A decoding apparatus includes a differential decoder, an error correction decoder and a controller. The differential decoder performs differential decoding according to a differential encoding dependency to generate a differential decoding result. The error correction decoder performs a decoding process on multiple packets that need to be corrected according to the differential decoding result to accordingly generate respective error correction records, wherein the packets are generated according to the differential decoding results, and the packets include a first packet and a second packet. When the error correction record of the first packet indicates that the decoding process of the first packet is unsuccessful, the controller generates a set of error position information according to the error correction record of the second packet, and requests the error correction decoder to perform another decoding process on the first packet according to the error position information.