Restructure ffmpeg (#2392)

* Refactor transcode generation
* Move phash generation into separate package
* Refactor image thumbnail generation
* Move JSONTime to separate package
* Ffmpeg refactoring
* Refactor live transcoding
* Refactor scene marker preview generation
* Refactor preview generation
* Refactor screenshot generation
* Refactor sprite generation
* Change ffmpeg.IsStreamable to return error
* Move frame rate calculation into ffmpeg
* Refactor file locking
* Refactor title set during scan
* Add missing lockmanager instance
* Return error instead of logging in MatchContainer

pkg/ffmpeg/frame_rate.go

@@ -0,0 +1,76 @@
+package ffmpeg
+
+import (
+	"bytes"
+	"context"
+	"math"
+	"regexp"
+	"strconv"
+)
+
+// FrameInfo contains the number of frames and the frame rate for a video file.
+type FrameInfo struct {
+	FrameRate      float64
+	NumberOfFrames int
+}
+
+// CalculateFrameRate calculates the frame rate and number of frames of the video file.
+// Used where the frame rate or NbFrames is missing or invalid in the ffprobe output.
+func (f FFMpeg) CalculateFrameRate(ctx context.Context, v *VideoFile) (*FrameInfo, error) {
+	var args Args
+	args = append(args, "-nostats")
+	args = args.Input(v.Path).
+		VideoCodec(VideoCodecCopy).
+		Format(FormatRawVideo).
+		Overwrite().
+		NullOutput()
+
+	command := f.Command(ctx, args)
+	var stdErrBuffer bytes.Buffer
+	command.Stderr = &stdErrBuffer // Frames go to stderr rather than stdout
+	err := command.Run()
+	if err == nil {
+		var ret FrameInfo
+		stdErrString := stdErrBuffer.String()
+		ret.NumberOfFrames = getFrameFromRegex(stdErrString)
+
+		time := getTimeFromRegex(stdErrString)
+		ret.FrameRate = math.Round((float64(ret.NumberOfFrames)/time)*100) / 100
+
+		return &ret, nil
+	}
+
+	return nil, err
+}
+
+var timeRegex = regexp.MustCompile(`time=\s*(\d+):(\d+):(\d+.\d+)`)
+var frameRegex = regexp.MustCompile(`frame=\s*([0-9]+)`)
+
+func getTimeFromRegex(str string) float64 {
+	regexResult := timeRegex.FindStringSubmatch(str)
+
+	// Bail early if we don't have the results we expect
+	if len(regexResult) != 4 {
+		return 0
+	}
+
+	h, _ := strconv.ParseFloat(regexResult[1], 64)
+	m, _ := strconv.ParseFloat(regexResult[2], 64)
+	s, _ := strconv.ParseFloat(regexResult[3], 64)
+	hours := h * 3600
+	minutes := m * 60
+	seconds := s
+	return hours + minutes + seconds
+}
+
+func getFrameFromRegex(str string) int {
+	regexResult := frameRegex.FindStringSubmatch(str)
+
+	// Bail early if we don't have the results we expect
+	if len(regexResult) < 2 {
+		return 0
+	}
+
+	result, _ := strconv.Atoi(regexResult[1])
+	return result
+}