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Opus Audio: Pairing Skype's SILC With CELT

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  • #16
    The catch would probably be that, Opus didn't exist until now. All those years of not having it, were a PITA.

    [oneman@rawdod4::/data2/music/music/Kraftwerk - The Man-Machine (1978) [FLAC]]$ time opusenc --bitrate 128 04\ -\ The\ Model.wav 04\ -\ The\ Model.opus
    Encoding using libopus 0.9.11-55-g7143b2d (audio)
    Input: 44.1kHz 2 channels
    Output: 2 channels (2 coupled)
    20ms packets, 128kbit/sec VBR
    Preskip: 356

    Encoding complete
    Encoded: 3 minutes and 42.52 seconds
    Runtime: 6.074 seconds
    (36.64x realtime)
    Wrote: 3439926 bytes, 11126 packets, 225 pages
    Bitrate: 122.682kbit/s (without overhead)
    Rate range: 1.2kbit/s to 221.2kbit/s
    (3 to 553 bytes per packet)
    Overhead: 0.8% (container+metadata)

    real 0m6.075s
    user 0m6.056s
    sys 0m0.012s


    • #17
      Nice, it's as fast encoding. I do wonder about decoding still.


      • #18
        it takes about 1.2 seconds to decode one minute of opus

        [oneman@rawdod4::/data2/music/music/Kraftwerk - The Man-Machine (1978) [FLAC]]$ time opusdec 04\ -\ The\ Model.opus 04\ -\ The\ Model.wav.test
        Decoding 44100 Hz audio (2 channels)
        Encoded with 0.1.0 0.1.0 (using libopus 0.9.11-55-g7143b2d)

        real 0m4.772s
        user 0m4.744s
        sys 0m0.016s
        [oneman@rawdod4::/data2/music/music/Kraftwerk - The Man-Machine (1978) [FLAC]]$


        • #19
          OK, so decoding opus needs five times the cpu of vorbis, approximately.


          • #20
            I would never reccomend storing your music collection in Opus. Opus is a CBR or constant bit rate codec. If you're going to store your music, you should either store it in a lossless or in a lossy VBR or variable bit rate codec. It should be noted that opus simply blows it's competitors out of the water when it comes to telephony. It would be amazing if all phones started using opus. It would be a great victory for open source in multimedia. Unless I am mistaken, after Opus, Xiph will begin focusing its efforts on transogg (a new media container), ghost (a new VBR lossy/lossless hybrid audio codec that is meant to be by far the best standard lossy audio codec), and daala (a new lossy video codec that is indended to be better than h.265). I'm sure they could use all the help they can get against MPEG LA, but if Opus is any indication, then maybe we can eventually win the fight for open codecs.
            Last edited by Prescience500; 06-04-2012, 11:06 PM.


            • #21
              According to their web page ( Opus can also do VBR. And btw, CBR/VBR is not really a feature of the codec but of the encoder and container format.