package src import ( "fmt" "log" ) type VideoStream struct { Stream quality Quality } func NewVideoStream(file *FileStream, quality Quality) *VideoStream { log.Printf("Creating a new video stream for %s in quality %s", file.Path, quality) ret := new(VideoStream) ret.quality = quality ret.Stream = NewStream(file, ret) return ret } func (vs *VideoStream) getFlags() Flags { return VideoF } func (vs *VideoStream) getOutPath(encoder_id int) string { return fmt.Sprintf("%s/segment-%s-%d-%%d.ts", vs.file.Out, vs.quality, encoder_id) } func (vs *VideoStream) getTranscodeArgs(segments string) []string { if vs.quality == Original { return []string{"-map", "0:V:0", "-c:v", "copy"} } return []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()), // 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, // sc_threshold is a scene detection mechanisum used to create a keyframe when the scene changes // this is on by default and inserts keyframes where we don't want to (it also breaks force_key_frames) // we disable it to prevents whole scenes from behing removed due to the -f segment failing to find the corresonding keyframe "-sc_threshold", "0", "-strict", "-2", } }