Subjective Quality Analysis of Bit Rate Exchange Between Temporal and SNR Scalability in the MPEG4 SVC Extension

It is well known that a compression trade-off exists between the spatial and temporal video quality. Various temporal scalability techniques have been considered for lowering the encoded frame rate such that the freed bit rate can be used to increase the PSNR quality of the remaining frames. Temporal scalability in the SVC extension of the MPEG4/AVC codec (ITU-T and ISO/IEC, 2006) is realized by the hierarchical B-frame structure or the open loop MCTF approach. We investigate the usefulness of the hierarchical B-frame structure as a tool for scaling the bit rate. We use the patented video quality metric (VQM) to measure the subjective quality, in this way explicitly taking into account temporal artifacts due to frame rate reduction. Our results indicate that there is little to no quality gain by exchanging frame rate for increased spatial quality at a given constant bit rate.