One ABR algorithm implemented on Puffer is BOLA-BASIC, the simplest variant of BOLA. BOLA finds wide use in industry, notably in the MPEG-DASH reference player used as the basis for video players at Akamai, BBC, Orange, and CBS. The overall goal of BOLA is to maximize each encoded chunk's video quality while minimizing rebuffering. To measure video quality, Puffer uses the structural similarity metric SSIM, whereas BOLA and other ABR algorithms like BBA, MPC, and Pensieve are more commonly implemented using bitrate (or a variant of bitrate). While bitrate is frequently used, BOLA allows the video provider to define its own proxy of video quality as the algorithm's "utility" function. However, using SSIM as utility proved surprisingly complex for BOLA-BASIC, despite the algorithm's simplicity. Given the rising popularity of SSIM and related quality metrics, we anticipate that a growing number of Puffer-like systems will face similar challenges. We hope developers of such systems find our experiences informative as they implement algorithms designed with bitrate-based utility in mind.

中文翻译：

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在 Puffer 上实现 BOLA-BASIC：在 ABR 逻辑中使用 SSIM 的经验教训

在 Puffer 上实现的一种 ABR 算法是 BOLA-BASIC，这是 BOLA 的最简单变体。BOLA 在工业中得到了广泛的应用，特别是在 MPEG-DASH 参考播放器中用作 Akamai、BBC、Orange 和 CBS 视频播放器的基础。BOLA 的总体目标是最大化每个编码块的视频质量，同时最小化重新缓冲。为了衡量视频质量，Puffer 使用结构相似性度量 SSIM，而 BOLA 和其他 ABR 算法（如 BBA、MPC 和 Pensieve）更常使用比特率（或比特率的变体）实现。虽然经常使用比特率，但 BOLA 允许视频提供商将其自己的视频质量代理定义为算法的“效用”函数。然而，尽管算法很简单，但事实证明，使用 SSIM 作为实用程序对于 BOLA-BASIC 来说非常复杂。鉴于 SSIM 和相关质量指标的日益普及，我们预计越来越多的类似 Puffer 的系统将面临类似的挑战。我们希望此类系统的开发人员在实现以基于比特率的实用程序设计的算法时能发现我们的经验有用。