From 9875acbe06c2a689f0bbf098e094e10739c4dbc2 Mon Sep 17 00:00:00 2001
From: Ron Evans <ron@hybridgroup.com>
Date: Thu, 19 Apr 2018 18:28:14 +0200
Subject: [PATCH] tello: improve video encoding rate API call

Signed-off-by: Ron Evans <ron@hybridgroup.com>
---
 examples/tello_opencv.go      |  3 ++-
 examples/tello_video.go       |  2 +-
 platforms/dji/tello/driver.go | 18 +++++++++++++++---
 3 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/examples/tello_opencv.go b/examples/tello_opencv.go
index 87d0eba3..b099aa03 100644
--- a/examples/tello_opencv.go
+++ b/examples/tello_opencv.go
@@ -64,7 +64,8 @@ func main() {
 			fmt.Println("Connected")
 			drone.StartVideo()
 			drone.SetExposure(1)
-			drone.SetVideoEncoderRate(3)
+			drone.SetVideoEncoderRate(4)
+
 			gobot.Every(250*time.Millisecond, func() {
 				drone.StartVideo()
 			})
diff --git a/examples/tello_video.go b/examples/tello_video.go
index f810e22f..580d98e1 100644
--- a/examples/tello_video.go
+++ b/examples/tello_video.go
@@ -36,7 +36,7 @@ func main() {
 		drone.On(tello.ConnectedEvent, func(data interface{}) {
 			fmt.Println("Connected")
 			drone.StartVideo()
-			drone.SetExposure(0)
+			drone.SetVideoEncoderRate(4)
 			gobot.Every(250*time.Millisecond, func() {
 				drone.StartVideo()
 			})
diff --git a/platforms/dji/tello/driver.go b/platforms/dji/tello/driver.go
index b883697f..0926387d 100644
--- a/platforms/dji/tello/driver.go
+++ b/platforms/dji/tello/driver.go
@@ -191,13 +191,13 @@ func (d *Driver) Start() error {
 
 	// send stick commands
 	go func() {
-		time.Sleep(100 * time.Millisecond)
+		time.Sleep(50 * time.Millisecond)
 		for {
 			err := d.SendStickCommand()
 			if err != nil {
 				fmt.Println("stick command error:", err)
 			}
-			time.Sleep(50 * time.Millisecond)
+			time.Sleep(20 * time.Millisecond)
 		}
 	}()
 
@@ -335,7 +335,19 @@ func (d *Driver) SetExposure(level int) (err error) {
 
 // SetVideoEncoderRate sets the drone video encoder rate.
 func (d *Driver) SetVideoEncoderRate(rate int) (err error) {
-	pkt := []byte{messageStart, 0x60, 0x00, 0x27, 0x68, videoEncoderRateCommand, 0x00, 0xe6, 0x01, byte(rate), 0x00, 0x00}
+	pkt := []byte{messageStart, 0x62, 0x00, 0x27, 0x68, videoEncoderRateCommand, 0x00, 0xe6, 0x01, byte(rate), 0x00, 0x00, 0x00}
+
+	// sets ending crc bytes for packet
+	l := len(pkt)
+	pkt[(l - 2)], pkt[(l - 1)] = CalculateCRC(pkt)
+
+	_, err = d.reqConn.Write(pkt)
+	return
+}
+
+// Rate does some still unknown thing.
+func (d *Driver) Rate() (err error) {
+	pkt := []byte{messageStart, 0x58, 0x00, 0x7c, 0x48, 40, 0x00, 0xe6, 0x01, 0x6c, 0x95}
 
 	// sets ending crc bytes for packet
 	l := len(pkt)