Question for Dave Murphy


#1

Dave what did you use to capture your video. I can read the data on the right side of the screen. I have been using Free video capture software but the resolution when you play it back makes everything fuzzy.

It was mentioned in one of the discussions that you could use vlc but I have not been able to get it work. I posted a question a couple of days ago on how to set it up but no one replied.

Did you see one of my posts where I put the network cable inside a plastic housing which made it float. I tried several different things on the cable, like fishing floats, round wood balls, ect. The tubing has worked so far.

Liked your videos.

thanks

John


#2

Hey John,

I read your first question about video capture but I didn't have the time to post an answer.

I use VLC for video capture and it works perfectly. It took me a while to find out the correct settings, so I want to share this with you and everybode else.

First, the full address for VLC making display or record the video stream is:

http://192.168.254.1:8090/?action=stream

or whatever IP address you use.

For recording on my Windows laptop I use the following command line command. I made a link on my desktop which I only have to double-click instead of setting all parameters via the user interface every time I want to record:

"C:\Program Files (x86)\VideoLAN\VLC\vlc.exe" -vvv http://192.168.254.1:8090/?action=stream --sout=#transcode{vcodec=h264,vb=1600,fps=15,scale=1}:standard{access=file,mux=mp4,dst="C:\Users\stefan\Desktop\OpenROV Capture\capture.mov"}

which means that I record to a MP4 file using h264 encoding. The other parameters are:

vb = video bitrate in kBits/s

fps = frames per second (should be the same as your setting in config.js at the beagelbone)

scale =1 means that the original video size and aspect ratio is used.

dst = name and directory of the file to be recorded

Good luck,

-Stefan


#3

Hi John

I had used Free screen to video software, was very easy to use.

http://free-screen-to-video.en.softonic.com/

I would like to look at Stefan's solution and others so that we could come up with one that works the best.

The biggest concern is to get one that will create the file and dump the video into it, rather than saving it to a file name after you stop the recording, so that if your battery dies on the laptop you don't loose anything before you get a chance to close the file. I had two dives where I lost the video, one the battery on the laptop was almost done so I put the system to sleep swapped the battery in the laptop thinking I would be good but because I pulled the battery it forced the system into a cold boot and I had to wait forever for it to boot all the time the ROV is on the bottom and I lost the recording. Now I may invest into a Battery backup for the laptop to get longer up time. Always a learning curve :)


#4

Yes I do remember your post using plastic housing.

How deep have you gone with that cable, I was just wondering how it reacts to the water pressure.How flexible is it? I think it would be so much nicer than ping pong balls because they can get caught on objects where as yours would slide over them and where did you buy it?

Regards

Dave


#5

Hi Dave,
I had this situation yesterday during a test dive in a swimming pool. The laptop shut off only a few seconds after it showed a low battery warning. I thought that the vlc recording was lost, but it was still there after I had changed the battery and rebooted the laptop. I don’t know if I was just lucky or if this would work under any similar circumstances.
-Stefan


#6

According to my depth sensor, on Monday night, I was at 21 ft. So I have not been very deep.

I bought out an electronics shop several years ago and ended up with a lot of cable, tubing, ect. (it took me 3 weeks everyday with my truck to empty the place).

So I have tried 5 or 6 different types of tubing and thought this was the best. It is Alpha PVC-105/5. It is sort of flexible, no problem reeling it up and seems slippery in the water, so less stuff get stuck on it.

1248-pvctubing.jpg (283 KB)

#7

Thanks John I will check it out.


#8

That is good to hear Stefan, I tried some quick test this afternoon with your settings and found that the recording seemed to miss some of the activity in front of the camera and I was not sure if this was because my system was a bit slow or not. I also noticed that the video became all garbled after a few minutes into the recording. Maybe if I had a faster laptop this might not be an issue but using Free Screen to Video had no issues. I tried uping the fps to 30 with no difference in quality. I have not tried playing with the other settings yet.