add customizable logging levels

main.go

@@ -15,6 +15,11 @@ import (
 	"strings"
 )
 
+const (
+	LogLevelInfo    int = 1
+	LogLevelVerbose int = 2
+)
+
 type config struct {
 	youtubeDl         string
 	mkvmerge          string
@@ -22,12 +27,19 @@ type config struct {
 	overrideOutput    string
 	subsOnly          bool
 	deleteTemporaries bool
+	loglevel          int
 }
 
 func performDownload(ctx context.Context, cfg *config, targetUrl string) error {
 
 	//
 
+	if cfg.loglevel >= LogLevelInfo {
+		fmt.Printf("Starting download for '%s'...\n", targetUrl)
+	}
+
+	//
+
 	var content []byte
 	var err error
 	if targetUrl == "-" {
@@ -70,16 +82,20 @@ func performDownload(ctx context.Context, cfg *config, targetUrl string) error {
 
 	// Download the video
 	ytdl := exec.CommandContext(ctx, cfg.youtubeDl, `-f`, `bestvideo+bestaudio`, "https://youtu.be/"+ltc.VideoID, `--merge-output-format`, `mkv`, "-o", filepath.Join(tmpdir, "downloaded"))
-	ytdl.Stdout = os.Stdout
-	ytdl.Stderr = os.Stderr
+	if cfg.loglevel >= LogLevelVerbose {
+		ytdl.Stdout = os.Stdout
+		ytdl.Stderr = os.Stderr
+	}
 	err = ytdl.Run()
 	if err != nil {
 		return err
 	}
 
 	// Determine video's total length
-	minfo := exec.CommandContext(ctx, cfg.mediainfo, `--Inform="General;%Duration%"`, filepath.Join(tmpdir, "downloaded.mkv"))
-	minfo.Stderr = os.Stderr
+	minfo := exec.CommandContext(ctx, cfg.mediainfo, `--Inform=General;%Duration%`, filepath.Join(tmpdir, "downloaded.mkv"))
+	if cfg.loglevel >= LogLevelVerbose {
+		minfo.Stderr = os.Stderr
+	}
 	ret, err := minfo.Output()
 	if err != nil {
 		return err
@@ -89,6 +105,10 @@ func performDownload(ctx context.Context, cfg *config, targetUrl string) error {
 		return err
 	}
 
+	if cfg.loglevel >= LogLevelVerbose {
+		fmt.Printf("Video duration is %d ms\n", msecsDuration)
+	}
+
 	// Create the subtitle file (clamped to total length)
 
 	fh, err := os.OpenFile(filepath.Join(tmpdir, "subtitles.srt"), os.O_CREATE|os.O_WRONLY, 0600)
@@ -105,8 +125,10 @@ func performDownload(ctx context.Context, cfg *config, targetUrl string) error {
 	// Mux the subtitles into the file
 
 	mkvm := exec.CommandContext(ctx, cfg.mkvmerge, `-o`, filepath.Join(tmpdir, "muxed.mkv"), filepath.Join(tmpdir, "downloaded.mkv"), filepath.Join(tmpdir, "subtitles.srt"))
-	mkvm.Stdout = os.Stdout
-	mkvm.Stderr = os.Stderr
+	if cfg.loglevel >= LogLevelVerbose {
+		mkvm.Stdout = os.Stdout
+		mkvm.Stderr = os.Stderr
+	}
 	err = mkvm.Run()
 	if err != nil {
 		return err
@@ -137,6 +159,10 @@ func performDownload(ctx context.Context, cfg *config, targetUrl string) error {
 
 	// Done
 
+	if cfg.loglevel >= LogLevelInfo {
+		fmt.Printf("Download complete for '%s'\n", outputFile)
+	}
+
 	return nil
 }
 
@@ -153,6 +179,7 @@ Options:
   --output PATH              Override output filename
                              (only valid for a single URL)
   --delete-temporary=false   Preserve temporary files
+  --loglevel 0|1|2           Set verbosity (0=silent, 1=normal, 2=verbose)
 `)
 	os.Exit(1)
 }
@@ -168,6 +195,7 @@ func main() {
 	flag.StringVar(&cfg.mediainfo, "mediainfo", "mediainfo", "")
 	flag.StringVar(&cfg.overrideOutput, "output", "", "")
 	flag.BoolVar(&cfg.deleteTemporaries, "delete-temporary", true, "")
+	flag.IntVar(&cfg.loglevel, "loglevel", 1, "")
 	flag.Usage = usage
 	flag.Parse()