This article is about the audio codec. For the video compression technique, see Smart Bitrate Control.
SBC, or low-complexity subband codec, is an audio subband codec specified by the Bluetooth Special Interest Group (SIG) for the Advanced Audio Distribution Profile (A2DP).[1] SBC is a digital audio encoder and decoder used to transfer data to Bluetooth audio output devices like headphones or loudspeakers. It can also be used on the Internet.[2] It was designed with Bluetooth bandwidth limitations and processing power in mind to obtain a reasonably good audio quality at medium bit rates with low computational complexity.[1][3] As of A2DP version 1.3, the Low Complexity Subband Coding remains the default codec and its implementation is mandatory for devices supporting that profile, but vendors are free to add their own codecs to match their needs.[1]
At CES 2020 the Bluetooth SIG announced LC3 as the successor of SBC. LC3 is used in the LE Audio protocol based on the Bluetooth 5.2 Core Specification.[4][5][6]
SBC supports mono and stereo streams, and certain sampling frequencies up to 48 kHz. Maximum bitrate required to be supported by decoders is 320 kbit/s for mono and 512 kbit/s for stereo streams. It uses 4 or 8 subbands, an adaptive bit allocation algorithm in combination with an adaptive block PCM quantizer.[1] Frans de Bont has based the SBC audio codec on his earlier work,[7] and – in parts – on the MPEG-1 Audio Layer II standard. In addition, the SBC is based on the algorithms described in the EP-0400755B1.[8] The patent owners wrote that they allow the free usage of SBC in Bluetooth applications with a goal of boosting the use of this technology.
up to 510 kbit/s (@ 44.1 kHz) up to 507 kbit/s (@ 48 kHz)
229 kbit/s (@ 44.1 kHz) 237 kbit/s (@ 48 kHz)
328 kbit/s (@ 44.1 kHz) 345 kbit/s (@ 48 kHz)
212 kbit/s (@ 48 kHz)
72 kbit/s (@ 16 kHz)
1411 kbit/s (@ 44.1 kHz)
Subbands
4 or 8
8
?
Bitpool
2 - 86 (@ 44.1 kHz) 2 - 78 (@ 48 kHz)
35 (@ 44.1 kHz) 33 (@ 48 kHz)
53 (@ 44.1 kHz) 51 (@ 48 kHz)
29
32
?
Middle and High QualityEdit
A2DP recommends encoders to support Middle Quality and High Quality presets as specified in the above table. As a result, most operating systems are using the High Quality profile as the default or even the only one supported encoding profile.[10]
Higher quality variantsEdit
However, A2DP requires decoders to support higher quality streams, up to 512 kbit/s, and there are some experimental encoders that use this feature: for example, SBC XQ, used by Lineage OS[14] and PipeWire.[15] With higher bit rate, audio quality is comparable to aptX HD (529 kbit/s).[16]
FastStreamEdit
While A2DP officially supports only one-way audio streams, CSR has found a way to send a voice-back stream opposite to the main stereo stream, making it possible to use A2DP in headsets with microphones. It was implemented in the FastStream codec, which is the SBC codec with set parameters and the voice-back stream added.[10][13]
ImplementationsEdit
The A2DP test specification (V1.0) contains a reference implementation of the encoder and decoder for the SBC codec. A Linux implementation is available at BlueZ - The Linux Bluetooth stack.
^ValdikSS (6 July 2019). "Bluetooth SBC Dual Channel HD audio mode". Lineage OS. Retrieved 6 April 2021.
^Frederic Danis (29 April 2022). "PipeWire: Bluetooth support status update". Retrieved 7 August 2022.
^Serge Smirnoff (29 June 2019). "Audio quality of SBC XQ Bluetooth audio codec". SoundExpert. Retrieved 6 April 2021.
October 19, 2023
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This article is about the audio codec For the video compression technique see Smart Bitrate Control SBC or low complexity subband codec is an audio subband codec specified by the Bluetooth Special Interest Group SIG for the Advanced Audio Distribution Profile A2DP 1 SBC is a digital audio encoder and decoder used to transfer data to Bluetooth audio output devices like headphones or loudspeakers It can also be used on the Internet 2 It was designed with Bluetooth bandwidth limitations and processing power in mind to obtain a reasonably good audio quality at medium bit rates with low computational complexity 1 3 As of A2DP version 1 3 the Low Complexity Subband Coding remains the default codec and its implementation is mandatory for devices supporting that profile but vendors are free to add their own codecs to match their needs 1 At CES 2020 the Bluetooth SIG announced LC3 as the successor of SBC LC3 is used in the LE Audio protocol based on the Bluetooth 5 2 Core Specification 4 5 6 Contents 1 Design 2 Variants 2 1 Overview 2 2 Middle and High Quality 2 3 Higher quality variants 2 4 FastStream 3 Implementations 4 See also 5 ReferencesDesign EditSBC supports mono and stereo streams and certain sampling frequencies up to 48 kHz Maximum bitrate required to be supported by decoders is 320 kbit s for mono and 512 kbit s for stereo streams It uses 4 or 8 subbands an adaptive bit allocation algorithm in combination with an adaptive block PCM quantizer 1 Frans de Bont has based the SBC audio codec on his earlier work 7 and in parts on the MPEG 1 Audio Layer II standard In addition the SBC is based on the algorithms described in the EP 0400755B1 8 The patent owners wrote that they allow the free usage of SBC in Bluetooth applications with a goal of boosting the use of this technology Variants EditOverview Edit SBC 1 9 SBC profiles 1 FastStream 10 Audio CDMiddle Quality High Qualitymain stream back stream for reference misc Launch May 2003 March 2008 11 1982Related patents EP 0400755B1 8 expired US 9398620B1 12 expired Free implementations BlueZ libsbc PulseAudio PipeWire PipeWire patches for PulseAudio 13 Proprietary implementations multiple hardware implementations hardware implementation in Qualcomm chips AudioEncoding Channels Mono 1 Joint Stereo 2 Joint Stereo 2 Joint Stereo 2 Mono 1 Stereo 2 Sampling rate 16 kHz32 kHz44 1 kHz48 kHz 44 1 kHz48 kHz 44 1 kHz48 kHz 16 kHz 44 1 kHz Bit rate up to 510 kbit s 44 1 kHz up to 507 kbit s 48 kHz 229 kbit s 44 1 kHz 237 kbit s 48 kHz 328 kbit s 44 1 kHz 345 kbit s 48 kHz 212 kbit s 48 kHz 72 kbit s 16 kHz 1411 kbit s 44 1 kHz Subbands 4 or 8 8 Bitpool 2 86 44 1 kHz 2 78 48 kHz 35 44 1 kHz 33 48 kHz 53 44 1 kHz 51 48 kHz 29 32 Middle and High Quality Edit A2DP recommends encoders to support Middle Quality and High Quality presets as specified in the above table As a result most operating systems are using the High Quality profile as the default or even the only one supported encoding profile 10 Higher quality variants Edit However A2DP requires decoders to support higher quality streams up to 512 kbit s and there are some experimental encoders that use this feature for example SBC XQ used by Lineage OS 14 and PipeWire 15 With higher bit rate audio quality is comparable to aptX HD 529 kbit s 16 FastStream Edit While A2DP officially supports only one way audio streams CSR has found a way to send a voice back stream opposite to the main stereo stream making it possible to use A2DP in headsets with microphones It was implemented in the FastStream codec which is the SBC codec with set parameters and the voice back stream added 10 13 Implementations EditThe A2DP test specification V1 0 contains a reference implementation of the encoder and decoder for the SBC codec A Linux implementation is available at BlueZ The Linux Bluetooth stack See also EditAudio codec aptX Bluetooth profile Adaptive differential pulse code modulation List of codecsReferences Edit a b c d e f Bluetooth SIG Specification of the Bluetooth System Profiles Advanced Audio Distribution Profile version 1 3 https www bluetooth org docman handlers DownloadDoc ashx doc id 260859 amp vId 290074 C Hoene F de Bont RTP Payload Format for Bluetooth s SBC audio codec IETF draft work in progress Dec 2010 https tools ietf org html draft ietf avt rtp sbc 01 Stephen Wray 26 June 2008 Bluetooth Sufficient fidelity even for average listeners EDN Network Retrieved 4 January 2012 Bluetooth Audio Gets a Big Upgrade at CES 2020 Bluetooth Technology Website 2020 01 13 Retrieved 2022 01 17 Frumusanu Andrei CES 2020 Bluetooth SIG Announces LE Audio Standard New Baseline For Next Decade www anandtech com Retrieved 2022 01 17 What is LE Audio and LC3 the latest in Bluetooth audio TIC 21 February 2020 Retrieved 2022 01 17 F de Bont M Groenewegen and W Oomen A High Quality Audio Coding System at 128 kb s 98th AES Convention Febr 25 28 1995 a b J B Rault Y F Dehery J Y Roudaut A A M Bruekers R N J Veldhuis Digital transmission system using subband coding of a digital signal Publication number EP0400755 B1 Priority number s EP19900201369 19900530 EP19890201408 19890602 ValdikSS Bluetooth A2DP SBC Codec Bitrate Calculator ValdikSS Retrieved 6 April 2021 a b c ValdikSS 18 June 2019 Audio over Bluetooth most detailed information about profiles codecs and devices Habr Retrieved 6 April 2021 CSR CSR presents handset makers with revolutionary audio processing technology CSR Archived from the original on 2008 05 09 Retrieved 9 May 2008 J J Lazzeroni M K Carevich J D Vertz P E H Hauser S J Kingston Simultaneous voice and audio traffic between two devices on a wireless personal area network Publication number US9398620 B1 a b Pali Rohar 2 June 2019 PATCH v11 07 11 bluetooth Add A2DP FastStream codec support pulseaudio discuss mailing list Retrieved 6 April 2021 ValdikSS 6 July 2019 Bluetooth SBC Dual Channel HD audio mode Lineage OS Retrieved 6 April 2021 Frederic Danis 29 April 2022 PipeWire Bluetooth support status update Retrieved 7 August 2022 Serge Smirnoff 29 June 2019 Audio quality of SBC XQ Bluetooth audio codec SoundExpert Retrieved 6 April 2021 Retrieved from https en wikipedia org w index php title SBC codec amp oldid 1169517546, wikipedia, wiki, book, books, library,
