Best packetization scheme for H.263 internet video communication

Introduction: Studies of packetization schemes for the H.263+ video codec, for example [1], tend to assume the one slice per packet recommendation contained in RFC 2429 section 3.2 [2], whereas in this letter a two-slice scheme is proposed. In [3], the burst length is identified (for H.264) as a source of peak signal-to-noise ratio (PSNR) degradation, as much as the average packet loss rate. In this letter, the method of delivery, either per frame bursts, or uniform (constant) inter-packet gap (IPG) is shown to be an additional determinant of PSNR performance. When a uniform scheme was deployed with a two slice per packet scheme, tests for an “Interview” video clip resulted in superior video quality. The tests were conducted on a network test-bed with precise real-time packet generation to examine video communication across a bottleneck link in a path across an internet. The proposed two-slice scheme has the effect of better bandwidth utilization through reduced header overhead, which also critically contributes to a reduction in packet loss. A uniform IPG compared to a ‘bursty’ delivery, reduces the stress on a router by smoothing the arrival rate, which otherwise leads to harmful packet loss patterns. The test on the video clip for some frames resulted in as much as 20 dB improvement in PSNR, when using a two-slice scheme with uniform delivery. The proposals are expected to be applicable to a variety of video structures.