clipper/backend/youtube/helpers.go

package youtube

import (
	"fmt"
	"sort"
	"strings"

	youtubev2 "github.com/kkdai/youtube/v2"
)

func FormatDebugString(format *youtubev2.Format, includeURL bool) string {
	url := "hidden"
	if includeURL {
		url = format.URL
	}
	return fmt.Sprintf(
		"iTag = %d, mime_type = %s, quality = %s, quality_label = %s, bitrate = %d, fps = %d, width = %d, height = %d, content_length = %d, duration = %v, audio_channels = %d, audio_sample_rate = %s, audio_quality = %s, url = %s",
		format.ItagNo,
		format.MimeType,
		format.Quality,
		format.QualityLabel,
		format.Bitrate,
		format.FPS,
		format.Width,
		format.Height,
		format.ContentLength,
		format.ApproxDurationMs,
		format.AudioChannels,
		format.AudioSampleRate,
		format.AudioQuality,
		url,
	)
}

// SortAudio returns the provided formats ordered in descending preferred
// order. The ideal candidate is opus-encoded stereo audio in a webm container,
// with the lowest available bitrate.
func SortAudio(inFormats youtubev2.FormatList) youtubev2.FormatList {
	var formats youtubev2.FormatList
	for _, format := range inFormats {
		if format.FPS == 0 && format.AudioChannels > 0 {
			formats = append(formats, format)
		}
	}
	sort.SliceStable(formats, func(i, j int) bool {
		isOpusI := strings.Contains(formats[i].MimeType, "opus")
		isOpusJ := strings.Contains(formats[j].MimeType, "opus")
		if isOpusI && isOpusJ {
			isStereoI := formats[i].AudioChannels == 2
			isStereoJ := formats[j].AudioChannels == 2
			if isStereoI && isStereoJ {
				return formats[i].ContentLength < formats[j].ContentLength
			}
			return isStereoI
		}
		return isOpusI
	})
	return formats
}

// SortVideo returns the provided formats ordered in descending preferred
// order. The ideal candidate is video in an mp4 container with a low
// bitrate, with audio channels (needed to allow synced playback on the
// website).
func SortVideo(inFormats youtubev2.FormatList) youtubev2.FormatList {
	var formats youtubev2.FormatList
	for _, format := range inFormats {
		if format.FPS > 0 && format.ContentLength > 0 {
			formats = append(formats, format)
		}
	}
	sort.SliceStable(formats, func(i, j int) bool {
		isMP4I := strings.Contains(formats[i].MimeType, "mp4")
		isMP4J := strings.Contains(formats[j].MimeType, "mp4")
		if isMP4I && isMP4J {
			return formats[i].ContentLength < formats[j].ContentLength
		}
		return isMP4I
	})
	return formats
}