Video spatial resolution conversion method based on code-rate type transcoding assistance

The invention discloses a video spatial resolution conversion method based on code-rate type transcoding assistance, which comprises two key technologies. The first key technology comprises the following steps of: performing code-rate type transcoding on a video stream obtained by decoding a code rate corresponding to the target spatial resolution, actively setting high-frequency information to zero, ensuring the accuracy of motion vector and macroblock pattern multiplexing and benefiting the reduction of calculation amount and transmission bandwidth by maintaining the uniform video spatial resolution of a coding end and a decoding end. The second key technology comprises the following steps of: decoding at a user end and simultaneously resampling the decoded video steam according to the target resolution. Because the resolution of resampling is matched with the resolution of intermediate-frequency domain sub-sampling in code-rate type transcoding, the aliasing effect caused by resampling can be effectively i