Encoder and decoder, encoding method and decoding method for drift-free padding and hashing of independent coding regions

A video encoder comprising at least one processor, the at least one processor configured to:

• encode a gradual decoder refresh (GDR) picture into a data stream;
• and
• encode a supplemental enhancement information (SEI) message comprising hash information into the data stream, the hash information comprising a first hash value for decoded sample values of a color component of a refreshed region of a gradual decoder refresh (GDR) picture,
• wherein the hash information is configured for use by a decoder to verify the decoded sample values of the color component of the refreshed region of the GDR.

A method of video decoding, the method comprising:

• receiving an encoded video signal, the encoded video signal including a supplemental enhancement information (SEI) message comprising hash information, the hash information comprising a first hash value for decoded sample values of a color component of a refreshed region of a gradual decoder refresh (GDR) picture;
• decoding the encoded video signal to obtain the decoded sample values of the color component of the refreshed region of the GDR picture;
• determining a second hash value based on the decoded sample values of the color component of the refreshed region of the GDR picture;
• and
• determining whether the decoded sample values of the color component of the refreshed region of the GDR picture are correct by comparing the first hash value and the second hash value.

A method of video encoding, the method comprising:

• encoding a gradual decoder refresh (GDR) picture into a data stream;
• and
• encoding a supplemental enhancement information (SEI) message comprising hash information into the data stream, the hash information comprising a first hash value for decoded sample values of a color component of a refreshed region of a gradual decoder refresh (GDR) picture,
• wherein the hash information is configured for use by a decoder to verify the decoded sample values of the color component of the refreshed region of the GDR.