num cpu

transcode/encode.go

@@ -7,6 +7,7 @@ import (
 	"os"
 	"os/exec"
 	"regexp"
+	"runtime"
 	"strconv"
 	"strings"
 )
@@ -57,11 +58,14 @@ func ExportSegments(
 	)
 	filterComplex := strings.Join(filterParts, ";")
 
+	numCpus := runtime.NumCPU()
+
 	cmd := exec.Command("ffmpeg",
 		"-i", inputPath,
 		"-filter_complex", filterComplex,
 		"-map", "[outv]",
 		"-map", "[outa]",
+		"-threads", strconv.Itoa(numCpus),
 		// around 80% compression
 		"-c:v", "libx264", "-crf", "28", "-preset", "veryfast",
 		"-c:a", "aac", "-b:a", "128k",