One-pass variable bit rate moving pictures encoding
AssigneeSTMicroelectronics Asia Pacific Pte Ltd
InventorYau Wei Lucas Hui
Life of this patent
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Abstract
A method and apparatus for encoding digital video utilizing a single pass variable bit rate encoding procedure. An encoding quality is set and the bit rate for encoding blocks or frames in the sequence of moving pictures is determined to achieve the selected quality according to the complexity of the video sequence. The bit rate is constrained by predetermined upper and lower bit rate limits.
Claims41
A method for variable bit rate control in a single pass moving pictures encoder, comprising:
- selecting a target picture encoding quality;
- selecting upper and lower bit rate limits;
- encoding at least one picture based on a target bit rate within the upper and lower bit rate limits;
- predicting a current bit rate and an encoding quality based on the result of the encoding step;
- comparing the encoding quality of the at least one encoded picture with the target picture encoding quality;
- adjusting the target bit rate within the upper and lower bit rate limits according to the result of said comparison and the predicted current bit rate, for encoding subsequent pictures;
- and
- repeating, for each picture in a sequence of pictures, said encoding, predicting, comparing and adjusting steps.
A control apparatus for a single pass moving pictures encoder, comprising:
- an input for receiving a target picture encoding quality;
- an input for receiving upper and lower bit rate limits;
- and
- a controller for controlling the encoder so as to encode at least one picture according to a target bit rate within the upper and lower bit rate limits, predict a current bit rate and an encoding quality based on the result of the encoding, compare the encoding quality of the at least one encoded picture with the target picture encoding quality, and adjust the target bit rate according to the result of said comparison and the predicted current bit rate for encoding subsequent pictures.
A single pass variable bit rate video picture encoder comprising:
- a picture input for receiving data for a plurality of moving pictures;
- a target quality input for receiving a target quality measure for encoded pictures;
- an encoder output for supplying encoded picture data;
- a bit rate limit input for receiving upper and lower bit rate limits for the encoded picture data;
- a bit rate predictor for predicting a current bit rate;
- a frequency transform processor for frequency transform encoding picture data from the picture input;
- a coefficient quantizer for quantizing the encoded picture data according to a quantization step size;
- an encoding quality estimator for measuring an encoding quality of quantized encoded pictures;
- and
- a bit rate controller for dynamically controlling the quantization step size of the coefficient quantizer based on the predicted current bit rate and a comparison of the target quality and the measured quality so that the encoder output remains within the upper and lower bit rate limits.
Dependencies are inferred from the claim text.