Perceptual Quality Evaluation of Low-Bit Rate Model-Assisted H.261-Compatible Video

Abstract

We describe an experiment conducted so as to evaluate the perceptual quality of low-bit rate H.261-compatible video. The video coding systems tested are based on CCITT Recommendation H.261, operating at the bit rates of 48 and 24 kbps, at the constant frame rates of 7.5, 5 and 2 fps, and are followed by a postprocessing module. One system uses the concept of model-assisted coding which results in a better rendition of facial features—producing better eye contact and lip synchronization—at the expense of a slightly lower quality in the rest of the image.