Special Reference Picture Reconstruction for Video Stream Switching

The patent applies preliminary action by constructing special reference pictures (SRP) in advance before stream switching occurs. The SRP is built by replacing reference pictures in the display picture buffer (DPB) with corresponding reference pictures from the target stream, ensuring that when switching happens, the reference pictures are already prepared and match, thus preventing reconstruction errors while enabling fast switching.

The patent applies local quality by making only the reference pictures local to the target stream while keeping the current picture encoding unchanged. Instead of re-encoding the entire current picture as an I/IDR frame, only the reference pictures used for prediction are replaced with SRP containing references from the target stream. This localized modification enables stream switching without the substantial bit rate overhead of frequent intra-coded pictures.

The patent introduces special reference pictures (SRP) as an intermediary mechanism that bridges the current stream and target stream. The SRP acts as a mediator containing reference pictures from the target stream, allowing the decoder to switch streams by simply replacing references in the DPB without implementing complex scalable video coding structures. This intermediary approach achieves bit rate adaptability with minimal additional complexity.

The patent applies copying by creating special reference pictures that copy reference picture data from the target stream into the current stream's decoding context. When stream switching is needed, the DPB is updated by copying reference pictures from the target stream's DPB into the current stream's DPB as SRP. This copying mechanism ensures that the reference pictures match the target stream, maintaining reconstruction accuracy while enabling flexible switching between multiple video versions.