High-Quality Live Video Streaming via Transcoding Time Prediction and Preset Selection

Video streaming often requires transcoding content into different resolutions and bitrates to match the recipient's bandwidth and screen capabilities. Video encoders like H.264 offer various presets, each with different tradeoffs between transcoding time and rate-distortion performance. Choosing the best preset for video transcoding is difficult, especially for live streaming, as trying all the presets and choosing the best one is not feasible. One solution is to predict the transcoding time for each preset and subsequently select the preset that ensures the highest quality while adhering to live streaming time constraints. Prediction of video transcoding time is also critical in minimizing streaming delays, deploying resource management algorithms, and load balancing. We propose a learning-based framework for predicting the transcoding time of videos across various presets. The features used by our predictor for video transcoding time prediction are derived directly from the ingested stream itself, primarily from the header or metadata. As a result, only minimal additional delay is incurred for feature extraction, rendering our approach ideal for live streaming applications. We evaluated our learning-based transcoding time prediction using a dataset of videos. The results demonstrate that our framework can accurately predict the transcoding time for different presets, with the MAPE of nearly 5.0%. Leveraging these predictions, we then select the most suitable transcoding preset for live video streaming. Utilizing our transcoding time prediction-based preset selection led to improvements in PSNR of up to 5 dB.