video.go

// video.go

// Copyright (C) 2018  Steve Merrony

// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

package tello

import (
	"log"
	"net"
	"strconv"
)

const (
	defaultTelloVideoPort = 6038
)

// VideoConnect attempts to connect to a Tello video channel at the provided addr and starts a listener.
// A channel of raw H.264 video frames is returned along with any error.
// The channel will be closed if the connection is lost.
func (tello *Tello) VideoConnect(udpAddr string, droneUDPPort int) (<-chan []byte, error) {
	droneAddr, err := net.ResolveUDPAddr("udp", ":"+strconv.Itoa(droneUDPPort))
	if err != nil {
		return nil, err
	}
	tello.videoConn, err = net.ListenUDP("udp", droneAddr)
	if err != nil {
		log.Printf("Error: VideoConnect - ListenUDP failed with %v\n", err)
		return nil, err
	}
	tello.videoStopChan = make(chan bool, 2)
	tello.videoChan = make(chan []byte, 100)
	go tello.videoResponseListener()
	//log.Println("Video connection setup complete")
	return tello.videoChan, nil
}

// VideoConnectDefault attempts to connect to a Tello video channel using default addresses, then starts a listener.
// A channel of raw H.264 video frames is returned along with any error.
func (tello *Tello) VideoConnectDefault() (<-chan []byte, error) {
	return tello.VideoConnect(defaultTelloAddr, defaultTelloVideoPort)
}

// VideoDisconnect closes the connection to the video channel.
func (tello *Tello) VideoDisconnect() {
	// TODO Should we tell the Tello we are stopping video listening?
	tello.videoStopChan <- true
	tello.videoConn.Close()
}

func (tello *Tello) videoResponseListener() {
	for {
		vbuf := make([]byte, 2048)
		if tello.videoConn == nil {
			// must have been closed
			log.Println("Info: videoResponseListener closing")
			close(tello.videoChan)
			return
		}
		n, _, err := tello.videoConn.ReadFromUDP(vbuf)
		if err != nil {
			log.Printf("Error reading from video channel - %v\n", err)
			close(tello.videoChan)
			return
		}
		select {
		case tello.videoChan <- vbuf[2:n]:
		case <-tello.videoStopChan:
			log.Println("Info: Closing Video Channel")
			close(tello.videoChan)
			return
		default: // so we don't block
		}
	}
}

// GetVideoBitrate requests the current video Mbps from the Tello.
func (tello *Tello) GetVideoBitrate() {
	tello.ctrlMu.Lock()
	defer tello.ctrlMu.Unlock()

	tello.ctrlSeq++
	pkt := newPacket(ptGet, msgQueryVideoBitrate, tello.ctrlSeq, 0)
	tello.ctrlConn.Write(packetToBuffer(pkt))
}

// SetVideoBitrate ask the Tello to use the specified bitrate (or auto) for video encoding.
func (tello *Tello) SetVideoBitrate(vbr VBR) {
	tello.ctrlMu.Lock()
	defer tello.ctrlMu.Unlock()

	tello.ctrlSeq++
	pkt := newPacket(ptSet, msgSetVideoBitrate, tello.ctrlSeq, 1)
	pkt.payload[0] = byte(vbr)
	tello.ctrlConn.Write(packetToBuffer(pkt))
}

// GetVideoSpsPps asks the Tello to send SPS and PPS in video stream.
// Calling this more often decreases video bandwidth, calling less often
// results in video artifacts.  Every 0.5 to 2.0 seconds seems a reasonable range.
func (tello *Tello) GetVideoSpsPps() {
	tello.ctrlMu.Lock()
	defer tello.ctrlMu.Unlock()

	pkt := newPacket(ptData2, msgQueryVideoSPSPPS, 0, 0)
	tello.ctrlConn.Write(packetToBuffer(pkt))
}

// SetVideoNormal requests video format to be (native) ~4:3 ratio.
func (tello *Tello) SetVideoNormal() {
	tello.ctrlMu.Lock()
	defer tello.ctrlMu.Unlock()

	tello.ctrlSeq++
	pkt := newPacket(ptSet, msgSwitchPicVideo, tello.ctrlSeq, 1)
	pkt.payload[0] = vmNormal
	tello.ctrlConn.Write(packetToBuffer(pkt))
}

// SetVideoWide requests video format to be (cropped) 16:9 ratio.
func (tello *Tello) SetVideoWide() {
	tello.ctrlMu.Lock()
	defer tello.ctrlMu.Unlock()

	tello.ctrlSeq++
	pkt := newPacket(ptSet, msgSwitchPicVideo, tello.ctrlSeq, 1)
	pkt.payload[0] = vmWide
	tello.ctrlConn.Write(packetToBuffer(pkt))
}