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/transcoder/transcode.go

@@ -0,0 +1,99 @@
+package transcoder
+
+import "github.com/stashapp/stash/pkg/ffmpeg"
+
+type TranscodeOptions struct {
+	OutputPath string
+	Format     ffmpeg.Format
+
+	VideoCodec ffmpeg.VideoCodec
+	VideoArgs  ffmpeg.Args
+
+	AudioCodec ffmpeg.AudioCodec
+	AudioArgs  ffmpeg.Args
+
+	// if XError is true, then ffmpeg will fail on warnings
+	XError bool
+
+	StartTime float64
+	SlowSeek  bool
+	Duration  float64
+
+	// Verbosity is the logging verbosity. Defaults to LogLevelError if not set.
+	Verbosity ffmpeg.LogLevel
+}
+
+func (o *TranscodeOptions) setDefaults() {
+	if o.Verbosity == "" {
+		o.Verbosity = ffmpeg.LogLevelError
+	}
+}
+
+func Transcode(input string, options TranscodeOptions) ffmpeg.Args {
+	options.setDefaults()
+
+	// TODO - this should probably be generalised and applied to all operations. Need to verify impact on phash algorithm.
+	const fallbackMinSlowSeek = 20.0
+
+	var fastSeek float64
+	var slowSeek float64
+
+	if !options.SlowSeek {
+		fastSeek = options.StartTime
+		slowSeek = 0
+	} else {
+		// In slowseek mode, try a combination of fast/slow seek instead of just fastseek
+		// Commonly with avi/wmv ffmpeg doesn't seem to always predict the right start point to begin decoding when
+		// using fast seek. If you force ffmpeg to decode more, it avoids the "blocky green artifact" issue.
+		if options.StartTime > fallbackMinSlowSeek {
+			// Handle seeks longer than fallbackMinSlowSeek with fast/slow seeks
+			// Allow for at least fallbackMinSlowSeek seconds of slow seek
+			fastSeek = options.StartTime - fallbackMinSlowSeek
+			slowSeek = fallbackMinSlowSeek
+		} else {
+			// Handle seeks shorter than fallbackMinSlowSeek with only slow seeks.
+			slowSeek = options.StartTime
+			fastSeek = 0
+		}
+	}
+
+	var args ffmpeg.Args
+	args = args.LogLevel(options.Verbosity).Overwrite()
+
+	if options.XError {
+		args = args.XError()
+	}
+
+	if fastSeek > 0 {
+		args = args.Seek(fastSeek)
+	}
+
+	args = args.Input(input)
+
+	if slowSeek > 0 {
+		args = args.Seek(slowSeek)
+	}
+
+	if options.Duration > 0 {
+		args = args.Duration(options.Duration)
+	}
+
+	// https://trac.ffmpeg.org/ticket/6375
+	args = args.MaxMuxingQueueSize(1024)
+
+	args = args.VideoCodec(options.VideoCodec)
+	args = args.AppendArgs(options.VideoArgs)
+
+	// if audio codec is not provided, then skip it
+	if options.AudioCodec == "" {
+		args = args.SkipAudio()
+	} else {
+		args = args.AudioCodec(options.AudioCodec)
+	}
+	args = args.AppendArgs(options.AudioArgs)
+
+	args = args.Format(options.Format)
+	args = args.Output(options.OutputPath)
+
+	return args
+}