Lyra codec is a new open-source audio codec for voice calls.
Google introduced Lyra in February 2021 and launched its beta version in April 2021. Lyra codec was primarily developed to reduce bandwidth usage of phone calls and therefore help the apps enabling communication to function better and faster. Consequently, its quality greatly surpassed the quality of other already existing audio codecs.
The main aim of Lyra is to produce high-quality voice calls by using machine learning.[1]
Lyra’s principle
Lyra codec consists of two main parts: encoder and decoder. They are responsible for the whole process of reproducing audio waves to listeners in a voice call. The first one, the encoder, starts the process by capturing features – distinctive attributes – from the speech. Then, the encoder divides these features into 40-millisecond pieces and compresses each of them. Finally, it sends compressed 40-millisecond pieces over the network. The second one, the decoder, decodes them back into audio waves via a generative model - one of the machine learning models, which can recreate an entire waveform from the limited number of compressed features. Recreated audio waves are further reproduced to the listener. In the end, the strength of Lyra is the ability of the generative model to reconstruct a high-quality voice signal. [2] Lyra is designed to use a bitrate of only 3 kbps and subjectively outperforms other audio codecs such as Opus at 6 kbps or Speex at 3kbps.[3] However, a recently proposed GAN vocoder is supposed to achieve similar quality at half the bitrate.[4]
Release
To provide necessary speed and good performance, Lyra codec is written in C++ language. It uses the Bazel build framework with Abseil and the GoogleTest framework.[5]
The code of Lyra is open-sourced under the Apache License 2.0.[6]
References
This article "Lyra codec" is from Wikipedia. The list of its authors can be seen in its historical and/or the page Edithistory:Lyra codec. Articles copied from Draft Namespace on Wikipedia could be seen on the Draft Namespace of Wikipedia and not main one.
- ↑ "Google launches Lyra codec in beta to reduce voice call bandwidth usage". VentureBeat. 2021-04-06. Retrieved 2021-12-02.
- ↑ "Lyra - enabling voice calls for the next billion users". Google Open Source Blog. Retrieved 2021-12-02.
- ↑ "Lyra: A New Very Low-Bitrate Codec for Speech Compression". Google AI Blog. Retrieved 2021-12-14.
- ↑ Mustafa, Ahmed; Büthe, Jan; Korse, Srikanth; Gupta, Kishan; Fuchs, Guillaume; Pia, Nicola (2021-08-09). "A Streamwise GAN Vocoder for Wideband Speech Coding at Very Low Bit Rate". arXiv:2108.04051 [eess.AS].
- ↑ "Google Open Sources Lyra In Beta". www.c-sharpcorner.com. Retrieved 2021-12-02.
- ↑ Lyra: a generative low bitrate speech codec, Google, 2021-12-13, retrieved 2021-12-14
