Multiple bitrate output transcoder based on requantizer and reencoder sharing

Isao Nagayoshi*, Hiroyuki Kasai, Tsuyoshi Hanamura, Hideyoshi Tominaga

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


This paper proposes a video transcoder that realizes efficiently the function of multirate conversion to multiple hitrates. The multirate conversion function is realized as follows. The decoder and the inverse quantizer are shared as a single processor. The requantizer and the reencoder with the same requantization step are shared among outputs. With these provisions, an architecture is proposed whereby the processing complexity in multirate conversion can be reduced. The number of requantization processing operations per macro-block is examined theoretically, and it is shown that the conversion processing complexity can be formulated as a function of the output bitrate. Lastly, the theoretical evaluation and the evaluation experiment based on these investigations show that the sharing of the requantizer/reencoder is the scheme that reduces the increase of the processing complexity as a function of the number of outputs, and can cope with any number of outputs with two to four times the processing complexity of the single-rate output scheme.

Original languageEnglish
Pages (from-to)21-33
Number of pages13
JournalElectronics and Communications in Japan, Part I: Communications (English translation of Denshi Tsushin Gakkai Ronbunshi)
Issue number2
Publication statusPublished - 2005 Feb


  • MPEG
  • Multirate output
  • Sharing of requantizer/reencoder
  • Video transcoder

ASJC Scopus subject areas

  • Computer Networks and Communications
  • Electrical and Electronic Engineering


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