| 摘要 |
<p>The present invention relates to a method and system for evaluating the quality of encoded video data without gaining access to the source data or the compressed video bitstream. The system is configured to decode compressed video data using an MPEG decoder to produce decompressed video data. The decoded data is analyzed to determine whether the decompressed video data is intra-coded. If so, a discrete cosine transform (DCT) is performed to produce a set of DCT coefficients for at least one AC frequency band in the decompressed video data. At the same time, quantization matrix data of a frame of the decompressed video data as well as a quantizer scale for each block of the decompressed video data are extracted. Thereafter, the variance of the converted DCT coefficients is obtained, and then an average quantization error for each set of said DCT coefficients is determined based on the variance, the quantization matrix, and the quantizer scale. Lastly, a peak signal to noise ratio (PSNR) is calculated based on the resultant average quantization error.</p> |
