| 摘要 |
The test method involves treating a digital image in blocks, each comprising luminance and chrominance signal samples, by applying non-zero discrete cosine transformation (DCT) coeffts. in the two dimensions to each block, or to the differences between blocks. The video coder is forced to use successively all the norms of bit rate compression concerned with compression management, including all vector movements, quantum steps, and bit rate reduction norms. The test signal may be inserted into a video signal, and the coder output is observed by a line spy which verifies that the number of bits created by the coding is correct, and analyses the coded data in deferred time. Alternatively the frame suppression line is used, and a decoder checks that the digital sum of the decoded signal is correct. ADVANTAGE - Guarantees quality of transmission at reduced bit rate, checks norms, gives objective assessment of picture.
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