streamplace / pkg / renditions / renditions.go

package renditions

import (
	"fmt"
	"math"

	"stream.place/streamplace/pkg/streamplace"
)

type FPS struct {
	Passthrough bool
	Num         uint
	Den         uint
}

type Rendition struct {
	Width     int64
	Height    int64
	Bitrate   int
	Framerate FPS
	Profile   string
	Name      string
	Parent    *Rendition
}

type JSONProfile struct {
	Name    string `json:"name,omitempty"`
	Width   int    `json:"width,omitempty"`
	Height  int    `json:"height,omitempty"`
	Bitrate int    `json:"bitrate,omitempty"`
	FPS     uint   `json:"fps,omitempty"`
	FPSDen  uint   `json:"fpsDen,omitempty"`
	Profile string `json:"profile,omitempty"`
	GOP     string `json:"gop,omitempty"`
	Encoder string `json:"encoder,omitempty"`
	Quality uint   `json:"quality,omitempty"`
}

func (r Rendition) ToLivepeerProfile() JSONProfile {
	p := JSONProfile{
		Name:    r.Name,
		Bitrate: r.Bitrate,
		FPS:     r.Framerate.Num,
		FPSDen:  r.Framerate.Den,
		Profile: r.Profile,
	}
	if r.Parent == nil {
		p.Width = int(r.Width)
		p.Height = int(r.Height)
	} else {
		// We want to set the dimension that is the same as the parent
		if r.Width < r.Height {
			if r.Parent.Width == r.Height {
				p.Height = int(r.Parent.Width)
			} else {
				p.Width = int(r.Parent.Height)
			}
		} else {
			if r.Parent.Height == r.Height {
				p.Height = int(r.Parent.Height)
			} else {
				p.Width = int(r.Parent.Width)
			}
		}
	}
	return p
}

type Renditions []Rendition

func (rs Renditions) ToLivepeerProfiles() []JSONProfile {
	profiles := make([]JSONProfile, len(rs))
	for i, r := range rs {
		profiles[i] = r.ToLivepeerProfile()
	}
	return profiles
}

var DesiredRenditions = []Rendition{
	{
		Name:    "1080p",
		Width:   1920,
		Height:  1080,
		Bitrate: 6_000_000,
		Framerate: FPS{
			Num: 60,
			Den: 1,
		},
		Profile: "h264constrainedhigh",
	},
	{
		Name:    "720p",
		Width:   1280,
		Height:  720,
		Bitrate: 3_000_000,
		Framerate: FPS{
			Num: 60,
			Den: 1,
		},
		Profile: "h264constrainedhigh",
	},
	{
		Name:    "360p",
		Width:   640,
		Height:  360,
		Bitrate: 1_000_000,
		Framerate: FPS{
			Num: 30,
			Den: 1,
		},
		Profile: "h264constrainedhigh",
	},
	{
		Name:    "240p",
		Width:   426,
		Height:  240,
		Bitrate: 500_000,
		Framerate: FPS{
			Num: 30,
			Den: 1,
		},
		Profile: "h264constrainedhigh",
	},
	{
		Name:    "160p",
		Width:   284,
		Height:  160,
		Bitrate: 250_000,
		Framerate: FPS{
			Num: 30,
			Den: 1,
		},
		Profile: "h264baseline",
	},
}

// GenerateRenditions generates renditions for a given spseg
func GenerateRenditions(spseg *streamplace.Segment) (Renditions, error) {
	vid := spseg.Video[0]
	if vid == nil {
		return nil, fmt.Errorf("no video stream found")
	}
	rs := []Rendition{}
	for _, r := range DesiredRenditions {
		vidWidth := int64(vid.Width)
		vidHeight := int64(vid.Height)
		vertical := vid.Height > vid.Width
		// do all the math as if it's horizontal then flip at the end
		if vertical {
			vidWidth, vidHeight = vidHeight, vidWidth
		}
		if vidWidth <= r.Width && vidHeight <= r.Height {
			continue
		}
		rAspectRatio := float64(r.Width) / float64(r.Height)
		vidAspectRatio := float64(vidWidth) / float64(vidHeight)
		if vidAspectRatio > rAspectRatio {
			// vid is wider than r
			// scale down to r.Width
			scale := float64(r.Width) / float64(vidWidth)
			vidWidth = r.Width
			vidHeight = int64(math.Round(float64(vidHeight) * scale))
		} else {
			// vid is taller than r
			// scale down to r.Height
			scale := float64(r.Height) / float64(vidHeight)
			vidHeight = r.Height
			vidWidth = int64(math.Round(float64(vidWidth) * scale))
		}
		outR := Rendition{
			Name:    r.Name,
			Parent:  &r,
			Profile: r.Profile,
		}
		if vertical {
			outR.Width = vidHeight
			outR.Height = vidWidth
		} else {
			outR.Width = vidWidth
			outR.Height = vidHeight
		}

		// if vertical {
		// 	ratio := float64(r.Height) / float64(vid.Height)
		// 	outR.Height = int64(float64(vid.Width) * (16.0 / 9.0) * ratio)
		// 	outR.Width = r.Height
		// } else {
		// 	ratio := float64(r.Width) / float64(vid.Width)
		// 	outR.Width = r.Width
		// 	outR.Height = int64(float64(vid.Width) * (9.0 / 16.0) * ratio)
		// }
		if vid.Framerate.Den > 0 {
			vidFPS := float64(vid.Framerate.Num) / float64(vid.Framerate.Den)
			rFPS := float64(r.Framerate.Num) / float64(r.Framerate.Den)
			delta := rFPS / vidFPS

			if rFPS < vidFPS {
				if delta < 0.75 {
					outR.Framerate.Num = uint(vid.Framerate.Num)
					outR.Framerate.Den = uint(vid.Framerate.Den * 2)
				}
			}
		}

		outR.Bitrate = r.Bitrate
		outR.Profile = r.Profile
		rs = append(rs, outR)
	}
	return rs, nil
}