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/browser.go

@@ -0,0 +1,136 @@
+package ffmpeg
+
+import (
+	"errors"
+	"fmt"
+)
+
+// only support H264 by default, since Safari does not support VP8/VP9
+var defaultSupportedCodecs = []string{H264, H265}
+
+var validForH264Mkv = []Container{Mp4, Matroska}
+var validForH264 = []Container{Mp4}
+var validForH265Mkv = []Container{Mp4, Matroska}
+var validForH265 = []Container{Mp4}
+var validForVp8 = []Container{Webm}
+var validForVp9Mkv = []Container{Webm, Matroska}
+var validForVp9 = []Container{Webm}
+var validForHevcMkv = []Container{Mp4, Matroska}
+var validForHevc = []Container{Mp4}
+
+var validAudioForMkv = []ProbeAudioCodec{Aac, Mp3, Vorbis, Opus}
+var validAudioForWebm = []ProbeAudioCodec{Vorbis, Opus}
+var validAudioForMp4 = []ProbeAudioCodec{Aac, Mp3}
+
+var (
+	// ErrUnsupportedVideoCodecForBrowser is returned when the video codec is not supported for browser streaming.
+	ErrUnsupportedVideoCodecForBrowser = errors.New("unsupported video codec for browser")
+
+	// ErrUnsupportedVideoCodecContainer is returned when the video codec/container combination is not supported for browser streaming.
+	ErrUnsupportedVideoCodecContainer = errors.New("video codec/container combination is unsupported for browser streaming")
+
+	// ErrUnsupportedAudioCodecContainer is returned when the audio codec/container combination is not supported for browser streaming.
+	ErrUnsupportedAudioCodecContainer = errors.New("audio codec/container combination is unsupported for browser streaming")
+)
+
+// IsStreamable returns nil if the file is streamable, or an error if it is not.
+func IsStreamable(videoCodec string, audioCodec ProbeAudioCodec, container Container) error {
+	supportedVideoCodecs := defaultSupportedCodecs
+
+	// check if the video codec matches the supported codecs
+	if !isValidCodec(videoCodec, supportedVideoCodecs) {
+		return fmt.Errorf("%w: %s", ErrUnsupportedVideoCodecForBrowser, videoCodec)
+	}
+
+	if !isValidCombo(videoCodec, container, supportedVideoCodecs) {
+		return fmt.Errorf("%w: %s/%s", ErrUnsupportedVideoCodecContainer, videoCodec, container)
+	}
+
+	if !IsValidAudioForContainer(audioCodec, container) {
+		return fmt.Errorf("%w: %s/%s", ErrUnsupportedAudioCodecContainer, audioCodec, container)
+	}
+
+	return nil
+}
+
+func isValidCodec(codecName string, supportedCodecs []string) bool {
+	for _, c := range supportedCodecs {
+		if c == codecName {
+			return true
+		}
+	}
+	return false
+}
+
+func isValidAudio(audio ProbeAudioCodec, validCodecs []ProbeAudioCodec) bool {
+	// if audio codec is missing or unsupported by ffmpeg we can't do anything about it
+	// report it as valid so that the file can at least be streamed directly if the video codec is supported
+	if audio == MissingUnsupported {
+		return true
+	}
+
+	for _, c := range validCodecs {
+		if c == audio {
+			return true
+		}
+	}
+
+	return false
+}
+
+// IsValidAudioForContainer returns true if the audio codec is valid for the container.
+func IsValidAudioForContainer(audio ProbeAudioCodec, format Container) bool {
+	switch format {
+	case Matroska:
+		return isValidAudio(audio, validAudioForMkv)
+	case Webm:
+		return isValidAudio(audio, validAudioForWebm)
+	case Mp4:
+		return isValidAudio(audio, validAudioForMp4)
+	}
+	return false
+}
+
+// isValidCombo checks if a codec/container combination is valid.
+// Returns true on validity, false otherwise
+func isValidCombo(codecName string, format Container, supportedVideoCodecs []string) bool {
+	supportMKV := isValidCodec(Mkv, supportedVideoCodecs)
+	supportHEVC := isValidCodec(Hevc, supportedVideoCodecs)
+
+	switch codecName {
+	case H264:
+		if supportMKV {
+			return isValidForContainer(format, validForH264Mkv)
+		}
+		return isValidForContainer(format, validForH264)
+	case H265:
+		if supportMKV {
+			return isValidForContainer(format, validForH265Mkv)
+		}
+		return isValidForContainer(format, validForH265)
+	case Vp8:
+		return isValidForContainer(format, validForVp8)
+	case Vp9:
+		if supportMKV {
+			return isValidForContainer(format, validForVp9Mkv)
+		}
+		return isValidForContainer(format, validForVp9)
+	case Hevc:
+		if supportHEVC {
+			if supportMKV {
+				return isValidForContainer(format, validForHevcMkv)
+			}
+			return isValidForContainer(format, validForHevc)
+		}
+	}
+	return false
+}
+
+func isValidForContainer(format Container, validContainers []Container) bool {
+	for _, fmt := range validContainers {
+		if fmt == format {
+			return true
+		}
+	}
+	return false
+}