Selection of screen content encoding mode based on block classification and evaluation order

One or more non-transitory computer-readable media having stored thereon computer-executable instructions for causing one or more processing units, when programmed thereby, to perform operations comprising:

• encoding one or more frames of video content, thereby producing encoded data in a bitstream, wherein the encoding the one or more frames of video content includes, for a block of one of the one or more frames of video content:
• prior to selecting an encoding mode for the block, evaluating pixel values of the block and, based on results of the evaluating the pixel values of the block, classifying the block in one of multiple categories, thereby generating a block classification that indicates the one of the multiple categories, the multiple categories including a simple vertical category, a simple horizontal category, a simple category, and a non-simple category, wherein the simple vertical category indicates, for each column of the block, that all of the pixel values of the block that are in that column are identical, wherein the simple horizontal category indicates, for each row of the block, that all of the pixel values of the block that are in that row are identical, and wherein the simple category indicates that all of the pixel values of the block are identical;
• based at least in part on the block classification, selecting, from multiple available encoding modes, the encoding mode for the block, the multiple available encoding modes including an intra block copy mode, a palette mode, and a directional spatial prediction mode, wherein the selecting the encoding mode for the block includes evaluating at least some of the multiple available encoding modes in an evaluation order, and wherein the evaluating the at least some of the multiple available encoding modes includes, based at least in part on the block classification being the simple vertical category, the simple horizontal category, or the simple category, skipping performing hash-based block searching during evaluation of the intra block copy mode;
• and encoding the block using the selected encoding mode;
• and outputting the encoded data in the bitstream.