Constant quality rate-control for video encoding based on activity segmentation

An enhanced, off-line, segment-based rate control approach is proposed for controlling the distortion variation across successive segments of a video sequence when encoding with single-layer (MPEG-4 Baseline, MPEG-4 AVC) and wavelet video codecs. Consistent quality is achieved by a time-efficient, predictive rate-distortion modeling per segment. The individual segments are either shots or subshots, that are defined based on shot segmentation and activity analysis techniques. The rate control method solves the quality stability problem of state-of-the-art codecs, especially for less mature rate control modules (such as present in MPEG-4 AVC). The processing overhead compared to classical two-pass VBR encoding is limited while the distortion variation is significantly reduced.