utils package, currently only for converting audio files

tgutils/audio.go

@@ -0,0 +1,95 @@
+// Package tgutils provides extra functions to make certain tasks easier.
+package tgutils
+
+import (
+	"github.com/syfaro/telegram-bot-api"
+	"log"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strconv"
+	"sync"
+	"time"
+)
+
+var rand uint32
+var randmu sync.Mutex
+
+func reseed() uint32 {
+	return uint32(time.Now().UnixNano() + int64(os.Getpid()))
+}
+
+func nextSuffix() string {
+	randmu.Lock()
+	r := rand
+	if r == 0 {
+		r = reseed()
+	}
+	r = r*1664525 + 1013904223 // constants from Numerical Recipes
+	rand = r
+	randmu.Unlock()
+	return strconv.Itoa(int(1e9 + r%1e9))[1:]
+}
+
+// this function ripped from ioutils.TempFile, except with a suffix, instead of prefix.
+func tempFileWithSuffix(dir, suffix string) (f *os.File, err error) {
+	if dir == "" {
+		dir = os.TempDir()
+	}
+
+	nconflict := 0
+	for i := 0; i < 10000; i++ {
+		name := filepath.Join(dir, nextSuffix()+suffix)
+		f, err = os.OpenFile(name, os.O_RDWR|os.O_CREATE|os.O_EXCL, 0600)
+		if os.IsExist(err) {
+			if nconflict++; nconflict > 10 {
+				randmu.Lock()
+				rand = reseed()
+				randmu.Unlock()
+			}
+			continue
+		}
+		break
+	}
+	return
+}
+
+// EncodeAudio takes a file and attempts to convert it to a .ogg for Telegram.
+// It then returns an AudioConfig.
+//
+// This function requires ffmpeg and opusenc to be installed on the system!
+func EncodeAudio(audio *tgbotapi.AudioConfig) error {
+	f, err := tempFileWithSuffix(os.TempDir(), "_tgutils.ogg")
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
+	log.Println(f.Name())
+
+	ffmpegArgs := []string{
+		"-i",
+		audio.FilePath,
+		"-f",
+		"wav",
+		"-",
+	}
+
+	opusArgs := []string{
+		"--bitrate",
+		"256",
+		"-",
+		f.Name(),
+	}
+
+	c1 := exec.Command("ffmpeg", ffmpegArgs...)
+	c2 := exec.Command("opusenc", opusArgs...)
+
+	c2.Stdin, _ = c1.StdoutPipe()
+	c2.Stdout = os.Stdout
+	c2.Start()
+	c1.Run()
+	c2.Wait()
+
+	return nil
+}