const { RTCVideoSource } = require('wrtc').nonstandard;
const ffmpeg = require('fluent-ffmpeg')

class VideoSourceService extends RTCVideoSource {
    constructor() {
        super() //videosource int
        this.command = null // 存储视频源
        this.cache = Buffer.alloc(0)
    }

    // 创建通道
    createTrack() {
        const track = super.createTrack()
        return track
    }


    // 获取视频源
    async start() {
        if (this.command !== null) this.stop()
        const width = 400, height = 300
        // libx264编码后花屏
        this.command = ffmpeg('/dev/video0')
            .size(`${width}x${height}`)
            .outputOptions(['-pix_fmt yuv420p'])
            .format("rawvideo")
            .on('start', () => {
                console.log('Video start !');
            })
            .on('error', (err) => {
                console.log('Video processing An error occurred: ' + err.message);
                // 退出进程
                process.exit(1)
            })
        this.ffstream = this.command.pipe();
        this.ffstream.on('data', (buffer) => {
            this.cache = Buffer.concat([this.cache, buffer])
        });

        // 整理buffer
        const frameSize = width * height * 1.5;
        const processData = () => {
            while (this.cache.length > frameSize) {
                const buffer = this.cache.slice(0, frameSize)
                this.cache = this.cache.slice(frameSize)
                this.onFrame({
                    width,
                    height,
                    data: new Uint8ClampedArray(buffer)
                })
            }
            if (this.command !== null) {
                setTimeout(() => processData())
            }
        }
        processData()
    }

    // 停止获取
    stop() {
        console.log("Video source stop");
        if (this.command != null) {
            this.command.kill("SIGHUP")
            this.command = null
        }
    }
}
module.exports = VideoSourceService