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SBC (codec)
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<h2 id="design">Design</h2> <p>SBC supports mono and stereo streams, and certain <a href="/facts/Sample_frequency/xxck7aLN">sampling frequencies</a> 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.<a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a> Frans de Bont has based the SBC audio codec on his earlier work,<a class="footnote-ref" id="fnref:10" href="#fn:10"><sup>10</sup></a> and – in parts – on the <a href="/facts/MPEG-1_Audio_Layer_II/eBSjFASu">MPEG-1 Audio Layer II</a> standard. In addition, the SBC is based on the algorithms described in the EP-0400755B1.<a class="footnote-ref" id="fnref:11" href="#fn:11"><sup>11</sup></a> 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. </p> <h2 id="variants">Variants</h2> <h3>Overview</h3> <table><tbody><tr><th rowspan="3" colspan="2"></th><th rowspan="3">SBC<a class="footnote-ref" id="fnref:12" href="#fn:12"><sup>12</sup></a><a class="footnote-ref" id="fnref:13" href="#fn:13"><sup>13</sup></a></th><th colspan="2">SBC profiles<a class="footnote-ref" id="fnref:14" href="#fn:14"><sup>14</sup></a></th><th colspan="2" rowspan="2">FastStream<a class="footnote-ref" id="fnref:15" href="#fn:15"><sup>15</sup></a></th><th rowspan="2"><a href="/facts/Compact_Disc_Digital_Audio/FDMqNLw5">Audio CD</a></th></tr><tr><th>Middle Quality</th><th>High Quality</th></tr><tr><th></th><th></th><th>main stream</th><th>back stream</th><th>(for reference)</th></tr><tr><th rowspan="4">misc.</th><th>Launch</th><td>–</td><td colspan="2">May 2003</td><td colspan="2">March 2008<a class="footnote-ref" id="fnref:16" href="#fn:16"><sup>16</sup></a></td><td>1982</td></tr><tr><th>Related <a href="/facts/Patent/LjT2bG3A">patents</a></th><td><a href="https://worldwide.espacenet.com/textdoc?DB=EPODOC&IDX=EP0400755B1">EP 0400755B1</a> <a class="footnote-ref" id="fnref:17" href="#fn:17"><sup>17</sup></a>(expired)</td><td colspan="2">–</td><td colspan="2"><a href="https://worldwide.espacenet.com/textdoc?DB=EPODOC&IDX=US9398620B1">US 9398620B1</a> <a class="footnote-ref" id="fnref:18" href="#fn:18"><sup>18</sup></a>(expired)</td><td>–</td></tr><tr><th><a href="/facts/Free_software/IaoVtJXn">Freeimplementations</a></th><td><a href="/facts/FFmpeg/85yf3kHI">FFmpeg</a>, libsbc</td><td colspan="2">libsbc</td><td colspan="2">libsbc</td><td>–</td></tr><tr><th><a href="/facts/Proprietary_software/9zcskxYL">Proprietaryimplementations</a></th><td>–</td><td colspan="2">multiple hardwareimplementations</td><td colspan="2">hardware implementationin <a href="/facts/Qualcomm/v54S3UgA">Qualcomm</a> chips</td><td>–</td></tr><tr><th rowspan="5">AudioEncoding</th><th>Channels</th><td>Mono (1)Joint Stereo (2)</td><td colspan="2">Joint Stereo (2)</td><td>Joint Stereo (2)</td><td>Mono (1)</td><td>Stereo (2)</td></tr><tr><th><a href="/facts/Sampling_rate/xxck7aLN">Sampling rate</a></th><td>16 kHz32 kHz44.1 kHz48 kHz</td><td colspan="2">44.1 kHz48 kHz</td><td>44.1 kHz48 kHz</td><td>16 kHz</td><td>44.1 kHz </td></tr><tr><th><a href="/facts/Bit_rate/ppUNMmVd">Bit rate</a></th><td>up to 510 kbit/s(@ 44.1 kHz)up to 507 kbit/s(@ 48 kHz)</td><td>229 kbit/s(@ 44.1 kHz)237 kbit/s(@ 48 kHz)</td><td>328 kbit/s(@ 44.1 kHz)345 kbit/s(@ 48 kHz)</td><td>212 kbit/s(@ 48 kHz)</td><td>72 kbit/s(@ 16 kHz)</td><td>1411 kbit/s(@ 44.1 kHz)</td></tr><tr><th>Subbands</th><td>4 or 8</td><td colspan="4">8</td><td>none</td></tr><tr><th>Bitpool</th><td>2...86 (@ 44.1 kHz)2...78 (@ 48 kHz)</td><td>35 (@ 44.1 kHz)33 (@ 48 kHz)</td><td>53 (@ 44.1 kHz)51 (@ 48 kHz)</td><td>29</td><td>32</td><td>none</td></tr></tbody></table> <h3>Middle and High Quality</h3> <p>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.<a class="footnote-ref" id="fnref:19" href="#fn:19"><sup>19</sup></a> </p> <h3>Higher quality variants</h3> <p>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 <a href="/facts/Lineage_OS/2EjbG71g">Lineage OS</a>.<a class="footnote-ref" id="fnref:20" href="#fn:20"><sup>20</sup></a> With higher bit rate, audio quality is comparable to <a href="/facts/AptX/cSevMczh">aptX HD</a> (529 kbit/s).<a class="footnote-ref" id="fnref:21" href="#fn:21"><sup>21</sup></a> </p> <h3>FastStream</h3> <p>While A2DP officially supports only one-way audio streams, <a href="/facts/CSR_(company)/mKGWb7X9">CSR</a> 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.<a class="footnote-ref" id="fnref:22" href="#fn:22"><sup>22</sup></a><a class="footnote-ref" id="fnref:23" href="#fn:23"><sup>23</sup></a> </p> <h2 id="implementations">Implementations</h2> <p>The A2DP test specification (V1.0) contains a <a href="/facts/Reference_implementation/k9B97xel">reference implementation</a> of the encoder and decoder for the SBC codec. A Linux implementation is available at <a href="/facts/BlueZ/MFzmTcos">BlueZ</a> - The Linux Bluetooth stack. </p> <h2 id="see-also">See also</h2> <ul><li><a href="/facts/Audio_codec/DkXoa6YP">Audio codec</a></li> <li><a href="/facts/AptX/cSevMczh">aptX</a></li> <li><a href="/facts/Bluetooth_profile/gYIdytMA">Bluetooth profile</a></li> <li><a href="/facts/Adaptive_differential_pulse-code_modulation/Q6cFrNUb">Adaptive differential pulse-code modulation</a></li> <li><a href="/facts/List_of_codecs/e5nTCc5X">List of codecs</a></li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>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&vId=290074 <a href="https://www.bluetooth.org/docman/handlers/DownloadDoc.ashx?doc_id=260859&vId=290074" target="_blank">https://www.bluetooth.org/docman/handlers/DownloadDoc.ashx?doc_id=260859&vId=290074</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>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 <a href="https://tools.ietf.org/html/draft-ietf-avt-rtp-sbc-01" target="_blank">https://tools.ietf.org/html/draft-ietf-avt-rtp-sbc-01</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>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&vId=290074 <a href="https://www.bluetooth.org/docman/handlers/DownloadDoc.ashx?doc_id=260859&vId=290074" target="_blank">https://www.bluetooth.org/docman/handlers/DownloadDoc.ashx?doc_id=260859&vId=290074</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>Stephen Wray (26 June 2008). "Bluetooth: Sufficient fidelity even for average listeners?". EDN Network. Retrieved 4 January 2012. <a href="http://www.edn.com/design/consumer/4326740/Bluetooth-Sufficient-fidelity-even-for-average-listeners-" target="_blank">http://www.edn.com/design/consumer/4326740/Bluetooth-Sufficient-fidelity-even-for-average-listeners-</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>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&vId=290074 <a href="https://www.bluetooth.org/docman/handlers/DownloadDoc.ashx?doc_id=260859&vId=290074" target="_blank">https://www.bluetooth.org/docman/handlers/DownloadDoc.ashx?doc_id=260859&vId=290074</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>"Bluetooth Audio Gets a Big Upgrade at CES 2020". Bluetooth Technology Website. 2020-01-13. Retrieved 2022-01-17. <a href="https://www.bluetooth.com/blog/bluetooth-audio-gets-a-big-upgrade-at-ces-2020/" target="_blank">https://www.bluetooth.com/blog/bluetooth-audio-gets-a-big-upgrade-at-ces-2020/</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> <li id="fn:7"><p>Frumusanu, Andrei. "CES 2020: Bluetooth SIG Announces LE Audio Standard: New Baseline For Next Decade". www.anandtech.com. Retrieved 2022-01-17. <a href="https://www.anandtech.com/show/15349/bluetooth-sig-announces-le-audio-standard-new-baseline-for-next-decade" target="_blank">https://www.anandtech.com/show/15349/bluetooth-sig-announces-le-audio-standard-new-baseline-for-next-decade</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li> <li id="fn:8"><p>"What is LE Audio and LC3, the latest in Bluetooth audio?". TIC. 21 February 2020. Retrieved 2022-01-17. <a href="https://ticcorp.com/blogs/news/what-is-le-audio-and-lc3-the-latest-in-bluetooth-audio" target="_blank">https://ticcorp.com/blogs/news/what-is-le-audio-and-lc3-the-latest-in-bluetooth-audio</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li> <li id="fn:9"><p>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&vId=290074 <a href="https://www.bluetooth.org/docman/handlers/DownloadDoc.ashx?doc_id=260859&vId=290074" target="_blank">https://www.bluetooth.org/docman/handlers/DownloadDoc.ashx?doc_id=260859&vId=290074</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li> <li id="fn:10"><p>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 href="#fnref:10" class="footnote-back-ref">↩</a></p></li> <li id="fn:11"><p>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 <a href="#fnref:11" class="footnote-back-ref">↩</a></p></li> <li id="fn:12"><p>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&vId=290074 <a href="https://www.bluetooth.org/docman/handlers/DownloadDoc.ashx?doc_id=260859&vId=290074" target="_blank">https://www.bluetooth.org/docman/handlers/DownloadDoc.ashx?doc_id=260859&vId=290074</a> <a href="#fnref:12" class="footnote-back-ref">↩</a></p></li> <li id="fn:13"><p>ValdikSS. "Bluetooth A2DP SBC Codec Bitrate Calculator". ValdikSS. Retrieved 6 April 2021. <a href="https://btcodecs.valdikss.org.ru/sbc-bitrate-calculator/" target="_blank">https://btcodecs.valdikss.org.ru/sbc-bitrate-calculator/</a> <a href="#fnref:13" class="footnote-back-ref">↩</a></p></li> <li id="fn:14"><p>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&vId=290074 <a href="https://www.bluetooth.org/docman/handlers/DownloadDoc.ashx?doc_id=260859&vId=290074" target="_blank">https://www.bluetooth.org/docman/handlers/DownloadDoc.ashx?doc_id=260859&vId=290074</a> <a href="#fnref:14" class="footnote-back-ref">↩</a></p></li> <li id="fn:15"><p>ValdikSS (18 June 2019). "Audio over Bluetooth: most detailed information about profiles, codecs, and devices". Habr. Retrieved 6 April 2021. <a href="https://habr.com/en/post/456182/" target="_blank">https://habr.com/en/post/456182/</a> <a href="#fnref:15" class="footnote-back-ref">↩</a></p></li> <li id="fn:16"><p>CSR. "CSR presents handset makers with revolutionary audio processing technology". CSR. Archived from the original on 2008-05-09. Retrieved 9 May 2008. <a href="https://web.archive.org/web/20080509054609/www.csr.com/pr/pr328.htm" target="_blank">https://web.archive.org/web/20080509054609/www.csr.com/pr/pr328.htm</a> <a href="#fnref:16" class="footnote-back-ref">↩</a></p></li> <li id="fn:17"><p>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 <a href="#fnref:17" class="footnote-back-ref">↩</a></p></li> <li id="fn:18"><p>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 href="#fnref:18" class="footnote-back-ref">↩</a></p></li> <li id="fn:19"><p>ValdikSS (18 June 2019). "Audio over Bluetooth: most detailed information about profiles, codecs, and devices". Habr. Retrieved 6 April 2021. <a href="https://habr.com/en/post/456182/" target="_blank">https://habr.com/en/post/456182/</a> <a href="#fnref:19" class="footnote-back-ref">↩</a></p></li> <li id="fn:20"><p>ValdikSS (6 July 2019). "Bluetooth SBC Dual Channel HD audio mode". Lineage OS. Retrieved 6 April 2021. <a href="https://lineageos.org/engineering/Bluetooth-SBC-XQ/" target="_blank">https://lineageos.org/engineering/Bluetooth-SBC-XQ/</a> <a href="#fnref:20" class="footnote-back-ref">↩</a></p></li> <li id="fn:21"><p>Serge Smirnoff (29 June 2019). "Audio quality of SBC XQ Bluetooth audio codec". SoundExpert. Retrieved 6 April 2021. <a href="http://soundexpert.org/articles/-/blogs/audio-quality-of-sbc-xq-bluetooth-audio-codec" target="_blank">http://soundexpert.org/articles/-/blogs/audio-quality-of-sbc-xq-bluetooth-audio-codec</a> <a href="#fnref:21" class="footnote-back-ref">↩</a></p></li> <li id="fn:22"><p>ValdikSS (18 June 2019). "Audio over Bluetooth: most detailed information about profiles, codecs, and devices". Habr. Retrieved 6 April 2021. <a href="https://habr.com/en/post/456182/" target="_blank">https://habr.com/en/post/456182/</a> <a href="#fnref:22" class="footnote-back-ref">↩</a></p></li> <li id="fn:23"><p>Pali Rohár (2 June 2019). "[PATCH v11 07/11] bluetooth: Add A2DP FastStream codec support". pulseaudio-discuss mailing list. Retrieved 6 April 2021. <a href="https://lists.freedesktop.org/archives/pulseaudio-discuss/2019-June/031175.html" target="_blank">https://lists.freedesktop.org/archives/pulseaudio-discuss/2019-June/031175.html</a> <a href="#fnref:23" class="footnote-back-ref">↩</a></p></li> </ol>