codec-isac

Go wrapper for WebRTC iSAC audio codec. Supports encoding/decoding at 16kHz and 32kHz sample rates.

Installation

1. Get the module

go get github.com/cc-integration-team/codec-isac

2. Build the iSAC library (required once)

After getting the module, navigate to the module directory and build the static library:

cd $(go env GOMODCACHE)/github.com/cc-integration-team/codec-isac@<version>
sudo ./build_isac.sh

Or clone and build manually:

git clone https://github.com/cc-integration-team/codec-isac.git
cd codec-isac
./build_isac.sh

Usage

package main

import (
    "fmt"
    isac "github.com/cc-integration-team/codec-isac"
)

func main() {
    // Create decoder (16kHz or 32kHz)
    decoder, err := isac.NewDecoder(isac.SampleRate16kHz)
    if err != nil {
        panic(err)
    }
    defer decoder.Close()

    // Decode iSAC to PCM
    encodedData := []byte{...} // your iSAC encoded data
    pcm, err := decoder.Decode(encodedData)
    if err != nil {
        panic(err)
    }
    fmt.Printf("Decoded %d samples\n", len(pcm))

    // Create encoder
    encoder, err := isac.NewEncoder(isac.SampleRate16kHz)
    if err != nil {
        panic(err)
    }
    defer encoder.Close()

    // Encode PCM to iSAC (10ms frames: 160 samples at 16kHz, 320 at 32kHz)
    pcmFrame := make([]int16, 160)
    encoded, err := encoder.Encode(pcmFrame)
    if err != nil {
        panic(err)
    }
    fmt.Printf("Encoded %d bytes\n", len(encoded))
}

API Reference

Constants

• SampleRate16kHz = 16000 - 16kHz sample rate
• SampleRate32kHz = 32000 - 32kHz sample rate

Decoder

• NewDecoder(sampleRate int) (*Decoder, error) - Create a new decoder
• (*Decoder) Decode(encoded []byte) ([]int16, error) - Decode iSAC to PCM
• (*Decoder) Close() - Release resources

Encoder

• NewEncoder(sampleRate int) (*Encoder, error) - Create a new encoder
• (*Encoder) Encode(pcm []int16) ([]byte, error) - Encode PCM to iSAC
• (*Encoder) Close() - Release resources

Frame Sizes

Sample Rate	Input Frame (10ms)	Output (max)
16kHz	160 samples	480-960 samples
32kHz	320 samples	960-1920 samples

Requirements

• Go 1.21+
• GCC (for building C library)
• Linux (tested on Ubuntu/Debian)

License

This project uses WebRTC's iSAC codec which is licensed under BSD-3-Clause license.