Quote:
Originally Posted by brumsky
Thank you for the detailed answer!
Is RDO predictions the Entropy coding you mentioned?
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The general sequence of video encoding (simple version)...
Prediction -> Calculate Residual Error after Prediction -> Discrete Cosine Transform the Residual Error -> Quantize the Transformed Residual Error -> Entropy Code the Prediction and the Transformed, Quantized Residual Error
Entropy coding is lossless compression (think of it like zip file compression). HEVC uses CABAC entropy coding. This is the last step for encoding each block.
When you're doing rate-distortion optimization (RDO), and you want to weigh the relative bit rate of multiple encoding candidates for a block of video, you have to do all of the above steps if you want the actual number of bits. This is very time consuming, of course, because you are doing a full transform, quant and entropy coding on every candidate, and you'll throw out all but the best candidate. So for faster settings, we just look at the # of bits for each candidate without doing the entropy coding. It's roughly accurate, but not as accurate.