opus

This Go package provides decoding of streams that have been encoded with the Opus codec. When provided with an opus stream the raw PCM data can be extracted.

The xiph.org opus, opusfile, and ogg C libraries are used to do the decoding.

decoding a stream

readSeeker, err := os.Open("an-opus-file.opus")
if err != nil { ... }

decoder, err := opus.NewDecoder(readSeeker)
if err != nil { ... }

var pcm = make([]int16, 2_000)
for {
    n, err := decoder.Read(pcm)
    fmt.Printf("read %d samples (per channel)\n", n)
    samples := pcm[:n]
    // Do something with the samples...

    if err == io.EOF {
        break
    }
}

decoder.Destroy()
readSeeker.Close()

building

Because of the use of cgo in the library, the Go toolchain will need to be able to find a C compiler (typically gcc or clang) and linker on the path.

When building an application that uses the opus package (with go build or go run) the first build may take several seconds. This is because of the use of a C compiler to compile the opus, opusfile, and ogg libraries. Subsequent builds will be much quicker as the built package will be cached by the Go toolchain.

examples

There are a couple of examples in the example directory.

• beep
  • Uses the beep package to play an Opus file.
  • go run example\beep\*.go [your-file.opus]
    • Without an argument, plays an embedded sample Opus file.
    • With an argument that is a path to an Opus file, will play the file.
• simple
  • Uses various methods of opus.Decoder to get and print various information about an Opus stream.
  • go run example\simple\*.go [your-file.opus]
    • Without an argument, uses an embedded sample Opus file.
    • With an argument that is a path to an Opus file, uses the file.

possible alternatives

pion/opus

https://github.com/pion/opus is a pure Go implementation of the Opus codec.

• It currently only supports the SILK codec, not the CELT codec. See issue #7.

hraban/opus

https://github.com/hraban/opus provides C bindings to the xiph.org C libraries.

• It is more comprehensive than this library, and supports encoding as well as decoding of Opus streams.
• It requires libopus and libopusfile development packages to be installed on the system.

development

pre-commit hook

• install goimports if not already installed
  • https://pkg.go.dev/golang.org/x/tools/cmd/goimports
• install golangci-lint if not already installed
  • https://golangci-lint.run/usage/install/#local-installation
• install the pre-commit application if not already installed
  • https://pre-commit.com/index.html#install
• install pre-commit hook in this repo's workspace
  • pre-commit install