── lib
│   ├── README
│   └── libwebp
│       ├── library.json
│       └── src
│           ├── Makefile.am
│           ├── dec
│           ├── demux
│           ├── dsp
│           ├── enc
│           ├── libwebp.pc.in
│           ├── libwebp.rc
│           ├── libwebpdecoder.pc.in
│           ├── libwebpdecoder.rc
│           ├── mux
│           ├── utils
│           └── webp
├── platformio.ini
├── src
│   └── main.cpp

lib/libwebp/library.json:

{
    "name": "libwebp",
    "build": {
        "srcFilter": [
            "+<src/**/*.c>"
        ],
        "unflags": [
            "-DHAVE_CONFIG_H"
        ]
    }
}

platformio.ini:

[env:webp]
platform = espressif32
board = esp32doit-devkit-v1
framework = arduino
board_build.f_cpu = 240000000L
monitor_speed = 115200
monitor_filters = esp32_exception_decoder
upload_port = /dev/cu.SLAB_USBtoUART

I’m running Visual Studio Code v1.55.2, running on MacOS Mojave, and PlatformIO Core v5.1.1.

I guess it’s not finding the definition of those functions, but I’m not sure what I should add/change to make it work.

Any suggestions would be much appreciated.

Thanks!

2

Your srcFilter expression is causing every C file to be ignored.

Just replace the library.json file with

{
    "name": "libwebp",
    "build": {
        "unflags": [
            "-DHAVE_CONFIG_H"
        ],
        "flags": [
            "-I."
        ]
    }
}
1 Like
3

Thank you @maxgerhardt! That did the trick! Now it’s building correctly