yt-dlp-bot/app/ytdlp.go

package main

import (
	"context"
	"encoding/json"
	"time"

	"github.com/lrstanley/go-ytdlp"
)

func GetFormats(url string) (*FormatOptions, error) {
	dl := ytdlp.New().
		SkipDownload().
		DumpJSON()

	result, err := dl.Run(context.TODO(), url)
	if err != nil {
		return nil, err
	}

	// Parse the JSON output
	var info struct {
		Formats []struct {
			VCodec       *string  `json:"vcodec"`
			ACodec       *string  `json:"acodec"`
			NeedsTesting *bool    `json:"__needs_testing"`
			Height       *int     `json:"height"`
			Resolution   string   `json:"resolution"`
			FormatID     string   `json:"format_id"`
			Format       string   `json:"format"`
			Ext          string   `json:"ext"`
			TBR          *float64 `json:"tbr"`
			Language     *string  `json:"language"`
			LanguagePref *int     `json:"language_preference"`
			URL          *string  `json:"url"`
			Protocol     *string  `json:"protocol"`
		} `json:"formats"`
	}

	if err := json.Unmarshal([]byte(result.Stdout), &info); err != nil {
		return nil, err
	}

	formatOpts := &FormatOptions{
		VideoOptions: []VideoOption{},
		AudioOptions: []AudioOption{},
	}

	for _, fmt := range info.Formats {
		// Skip formats that need testing
		if fmt.NeedsTesting != nil && *fmt.NeedsTesting {
			continue
		}

		// Skip SABR formats (https://github.com/yt-dlp/yt-dlp/issues/12482)
		if fmt.URL == nil || *fmt.URL == "" {
			continue
		}

		// Video-only: has video codec but no audio codec
		if fmt.VCodec != nil && *fmt.VCodec != "none" &&
			fmt.ACodec != nil && *fmt.ACodec == "none" {
			formatOpts.VideoOptions = append(formatOpts.VideoOptions, VideoOption{
				Height:     fmt.Height,
				Resolution: fmt.Resolution,
				FormatID:   fmt.FormatID,
				Ext:        fmt.Ext,
				TBR:        fmt.TBR,
			})
		}

		// Audio-only: has audio codec but no video codec
		if fmt.ACodec != nil && *fmt.ACodec != "none" &&
			fmt.VCodec != nil && *fmt.VCodec == "none" {
			audioOpt := AudioOption{
				Format:   fmt.Format,
				FormatID: fmt.FormatID,
				Ext:      fmt.Ext,
				TBR:      fmt.TBR,
			}

			// Use language if available, otherwise use language_preference
			if fmt.Language != nil {
				audioOpt.Language = fmt.Language
			}

			formatOpts.AudioOptions = append(formatOpts.AudioOptions, audioOpt)
		}
	}

	return formatOpts, nil
}

func DownloadVideo(out_dir, url string, opts DownloadOptions, progressChan chan<- ProgressUpdate) {
	defer close(progressChan)

	var lastPhase string

	dl := ytdlp.New().
		SetWorkDir(out_dir).
		RecodeVideo("mp4").
		ProgressFunc(100*time.Millisecond, func(prog ytdlp.ProgressUpdate) {
			// Detect phase transition -- differentiate "downloading" as the main download
			// and "post processing" when the file name changes, preventing it from appearing "reset"
			phase := "downloading"
			if prog.Status == ytdlp.ProgressStatusDownloading && prog.Percent() == 0.0 {
				// If we already had progress, it's likely post-processing
				if lastPhase == "downloading" {
					phase = "post-processing"
				}
			} else if prog.Status != ytdlp.ProgressStatusDownloading {
				phase = "post-processing"
			}

			lastPhase = phase

			progressChan <- ProgressUpdate{
				Status:   prog.Status,
				Percent:  prog.PercentString(),
				ETA:      prog.ETA(),
				Filename: prog.Filename,
				Phase:    phase,
			}
		}).
		Output("%(title)s.%(ext)s")

	// Set format if both video and audio format IDs are provided
	if opts.VideoFormatID != "" && opts.AudioFormatID != "" {
		dl = dl.Format(opts.VideoFormatID + "+" + opts.AudioFormatID)
	} else if opts.VideoFormatID != "" {
		dl = dl.Format(opts.VideoFormatID)
	} else if opts.AudioFormatID != "" {
		dl = dl.Format(opts.AudioFormatID)
	} else {
		// Default format selection if none specified
		dl = dl.FormatSort("res,ext:mp4:m4a")
	}

	if opts.EmbedThumbnail {
		dl = dl.EmbedThumbnail()
	}

	if opts.IncludeSubtitles {
		dl = dl.CompatOptions("no-keep-subs")
		dl = dl.EmbedSubs()
		dl = dl.SubLangs("en,en*")
		dl = dl.WriteAutoSubs()
		dl = dl.WriteSubs()
	}

	_, err := dl.Run(context.TODO(), url)
	if err != nil {
		panic(err)
	}
}