LDAC (codec)

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LDAC
LDAC logo.tiff
Developed bySony
Type of formatAudio codec

LDAC is a proprietary audio coding technology developed by Sony, which allows streaming high-resolution audio over Bluetooth connections at up to 990 kbps at 24 bit/96 kHz. It is used by various Sony 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[edit]

LDAC is an alternative to Bluetooth SIG's SBC and LC3 codecs. Its main competitors are Qualcomm's aptX-HD/aptX Adaptive and the HWA Union/Savitech's LHDC.[1]

LDAC combines lossy and lossless audio technology[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 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. When the codec is set to 16 bits/44.1kHz at 909 kbps (or 16 bits/48kHz at 990 kbps) LDAC can stream lossless audio that is identical in quality to (or slightly higher than) Audio CD.[8]

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.[9][10] The encoder library is open source and the implementation for Linux is already present in bluez-alsa,[11] pulseaudio-modules-bt,[12][13] and in PipeWire's bluez5 module.[14][15] It is available on Fedora with RPM Fusion since Fedora 30.[16] However the decoder library is proprietary, so receiving devices require licenses.[17]

On 17 September 2019, the Japan Audio Society (JAS) certified LDAC with their Hi-Res Audio Wireless certification. Currently the only codecs with the Hi-Res Audio Wireless certification are LDAC and LHDC.[18]

See also[edit]

References[edit]

  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. ^ "libldac android source code".
  5. ^ "What you need to know about Sony's LDAC". Android Authority. 22 August 2017. Retrieved 8 January 2021.
  6. ^ "The ultimate guide to Bluetooth headphones: LDAC isn't Hi-res". SoundGuys. 16 December 2018. Retrieved 22 September 2019.
  7. ^ "Releases · PipeWire / pipewire". GitLab. Retrieved 11 June 2021.
  8. ^ "The ultimate guide to Bluetooth headphones: LDAC isn't Hi-res". SoundGuys. 16 December 2018. Retrieved 7 January 2021.
  9. ^ "What you need to know about Sony's LDAC". 22 August 2017.
  10. ^ "platform/external/libldac - Git at Google". android.googlesource.com. Retrieved 30 November 2018.
  11. ^ "LDAC support? · Issue #104 · Arkq/bluez-alsa". GitHub. Retrieved 20 March 2019.
  12. ^ 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
  13. ^ eischmann (11 February 2019). "Better Bluetooth sound quality on Linux". Brno hat. Retrieved 20 March 2019.
  14. ^ "List of commits on the PipeWire project pertaining to LDAC support". freedesktop.org Gitlab. 31 December 2020. Retrieved 31 December 2020.
  15. ^ "Achieve parity and/or surpass PulseAudio in Bluetooth audio support". 31 December 2020. Retrieved 31 December 2020.
  16. ^ "1671064 – Review Request: libldac - LDAC library from AOSP". bugzilla.redhat.com. Retrieved 20 March 2019.
  17. ^ "Audio over Bluetooth: most detailed information about profiles, codecs, and devices". habr.com. Retrieved 9 May 2020.
  18. ^ Yeow, Goh Beng (17 September 2019). "Japan Audio Society certifies LHDC™ for "Hi-Res Audio Wireless" certification". Porta-Fi™. Retrieved 22 September 2019.

External links[edit]