Real-time, hardware-implementable Structured Similarity (SSIM)-based rate distortion optimization (RDO) techniques for video transmission are described. The disclosed techniques provide efficient application of SSIM as a distortion metric in selecting prediction modes for encoding video for transmission. A prediction mode, at a high level, specifies which previously encoded group of pixels can be utilized to encode a subsequent block of pixels in a video frame. A less compute intensive distortion metric is first used to select a subset of candidate prediction modes. Then a more compute intensive SSIM-based selection is made on the subset. By utilizing the disclosed techniques during video encoding, tradeoffs between distortion and transmission rate can be made that are more relevant to human perception.