Combining flatness-based control, model-free control and algebraic estimation techniques permits to trivialize several key issues in the adaptive bitrate (ABR) setting, now the dominant industry approach in video streaming: 1) A straightforward open-loop strategy for the bitrate and the buffer level; 2) closing the loop permits not only to take into account unavoidable mismatches and disturbances, like Internet fluctuations, but also the inherently discrete nature of the bitrate; 3) an easily implementable closed-form estimate for a bandwidth allows to handle severe variations of the channel capacity. Several computer experiments and metrics for evaluating the Quality of Experience (QoE) are displayed and discussed.

翻译：结合平坦性控制、无模型控制与代数估计技术，可简化自适应比特率（ABR）设置中的若干关键问题——该技术现已成为视频流领域的主流行业方案：1）针对码率与缓冲区水平的直接开环策略；2）闭环控制不仅能应对不可避免的失配与干扰（如网络波动），还可解决码率固有的离散特性；3）易于实现的带宽闭式估计方法可处理信道容量的剧烈变化。文章展示并讨论了多种计算机实验及体验质量（QoE）评估指标。