Add offline route

transcoder/main.go

@@ -48,11 +48,11 @@ func (h *Handler) GetOffline(c echo.Context) error {
 		return err
 	}
 
-	ret, err := h.downloader.GetOffline(path, quality)
+	ret, path, err := h.downloader.GetOffline(path, quality)
 	if err != nil {
 		return err
 	}
-	return c.String(http.StatusOK, ret)
+	return ServeOfflineFile(path, ret, c)
 }
 
 // Get master playlist

transcoder/src/downloader.go

@@ -1,11 +1,94 @@
 package src
 
-type Downloader struct{}
+import (
+	"fmt"
+	"log"
+	"os/exec"
+	"sync"
+)
+
+type Key struct {
+	path    string
+	quality Quality
+}
+
+type Value struct {
+	done chan struct{}
+	path string
+}
+
+type Downloader struct {
+	processing map[Key]Value
+	lock       sync.Mutex
+}
 
 func NewDownloader() *Downloader {
-	return nil
+	return &Downloader{
+		processing: make(map[Key]Value),
+	}
 }
 
-func (d *Downloader) GetOffline(path string, quality Quality) (string, error) {
-	return "", nil
+func (d *Downloader) GetOffline(path string, quality Quality) (<-chan struct{}, string, error) {
+	key := Key{path, quality}
+	d.lock.Lock()
+	defer d.lock.Unlock()
+	existing, ok := d.processing[key]
+
+	if ok {
+		return existing.done, existing.path, nil
+	}
+
+	info, err := GetInfo(path)
+	if err != nil {
+		return nil, "", err
+	}
+	outpath := fmt.Sprintf("%s/dl-%s-%s.mkv", GetOutPath(), info.Sha, quality)
+
+	ret := make(chan struct{})
+	d.processing[key] = Value{ret, outpath}
+
+	go func() {
+		cmd := exec.Command(
+			"ffmpeg",
+			"-nostats", "-hide_banner", "-loglevel", "warning",
+			"-i", path,
+		)
+		cmd.Args = append(cmd.Args, quality.getTranscodeArgs(nil)...)
+		// TODO: add custom audio settings depending on quality
+		cmd.Args = append(cmd.Args,
+			"-map", "0:a?",
+			"-c:a", "aac",
+			"-ac", "2",
+			"-b:a", "128k",
+		)
+		// also include subtitles, font attachments and chapters.
+		cmd.Args = append(cmd.Args,
+			"-map", "0:s?", "-c:s", "copy",
+			"-map", "0:d?",
+			"-map", "0:t?",
+		)
+		cmd.Args = append(cmd.Args, outpath)
+
+		log.Printf(
+			"Starting offline transcode (quality %s) of %s with the command: %s",
+			quality,
+			path,
+			cmd,
+		)
+		cmd.Stdout = nil
+		err := cmd.Run()
+		if err != nil {
+			log.Println("Error starting ffmpeg extract:", err)
+			// TODO: find a way to inform listeners that there was an error
+
+			d.lock.Lock()
+			delete(d.processing, key)
+			d.lock.Unlock()
+		} else {
+			log.Println("Transcode finished")
+		}
+
+		close(ret)
+	}()
+	return ret, outpath, nil
 }

transcoder/src/extract.go

@@ -57,6 +57,7 @@ func (e *Extractor) RunExtractor(path string, sha string, subs *[]Subtitle) <-ch
 		fmt.Printf("Extract subs and fonts for %s", path)
 		cmd := exec.Command(
 			"ffmpeg",
+			"-nostats", "-hide_banner", "-loglevel", "warning",
 			"-dump_attachment:t", "",
 			"-i", path,
 		)

transcoder/src/stream.go

@@ -111,7 +111,7 @@ func (ts *Stream) run(start int32) error {
 		"-copyts",
 	}
 	args = append(args, ts.handle.getTranscodeArgs(segments_str)...)
-	args = append(args, []string{
+	args = append(args,
 		"-f", "segment",
 		"-segment_time_delta", "0.2",
 		"-segment_format", "mpegts",
@@ -120,7 +120,7 @@ func (ts *Stream) run(start int32) error {
 		"-segment_list_type", "flat",
 		"-segment_list", "pipe:1",
 		outpath,
-	}...)
+	)
 
 	cmd := exec.Command("ffmpeg", args...)
 	log.Printf("Running %s", strings.Join(cmd.Args, " "))

transcoder/src/videostream.go

@@ -23,22 +23,32 @@ func (vs *VideoStream) getOutPath() string {
 }
 
 func (vs *VideoStream) getTranscodeArgs(segments string) []string {
-	if vs.quality == Original {
+	return vs.quality.getTranscodeArgs(&segments)
+}
+
+func (quality Quality) getTranscodeArgs(segments *string) []string {
+	if quality == Original {
 		return []string{"-map", "0:V:0", "-c:v", "copy"}
 	}
 
-	return []string{
+	ret := []string{
 		// superfast or ultrafast would produce a file extremly big so we prever veryfast or faster.
 		"-map", "0:V:0", "-c:v", "libx264", "-crf", "21", "-preset", "faster",
 		// resize but keep aspect ratio (also force a width that is a multiple of two else some apps behave badly.
-		"-vf", fmt.Sprintf("scale=-2:'min(%d,ih)'", vs.quality.Height()),
+		"-vf", fmt.Sprintf("scale=-2:'min(%d,ih)'", quality.Height()),
 		// Even less sure but bufsize are 5x the avergae bitrate since the average bitrate is only
 		// useful for hls segments.
-		"-bufsize", fmt.Sprint(vs.quality.MaxBitrate() * 5),
-		"-b:v", fmt.Sprint(vs.quality.AverageBitrate()),
-		"-maxrate", fmt.Sprint(vs.quality.MaxBitrate()),
-		// Force segments to be split exactly on keyframes (only works when transcoding)
-		"-force_key_frames", segments,
+		"-bufsize", fmt.Sprint(quality.MaxBitrate() * 5),
+		"-b:v", fmt.Sprint(quality.AverageBitrate()),
+		"-maxrate", fmt.Sprint(quality.MaxBitrate()),
 		"-strict", "-2",
 	}
+	if segments != nil {
+		ret = append(ret,
+			// Force segments to be split exactly on keyframes (only works when transcoding)
+			"-force_key_frames", *segments,
+		)
+	}
+
+	return ret
 }

transcoder/utils.go

@@ -4,6 +4,8 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"io"
+	"log"
 	"net/http"
 	"os"
 	"strings"
@@ -94,3 +96,66 @@ func ErrorHandler(err error, c echo.Context) {
 		Errors []string `json:"errors"`
 	}{Errors: []string{message}})
 }
+
+func ServeOfflineFile(path string, done <-chan struct{}, c echo.Context) error {
+	select {
+	case <-done:
+		// if the transcode is already finished, no need to do anything, just return the file
+		return c.File(path)
+	default:
+		break
+	}
+
+	var f *os.File
+	var err error
+	for {
+		// wait for the file to be created by the transcoder.
+		f, err = os.Open(path)
+		if err == nil {
+			break
+		}
+		time.Sleep(2 * time.Second)
+	}
+	defer f.Close()
+
+	// Offline transcoding always return a mkv and video/webm allow some browser to play a mkv video
+	c.Response().Header().Set(echo.HeaderContentType, "video/webm")
+	c.Response().Header().Set("Trailer", echo.HeaderContentLength)
+	c.Response().WriteHeader(http.StatusOK)
+
+	buffer := make([]byte, 1024)
+	not_done := true
+
+	for not_done {
+		select {
+		case <-done:
+			info, err := f.Stat()
+			if err != nil {
+				log.Printf("Stats error %s", err)
+				return err
+			}
+			c.Response().Header().Set(echo.HeaderContentLength, fmt.Sprint(info.Size()))
+			c.Response().WriteHeader(http.StatusOK)
+			not_done = false
+		case <-time.After(5 * time.Second):
+		}
+	read:
+		for {
+			size, err := f.Read(buffer)
+			if size == 0 && err == io.EOF {
+				break read
+			}
+			if err != nil && err != io.EOF {
+				return err
+			}
+
+			_, err = c.Response().Writer.Write(buffer[:size])
+			if err != nil {
+				log.Printf("Could not write transcoded file to response.")
+				return nil
+			}
+		}
+		c.Response().Flush()
+	}
+	return nil
+}