Opus Recommended Settings: Difference between revisions

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(Add some stuff about mono/stereo switching)
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|-
|-
!Bitrate target
!Bitrate target
!Stereo mode
!Bandwidth
!typ SILK/CELT use
!Music quality notes
!Music quality notes
!Use cases/notes/competitive codecs
!Use cases/notes/competitive codecs
|-
|-
!6 kbps
!6 kbps
|mono
|4 kHz
|SILK
|Poor, muffled sound but intelligible lyrics.
|Poor, muffled sound but intelligible lyrics.
| -
| -
|-
|-
!8 kbps
!8 kbps
|mono
|4 kHz
|SILK
|Poor, muffled but OK for bitrate
|Poor, muffled but OK for bitrate
| -
| -
|-
|-
!14 to 16 kbps
!14 to 16 kbps
|mono
|6 kHz
|SILK
|Fairly Poor but OK for bitrate
|Fairly Poor but OK for bitrate
|Perhaps acceptable for incidental music
|Perhaps acceptable for incidental music
|-
|-
!22 to 24 kbps
!22 to 24 kbps
|mono
|8 kHz
|SILK
|Fair but OK for bitrate
|Fair but OK for bitrate
|OK for incidental music
|OK for incidental music
|-
|-
!32 kbps
!32 kbps
|mono
|12 kHz
|hybrid
|Moderately good mono, reasonably bright treble (c.f. mono cassette)
|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.
|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
!36 to 40 kbps
|stereo
|12 kHz
|hybrid/CELT
|Moderately good stereo, reasonably bright treble (c.f. stereo cassette)
|Moderately good stereo, reasonably bright treble (c.f. stereo cassette)
|Stereo podcasts, audiobooks, very low bitrate music
|Stereo podcasts, audiobooks, very low bitrate music
|-
|-
!48 kbps
!48 kbps
|stereo
|20 kHz
|CELT
|Full bandwidth stereo music, some artifacts, rarely nasty
|Full bandwidth stereo music, some artifacts, rarely nasty
|Stereo podcasts, audiobooks, low bitrate music
|Stereo podcasts, audiobooks, low bitrate music
|-
|-
!64 kbps
!64 kbps
|stereo
|20 kHz
|CELT
|Full bandwidth stereo music, nice sound, detectable differences to original (mostly 'not annoying')
|Full bandwidth stereo music, nice sound, detectable differences to original (mostly 'not annoying')
|Music storage & streaming. Beat HE-AAC, Vorbis, MP3 in [http://people.xiph.org/~greg/opus/ha2011/ listening test]
|Music storage & streaming. Beat HE-AAC, Vorbis, MP3 in [http://people.xiph.org/~greg/opus/ha2011/ listening test]
|-
|-
!96 kbps
!96 kbps
|stereo
|20 kHz
|CELT
|Full bandwidth stereo music, good quality approaching transparency
|Full bandwidth stereo music, good quality approaching transparency
|Music storage & high quality streaming. Beat LC-AAC, Vorbis, MP3 in [http://listening-test.coresv.net/results.htm listening test]
|Music storage & high quality streaming. Beat LC-AAC, Vorbis, MP3 in [http://listening-test.coresv.net/results.htm listening test]
|-
|-
!112 kbps
!112 kbps
|stereo
|20 kHz
|CELT
|Fairly close to transparency (needs more testing)
|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)
|Music storage & high quality streaming. Very low-latency stereo networked music performance/jam sessions at OK quality (see below table)
|-
|-
!128 kbps
!128 kbps
|stereo
|20 kHz
|CELT
|Very close to transparency (needs more testing). Most modern codecs competitive (AAC-LC, Vorbis, MP3)
|Very close to transparency (needs more testing). Most modern codecs competitive (AAC-LC, Vorbis, MP3)
|Music storage & streaming. Future download music sales.
|Music storage & streaming. Future download music sales.
|-
|-
!256 kbps
!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.
|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, [http://en.wikipedia.org/wiki/Bluetooth_profile#Advanced_Audio_Distribution_Profile_.28A2DP.29 A2DP-bluetooth] type links).  
|Music storage & streaming, dedicated limited-bandwidth audio links (e.g. wireless, [http://en.wikipedia.org/wiki/Bluetooth_profile#Advanced_Audio_Distribution_Profile_.28A2DP.29 A2DP-bluetooth] type links).  
|-
|-
!510 kbps
!510 kbps
|stereo
|Maximum possible stereo bitrate target (actual rate often less than 510 for default frame size). At these bitrates, you probably want to be using [[FLAC]]...
|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 | 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.
|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
!>510 kbps
| -
|Above Opus bitrate range allowed for stereo sources.
| -
|Settle for 510kbps or use [[FLAC]].
| -
|Above Opus bitrate range allowed for stereo sources
|Settle for 510kbps or use [[lossless]], [[lossyWAV]], [[WavPack | WavPack lossy]] or lossy transform/subband codecs like [[Vorbis]], [[Musepack]] at very high settings.
|-
|-
|}
|}

Revision as of 14:41, 2 June 2016

Depending on what kinds of sounds you want to encode with Opus, you'll want different settings.

Mono/Stereo

Opus tends to start downmixing stereo inputs to mono from roughly 30 Kb/s and lower. You can check the details in the opus_encoder.c source file.

You can force downmixing by using the following command-line parameters:

--downmix-mono - downmixes input channels to mono

--downmix-stereo - downmixes input channels to stereo (if there are more than 2)

Bandwidth Transition Thresholds

The following table shows where Opus decides to switch between different bandwidths. It was copied from the opus_encoder.c source file.

(bitrates in Kb/s) 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

Usage Table

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 Music quality notes Use cases/notes/competitive codecs
6 kbps Poor, muffled sound but intelligible lyrics. -
8 kbps Poor, muffled but OK for bitrate -
14 to 16 kbps Fairly Poor but OK for bitrate Perhaps acceptable for incidental music
22 to 24 kbps Fair but OK for bitrate OK for incidental music
32 kbps 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 Moderately good stereo, reasonably bright treble (c.f. stereo cassette) Stereo podcasts, audiobooks, very low bitrate music
48 kbps Full bandwidth stereo music, some artifacts, rarely nasty Stereo podcasts, audiobooks, low bitrate music
64 kbps 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 Full bandwidth stereo music, good quality approaching transparency Music storage & high quality streaming. Beat LC-AAC, Vorbis, MP3 in listening test
112 kbps 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 Very close to transparency (needs more testing). Most modern codecs competitive (AAC-LC, Vorbis, MP3) Music storage & streaming. Future download music sales.
256 kbps 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 Maximum possible stereo bitrate target (actual rate often less than 510 for default frame size). At these bitrates, you probably want to be using FLAC... 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 FLAC.
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