QAudioDecoder cannot provide QAudioFormat

I created a QAudioDecode instance, linked the formatChanged signal to one of my slot functions, and then called the setSource function to load a wav file. I found that the meta information of the wav file was output on the console, but the formatChanged signal was not transmitted.

I tried to obtain QAudioFormat from QAudioDecoder myself, but returned a default empty QAudioFormat. I am currently unable to obtain basic audio information normally.