Opus Recommended Settings

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Revision as of 14:56, 2 June 2016 by MrZeus (talk | contribs) (add bandwidth transision table)
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Depending on what kinds of sounds you want to encode with Opus, you'll want different settings.

The following table has rough guidelines to help you get your required quality, file size or latency. The table is originally taken from the HydrogenAudio wiki, which has some great information on Opus and its usage.

Bitrate target Stereo mode Bandwidth typ SILK/CELT use Music quality notes Use cases/notes/competitive codecs
6 kbps mono 4 kHz SILK Poor, muffled sound but intelligible lyrics. -
8 kbps mono 4 kHz SILK Poor, muffled but OK for bitrate -
14 to 16 kbps mono 6 kHz SILK Fairly Poor but OK for bitrate Perhaps acceptable for incidental music
22 to 24 kbps mono 8 kHz SILK Fair but OK for bitrate OK for incidental music
32 kbps mono 12 kHz hybrid Moderately good mono, reasonably bright treble (c.f. mono cassette) Good for podcasts, audiobooks, CELT-only poss for music. Competitor HE-AAC@32kbps is stereo full-band but with annoying artifacts.
36 to 40 kbps stereo 12 kHz hybrid/CELT Moderately good stereo, reasonably bright treble (c.f. stereo cassette) Stereo podcasts, audiobooks, very low bitrate music
48 kbps stereo 20 kHz CELT Full bandwidth stereo music, some artifacts, rarely nasty Stereo podcasts, audiobooks, low bitrate music
64 kbps stereo 20 kHz CELT Full bandwidth stereo music, nice sound, detectable differences to original (mostly 'not annoying') Music storage & streaming. Beat HE-AAC, Vorbis, MP3 in listening test
96 kbps stereo 20 kHz CELT Full bandwidth stereo music, good quality approaching transparency Music storage & high quality streaming. Beat LC-AAC, Vorbis, MP3 in listening test
112 kbps stereo 20 kHz CELT Fairly close to transparency (needs more testing) Music storage & high quality streaming. Very low-latency stereo networked music performance/jam sessions at OK quality (see below table)
128 kbps stereo 20 kHz CELT Very close to transparency (needs more testing). Most modern codecs competitive (AAC-LC, Vorbis, MP3) Music storage & streaming. Future download music sales.
256 kbps stereo 20 kHz CELT Transparent with very low chance of artifacts (a few killer samples still detectable). Most old & new lossy codecs competitive. Music storage & streaming, dedicated limited-bandwidth audio links (e.g. wireless, A2DP-bluetooth type links).
510 kbps stereo 20 kHz CELT Maximum possible stereo bitrate target (actual rate often less than 510 for default frame size). Most old and new lossy codecs competitive, plus near-lossless lossyWAV and WavPack lossy Music storage, dedicated limited-bitrate audio links (e.g. wireless, minimum latency high quality audio. LossyWAV and WavPack lossy are very competitive for storage, and WavPack lossy --blocksize=256 may be competitive with minimum latency mode also.
>510 kbps - - - Above Opus bitrate range allowed for stereo sources Settle for 510kbps or use lossless, lossyWAV, WavPack lossy or lossy transform/subband codecs like Vorbis, Musepack at very high settings.

Bandwidth Transition Thresholds

The following table was copied from the opus_encoder.c source file.

(bitrates in KHz) Mono Stereo
Voice Music Voice Music
NB ↔ MB 11 ± 1 12 ± 1 11 ± 1 12 ± 2
MB ↔ WB 14 ± 1 15 ± 1 14 ± 2 18 ± 2
WB ↔ SWB 17 ± 1 18 ± 1 21 ± 2 21 ± 2
SWB ↔ FB 21 ± 1 22 ± 2 28 ± 2 30 ± 2