Piped/src/utils/DashUtils.js

// Based of https://github.com/GilgusMaximus/yt-dash-manifest-generator/blob/master/src/DashGenerator.js

const xml = require('xml-js')

const DashUtils = {
    generate_dash_file_from_formats(VideoFormats, VideoLength) {
        const generatedJSON = this.generate_xmljs_json_from_data(VideoFormats, VideoLength)
        return xml.json2xml(generatedJSON)
    },
    generate_xmljs_json_from_data(VideoFormatArray, VideoLength) {
        const convertJSON = {
            "declaration": {
                "attributes": {
                    "version": "1.0",
                    "encoding": "utf-8"
                }
            },
            "elements": [
                {
                    "type": "element",
                    "name": "MPD",
                    "attributes": {
                        "xmlns": "urn:mpeg:dash:schema:mpd:2011",
                        "profiles": "urn:mpeg:dash:profile:full:2011",
                        "minBufferTime": "PT1.5S",
                        "type": "static",
                        "mediaPresentationDuration": `PT${VideoLength}S`
                    },
                    "elements": [
                        {
                            "type": "element",
                            "name": "Period",
                            "elements": this.generate_adaptation_set(VideoFormatArray)
                        }
                    ]
                }
            ]
        }
        return convertJSON
    },
    generate_adaptation_set(VideoFormatArray) {
        const adaptationSets = []
        const mimeTypes = []
        const mimeObjects = [[]]
        // sort the formats by mime types
        VideoFormatArray.forEach((videoFormat) => {
            // the dual formats should not be used
            if (videoFormat.mimeType.indexOf("video") != -1 && !videoFormat.videoOnly) {
                return
            }
            // if these properties are not available, then we skip it because we cannot set these properties
            //if (!(videoFormat.hasOwnProperty('initRange') && videoFormat.hasOwnProperty('indexRange'))) {
            //   return
            //}
            const mimeType = videoFormat.mimeType
            const mimeTypeIndex = mimeTypes.indexOf(mimeType)
            if (mimeTypeIndex > -1) {
                mimeObjects[mimeTypeIndex].push(videoFormat)
            } else {
                mimeTypes.push(mimeType)
                mimeObjects.push([])
                mimeObjects[mimeTypes.length - 1].push(videoFormat)
            }
        })
        // for each MimeType generate a new Adaptation set with Representations as sub elements
        for (let i = 0; i < mimeTypes.length; i++) {
            let isVideoFormat = false
            const adapSet = {
                "type": "element",
                "name": "AdaptationSet",
                "attributes": {
                    "id": i,
                    "mimeType": mimeTypes[i],
                    "startWithSAP": "1",
                    "subsegmentAlignment": "true"
                },
                "elements": []
            }
            if (!mimeTypes[i].includes("audio")) {
                adapSet.attributes.scanType = "progressive"
                isVideoFormat = true
            }
            mimeObjects[i].forEach((format) => {
                if (isVideoFormat) {
                    adapSet.elements.push(this.generate_representation_video(format))
                } else {
                    adapSet.elements.push(this.generate_representation_audio(format))
                }
            })
            adaptationSets.push(adapSet)
        }
        return adaptationSets
    }, generate_representation_audio(Format) {
        const representation =
        {
            "type": "element",
            "name": "Representation",
            "attributes": {
                "id": Format.itag,
                "codecs": Format.codec,
                "bandwidth": Format.bitrate
            },
            "elements": [
                {
                    "type": "element",
                    "name": "AudioChannelConfiguration",
                    "attributes": {
                        "schemeIdUri": "urn:mpeg:dash:23003:3:audio_channel_configuration:2011",
                        "value": "2"
                    },
                },
                {
                    "type": "element",
                    "name": "BaseURL",
                    "elements": [
                        {
                            "type": "text",
                            "text": Format.url
                        }
                    ]
                },
                {
                    "type": "element",
                    "name": "SegmentBase",
                    "attributes": {
                        "indexRange": `${Format.indexStart}-${Format.indexEnd}`
                    },
                    "elements": [
                        {
                            "type": "element",
                            "name": "Initialization",
                            "attributes": {
                                "range": `${Format.initStart}-${Format.initEnd}`
                            }
                        }
                    ]
                }
            ]
        }
        return representation
    },
    generate_representation_video(Format) {
        const representation =
        {
            "type": "element",
            "name": "Representation",
            "attributes": {
                "id": Format.itag,
                "codecs": Format.codec,
                "bandwidth": Format.bitrate,
                "width": Format.width,
                "height": Format.height,
                "maxPlayoutRate": "1",
                "frameRate": Format.fps
            },
            "elements": [
                {
                    "type": "element",
                    "name": "BaseURL",
                    "elements": [
                        {
                            "type": "text",
                            "text": Format.url
                        }
                    ]
                },
                {
                    "type": "element",
                    "name": "SegmentBase",
                    "attributes": {
                        "indexRange": `${Format.indexStart}-${Format.indexEnd}`
                    },
                    "elements": [
                        {
                            "type": "element",
                            "name": "Initialization",
                            "attributes": {
                                "range": `${Format.initStart}-${Format.initEnd}`
                            }
                        }
                    ]
                }
            ]
        }
        return representation
    }
}

export default DashUtils;