Intra-frame predictive coding method and system for 360-degree video and medium

An intra-frame predictive coding system for a 360-degree video, comprising:

• a processor;
• and
• a storage medium coupling to the processor, and the storage medium comprises:
• a fast partition module, executed by the processor, is configured to input a coding unit feature, a texture feature, and a 360-degree video feature of a coding unit (CU) block to be partitioned into a neural network corresponding to each partition mode when intra-frame block partition is performed on a current CU block, skip a partition mode in which the output of the neural network is smaller than a corresponding output threshold, perform the intra-frame block partition on the CU block to be partitioned according to a partition mode that is not skipped, and obtain a plurality of intra-frame block partition schemes of the current CU block, wherein intra-frame block partition modes include quadtree (QT), binary tree horizontal (BTH), binary tree vertical (BTV), tertiary tree horizontal (TTH), and tertiary tree vertical (TTV), and the CU block to be partitioned is the current CU block or a sub-CU block obtained after each intra-frame block partition,
• wherein the coding unit feature comprises:
• several ones of a width, a height, a depth, a quadtree depth, a multi-tree depth, a block shape ration, a quantization parameter, a horizontal angle mode type, and a vertical angle mode type of a CU block,
• the texture feature comprises:
• several ones of a variance of a pixel value, a normalized mean square error, a horizontal texture factor, a vertical texture factor, a weight between the horizontal and vertical textures, and directional complexity of the CU block, and
• the 360-degree video feature comprises a latitude of the CU block and a sampling factor at each latitude;
• a mode deciding module, executed by the processor, is configured to determine a length n of a rough mode decision (RMD) candidate list according to the coding unit feature and the texture feature of the sub-CU block when an intra-frame angle mode is decided for each sub-CU block in each intra-frame block partition scheme, decide the intra-frame angle mode based on the RMD candidate list of the length n, and obtain the intra-frame angle mode to fill pixels in each intra-frame block partition scheme,
• wherein when w≥wth, h≥hth, var<varth, NMSE<NMSEth, and compTHTV<compth), the length n is 1, and
• when w≥wth&&h≥ hth&& (ratioTHTV>thH∥1/ratioTHTV>thV), the length n is 2;
• otherwise, the length n is 3,
• where w and h respectively are the width and the height the CU block, var and NMSE respectively are the variance of the pixel value and the normalized mean square error of the CU block, compTHTV is the directional complexity, ratioTHTV is the weight between the horizontal and vertical textures, wth, hth, varth, NMSEth, and compth respectively are threshold values corresponding to w, h, var, NMSE, and compTHTV, thy is a threshold value of the horizontal angle mode, and thy is a threshold value of the vertical angle mode;
• and
• a coding module, executed by the processor, is configured to calculate rate distortion optimization (RDO) loss between each intra-frame block partition scheme and the current CU block after pixel filling and perform intra-frame coding predictive coding on the current CU block based on the intra-frame block partition scheme corresponding to the minimum RDO loss, wherein the fast partition module, the mode deciding module, and the coding module are repeatedly executed until intra-frame predictive coding is performed on all CU blocks of the 360-degree video frame.