Slice-balancing H.264 video encoding for improved scalability of multicore decoding

  • Authors:

  • Michael Roitzsch

  • Affiliations:

  • Technische Universität Dresden, Dresden, Germany

  • Venue:
  • EMSOFT '07 Proceedings of the 7th ACM & IEEE international conference on Embedded software
  • Year:
  • 2007

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Abstract

With multicore architectures being introduced to the market, the research community is revisiting problems to evaluate them under the new preconditions set by those new systems. Algorithms need to be implemented with scalability in mind. One problem that is known to be computationally demanding is video decoding. In this paper, we will present a technique that increases the scalability of H.264 video decoding by modifying only the encoder stage. In embedded scenarios, increased scalability can also enable reduced clock speeds of the individual cores, thus lowering overall power consumption. The key idea is to equalize the potentially differing decoding times of one frame's slices by applying decoding time prediction at the encoder stage. Virtually no added penalty is inflicted on the quality or size of the encoded video. Because decoding times are predicted rather than measured, the encoder does not rely on accurate timing and can therefore run as a batch job on an encoder farm as is current practice today. In addition, apart from a decoder capable of slice-parallel decoding, no changes to the installed client systems are required, because the resulting bitstreams will still be fully compliant to the H.264 standard. Consequently, this paper also contributes a way to accurately predict H.264 decoding times with average relative errors down to 1%.