First of all, audio postcards are web-based, and each QR code is unique. Each QR code corresponds to a specific address (website) on the postcard company server. The basic principle is as follows:

Sender: Enter the "mobile phone sticker" software-> Scan the QR code (the software will get the specific address on the server)-> Upload information such as sound photos.

Receiver: Enter the "mobile phone sticker" software-> Scan QR code (the software will get the same address on the server)-> Read information such as sound pictures.

The QR code is indeed entered first and then generated. This company first enters every address on the server into the QR code, then sells the QR code to customers, and then it is the same as above.