From 9f08bf0e3adba0b58820121863be0ba8f7fede48 Mon Sep 17 00:00:00 2001
From: FrantaBOT <frantabot@voic.eu>
Date: Tue, 9 Jun 2026 05:55:46 +0200
Subject: [PATCH] Added decode-webm example

---
 examples/decode-webm/README.md | 35 +++++++++++++++++
 examples/decode-webm/go.mod    |  8 ++++
 examples/decode-webm/go.sum    | 12 ++++++
 examples/decode-webm/main.go   | 71 ++++++++++++++++++++++++++++++++++
 4 files changed, 126 insertions(+)
 create mode 100644 examples/decode-webm/README.md
 create mode 100644 examples/decode-webm/go.mod
 create mode 100644 examples/decode-webm/go.sum
 create mode 100644 examples/decode-webm/main.go

diff --git a/examples/decode-webm/README.md b/examples/decode-webm/README.md
new file mode 100644
index 0000000..2e4f050
--- /dev/null
+++ b/examples/decode-webm/README.md
@@ -0,0 +1,35 @@
+# decode-webm
+decode-webm demonstrates decoding a webm file and saving the results to a single file
+
+## Instructions
+### Install decode-webm
+Download and install the decode-webm
+
+```
+go install github.com/pion/opus/examples/decode-webm@latest
+```
+
+### Create a webm file to decode
+Encode Opus into an webm file, or use one that you already have.
+
+```
+ffmpeg -i $INPUT_FILE -c:a libopus -ac 1 -b:a 64K output.webm
+```
+
+### Decode
+Demux and decode the provided `webm` file. The output audio samples will be saved to disk.
+
+```
+decode-webm `pwd`/output.webm `audio-samples.pcm`
+```
+
+### Play your audio
+Now play the audio with the tool of your choice.
+
+```
+gst-launch-1.0 filesrc location=audio-samples.pcm ! audio/x-raw, format=S16LE, rate=48000,channels=1  ! autoaudiosink -v
+```
+
+```
+ffplay -f s16le -ar 48000 audio-samples.pcm
+```
diff --git a/examples/decode-webm/go.mod b/examples/decode-webm/go.mod
new file mode 100644
index 0000000..85a6c86
--- /dev/null
+++ b/examples/decode-webm/go.mod
@@ -0,0 +1,8 @@
+module github.com/pion/opus/examples/decode-webm
+
+go 1.24.0
+
+require (
+	github.com/at-wat/ebml-go v0.18.0
+	github.com/pion/opus v0.1.0
+)
diff --git a/examples/decode-webm/go.sum b/examples/decode-webm/go.sum
new file mode 100644
index 0000000..fd3a7d4
--- /dev/null
+++ b/examples/decode-webm/go.sum
@@ -0,0 +1,12 @@
+github.com/at-wat/ebml-go v0.18.0 h1:SNkpBFR4jCQV1rI4Bm1tSuIYnusxe2qQ4GHJia9eQg4=
+github.com/at-wat/ebml-go v0.18.0/go.mod h1:w1cJs7zmGsb5nnSvhWGKLCxvfu4FVx5ERvYDIalj1ww=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/pion/opus v0.1.0 h1:GgK/a3DNDrffKjUFsK39rZKqfv7bQ2S2eqRKt0BnqAE=
+github.com/pion/opus v0.1.0/go.mod h1:t5Xog2n682JnawoykACE6nKVmupFvmJvkpM7x6bTv6g=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/testify v1.11.1 h1:7s2iGBzp5EwR7/aIZr8ao5+dra3wiQyKjjFuvgVKu7U=
+github.com/stretchr/testify v1.11.1/go.mod h1:wZwfW3scLgRK+23gO65QZefKpKQRnfz6sD981Nm4B6U=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
diff --git a/examples/decode-webm/main.go b/examples/decode-webm/main.go
new file mode 100644
index 0000000..317e667
--- /dev/null
+++ b/examples/decode-webm/main.go
@@ -0,0 +1,71 @@
+// SPDX-FileCopyrightText: 2026 The Pion community <https://pion.ly>
+// SPDX-License-Identifier: MIT
+
+// Package main is an example of an Opus decoder that from webm save the output PCM to disk
+package main
+
+import (
+	"os"
+
+	"github.com/at-wat/ebml-go"
+	"github.com/at-wat/ebml-go/webm"
+	"github.com/pion/opus"
+)
+
+func main() { // nolint:cyclop
+	if len(os.Args) != 3 {
+		panic("Usage: <in-file> <out-file>")
+	}
+
+	inputFile, err := os.Open(os.Args[1]) // #nosec G703
+	if err != nil {
+		panic(err)
+	}
+
+	var webmData struct {
+		Segment webm.Segment `ebml:"Segment"`
+	}
+
+	err = ebml.Unmarshal(inputFile, &webmData)
+	if err != nil {
+		panic(err)
+	}
+
+	var opusTrackNumber uint64
+	for _, trackEntry := range webmData.Segment.Tracks.TrackEntry {
+		if trackEntry.CodecID == "A_OPUS" {
+			opusTrackNumber = trackEntry.TrackNumber
+		}
+	}
+
+	if opusTrackNumber == 0 {
+		panic("Missing opus track")
+	}
+
+	buffer := make([]byte, 1920)
+	outputFile, err := os.Create(os.Args[2]) // #nosec G703
+	if err != nil {
+		panic(err)
+	}
+
+	decoder := opus.NewDecoder()
+	for _, cluster := range webmData.Segment.Cluster {
+		for _, simpleBlock := range cluster.SimpleBlock {
+			if simpleBlock.TrackNumber != opusTrackNumber {
+				continue
+			}
+
+			for _, data := range simpleBlock.Data {
+				_, _, err = decoder.Decode(data, buffer)
+				if err != nil {
+					panic(err)
+				}
+
+				_, err := outputFile.Write(buffer)
+				if err != nil {
+					panic(err)
+				}
+			}
+		}
+	}
+}