H.264/SVC Rate Allocation based on Graceful Degradation of Subjective Quality in Frame Rate Switching

ABSTRACT

H.264 scalable extension (SVC), which is constructed based on H.264/AVC, is the most recent scalable video coding standard. H.264/SVC is incorporate temporal, spatial, and SNR scalability so that not only it has high compression efficiency but also the encoded stream can be adapted to heterogeneous user/network environments without transcoding. Temporal scalability can support multiple display frame rates with a wide range of bitrates. When we adopt the JVT recommended QP setting for H.264/SVC temporal layers, a big subjective quality gap between different layers is occurred in frame rate switching. Thus how to efficiently allocate a given total bitrate among multiple temporal layers to reduce the difference of subjective quality is an important issue.

This thesis proposes a rate allocation method for SVC temporal scalability based on perceptual quality metric. The proposed method gracefully lowers video quality in frame rate switching under the circumstance of bandwidth fluctuation. We utilize the subjective quality metric, instead of the conventional objective measurement PSNR, to measure video quality. Each temporal layer is measured by the subjective quality metric and allocated with the corresponding rate to achieve closer subjective quality between different frame rates. In simulations, several video sequences with various total rate constraints are experimented. The proposed method can efficiently allocate the rate for each temporal layer with closer subjective video quality when the bandwidth is insufficient. Compared with the JVT recommended method, the difference of subjective quality is reduced from 4.03dB to 2.8dB.