1. A video decoding device operable to decode video data encoded by video coding standards using Huffman trees, the video decoding device comprising: a receiving module operable to receive video data encoded by one video coding standard using the Huffman tree, and transform the video data from a Huffman tree to at least one full tree and at least one one-side tree; a storage module operable to store a plurality of microcodes and a plurality of corresponding decoding tables, wherein each microcode and corresponding decoding table corresponding to one video coding standard, each microcode is stored in the storage module in an address sequence according to the corresponding decoding table, and a format of each microcode comprises a leaf, a full tree, and a one-side tree, wherein the microcode with a leaf format comprises a consuming length field and a decoding field, the consuming length field indicates a bit number of video data to be decoded, and the decoding field indicates how to decode video data; a microcode processing module operable to read one microcode corresponding to the video coding standard coding the received video data and determine a format of the read microcode; a video processing module operable to read video data from the transformed video data according to the consuming length of the read microcode when the format of the read microcode is a leaf; a decoding module operable to decode the read video data according to the decoding field of the read microcode to output a decoding result when the format of the read microcode is a leaf; and at least one processor operable to execute the receiving module, the storage module, the microcode processing module, the video processing module, and the decoding module.