LDAC (codec)

From HandWiki
Short description: Digital audio encoding technology
LDAC
File: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 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

LDAC is an alternative to Bluetooth SIG's SBC codec. Its main competitors are 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 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.


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 with RPM Fusion since Fedora 30.[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. Currently the only codecs with the Hi-Res Audio Wireless certification are LDAC and LHDC.[16]

See also

References

  1. ↑ "Best Wireless Headphones of 2018". 2017-11-13. https://www.themasterswitch.com/best-wireless-headphones#4.1vsaptxbluetooth. 
  2. ↑ Darko, John H. (2017-03-29). "The inconvenient truth about Bluetooth audio". https://darko.audio/2017/03/the-inconvenient-truth-about-bluetooth-audio/. 
  3. ↑ "What is Sony LDAC, and how does it do it?". 2015-08-24. https://www.avhub.com.au/news/sound-image/what-is-sony-ldac-and-how-does-it-do-it-408285. 
  4. ↑ "src/ldaclib_api.c - platform/external/libldac". https://android.googlesource.com/platform/external/libldac/+/master/src/ldaclib_api.c#691. 
  5. ↑ 5.0 5.1 Triggs, Robert (2017-08-22). "What you need to know about Sony's LDAC" (in en-US). https://www.androidauthority.com/sony-ldac-codec-790690/. 
  6. ↑ 6.0 6.1 Triggs, Robert (2018-12-16). "The ultimate guide to Bluetooth headphones: LDAC isn't Hi-res" (in en-US). https://www.soundguys.com/ldac-ultimate-bluetooth-guide-20026/. 
  7. ↑ "Releases · PipeWire / pipewire" (in en). https://gitlab.freedesktop.org/pipewire/pipewire/-/releases. 
  8. ↑ "platform/external/libldac" (in en). https://android.googlesource.com/platform/external/libldac. 
  9. ↑ "LDAC support? · Issue #104 · Arkq/bluez-alsa" (in en). https://github.com/Arkq/bluez-alsa/issues/104. 
  10. ↑ H.H, Bao (2019-03-20), Adds Sony LDAC, aptX, aptX HD, AAC codecs (A2DP Audio) support to PulseAudio on Linux: EHfive/pulseaudio-modules-bt, https://github.com/EHfive/pulseaudio-modules-bt, retrieved 2019-03-20 
  11. ↑ eischmann (2019-02-11). "Better Bluetooth sound quality on Linux" (in en). https://eischmann.wordpress.com/2019/02/11/better-bluetooth-sound-quality-on-linux/. 
  12. ↑ "List of commits on the PipeWire project pertaining to LDAC support" (in en). 2020-12-31. https://gitlab.freedesktop.org/search?utf8=%E2%9C%93&snippets=false&scope=commits&repository_ref=master&search=ldac&group_id=10138&project_id=4753. 
  13. ↑ "Achieve parity and/or surpass PulseAudio in Bluetooth audio support". 2020-12-31. https://gitlab.freedesktop.org/pipewire/pipewire/-/issues/249. 
  14. ↑ "1671064 – Review Request: libldac - LDAC library from AOSP". https://bugzilla.redhat.com/show_bug.cgi?id=1671064. 
  15. ↑ "Audio over Bluetooth: most detailed information about profiles, codecs, and devices" (in en). https://habr.com/en/post/456182/. 
  16. ↑ Yeow, Goh Beng (2019-09-17). "Japan Audio Society certifies LHDC™ for "Hi-Res Audio Wireless" certification" (in en-GB). https://porta-fi.com/japan-audio-society-certifies-lhdc/. 

External links



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