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LDAC (codec)

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LDAC
Developed bySony
Type of formatAudio codec

LDAC (Lossless Digital Audio Codec) is a proprietary audio coding technology developed by Sony, which allows streaming high-resolution audio over Bluetooth connections at up to 990 kbps at 32 bits/96 kHz. It is used by various products, including headphones, earphones, smartphones, portable media players, active speakers, and home theaters.

The encoder of LDAC is open-source under Apache License 2.0, so that any device can be coded to transmit LDAC streams without patent or licensing issues. The decoder design remains proprietary.

Audio coding

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LDAC is an alternative to Bluetooth SIG's SBC codec. Its main competitors are Huawei's L2HC, Qualcomm's aptX-HD/aptX Adaptive and the HWA Union/Savitech's LHDC.[1]

LDAC utilizes a type of lossy compression[2][3] by employing a hybrid coding scheme based on the modified discrete cosine transform[4] and Huffman coding[5] to provide more efficient data compression. By default, LDAC audio bitrate settings are set to Best Effort, which switches between discrete bitrate steps (CBR) 330/660/990 kbps depending on connection strength;[6] however, audio bitrate and resolution can be manually adjusted on Linux (when using PipeWire[7]), some Android platforms (which generally requires access to the "Developer Settings" menu), and Sony's own smartphones and Walkman devices at the following rates; 330/660/990 kbps at 96/48 kHz and 303/606/909 kbps at 88.2/44.1 kHz with depth of 32, 24 or 16 bits.[6] Lossless audio transmission can be achieved by manually configuring the codec's resolution to 44.1 kHz, 16 bits and selecting 'Sound quality preferred' for high bitrate streaming at 909 kbps. This setup is identical to a wired audio or an Audio-CD sound quality.[citation needed]

Starting from Android 8.0 "Oreo", LDAC is part of the Android Open Source Project, enabling every OEM to integrate this standard into their own Android devices freely.[5][8] The encoder library is open source and the implementation for Linux is already present in bluez-alsa,[9] pulseaudio-modules-bt,[10][11] and in PipeWire's bluez5 module.[12][13] It is available on Fedora since Fedora 29.[14] However the decoder library is proprietary, so receiving devices require licenses.[15]

On 17 September 2019, the Japan Audio Society (JAS) certified LDAC with their Hi-Res Audio Wireless certification.[16] As of June 2024, the codecs certified by the JAS to bear the Hi-Res Audio Wireless logo are LHDC, LDAC, SCL6, LC3plus, SHDC, and aptX Adaptive.[17]

See also

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References

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  1. ^ "Best Wireless Headphones of 2018". 13 November 2017. Retrieved 9 March 2018.
  2. ^ Darko, John H. (29 March 2017). "The inconvenient truth about Bluetooth audio". DAR__KO. Retrieved 13 January 2018.
  3. ^ "What is Sony LDAC, and how does it do it?". AVHub. 24 August 2015. Retrieved 13 January 2018.
  4. ^ "src/ldaclib_api.c - platform/external/libldac". android Git repositories - Git at Google.
  5. ^ a b Triggs, Robert (22 August 2017). "What you need to know about Sony's LDAC". Android Authority. Retrieved 8 January 2021.
  6. ^ a b Triggs, Robert (16 December 2018). "The ultimate guide to Bluetooth headphones: LDAC isn't Hi-res". SoundGuys. Retrieved 22 September 2019.
  7. ^ "Releases · PipeWire / pipewire". GitLab. Retrieved 11 June 2021.
  8. ^ "platform/external/libldac". android Git repositories - Git at Google. Retrieved 30 November 2018.
  9. ^ "LDAC support? · Issue #104 · Arkq/bluez-alsa". GitHub. Retrieved 20 March 2019.
  10. ^ H.H, Bao (20 March 2019), Adds Sony LDAC, aptX, aptX HD, AAC codecs (A2DP Audio) support to PulseAudio on Linux: EHfive/pulseaudio-modules-bt, retrieved 20 March 2019
  11. ^ eischmann (11 February 2019). "Better Bluetooth sound quality on Linux". Brno hat. Retrieved 20 March 2019.
  12. ^ "List of commits on the PipeWire project pertaining to LDAC support". freedesktop.org Gitlab. 31 December 2020. Retrieved 31 December 2020.
  13. ^ "Achieve parity and/or surpass PulseAudio in Bluetooth audio support". 31 December 2020. Retrieved 31 December 2020.
  14. ^ "1671064 – Review Request: libldac - LDAC library from AOSP". bugzilla.redhat.com. Retrieved 20 March 2019.
  15. ^ "Audio over Bluetooth: most detailed information about profiles, codecs, and devices". habr.com. Retrieved 9 May 2020.
  16. ^ Yeow, Goh Beng (17 September 2019). "Japan Audio Society certifies LHDC™ for "Hi-Res Audio Wireless" certification". Porta-Fi™. Retrieved 22 September 2019.
  17. ^ "Definition of Hi-Res Audio (Announced on June 12th 2014)". Japan Audio Society. 12 June 2024. Retrieved 26 June 2024.
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