SILK: Super Wideband Audio Codec
SILK—a speech codec for real-time, packet-based voice communications—is the preferred audio codec for Skype-to-Skype calls.
SILK targets a diverse range of operating environments, and provides dynamic scalability in several dimensions on a frame-by-frame basis:
- supports encoding the audio input signal at 8, 12, 16 or 24 kHz
- adapts to network conditions through dynamic control and/or use of:
- packet rate
- packet loss resilience
- discontinuous transmission (DTX)
- supports multiple complexity levels to take advantage of available processing power without relying on it
Skype provides the following documentation regarding SILK, its specification and payload format, and audio samples:
- SILK Data Sheet—SILKDataSheet.pdf (344 KB)
- SILK RTP Payload Format Description—SILK_RTP_PayloadFormat.pdf (59 KB)
- SILK Demo Audio Samples—SILK_audio_samples.zip (7.8 MB)
Skype has additionally contributed SILK source code to the Internet Engineering Task Force working group:
- SILK Speech Codec Description—http://tools.ietf.org/html/draft-vos-silk-02 (1.33 MB).
Copyright in this software is licensed under the terms set out in the source code.
Skype Limited hereby separately grants to you a license under its patents to use the SILK software made available as a download below for internal evaluation and testing purposes only. This license expressly excludes the use of the SILK software for distribution or use in any commercial product or service.
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To use the SILK software for any purpose other than internal evaluation and testing, you are required to accept the SILK Patent License.