init

extractor/ytdl/providers.go

@@ -0,0 +1,35 @@
+package ytdl
+
+import (
+	"git.nobrain.org/r4/dischord/extractor"
+
+	"strings"
+)
+
+func init() {
+	extractor.AddExtractor("youtube-dl", &Extractor{})
+}
+
+type Extractor struct{}
+
+func (e *Extractor) DefaultConfig() extractor.ProviderConfig {
+	return extractor.ProviderConfig{
+		"youtube-dl-path": "youtube-dl",
+	}
+}
+
+func (e *Extractor) Matches(cfg extractor.ProviderConfig, input string) bool {
+	return strings.HasPrefix(input, "http://") || strings.HasPrefix(input, "https://")
+}
+
+func (e *Extractor) Extract(cfg extractor.ProviderConfig, input string) ([]extractor.Data, error) {
+	var res []extractor.Data
+	dch, errch := ytdlGet(cfg["youtube-dl-path"].(string), input)
+	for v := range dch {
+		res = append(res, v)
+	}
+	for err := range errch {
+		return nil, err
+	}
+	return res, nil
+}

extractor/ytdl/ytdl.go

@@ -0,0 +1,135 @@
+package ytdl
+
+import (
+	"git.nobrain.org/r4/dischord/extractor"
+
+	"bufio"
+	"encoding/json"
+	"errors"
+	"os/exec"
+	"strings"
+	"time"
+)
+
+var (
+	ErrUnsupportedUrl = errors.New("unsupported URL")
+)
+
+// A very reduced version of the JSON structure returned by youtube-dl
+type ytdlMetadata struct {
+	Title       string  `json:"title"`
+	Extractor   string  `json:"extractor"`
+	Duration    float32 `json:"duration"`
+	WebpageUrl  string  `json:"webpage_url"`
+	Playlist    string  `json:"playlist"`
+	Uploader    string  `json:"uploader"`
+	Description string  `json:"description"`
+	Formats     []struct {
+		Url    string `json:"url"`
+		Format string `json"format"`
+		VCodec string `json:"vcodec"`
+	} `json:"formats"`
+}
+
+// Gradually sends all audio URLs through the string channel. If an error occurs, it is sent through the
+// error channel. Both channels are closed after either an error occurs or all URLs have been output.
+func ytdlGet(youtubeDLPath, input string) (<-chan extractor.Data, <-chan error) {
+	out := make(chan extractor.Data)
+	errch := make(chan error, 1)
+
+	go func() {
+		defer close(out)
+		defer close(errch)
+
+		// Set youtube-dl args
+		var ytdlArgs []string
+		ytdlArgs = append(ytdlArgs, "-j", input)
+
+		// Prepare command for execution
+		cmd := exec.Command(youtubeDLPath, ytdlArgs...)
+		cmd.Env = []string{"LC_ALL=en_US.UTF-8"} // Youtube-dl doesn't recognize some chars if LC_ALL=C or not set at all
+		stdout, err := cmd.StdoutPipe()
+		if err != nil {
+			errch <- err
+			return
+		}
+		stderr, err := cmd.StderrPipe()
+		if err != nil {
+			errch <- err
+			return
+		}
+
+		// Catch any errors put out by youtube-dl
+		stderrReadDoneCh := make(chan struct{})
+		var ytdlError string
+		go func() {
+			sc := bufio.NewScanner(stderr)
+			for sc.Scan() {
+				line := sc.Text()
+				if strings.HasPrefix(line, "ERROR: ") {
+					ytdlError = strings.TrimPrefix(line, "ERROR: ")
+				}
+			}
+			stderrReadDoneCh <- struct{}{}
+		}()
+
+		// Start youtube-dl
+		if err := cmd.Start(); err != nil {
+			errch <- err
+			return
+		}
+
+		// We want to let our main loop know when youtube-dl is done
+		donech := make(chan error)
+		go func() {
+			donech <- cmd.Wait()
+		}()
+
+		// Main JSON decoder loop
+		dec := json.NewDecoder(stdout)
+		for dec.More() {
+			// Read JSON
+			var m ytdlMetadata
+			if err := dec.Decode(&m); err != nil {
+				errch <- err
+				return
+			}
+
+			// Extract URL from metadata (the latter formats are always the better with youtube-dl)
+			for i := len(m.Formats) - 1; i >= 0; i-- {
+				format := m.Formats[i]
+				if format.VCodec == "none" {
+					out <- extractor.Data{
+						SourceUrl:     m.WebpageUrl,
+						StreamUrl:     format.Url,
+						Title:         m.Title,
+						PlaylistTitle: m.Playlist,
+						Description:   m.Description,
+						Uploader:      m.Uploader,
+						Duration:      int(m.Duration),
+						Expires:       time.Now().Add(10 * 365 * 24 * time.Hour),
+					}
+					break
+				}
+			}
+		}
+
+		// Wait for command to finish executing and catch any errors
+		err = <-donech
+		<-stderrReadDoneCh
+		if err != nil {
+			if ytdlError == "" {
+				errch <- err
+			} else {
+				if strings.HasPrefix(ytdlError, "Unsupported URL: ") {
+					errch <- ErrUnsupportedUrl
+				} else {
+					errch <- errors.New("ytdl: " + ytdlError)
+				}
+			}
+			return
+		}
+	}()
+
+	return out, errch
+}