stream-poc2/handlersMedia.go

package main

import (
	"fmt"
	"log"
	"net/http"
	"os"
	"path"
	"strconv"
	"stream-poc2/ffmpeg"
	"stream-poc2/model"
	"time"

	"github.com/gin-gonic/gin"
)

func mediaListingHandler(ctx *gin.Context) {
	entries, err := os.ReadDir("db")
	if err != nil {
		log.Println("Failed to list dir", err)
		ctx.Status(500)
		return
	}

	var medias []model.APIMedia

	for _, e := range entries {
		if !e.IsDir() {
			continue
		}
		var m model.MediaMetadata
		m, err = loadMediaMetadata(e.Name())
		if err != nil {
			log.Println("Failed to load metadata for", e)
			continue
		}
		medias = append(medias, model.APIMedia{
			Name:         e.Name(),
			FriendlyName: m.FriendlyName,
		})
	}

	log.Println("loaded", medias)
	ctx.JSON(200, medias)
}

func metadataHandler(ctx *gin.Context) {
	_, m := getMetadata(ctx)
	ctx.JSON(http.StatusOK, m)
}

func masterPlaylistHandler(ctx *gin.Context) {
	mediaID, metadata := getMetadata(ctx)

	masterPlaylist := fmt.Sprintf("#EXTM3U\n\n# Master playlist for %s\n\n", mediaID)

	for profile, profileSettings := range model.VideoProfiles {
		masterPlaylist += fmt.Sprintf(
			"#EXT-X-STREAM-INF:BANDWIDTH=%d,AVERAGE-BANDWIDTH=%d,CODECS=\"%s\",RESOLUTION=%s,FRAME-RATE=%.6f,AUDIO=\"audios\",NAME=\"%s\",STABLE-VARIANT-ID\"%s\"\n",
			profileSettings.MaxBitrate,
			profileSettings.AvgBitrate,
			profileSettings.HLSCodec(),
			profileSettings.Resolution.String(),
			metadata.VideoStream.FrameRate,
			profile, profile,
		)
		masterPlaylist += fmt.Sprintf("video/%s/playlist.m3u8\n\n", profile)
	}

	profile := "orig"
	masterPlaylist += fmt.Sprintf(
		"#EXT-X-STREAM-INF:BANDWIDTH=%d,AVERAGE-BANDWIDTH=%d,CODECS=\"%s\",RESOLUTION=%s,FRAME-RATE=%.6f,AUDIO=\"audios\",NAME=\"%s\",STABLE-VARIANT-ID\"%s\"\n",
		metadata.VideoStream.PeakBitrate,
		metadata.VideoStream.AvgBitrate,
		metadata.VideoStream.HLSCodecsString,
		metadata.VideoStream.Resolution,
		metadata.VideoStream.FrameRate,
		profile, profile,
	)
	masterPlaylist += fmt.Sprintf("video/%s/playlist.m3u8\n\n", profile)

	defaultMarked := false
	for _, audioStream := range metadata.AudioStreams {
		autoSelect := ""
		if audioStream.Default && !defaultMarked {
			autoSelect = ",AUTOSELECT=YES,DEFAULT=YES"
			defaultMarked = true
		}
		audioStreamPath := fmt.Sprintf("audio/%d/playlist.m3u8", audioStream.Index)
		masterPlaylist += fmt.Sprintf(
			"#EXT-X-MEDIA:TYPE=AUDIO,GROUP-ID=\"audios\",NAME=\"%s\",LANGUAGE=\"%s\"%s,CHANNELS=\"%d\",SAMPLE-RATE=%d,URI=\"%s\"\n",
			audioStream.Title, audioStream.Lang, autoSelect, audioStream.Channels, audioStream.SampleRate, audioStreamPath,
		)
	}

	ctx.Data(200, "application/vnd.apple.mpegurl", []byte(masterPlaylist))
}

func videoPlaylistHandler(ctx *gin.Context) {
	_, metadata := getMetadata(ctx)

	playlist := fmt.Sprintf(`#EXTM3U
#EXT-X-VERSION:3
#EXT-X-TARGETDURATION:%f
#EXT-X-MEDIA-SEQUENCE:0
#EXT-X-PLAYLIST-TYPE:VOD
`, metadata.TargetDuration)

	for i, chunk := range metadata.VideoStream.VideoChunks {
		lenStr := strconv.FormatFloat(chunk.Length, 'f', 6, 64)
		playlist += fmt.Sprintf("#EXTINF:%s,\n", lenStr)
		playlist += fmt.Sprintf("s%d.ts\n", i)
	}

	playlist += "#EXT-X-ENDLIST"
	ctx.Data(200, "application/vnd.apple.mpegurl", []byte(playlist))
}

func audioPlaylistHandler(ctx *gin.Context) {
	_, metadata := getMetadata(ctx)
	idxStr := ctx.Param("idx")
	idx, err := strconv.Atoi(idxStr)
	if err != nil {
		log.Println("Invalid index")
		ctx.Status(404)
		return
	}

	var langChunks []model.Chunk

	for _, audioStream := range metadata.AudioStreams {
		if audioStream.Index == idx {
			langChunks = audioStream.AudioChunks
			break
		}
	}

	if langChunks == nil {
		log.Println("index not found")
		ctx.Status(404)
		return
	}

	playlist := fmt.Sprintf(`#EXTM3U
#EXT-X-VERSION:3
#EXT-X-TARGETDURATION:%f
#EXT-X-MEDIA-SEQUENCE:0
#EXT-X-PLAYLIST-TYPE:VOD
`, metadata.TargetDuration)
	for i, chunk := range langChunks {
		lenStr := strconv.FormatFloat(chunk.Length, 'f', 6, 64)
		playlist += fmt.Sprintf("#EXTINF:%s,\n", lenStr)
		playlist += fmt.Sprintf("s%d.ts\n", i)
	}

	playlist += "#EXT-X-ENDLIST"
	ctx.Data(200, "application/vnd.apple.mpegurl", []byte(playlist))
}

// serveChunk must be the last function call in the branch
func serveChunk(ctx *gin.Context, chunkPath string) {
	stat, err := os.Stat(chunkPath)
	if err != nil {
		log.Printf("failed to stat chunk %s: %s", chunkPath, err)
		if os.IsNotExist(err) {
			ctx.Status(404)
			return
		}
		ctx.Status(500)
		return
	}
	f, err := os.OpenFile(chunkPath, os.O_RDONLY, 0)
	if err != nil {
		log.Printf("failed to open chunk %s: %s", chunkPath, err)
		ctx.Status(500)
		return
	}
	defer func(f *os.File) {
		err := f.Close()
		if err != nil {
			log.Println("failed to close chunk:", err)
		}
	}(f)
	ctx.DataFromReader(200, stat.Size(), "video/MP2T; charset=binary", f, nil)
}

func videoSegmentHandler(ctx *gin.Context) {
	mediaID, metadata := getMetadata(ctx)

	profile := ctx.Param("profile")
	segment := ctx.Param("segment")
	origSegmentPath := path.Join("db", mediaID, "video", segment)

	// quick path for identity stream
	if profile == "orig" {
		log.Println("Serving identity")
		serveChunk(ctx, origSegmentPath)
		return
	}

	profileSettings, ok := model.VideoProfiles[profile]
	if !ok {
		log.Println("invalid profile")
		ctx.Status(404)
		return
	}

	preEncodedSegmentPath := path.Join("db", mediaID, "cache", "video", profile, segment)
	if isFile(preEncodedSegmentPath) {
		log.Println("Serving from cache")
		serveChunk(ctx, preEncodedSegmentPath)
		return
	}

	log.Println("Serving transcode")

	// transcode video
	ctx.Writer.Header().Set("Content-Type", "video/MP2T; charset=binary")
	ctx.Writer.WriteHeader(200)

	encodeStartTime := time.Now()
	err := ffmpeg.EncodeChunk(profileSettings, metadata.VideoStream.Resolution.Height, getCurrentPreset(), origSegmentPath, ctx.Writer)
	if err != nil {
		log.Println("!!! WARNING: Something went wrong while encoding: ", err)
	}
	log.Println("transcode took ", time.Since(encodeStartTime))
}

func audioSegmentHandler(ctx *gin.Context) {
	mediaID, _ := getMetadata(ctx)
	idx := ctx.Param("idx")
	segment := ctx.Param("segment")

	origSegmentPath := path.Join("db", mediaID, "audio", idx, segment)

	serveChunk(ctx, origSegmentPath)
}