Allow additional youtube-dl arguments

This allows inserting arbitrary extra arguments into the youtube-dl command-line within each podcast feed entry. This allows, for example, requesting that youtube-dl embed subtitles and captions into the video file, or configuring additional postprocessor arguments.

No effort has been made to make sure no incompatible arguments are provided, with the expectation that the end-user will understand what's possible, and that this is an option expressly for advanced users.

This would fix #162,and theoretically also #136!

README.md

@@ -80,6 +80,7 @@ vimeo = [ # Multiple keys will be rotated.
   # filters = { title = "regex for title here", not_title = "regex for negative title match", description = "...", not_description = "..." } # Optional Golang regexp format. If set, then only download matching episodes.
   # opml = true|false # Optional inclusion of the feed in the OPML file (default value: false)
   # clean = { keep_last = 10 } # Keep last 10 episodes (order desc by PubDate)
+  # youtube_dl_args = [ "--write-sub", "--embed-subs", "--sub-lang", "en,en-US,en-GB" ] # Optional extra arguments passed to youtube-dl when downloading videos from this feed. This example would embed available English closed captions in the videos. Note that setting '--audio-format' for audio format feeds, or '--format' or '--output' for any format may cause unexpected behaviour. You should only use this if you know what you are doing, and have read up on youtube-dl's options!
 
 [database]
   badger = { truncate = true, file_io = true } # See https://github.com/dgraph-io/badger#memory-usage

pkg/config/config.go

@@ -40,6 +40,8 @@ type Feed struct {
 	Clean Cleanup `toml:"clean"`
 	// Custom is a list of feed customizations
 	Custom Custom `toml:"custom"`
+	// List of additional youtube-dl arguments passed at download time
+	YouTubeDLArgs []string `toml:"youtube_dl_args"`
 	// Included in OPML file
 	OPML bool `toml:"opml"`
 }

pkg/ytdl/ytdl.go

@@ -214,6 +214,9 @@ func buildArgs(feedConfig *config.Feed, episode *model.Episode, outputFilePath s
 		args = append(args, "--extract-audio", "--audio-format", "mp3", "--format", format)
 	}
 
+	// Insert additional per-feed youtube-dl arguments
+	args = append(args, feedConfig.YouTubeDLArgs...)
+
 	args = append(args, "--output", outputFilePath, episode.VideoURL)
 	return args
 }

pkg/ytdl/ytdl_test.go

@@ -17,6 +17,7 @@ func TestBuildArgs(t *testing.T) {
 		maxHeight int
 		output    string
 		videoURL  string
+		ytdlArgs  []string
 		expect    []string
 	}{
 		{
@@ -91,14 +92,24 @@ func TestBuildArgs(t *testing.T) {
 			videoURL:  "http://url1",
 			expect:    []string{"--format", "bestvideo[height<=1024][ext=mp4]+bestaudio[ext=m4a]/best[ext=mp4]/best", "--output", "/tmp/2", "http://url1"},
 		},
+		{
+			name:     "Video high quality with custom youtube-dl arguments",
+			format:   model.FormatVideo,
+			quality:  model.QualityHigh,
+			output:   "/tmp/2",
+			videoURL: "http://url1",
+			ytdlArgs: []string{"--write-sub", "--embed-subs", "--sub-lang", "en,en-US,en-GB"},
+			expect:   []string{"--format", "bestvideo[ext=mp4]+bestaudio[ext=m4a]/best[ext=mp4]/best", "--write-sub", "--embed-subs", "--sub-lang", "en,en-US,en-GB", "--output", "/tmp/2", "http://url1"},
+		},
 	}
 
 	for _, tst := range tests {
 		t.Run(tst.name, func(t *testing.T) {
 			result := buildArgs(&config.Feed{
-				Format:    tst.format,
-				Quality:   tst.quality,
-				MaxHeight: tst.maxHeight,
+				Format:        tst.format,
+				Quality:       tst.quality,
+				MaxHeight:     tst.maxHeight,
+				YouTubeDLArgs: tst.ytdlArgs,
 			}, &model.Episode{
 				VideoURL: tst.videoURL,
 			}, tst.output)