av/revid/revid.go

/*
NAME
  revid.go

AUTHORS
  Saxon A. Nelson-Milton <saxon@ausocean.org>
  Alan Noble <alan@ausocean.org>
  Dan Kortschak <dan@ausocean.org>
  Trek Hopton <trek@ausocean.org>

LICENSE
  revid is Copyright (C) 2017-2018 the Australian Ocean Lab (AusOcean)

  It is free software: you can redistribute it and/or modify them
  under the terms of the GNU General Public License as published by the
  Free Software Foundation, either version 3 of the License, or (at your
  option) any later version.

  It is distributed in the hope that it will be useful, but WITHOUT
  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
  for more details.

  You should have received a copy of the GNU General Public License
  in gpl.txt.  If not, see http://www.gnu.org/licenses.
*/

// Package revid provides an API for reading, transcoding, and writing audio/video streams and files.
package revid

import (
	"errors"
	"fmt"
	"io"
	"net"
	"os"
	"os/exec"
	"strconv"
	"strings"
	"sync"
	"time"

	"bitbucket.org/ausocean/av/codec/codecutil"
	"bitbucket.org/ausocean/av/codec/h264"
	"bitbucket.org/ausocean/av/codec/h265"
	"bitbucket.org/ausocean/av/container/flv"
	"bitbucket.org/ausocean/av/container/mts"
	"bitbucket.org/ausocean/av/input/audio"
	"bitbucket.org/ausocean/av/protocol/rtcp"
	"bitbucket.org/ausocean/av/protocol/rtp"
	"bitbucket.org/ausocean/av/protocol/rtsp"
	"bitbucket.org/ausocean/iot/pi/netsender"
	"bitbucket.org/ausocean/utils/ioext"
	"bitbucket.org/ausocean/utils/logger"
)

// mtsSender ringBuffer sizes.
const (
	rbSize        = 1000
	rbElementSize = 100000
)

// RTMP connection properties.
const (
	rtmpConnectionMaxTries = 5
	rtmpConnectionTimeout  = 10
)

const (
	rtpPort               = 60000
	rtcpPort              = 60001
	defaultServerRTCPPort = 17301
)

const pkg = "revid:"

type Logger interface {
	SetLevel(int8)
	Log(level int8, message string, params ...interface{})
}

// Revid provides methods to control a revid session; providing methods
// to start, stop and change the state of an instance using the Config struct.
type Revid struct {
	// config holds the Revid configuration.
	// For historical reasons it also handles logging.
	// FIXME(kortschak): The relationship of concerns
	// in config/ns is weird.
	config Config

	// ns holds the netsender.Sender responsible for HTTP.
	ns *netsender.Sender

	// setupInput holds the current approach to setting up
	// the input stream. It returns a function used for cleaning up, and any errors.
	setupInput func() (func() error, error)

	// closeInput holds the cleanup function return from setupInput and is called
	// in Revid.Stop().
	closeInput func() error

	// cmd is the exec'd process that may be used to produce
	// the input stream.
	// FIXME(kortschak): This should not exist. Replace this
	// with a context.Context cancellation.
	cmd *exec.Cmd

	// lexTo, encoder and packer handle transcoding the input stream.
	lexTo func(dest io.Writer, src io.Reader, delay time.Duration, bufSize int) error

	// encoders will hold the multiWriteCloser that writes to encoders from the lexer.
	encoders io.WriteCloser

	// isRunning is used to keep track of revid's running state between methods.
	isRunning bool

	// wg will be used to wait for any processing routines to finish.
	wg sync.WaitGroup

	// err will channel errors from revid routines to the handle errors routine.
	err chan error
}

// New returns a pointer to a new Revid with the desired configuration, and/or
// an error if construction of the new instance was not successful.
func New(c Config, ns *netsender.Sender) (*Revid, error) {
	r := Revid{ns: ns, err: make(chan error)}
	err := r.reset(c)
	if err != nil {
		return nil, err
	}
	go r.handleErrors()
	return &r, nil
}

// Config returns a copy of revids current config.
//
// Config is not safe for concurrent use.
func (r *Revid) Config() Config {
	return r.config
}

// TODO(Saxon): put more thought into error severity.
func (r *Revid) handleErrors() {
	for {
		err := <-r.err
		if err != nil {
			r.config.Logger.Log(logger.Error, pkg+"async error", "error", err.Error())
			r.Stop()
			err = r.Start()
			if err != nil {
				r.config.Logger.Log(logger.Error, pkg+"failed to restart revid", "error", err.Error())
			}
		}
	}
}

// Bitrate returns the result of the  most recent bitrate check.
//
// TODO: get this working again.
func (r *Revid) Bitrate() int {
	return -1
}

// reset swaps the current config of a Revid with the passed
// configuration; checking validity and returning errors if not valid. It then
// sets up the data pipeline accordingly to this configuration.
func (r *Revid) reset(config Config) error {
	err := r.setConfig(config)
	if err != nil {
		return err
	}

	r.config.Logger.SetLevel(config.LogLevel)

	err = r.setupPipeline(
		func(dst io.WriteCloser, fps float64) (io.WriteCloser, error) {
			var st int
			switch r.config.Input {
			case Raspivid, File, V4L:
				st = mts.EncodeH264
			case RTSP:
				st = mts.EncodeH265
			case Audio:
				st = mts.EncodeAudio
			}
			e := mts.NewEncoder(dst, float64(fps), st)
			return e, nil
		},
		func(dst io.WriteCloser, fps int) (io.WriteCloser, error) {
			return flv.NewEncoder(dst, true, true, fps)
		},
		ioext.MultiWriteCloser,
	)

	if err != nil {
		return err
	}

	return nil
}

// setConfig takes a config, checks it's validity and then replaces the current
// revid config.
func (r *Revid) setConfig(config Config) error {
	r.config.Logger = config.Logger
	err := config.Validate(r)
	if err != nil {
		return errors.New("Config struct is bad: " + err.Error())
	}
	r.config = config
	return nil
}

// setupPipeline constructs the revid dataPipeline. Inputs, encoders and
// senders are created and linked based on the current revid config.
//
// mtsEnc and flvEnc will be called to obtain an mts encoder and flv encoder
// respectively. multiWriter will be used to create an ioext.multiWriteCloser
// so that encoders can write to multiple senders.
func (r *Revid) setupPipeline(mtsEnc func(dst io.WriteCloser, rate float64) (io.WriteCloser, error), flvEnc func(dst io.WriteCloser, rate int) (io.WriteCloser, error), multiWriter func(...io.WriteCloser) io.WriteCloser) error {
	// encoders will hold the encoders that are required for revid's current
	// configuration.
	var encoders []io.WriteCloser

	// mtsSenders will hold the senders the require MPEGTS encoding, and flvSenders
	// will hold senders that require FLV encoding.
	var mtsSenders, flvSenders []io.WriteCloser

	// We will go through our outputs and create the corresponding senders to add
	// to mtsSenders if the output requires MPEGTS encoding, or flvSenders if the
	// output requires FLV encoding.
	var w io.WriteCloser
	for _, out := range r.config.Outputs {
		switch out {
		case Http:
			w = newMtsSender(newHttpSender(r.ns, r.config.Logger.Log), r.config.Logger.Log, rbSize, rbElementSize, 0)
			mtsSenders = append(mtsSenders, w)
		case Rtp:
			w, err := newRtpSender(r.config.RtpAddress, r.config.Logger.Log, r.config.FrameRate)
			if err != nil {
				r.config.Logger.Log(logger.Warning, pkg+"rtp connect error", "error", err.Error())
			}
			mtsSenders = append(mtsSenders, w)
		case File:
			w, err := newFileSender(r.config.OutputPath)
			if err != nil {
				return err
			}
			mtsSenders = append(mtsSenders, w)
		case Rtmp:
			w, err := newRtmpSender(r.config.RtmpUrl, rtmpConnectionTimeout, rtmpConnectionMaxTries, r.config.Logger.Log)
			if err != nil {
				r.config.Logger.Log(logger.Warning, pkg+"rtmp connect error", "error", err.Error())
			}
			flvSenders = append(flvSenders, w)
		}
	}

	// If we have some senders that require MPEGTS encoding then add an MPEGTS
	// encoder to revid's encoder slice, and give this encoder the mtsSenders
	// as a destination.
	if len(mtsSenders) != 0 {
		mw := multiWriter(mtsSenders...)
		e, _ := mtsEnc(mw, r.config.WriteRate)
		encoders = append(encoders, e)
	}

	// If we have some senders that require FLV encoding then add an FLV
	// encoder to revid's encoder slice, and give this encoder the flvSenders
	// as a destination.
	if len(flvSenders) != 0 {
		mw := multiWriter(flvSenders...)
		e, err := flvEnc(mw, int(r.config.FrameRate))
		if err != nil {
			return err
		}
		encoders = append(encoders, e)
	}

	r.encoders = multiWriter(encoders...)

	switch r.config.Input {
	case Raspivid:
		r.setupInput = r.startRaspivid
		r.lexTo = h264.Lex
	case V4L:
		r.setupInput = r.startV4L
		r.lexTo = h264.Lex
	case File:
		r.setupInput = r.setupInputForFile
		r.lexTo = h264.Lex
	case RTSP:
		r.setupInput = r.startRTSPCamera
		r.lexTo = h265.NewLexer(false).Lex
	case Audio:
		r.setupInput = r.startAudioDevice
		r.lexTo = codecutil.LexBytes
	}

	return nil
}

// Start invokes a Revid to start processing video from a defined input
// and packetising (if theres packetization) to a defined output.
//
// Start is not safe for concurrent use.
func (r *Revid) Start() error {
	if r.isRunning {
		r.config.Logger.Log(logger.Warning, pkg+"start called, but revid already running")
		return nil
	}
	r.config.Logger.Log(logger.Info, pkg+"starting Revid")
	r.isRunning = true
	var err error
	r.closeInput, err = r.setupInput()
	if err != nil {
		r.Stop()
	}
	return err
}

// Stop closes down the pipeline. This closes encoders and sender output routines,
// connections, and/or files.
//
// Stop is not safe for concurrent use.
func (r *Revid) Stop() {
	if !r.isRunning {
		r.config.Logger.Log(logger.Warning, pkg+"stop called but revid isn't running")
		return
	}

	if r.closeInput != nil {
		err := r.closeInput()
		if err != nil {
			r.config.Logger.Log(logger.Error, pkg+"could not close input", "error", err.Error())
		}
	}

	r.config.Logger.Log(logger.Info, pkg+"closing pipeline")
	err := r.encoders.Close()
	if err != nil {
		r.config.Logger.Log(logger.Error, pkg+"failed to close pipeline", "error", err.Error())
	}

	if r.cmd != nil && r.cmd.Process != nil {
		r.config.Logger.Log(logger.Info, pkg+"killing input proccess")
		r.cmd.Process.Kill()
	}
	r.wg.Wait()
	r.isRunning = false
}

// Update takes a map of variables and their values and edits the current config
// if the variables are recognised as valid parameters.
//
// Update is not safe for concurrent use.
func (r *Revid) Update(vars map[string]string) error {
	if r.isRunning {
		r.Stop()
	}

	//look through the vars and update revid where needed
	for key, value := range vars {
		switch key {
		case "Saturation":
			s, err := strconv.ParseInt(value, 10, 0)
			if err != nil {
				r.config.Logger.Log(logger.Warning, pkg+"invalid saturation param", "value", value)
			}
			r.config.Saturation = int(s)
		case "Brightness":
			b, err := strconv.ParseUint(value, 10, 0)
			if err != nil {
				r.config.Logger.Log(logger.Warning, pkg+"invalid brightness param", "value", value)
			}
			r.config.Brightness = uint(b)
		case "Exposure":
			r.config.Exposure = value
		case "AutoWhiteBalance":
			r.config.AutoWhiteBalance = value
		case "Output":
			outputs := strings.Split(value, ",")
			r.config.Outputs = make([]uint8, len(outputs))

			for i, output := range outputs {
				switch output {
				case "File":
					r.config.Outputs[i] = File
				case "Http":
					r.config.Outputs[i] = Http
				case "Rtmp":
					r.config.Outputs[i] = Rtmp
				case "Rtp":
					r.config.Outputs[i] = Rtp
				default:
					r.config.Logger.Log(logger.Warning, pkg+"invalid output param", "value", value)
					continue
				}
			}

		case "RtmpUrl":
			r.config.RtmpUrl = value
		case "RtpAddress":
			r.config.RtpAddress = value
		case "Bitrate":
			v, err := strconv.ParseUint(value, 10, 0)
			if err != nil {
				r.config.Logger.Log(logger.Warning, pkg+"invalid framerate param", "value", value)
				break
			}
			r.config.Bitrate = uint(v)
		case "OutputPath":
			r.config.OutputPath = value
		case "InputPath":
			r.config.InputPath = value
		case "Height":
			h, err := strconv.ParseUint(value, 10, 0)
			if err != nil {
				r.config.Logger.Log(logger.Warning, pkg+"invalid height param", "value", value)
				break
			}
			r.config.Height = uint(h)
		case "Width":
			w, err := strconv.ParseUint(value, 10, 0)
			if err != nil {
				r.config.Logger.Log(logger.Warning, pkg+"invalid width param", "value", value)
				break
			}
			r.config.Width = uint(w)
		case "FrameRate":
			v, err := strconv.ParseUint(value, 10, 0)
			if err != nil {
				r.config.Logger.Log(logger.Warning, pkg+"invalid framerate param", "value", value)
				break
			}
			r.config.FrameRate = uint(v)
		case "Rotation":
			v, err := strconv.ParseUint(value, 10, 0)
			if err != nil || v > 359 {
				r.config.Logger.Log(logger.Warning, pkg+"invalid rotation param", "value", value)
				break
			}
			r.config.Rotation = uint(v)
		case "HttpAddress":
			r.config.HttpAddress = value
		case "Quantization":
			q, err := strconv.ParseUint(value, 10, 0)
			if err != nil {
				r.config.Logger.Log(logger.Warning, pkg+"invalid quantization param", "value", value)
				break
			}
			r.config.Quantization = uint(q)
		case "IntraRefreshPeriod":
			p, err := strconv.ParseUint(value, 10, 0)
			if err != nil {
				r.config.Logger.Log(logger.Warning, pkg+"invalid intrarefreshperiod param", "value", value)
				break
			}
			r.config.IntraRefreshPeriod = uint(p)

		case "HorizontalFlip":
			switch strings.ToLower(value) {
			case "true":
				r.config.FlipHorizontal = true
			case "false":
				r.config.FlipHorizontal = false
			default:
				r.config.Logger.Log(logger.Warning, pkg+"invalid HorizontalFlip param", "value", value)
			}
		case "VerticalFlip":
			switch strings.ToLower(value) {
			case "true":
				r.config.FlipVertical = true
			case "false":
				r.config.FlipVertical = false
			default:
				r.config.Logger.Log(logger.Warning, pkg+"invalid VerticalFlip param", "value", value)
			}
		case "BurstPeriod":
			v, err := strconv.ParseUint(value, 10, 0)
			if err != nil {
				r.config.Logger.Log(logger.Warning, pkg+"invalid BurstPeriod param", "value", value)
				break
			}
			r.config.BurstPeriod = uint(v)
		case "Logging":
			switch value {
			case "Debug":
				r.config.LogLevel = logger.Debug
			case "Info":
				r.config.LogLevel = logger.Info
			case "Warning":
				r.config.LogLevel = logger.Warning
			case "Error":
				r.config.LogLevel = logger.Error
			case "Fatal":
				r.config.LogLevel = logger.Fatal
			default:
				r.config.Logger.Log(logger.Warning, pkg+"invalid Logging param", "value", value)
			}
		}
	}
	r.config.Logger.Log(logger.Info, pkg+"revid config changed", "config", fmt.Sprintf("%+v", r.config))
	return r.reset(r.config)
}

// startRaspivid sets up things for input from raspivid i.e. starts
// a raspivid process and pipes it's data output.
func (r *Revid) startRaspivid() (func() error, error) {
	r.config.Logger.Log(logger.Info, pkg+"starting raspivid")

	const disabled = "0"
	args := []string{
		"--output", "-",
		"--nopreview",
		"--timeout", disabled,
		"--width", fmt.Sprint(r.config.Width),
		"--height", fmt.Sprint(r.config.Height),
		"--bitrate", fmt.Sprint(r.config.Bitrate),
		"--framerate", fmt.Sprint(r.config.FrameRate),
		"--rotation", fmt.Sprint(r.config.Rotation),
		"--brightness", fmt.Sprint(r.config.Brightness),
		"--saturation", fmt.Sprint(r.config.Saturation),
		"--exposure", fmt.Sprint(r.config.Exposure),
		"--awb", fmt.Sprint(r.config.AutoWhiteBalance),
	}

	if r.config.FlipHorizontal {
		args = append(args, "--hflip")
	}

	if r.config.FlipVertical {
		args = append(args, "--vflip")
	}
	if r.config.FlipHorizontal {
		args = append(args, "--hflip")
	}

	switch r.config.InputCodec {
	default:
		return nil, fmt.Errorf("revid: invalid input codec: %v", r.config.InputCodec)
	case codecutil.H264:
		args = append(args,
			"--codec", "H264",
			"--inline",
			"--intra", fmt.Sprint(r.config.IntraRefreshPeriod),
		)
		if r.config.Quantize {
			args = append(args, "-qp", fmt.Sprint(r.config.Quantization))
		}
	case codecutil.MJPEG:
		args = append(args, "--codec", "MJPEG")
	}
	r.config.Logger.Log(logger.Info, pkg+"raspivid args", "raspividArgs", strings.Join(args, " "))
	r.cmd = exec.Command("raspivid", args...)

	stdout, err := r.cmd.StdoutPipe()
	if err != nil {
		return nil, err
	}
	err = r.cmd.Start()
	if err != nil {
		r.config.Logger.Log(logger.Fatal, pkg+"cannot start raspivid", "error", err.Error())
	}

	r.wg.Add(1)
	go r.processFrom(stdout, 0, 0)
	return nil, nil
}

func (r *Revid) startV4L() (func() error, error) {
	const defaultVideo = "/dev/video0"

	r.config.Logger.Log(logger.Info, pkg+"starting webcam")
	if r.config.InputPath == "" {
		r.config.Logger.Log(logger.Info, pkg+"using default video device", "device", defaultVideo)
		r.config.InputPath = defaultVideo
	}

	args := []string{
		"-i", r.config.InputPath,
		"-f", "h264",
		"-r", fmt.Sprint(r.config.FrameRate),
	}

	args = append(args,
		"-b:v", fmt.Sprint(r.config.Bitrate),
		"-maxrate", fmt.Sprint(r.config.Bitrate),
		"-bufsize", fmt.Sprint(r.config.Bitrate/2),
		"-s", fmt.Sprintf("%dx%d", r.config.Width, r.config.Height),
		"-",
	)

	r.config.Logger.Log(logger.Info, pkg+"ffmpeg args", "args", strings.Join(args, " "))
	r.cmd = exec.Command("ffmpeg", args...)

	stdout, err := r.cmd.StdoutPipe()
	if err != nil {
		return nil, nil
	}

	err = r.cmd.Start()
	if err != nil {
		r.config.Logger.Log(logger.Fatal, pkg+"cannot start webcam", "error", err.Error())
		return nil, nil
	}

	r.wg.Add(1)
	go r.processFrom(stdout, time.Duration(0), 0)
	return nil, nil
}

// setupInputForFile sets things up for getting input from a file
func (r *Revid) setupInputForFile() (func() error, error) {
	f, err := os.Open(r.config.InputPath)
	if err != nil {
		r.config.Logger.Log(logger.Error, err.Error())
		r.Stop()
		return nil, err
	}

	// TODO(kortschak): Maybe we want a context.Context-aware parser that we can stop.
	r.wg.Add(1)
	go r.processFrom(f, 0, 0)
	return func() error { return f.Close() }, nil
}

// startAudioDevice is used to start capturing audio from an audio device and processing it.
func (r *Revid) startAudioDevice() (func() error, error) {
	// Create audio device.
	ac := &audio.Config{
		SampleRate: r.config.SampleRate,
		Channels:   r.config.Channels,
		RecPeriod:  r.config.RecPeriod,
		BitDepth:   r.config.BitDepth,
		Codec:      r.config.InputCodec,
	}
	mts.Meta.Add("sampleRate", strconv.Itoa(r.config.SampleRate))
	mts.Meta.Add("channels", strconv.Itoa(r.config.Channels))
	mts.Meta.Add("period", fmt.Sprintf("%.6f", r.config.RecPeriod))
	mts.Meta.Add("bitDepth", strconv.Itoa(r.config.BitDepth))
	switch r.config.InputCodec {
	case codecutil.PCM:
		mts.Meta.Add("codec", "pcm")
	case codecutil.ADPCM:
		mts.Meta.Add("codec", "adpcm")
	default:
		r.config.Logger.Log(logger.Fatal, pkg+"no audio codec set in config")
	}

	ai, err := audio.NewDevice(ac, r.config.Logger)
	if err != nil {
		r.config.Logger.Log(logger.Fatal, pkg+"failed to create audio device", "error", err.Error())
	}

	// Start audio device
	err = ai.Start()
	if err != nil {
		r.config.Logger.Log(logger.Fatal, pkg+"failed to start audio device", "error", err.Error())
	}

	// Process output from audio device.
	r.wg.Add(1)
	go r.processFrom(ai, time.Duration(float64(time.Second)/r.config.WriteRate), ai.ChunkSize())
	return func() error {
		ai.Stop()
		return nil
	}, nil
}

// startRTSPCamera uses RTSP to request an RTP stream from an IP camera. An RTP
// client is created from which RTP packets containing either h264/h265 can read
// by the selected lexer.
func (r *Revid) startRTSPCamera() (func() error, error) {
	rtspClt, local, remote, err := rtsp.NewClient(r.config.RTSPURL)
	if err != nil {
		return nil, err
	}

	resp, err := rtspClt.Options()
	if err != nil {
		return nil, err
	}
	r.config.Logger.Log(logger.Info, pkg+"RTSP OPTIONS response", "response", resp.String())

	resp, err = rtspClt.Describe()
	if err != nil {
		return nil, err
	}
	r.config.Logger.Log(logger.Info, pkg+"RTSP DESCRIBE response", "response", resp.String())

	resp, err = rtspClt.Setup("track1", fmt.Sprintf("RTP/AVP;unicast;client_port=%d-%d", rtpPort, rtcpPort))
	if err != nil {
		return nil, err
	}
	r.config.Logger.Log(logger.Info, pkg+"RTSP SETUP response", "response", resp.String())
	rtpCltAddr, rtcpCltAddr, rtcpSvrAddr, err := formAddrs(local, remote, *resp)
	if err != nil {
		return nil, err
	}

	resp, err = rtspClt.Play()
	if err != nil {
		return nil, err
	}
	r.config.Logger.Log(logger.Info, pkg+"RTSP server PLAY response", "response", resp.String())

	rtpClt, err := rtp.NewClient(rtpCltAddr)
	if err != nil {
		return nil, err
	}

	rtcpClt, err := rtcp.NewClient(rtcpCltAddr, rtcpSvrAddr, rtpClt, r.config.Logger.Log)
	if err != nil {
		return nil, err
	}

	// Check errors from RTCP client until it has stopped running.
	go func() {
		for {
			err, ok := <-rtcpClt.Err()
			if ok {
				r.config.Logger.Log(logger.Warning, pkg+"RTCP error", "error", err.Error())
			} else {
				return
			}
		}
	}()

	// Start the RTCP client.
	rtcpClt.Start()

	// Start reading data from the RTP client.
	r.wg.Add(1)
	go r.processFrom(rtpClt, time.Second/time.Duration(r.config.FrameRate), 0)

	return func() error {
		rtspClt.Close()
		rtcpClt.Stop()
		return nil
	}, nil
}

// formAddrs is a helper function to form the addresses for the RTP client,
// RTCP client, and the RTSP server's RTCP addr using the local, remote addresses
// of the RTSP conn, and the SETUP method response.
func formAddrs(local, remote *net.TCPAddr, setupResp rtsp.Response) (rtpCltAddr, rtcpCltAddr, rtcpSvrAddr string, err error) {
	svrRTCPPort, err := parseSvrRTCPPort(setupResp)
	if err != nil {
		return "", "", "", err
	}
	rtpCltAddr = strings.Split(local.String(), ":")[0] + ":" + strconv.Itoa(rtpPort)
	rtcpCltAddr = strings.Split(local.String(), ":")[0] + ":" + strconv.Itoa(rtcpPort)
	rtcpSvrAddr = strings.Split(remote.String(), ":")[0] + ":" + strconv.Itoa(svrRTCPPort)
	return
}

// parseServerRTCPPort is a helper function to get the RTSP server's RTCP port.
func parseSvrRTCPPort(resp rtsp.Response) (int, error) {
	transport := resp.Header.Get("Transport")
	for _, p := range strings.Split(transport, ";") {
		if strings.Contains(p, "server_port") {
			port, err := strconv.Atoi(strings.Split(p, "-")[1])
			if err != nil {
				return 0, err
			}
			return port, nil
		}
	}
	return 0, errors.New("SETUP response did not provide RTCP port")
}

func (r *Revid) processFrom(read io.Reader, delay time.Duration, bufSize int) {
	r.config.Logger.Log(logger.Info, pkg+"reading input data")
	r.err <- r.lexTo(r.encoders, read, delay, bufSize)
	r.config.Logger.Log(logger.Info, pkg+"finished reading input data")
	r.wg.Done()
}