%% You should probably cite draft-ietf-payload-rtp-opus instead of this I-D.
@techreport{spittka-payload-rtp-opus-00,
    number =    {draft-spittka-payload-rtp-opus-00},
    type =      {Internet-Draft},
    institution =   {Internet Engineering Task Force},
    publisher = {Internet Engineering Task Force},
    note =      {Work in Progress},
    url =       {https://datatracker.ietf.org/doc/draft-spittka-payload-rtp-opus/00/},
    author =    {Julian Spittka and Koen Vos and Jean-Marc Valin},
    title =     {{RTP Payload Format and File Storage Format for Opus Speech and Audio Codec}},
    pagetotal = 26,
    year =      2011,
    month =     jul,
    day =       4,
    abstract =  {This document defines the Real-time Transport Protocol (RTP) payload format and file storage format for packetization of Opus encoded speech and audio data that is essential to integrate the codec in the most compatible way. Further, media type registrations are described for the RTP payload format and the file storage format.},
}