Method and apparatus for inserting additional data into video stream without degrading picture quality

An apparatus for inserting additional data into a moving image stream, the apparatus comprising:

• a bitstream input unit configured to receive a coded bitstream;
• a first picture selection unit configured to select a first coded picture (PA) among the received coded bitstream,
• wherein the additional data is to be inserted into the selected first coded picture (PA);
• an additional data insertion unit configured to generate a first additional data inserted picture (PA′) by inserting the additional data into the selected first coded picture (PA);
• a second picture selection unit configured to select a second coded picture (PB) among the received coded bitstream,
• wherein the second coded picture (PB) directly refers to the first picture (PA);
• a transform and coding unit configured to generate a re-coded picture (PB′),
• wherein the generated second re-coded picture (PB′) is decoded by referring to the first additional data inserted picture (PA′), and
• wherein the decoded second picture (PB′) is same as the second coded picture (PB);
• and
• a data sequence generation unit configured to generate a data sequence based on the first additional data inserted picture (PA′) and the second re-coded picture (PB′).