ways to wirelessly transmit live video

[ahedgehog]

I would like to make a robot that I can drive with a wireless keyboard, and with a camera attached to a maplins robotic arm. My plan is to attach a USB camera just behind the gripper for the arm, so I can look around using the arm.

My first thought about how to get live video from the camera would be to live stream it using a WiFi dongle and the motion daemon. However, this would limit the range of the robot because ot would alyways need an internet connection and would have a low FPS. Does anyone know any better ways to receive live video (that aren't limited by WiFi or have a higher FPS), bearing in mind that I have to be quite close to control it anyway?

Thanks in advance for any help

[kusti8]

Haven't tried this but in theory you could make a ad-hoc network on the raspberry pi and then connect the device to it to see the video. How far do you want the range to be?

[Duane Degn]

I haven't used a WiFi camera myself, but I wasn't aware one needed internet access to use a WiFi camera. I thought one just needed access to your local network. (Edit: I hadn't seen Kusti8's reply. It appears Kusti8 also thinks an internet connection isn't needed.)

I imagine streaming video from a USB camera could be a challenge with a poor WiFi signal.

While I've never used a WiFi camera, I've flown video cameras on radio controlled aircraft many times. "FPV" cameras are very popular among radio controlled aircraft enthusiast. You might want to check some of these sort of websites for information.

I think it's much more common for FPV video links to transmit analog signals (NTSC or PAL) rather than WiFi with their setups. I personally use a 900MHz system for transmitting video. While there are a variety of frequencies used for transmitting video, in general the lower the frequency of the transmission, the greater the range at identical power settings. This doesn't mean the higher frequency systems aren't a good option. I've seen some very impressive results with 5.8GHz systems.

NTSC or PAL cameras, are generally lower resolution than a USB web cam or other computer ready camera. If you want to view the video on a smart phone, getting the video from the NTSC or PAL signal would require some sort of video capture device to digitize the signal. Using the image for machine vision also requires a way to digitize the images.

As with many things in robotics, so much depends on a particular application. What sort of range do you want. What resolution do you want. Do you also want to transmit data?

Hopefully someone familiar with streaming digital video will provide some insight to alternatives offered by WiFi or similar method of transmitting video. While transmitting analog video is often the best option for long distances wireless video, I'm not sure how far "long distance" is. Some sort of digital streaming may still be a good option for the distances you wish to cover.

Edit to add: Here are a few links to FPV sites.
ReadyMadeRc makes/sells some good stuff. I haven't purchased from them myself but I've heard good things about them.

FPV at RC Groups. Lots of information.

[ahedgehog]

Haven't tried this but in theory you could make a ad-hoc network on the raspberry pi and then connect the device to it to see the video. How far do you want the range to be?

I would like a range of about 10 metres or so, because I need to be pretty close to control it anyway. Thanks for the advice, I shall look into as hoc networks

[kusti8]

You could make the ad hoc network like this as sudo:

Code: Select all

(the first line might not be necessary)
ifconfig wlan0 up
iwconfig wlan0 mode ad-hoc
iwconfig wlan0 essid "Pi"
ifconfig wlan0 192.168.1.1 netmask 255.255.255.0

Then, start motion (I personally like to use mjpg-streamer since you can see it on any device without flash or anything) and open up the page in the web browser of your device and type in the address of the pi: 192.168.1.1 and then the port. If you run into any problems, I will try to answer them.

[nikjav93]

I am working on the same kind of a project. Only that this is my final year Engineering project and so i have a time restraint of 2 months from today to get it working.

I am building a Quadcopter that will be autonomous and it would control a ground based multi robotic system. For this operation, i am using Raspi Cam along with Raspberry pi model B+. I want to wirelessly transmit a live video feed over Wifi and so i bought a TP-Link WN725N wifi v2 adapter and connected it to my pi. I was successful to establish internet connection with some additional installation of drivers (easy setup). For some reason, my kernel is not letting me download gstreamer, which i heard can give you latencies lower than 200ms over wifi. So, I tried out motion deamon which gave a latency of 5s and very low fps. I came across this video and tried the vlc streamer and it worked beautiful (1080p with 30fps & no distortion) except for a 2s latency. I'll post the link of the video below so it can help anyone who needs a solution to wifi streaming and would do with a latency of about 2s.

However, it is imperative for me to have a latency lower than 200ms for my project to work flawlessly. I have narrowed down some problems after a bit of brainstorming. If anyone has any inputs, please do comment. It would really help me alot.

So here are the problems that i could think of, that could possibly improve the stream latency. If you happen to know the solution, please do comment.

1) My wifi is designed to support 802.11n which can support upto 150mb/s speed. However, my iwconfig is showing me that my adapter is working at 72.2mb/s. How can i resolve this issue? I know that i will be needing a 40 MHz band for 150mbps but i dont know how to configure elements in my system to achieve that rate.

2)I dont know what bitrate the usb of the pi outputs the data at, im guessing 9600 standard. Is there any way to increase the bitrate and can that give a boost to my stream?

3) I heard that ad-hoc networks can give you better speeds. How can you configure an ad-hoc network to solve the problems specified above? Well, for my project i just need a piped stream from the pi to my laptop, i dont care if theres an AP in between or no, the lesser the delay, the better. So is there any way i can transmit data directly from the pi-wifi to my laptop without routing the data through any other element?

4) Any other transcoder than H264 that can give me faster rate?

5) Any other streaming protocols than http that will work faster? (there is a rtsp code for streaming using cvlc but unfortunately it isnt working for me as i cant see the stream either on vlc player or the site to where it is streamed at)

6) Any other alternative solutions?

And heres the link: https://www.youtube.com/watch?v=JjPsW-7FUng

Thanks in advance,
Nikhil

[Biclo]

Hi i'm working with the same concept of live streaming wirelessly but i'm using it as a coral monitoring system. I need help on what kind of camera should I use. A lot of people suggested that I should use just use the raspberry pi's camera but the problem is that I wanted my project to send live video without WiFi. I found that an fpv camera can do the same but the range needs to be very large.