From ec4cd6d66156bf4933ca3902f90e228dbad702f8 Mon Sep 17 00:00:00 2001
From: diamondburned <diamond@arikawa-hi.me>
Date: Sun, 3 Apr 2022 17:49:21 -0700
Subject: [PATCH] examples: Add voice example

---
 0-examples/voice/go.mod  |  19 ++++++
 0-examples/voice/go.sum  |  20 ++++++
 0-examples/voice/main.go | 127 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 166 insertions(+)
 create mode 100644 0-examples/voice/go.mod
 create mode 100644 0-examples/voice/go.sum
 create mode 100644 0-examples/voice/main.go

diff --git a/0-examples/voice/go.mod b/0-examples/voice/go.mod
new file mode 100644
index 0000000..453957c
--- /dev/null
+++ b/0-examples/voice/go.mod
@@ -0,0 +1,19 @@
+module github.com/diamondburned/arikawa/v3/0-examples/voice
+
+go 1.17
+
+replace github.com/diamondburned/arikawa/v3 => ../../
+
+require (
+	github.com/diamondburned/arikawa/v3 v3.0.0-rc.6
+	github.com/diamondburned/oggreader v0.0.0-20201118014549-87df9534b647
+	github.com/pkg/errors v0.9.1
+)
+
+require (
+	github.com/gorilla/schema v1.2.0 // indirect
+	github.com/gorilla/websocket v1.4.2 // indirect
+	golang.org/x/crypto v0.0.0-20210921155107-089bfa567519 // indirect
+	golang.org/x/sys v0.0.0-20211001092434-39dca1131b70 // indirect
+	golang.org/x/time v0.0.0-20210723032227-1f47c861a9ac // indirect
+)
diff --git a/0-examples/voice/go.sum b/0-examples/voice/go.sum
new file mode 100644
index 0000000..7fcb949
--- /dev/null
+++ b/0-examples/voice/go.sum
@@ -0,0 +1,20 @@
+github.com/diamondburned/oggreader v0.0.0-20201118014549-87df9534b647 h1:TJWvffl1cMLzSOvw8Wv3CQicuU9NaKDKXvBfh5T9W00=
+github.com/diamondburned/oggreader v0.0.0-20201118014549-87df9534b647/go.mod h1:xEJuvlmPx1wBKUWkx+MUp1ULSMQwSM9FS+bnFJhPQkk=
+github.com/gorilla/schema v1.2.0 h1:YufUaxZYCKGFuAq3c96BOhjgd5nmXiOY9NGzF247Tsc=
+github.com/gorilla/schema v1.2.0/go.mod h1:kgLaKoK1FELgZqMAVxx/5cbj0kT+57qxUrAlIO2eleU=
+github.com/gorilla/websocket v1.4.2 h1:+/TMaTYc4QFitKJxsQ7Yye35DkWvkdLcvGKqM+x0Ufc=
+github.com/gorilla/websocket v1.4.2/go.mod h1:YR8l580nyteQvAITg2hZ9XVh4b55+EU/adAjf1fMHhE=
+github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
+github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
+golang.org/x/crypto v0.0.0-20210921155107-089bfa567519 h1:7I4JAnoQBe7ZtJcBaYHi5UtiO8tQHbUSXxL+pnGRANg=
+golang.org/x/crypto v0.0.0-20210921155107-089bfa567519/go.mod h1:GvvjBRRGRdwPK5ydBHafDWAxML/pGHZbMvKqRZ5+Abc=
+golang.org/x/net v0.0.0-20210226172049-e18ecbb05110/go.mod h1:m0MpNAwzfU5UDzcl9v0D8zg8gWTRqZa9RBIspLL5mdg=
+golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20210615035016-665e8c7367d1/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20211001092434-39dca1131b70 h1:pGleJoyD1yA5HfvuaksHxD0404gsEkNDerKsQ0N0y1s=
+golang.org/x/sys v0.0.0-20211001092434-39dca1131b70/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
+golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
+golang.org/x/time v0.0.0-20210723032227-1f47c861a9ac h1:7zkz7BUtwNFFqcowJ+RIgu2MaV/MapERkDIy+mwPyjs=
+golang.org/x/time v0.0.0-20210723032227-1f47c861a9ac/go.mod h1:tRJNPiyCQ0inRvYxbN9jk5I+vvW/OXSQhTDSoE431IQ=
+golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
diff --git a/0-examples/voice/main.go b/0-examples/voice/main.go
new file mode 100644
index 0000000..b953cfe
--- /dev/null
+++ b/0-examples/voice/main.go
@@ -0,0 +1,127 @@
+package main
+
+import (
+	"context"
+	"flag"
+	"log"
+	"os"
+	"os/exec"
+	"os/signal"
+	"path/filepath"
+	"strconv"
+	"time"
+
+	"github.com/diamondburned/arikawa/v3/discord"
+	"github.com/diamondburned/arikawa/v3/state"
+	"github.com/diamondburned/arikawa/v3/voice"
+	"github.com/diamondburned/arikawa/v3/voice/udp"
+	"github.com/diamondburned/oggreader"
+	"github.com/pkg/errors"
+)
+
+func main() {
+	flag.Parse()
+
+	file := flag.Arg(0)
+	if file == "" {
+		log.Fatalln("usage:", filepath.Base(os.Args[0]), "<audio file>")
+	}
+
+	voiceID, err := discord.ParseSnowflake(os.Getenv("VOICE_ID"))
+	if err != nil {
+		log.Fatalln("failed to parse $VOICE_ID:", err)
+	}
+	chID := discord.ChannelID(voiceID)
+
+	state := state.New("Bot " + os.Getenv("BOT_TOKEN"))
+	voice.AddIntents(state)
+
+	ctx, cancel := signal.NotifyContext(context.Background(), os.Interrupt)
+	defer cancel()
+
+	if err := state.Open(ctx); err != nil {
+		log.Fatalln("failed to open:", err)
+	}
+	defer state.Close()
+
+	if err := start(ctx, state, chID, file); err != nil {
+		// Ignore context canceled errors as they're often intentional.
+		if !errors.Is(err, context.Canceled) {
+			log.Fatalln(err)
+		}
+	}
+}
+
+// Optional constants to tweak the Opus stream.
+const (
+	frameDuration = 60 // ms
+	timeIncrement = 2880
+)
+
+func start(ctx context.Context, s *state.State, id discord.ChannelID, file string) error {
+	v, err := voice.NewSession(s)
+	if err != nil {
+		return errors.Wrap(err, "cannot make new voice session")
+	}
+
+	// Optimize Opus frame duration. This step is optional, but it is
+	// recommended.
+	v.SetUDPDialer(udp.DialFuncWithFrequency(
+		frameDuration*time.Millisecond, // correspond to -frame_duration
+		timeIncrement,
+	))
+
+	ffmpeg := exec.CommandContext(ctx,
+		"ffmpeg", "-hide_banner", "-loglevel", "error",
+		// Streaming is slow, so a single thread is all we need.
+		"-threads", "1",
+		// Input file.
+		"-i", file,
+		// Output format; leave as "libopus".
+		"-c:a", "libopus",
+		// Bitrate in kilobits. This doesn't matter, but I recommend 96k as the
+		// sweet spot.
+		"-b:a", "96k",
+		// Frame duration should be the same as what's given into
+		// udp.DialFuncWithFrequency.
+		"-frame_duration", strconv.Itoa(frameDuration),
+		// Disable variable bitrate to keep packet sizes consistent. This is
+		// optional.
+		"-vbr", "off",
+		// Output format, which is opus, so we need to unwrap the opus file.
+		"-f", "opus",
+		"-",
+	)
+
+	ffmpeg.Stderr = os.Stderr
+
+	stdout, err := ffmpeg.StdoutPipe()
+	if err != nil {
+		return errors.Wrap(err, "failed to get stdout pipe")
+	}
+
+	// Kickstart FFmpeg before we join. FFmpeg will wait until we start
+	// consuming the stream to process further.
+	if err := ffmpeg.Start(); err != nil {
+		return errors.Wrap(err, "failed to start ffmpeg")
+	}
+
+	// Join the voice channel.
+	if err := v.JoinChannelAndSpeak(ctx, id, false, true); err != nil {
+		return errors.Wrap(err, "failed to join channel")
+	}
+	defer v.Leave(ctx)
+
+	// Start decoding FFmpeg's OGG-container output and extract the raw Opus
+	// frames into the stream.
+	if err := oggreader.DecodeBuffered(v, stdout); err != nil {
+		return errors.Wrap(err, "failed to decode ogg")
+	}
+
+	// Wait until FFmpeg finishes writing entirely and leave.
+	if err := ffmpeg.Wait(); err != nil {
+		return errors.Wrap(err, "failed to finish ffmpeg")
+	}
+
+	return nil
+}