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2017-01-30 17:31:44 -0500 commented question roslibjs audio_common_msgs wrong array length

It's correct with "atob()". Thanks!

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2017-01-30 04:38:55 -0500 commented question roslibjs audio_common_msgs wrong array length

Excellent comment. This was so obvious but I didn't think of it. I try to enocde it in the evening and see if it's true. base64: 64 = 2^6, so 6 bits instead of 8: (512/6) *8 = 682,6. So it is not exactly 684, but very close and it could be filled up to 684 (next even number) or something like that.

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2017-01-29 20:19:52 -0500 asked a question roslibjs audio_common_msgs wrong array length

Hi,

I publish audio_common_msgs Audiodata from my ros module and subscribe to it via roslibjs

    var audio_topic = new ROSLIB.Topic({
    ros : ros,
    name : '/camera/audio',
    messageType : 'audio_common_msgs/AudioData'
});

It works but the length of the data is incorrect. I send predefined array sizes of 512 and check in my ros module if the length is really 512. However in my roslibjs webpage the data is of length 684. I dont know where the other array values come from. Can someone help me out?

thanks

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2017-01-22 15:46:36 -0500 commented question Display ros image on webpage using roslibjs

I had the same problem. My solution was:

    var imageTopic = new ROSLIB.Topic({
    ros : ros,
    name : '/camera/image/compressed',
    messageType : 'sensor_msgs/CompressedImage'
});

subscribe the compressed image. The normal image is pixeldata, so uncompressed.

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2017-01-22 15:14:32 -0500 commented question roslibjs subscribe to sensor_msgs/image

Found a solution:

var imageTopic = new ROSLIB.Topic({
    ros : ros,
    name : '/camera/image/compressed',
    messageType : 'sensor_msgs/CompressedImage'
});

the compressed image can be retrieved via:

var imagedata = "data:image/jpg;base64," + message.data;
2017-01-20 19:09:33 -0500 asked a question roslibjs subscribe to sensor_msgs/image

Hello,

I couldn't find an example of how to subscribe to a sensor_msgs/image and display it in a html5 canvas. I already have a page running and I can somehow access the data, but it won't display in an image nor in a html5 canvas. This is an excerpt of my test code:

imageTopic.subscribe(function(message)
{
   var imagedata = "data:image/jpeg;base64," + message.data;
   document.getElementById('xy_image').setAttribute('src', imagedata);
   imageTopic.unsubscribe();
});

First of all: how can I access the frames without subscribing to the topic every time and unsubscribing to it again? Second: The message.data seems correct, but the header doesnt work and the image is not displayed. I tried png as well, with no success. I would be happy if you could help me out - maybe with a basic example.

Thanks in advance

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2017-01-03 05:43:47 -0500 commented question roslibjs tutorials not working

Strange thing happened: I did the same thing at my work PC: copy roslibjs folder to /var/www/html and called the file via apache and it works without a problem here. It's on localhost but it should be the same, when accessing it from another PC in the network. Thanks for helping!

2017-01-02 16:40:07 -0500 commented question roslibjs tutorials not working

Ok, I can open the files now, after I copied the files to /var/www/html/ and also copied the whole roslibjs folder to it. Connecting to ip/roslibjs/examples/fibonacci.html returns: "Error in the backend! Connection closed." And connecting to ip/fibonacci.html returns: Connecting to rosbridge...

2017-01-02 16:24:43 -0500 commented question roslibjs tutorials not working

Thank you for your clarification, I haven't thought about this. Unfortunately I am running it on a headless raspberry pi with Ubuntu Server. To my understanding, it should work, if I install apache on it and run the html remotely within the network. I'm going to try that out now.

2017-01-02 16:24:20 -0500 answered a question roslibjs tutorials not working

Thank you for your clarification, I haven't thought about this. Unfortunately I am running it on a headless raspberry pi with Ubuntu Server. To my understanding, it should work, if I install apache on it and run the html remotely within the network. I'm going to try that out now.

2017-01-02 09:37:11 -0500 asked a question roslibjs tutorials not working

Hello,

I have installed ROS indigo at work and kinetic at home and with both installations the tutorials dont work properly. Here is how I start it:

1.) roscore

2.) roslaunch rosbridge_server rosbridge_websocket.launch

3.) rosrun actionlib_tutorials fibonacci_server

4.) Browser: localhost:9090

The output I get is: Can "Upgrade" only to "WebSocket".

Is there any working tutorial on how to use this framework? The tutorial seems incomplete to me: "You can open up the file directly in the browser without running a web server" - no information given which URL one has to type, so I typed localhost:9090, then tried with /fibonacci_server then other paths, with no success. It is a pain to have such a powerful tool with the tutorials not working.

Please give me a hint, this will be very appreciated. Thanks in advance!

2016-12-22 09:38:40 -0500 answered a question Raspberry pi audio

I just saw, that a very low number of threads in this forum has more than 1 answer and many dont have a single answer. Is this the right forum to ask questions?

2016-12-22 08:07:58 -0500 asked a question Raspberry pi audio

Hello,

I have a raspberry pi 2 with Ubuntu Server 16.04 and ROS Kinetic Kame installed. No I plugin my Logitech C270 USB webcam and usually I easily get images from it via OpenCV and can process them the way I like. Now I would like to also get the audio and I wanted to ask, If there is someone with knowledge, how to acquire Audio and Video from this webcam within a ROS node, so that I can send it further to another ROS node in the network? I tried a few tutorials and got a module running, using audio_common. But It always has the problem finding the audio source I think.

Please help me, this problem is killing me. thank you in advance!

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2016-05-30 05:27:16 -0500 commented question Starting with Kinetic Kame

Thanks Javier, small problems wouldn't hurt me, a question to me is, whether all packages in Kinetic are available or not, which are available in indigo. I usually tend to use the newest stuff, so I would love to go with Kinetic.

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2016-05-25 10:03:01 -0500 asked a question Starting with Kinetic Kame

Hello,

I want to start using ROS for a private project and my question is: Should I start with Kinetic Kame, or should I go with Indigo? I would use it mainly on raspbian jessie, Linux Mint 17.3 or 18 and Debian Jessie 8.4. I'm not sure if I can use all packages in newer versions, thats why I'm asking.

Thanks in advance