Low-latency streaming of pre-encoded video using channel-adaptive bitstream assembly

Today's Internet video streaming systems employ buffering and retransmission to guarantee the correct reception of each packet. This leads to high latency in media delivery. In this paper, we present an efficient low-latency Internet video streaming system that does not require retransmission of lost packets. We pre-store multiple representations of certain frames on the server such that a representation using a more reliable reference frame will be selected and sent during transmission. The potential mismatch error during bitstream assembly at transmission is avoided by using a novel layered coding structure with coding restrictions. The optimal picture type is determined within a rate-distortion framework during pre-encoding and transmission, adapting to the channel, so that the expected end-to-end distortion is minimized under the given rate constraint. The expected distortion is calculated based on an accurate binary tree modeling with the effects of channel loss and error concealment taken into account. Experiments demonstrate that the proposed scheme provides significant performance gains over a simple INTRA-insertion scheme. The increased error-resilience eliminates the need for retransmission, which allows to reduce the latency of streaming from 10-15 seconds to a few hundred milliseconds, with good video quality maintained.