As a result, the authors proposed a method called quality-enhancing retransmission. Low-quality real-time frames transmitted during periods of low bandwidth can be retransmitted at a higher bitrate during a later period of high bandwidth while the live streaming session is ongoing, thus improving the video quality for delayed, time-shifted viewers. Choosing the optimal tradeoff between the drop in real-time quality(because of the retransmission) and the improvement in delayed video quality can be envisioned as a quality (SSIM) maximization problem across the time-shifted delays