Added ExtractAudio option

Let's you extract audio from combined video+audio media (most websites
supported by yt-dlp)

download.go

@@ -78,7 +78,28 @@ func downloadVideo(url string, path string, group GroupConfig) (err error) {
     }
 
     /* AUDIO */
-    if group.AudioFormat != "" {
+    if group.ExtractFormat != "" {
+        log.Debugf("Extracting audio from \"%s\" with format \"%s\"", video.Info.ID, group.ExtractFormat)
+
+        audioDLResult, err := video.Download(context.Background(), group.ExtractFormat)
+        if err != nil {
+            return err
+        }
+
+        defer audioDLResult.Close()
+
+        file, err := os.OpenFile(tempPath+"-extract", os.O_CREATE|os.O_TRUNC|os.O_WRONLY, 0644)
+        if err != nil {
+            return err
+        }
+
+        defer file.Close()
+
+        io.Copy(file, audioDLResult)
+
+        audioDLResult.Close()
+        file.Close()
+    } else if group.AudioFormat != "" {
         log.Debugf("Downloading audio \"%s\" with format \"%s\"", video.Info.ID, group.AudioFormat)
 
         audioDLResult, err := video.Download(context.Background(), group.AudioFormat)
@@ -112,6 +133,14 @@ func downloadVideo(url string, path string, group GroupConfig) (err error) {
         if err := os.Remove(tempPath+"-audio"); err != nil {
             log.Warnf("Could not remove file \"%s\"", tempPath+"-audio")
         }
+    } else if group.ExtractFormat != "" {
+        if err := extractAudio(tempPath+"-extract", group.CFormat, path); err != nil {
+            log.Errorf("Could not extract audio from \"%s\" to \"%s\"", tempPath+"-extract", path)
+        }
+
+        if err := os.Remove(tempPath+"-extract"); err != nil {
+            log.Warnf("Could not remove file \"%s\"", tempPath+"-extract")
+        }
     } else if group.VideoFormat != "" {
         copyFile(tempPath+"-vid", path)
 

ffmpeg.go

@@ -29,3 +29,26 @@ func mergeStreams(path1 string, path2 string, format string, output string) (err
 
     return ffmpeg.Output(input, output, kwArgs).OverWriteOutput().ErrorToStdOut().Silent(silent).Run()
 }
+
+func extractAudio(path1 string, format string, output string) (err error) {
+    input := []*ffmpeg.Stream{ffmpeg.Input(path1)}
+
+    defaultArgs := ffmpeg.KwArgs{"map": "0:a", "c:a": "copy", "format": format}
+
+    var ffmpegLogLevel ffmpeg.KwArgs
+    var silent bool
+
+    if Flags.Verbose {
+        ffmpegLogLevel = ffmpeg.KwArgs{"v": "info"}
+        silent = false
+    } else if Flags.Quiet {
+        ffmpegLogLevel = ffmpeg.KwArgs{"v": "quiet"}
+        silent = true
+    } else {
+        ffmpegLogLevel = ffmpeg.KwArgs{"v": "error"}
+        silent = true
+    }
+
+    kwArgs := ffmpeg.MergeKwArgs([]ffmpeg.KwArgs{ffmpegLogLevel, defaultArgs})
+    return ffmpeg.Output(input, output, kwArgs).OverWriteOutput().ErrorToStdOut().Silent(silent).Run()
+}

ytva.go

@@ -45,8 +45,11 @@ type GroupConfig struct {
     OutputDir           string
     FileName            string
     CFormat             string
+    ExtractFormat       string
     VideoFormat         string
     AudioFormat         string
+    DownloadSubtitles   bool // Currently useless
+    DownloadThumbnails  bool // Currently useless
     NumVideos           uint
     SizeLimit           float64
     Filters             []struct {