Shared Coded Picture Technique for Tile-based Viewport-adaptive Streaming of Omnidirectional Video
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|Julkaisu||IEEE Transactions on Circuits and Systems for Video Technology|
|DOI - pysyväislinkit|
|Tila||Julkaistu - 2018|
Tile-based viewport-adaptive streaming methods have been used in delivering omnidirectional video for virtual reality applications. In these methods, the 360° video is encoded in multiple quality versions by using motion constrained tile set (MCTS) technique. A set of high-quality and low-quality tiles, corresponding to viewport and non-viewport areas respectively, are selected and transmitted to the user. However, these methods require frequent intra random access points to ensure seamless viewport switching capability, very high decoding complexity or multi-layer coding scheme. The frequent intra random access points include very high bitrate in viewport switching points. The high decoding complexity and multi-layer decoder requirements are not aligned with the Omnidirectional MediA Format (OMAF) standard. Such requirements make these methods sub-optimal or impractical for streaming the omnidirectional video. This work studies the current tile-based solutions for delivering the omnidirectional content. Moreover, OMAF-compliant Shared Coded Picture (SCP) based scheme is proposed in this work for streaming the omnidirectional video. The core concept of the SCP-based method is to manipulate the switching point pictures in a way that the frequent intra-coded pictures are no longer required for the viewport switching operations between different quality versions of the content. The experiments illustrated that the SCP-based method outperforms the MCTS-based method on average by 11% to 14% in terms of streaming bitrate reduction with only 4% extra decoding complexity.