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• GStreamer x264enc and SIGSEGV on Android

  18 juillet 2012, par Cipi

  I am trying to play around with GStreamer-java and it's h.264 encoder (x264enc) on Android.

  Now, I tried to encode raw video from test video source (set its is-live property to TRUE), and when data starts flowing into the x264enc Element, I get SIGSEGV in libx264.so and my app crashes. And it looks like code is dereferencing a NULL... Exact error location is in file "gstreamer_ndk_bundle/x264/encoder/analyse.c" line 963. And it is this line :

  h->mc.memcpy_aligned( h->mb.pic.i8x8_dct_buf, h->dct.luma8x8, sizeof(h->mb.pic.i8x8_dct_buf) );

  My device's CPU is Cortex 8 and it has NEON feature...

  I tried to printout to a file all h structure fields, and no field is uninitialized.

  Android DEBUG info from LogCat : HERE

  My questions :

  1. How can I know what is throwing SIGSEGV, because this line of code seems to be ok ?
  2. Is this a known bug or an expected behavior of x264 encoder on ARM CPU or I am missing some encoder configuration ?
  3. I noticed that if I set property analyse of the encoder to 0x3:0x113 (some random value I found online) I don't get SIGSEGV, encoder seems to work, but I get error in pipeline : Data flow error. Can I just set analyse to a meaningful value ?

  Update

  I fprintf-ed all important "h" fields just before execution runs in x264_mb_analyse_intra() function and just before the line that it breaks, guess it could help : http://pastebin.com/sAfX239j

• How to play back a video stream on website ?

  11 juillet 2012, par John Smith

  Lets suppose I have a streaming generated from ffmpeg :

  ffmpeg -f dshow -i video="UScreenCapture" -vcodec libx264 -g 30 -f mpegts tcp://127.0.0.1:1234

  on the server Im catching the stuffes like this :

   error_reporting(E_ALL); /* Allow the script to hang around waiting for connections. */
  
   set_time_limit(30); /* Turn on implicit output flushing so we see what we're getting as it comes in. */
  
   ob_implicit_flush();
  
  
  
   $address = '127.0.0.1';
  
   $port = 1234;
  
   $outfile = dirname(__FILE__)."/output.flv";
  
   $ofp = fopen($outfile, 'wb');
  
  
  
   if (($sock = socket_create(AF_INET, SOCK_STREAM, SOL_TCP)) === false) { echo "socket_create() failed: reason: " . socket_strerror(socket_last_error()) . "\n"; sleep (5); die; }
  
   if (socket_bind($sock, $address, $port) === false) { echo "socket_bind() failed: reason: " . socket_strerror(socket_last_error($sock)) . "\n"; sleep (5); die; }
  
   if (socket_listen($sock, 5) === false) { echo "socket_listen() failed: reason: " . socket_strerror(socket_last_error($sock)) . "\n"; sleep (5); die; }
  
   if (($msgsock = socket_accept($sock)) === false) { echo "socket_accept() failed: reason: " . socket_strerror(socket_last_error($sock)) . "\n"; sleep (5); break; }
  
   do {
  
      $a = '';
  
      socket_recv ($msgsock, $a, 65536, MSG_WAITALL);
  
      fwrite ($ofp, $a);
  
      fclose ($ofp);
  
      $ofp = fopen($outfile, 'ab');
  
      //echo strlen($a)."\r\n";
  
   } while (true);

  now Im stuck replaying this. VCL player can replay this so its got to be good, but how to put it onto a site ? I know theres HTML5 video tags, but lets not use it, because it might unsupported, and I also failed make it work every way. Is there a flash solution ? Its a dymanic stream, so no start-end !

• OpenCV and Cloud Cameras

  8 mai 2014, par Alexander

  So as a bit of context ; this program was built originally to work with USB cameras - but a few things changed. I’m trying to convert it to work with networked cameras, but my presence here should make it quite apparent what my level of success has been. I still consider myself somewhat new at programming, and definately new at visual processing/OpenCV - so please forgive a few blunders if I make them. I’m going to try to provide as much detail as possible, so apologies for the length below.

  ---

  I’m using :

  • OpenCV 2.4.6.0
  • Microsoft Visual Studio Express 2012
  • C++
  • D-Link Cloud Camera 7100

  ---

  I am trying to access the DLink camera’s video feed through OpenCV.

  I can access the camera through it’s IP address with a browser without any issues. Unfourtunately ; my program is less cooperative. I’ve put it on two computers (excluding the computer it gets compiled on, which for unrelated/unchangable reasons cannot be placed on the same network the network camera is on) which both fail to grant my program access to the camera. One computer gives the OpenCV-generated error :

  warning : Error opening file (../../modules/highgui/src/cap_ffmpeg_impl.hpp:529)

  This error occurs with just about everything I try that doesn’t somehow generate more problems. The other computer (same code) generates no such error - it just doesn’t get the camera’s output either.

  For reference - the code in OpenCV’s cap_ffmpeg_impl.hpp around line 529 is as follows :

  522    bool CvCapture_FFMPEG::open( const char* _filename )
  
  523    {
  
  524        unsigned i;
  
  525        bool valid = false;
  
  526
  
  527        close();
  
  528
  
  529    #if LIBAVFORMAT_BUILD >= CALC_FFMPEG_VERSION(52, 111, 0)
  
  530        int err = avformat_open_input(&ic, _filename, NULL, NULL);
  
  531    #else
  
  532        int err = av_open_input_file(&ic, _filename, NULL, 0, NULL);
  
  533    #endif
  
  ...
  
  616    }

  ...for which I have no idea what I’m looking at.

  My entire program is rather large, so I’m editing it down as much as possible to help keep this readable - if I miss something you think is important please leave a comment telling me as much so I can throw it in...

  First up - this is one of the first things in main() so I don’t have to recompile every time I want to try a different value :

  3380    cout << "Please Enter Video Location: ";
  
  3381    cin >> videoFeedAddress;
  
  3382    cout << "videoFeedAddress: " << videoFeedAddress << endl;

  Just a simple string value.
  Next up - the actual place we’re having the problem ! Probably...

  Note that in the below code - if networkCam is false and a USB camera is connected there is no problem. The error here is caused by line 153.

  121    void displayCameraView()
  
  122    {
  
  123     if(camviewOn) // displayCameraView is triggered by a button the user can press as often as they want. Doesn't mean we want to let them break everything.
  
  124     {return;}
  
  125     else
  
  126     {
  
  127         CvCapture* cv_cap;
  
  128         VideoCapture cv_cap_IP;
  
  129         Mat color_img_IP;
  
  130         camviewOn = true;
  
  131         int capture;
  
  132         IplImage* color_img;
  
  133         if(!networkCam)
  
  134         {
  
  135             cv_cap = cvCaptureFromCAM(0);
  
  136             Sleep(100);
  
  137             if(!cv_cap)
  
  138             {
  
  139                 setExitError(1002);
  
  140                 if(textOutput){cout << "Video Error: Video input will not work.\n";}
  
  141                 MessageBox(hwnd, "Error opening camera.", "Error", MB_ICONEXCLAMATION);
  
  142                 cvReleaseCapture( &cv_cap );
  
  143                 cvDestroyWindow("Camera View");
  
  144                 return;
  
  145             }
  
  146             color_img = cvQueryFrame(cv_cap);
  
  147             clickPointStorage.create(((Mat)color_img).rows, ((Mat)color_img).cols, CV_8UC3);
  
  148         }
  
  149         else
  
  150         {
  
  151             ///*\
  
  152             
  
  153             cv_cap_IP.open(videoFeedAddress);
  
  154             Sleep(100);
  
  155             if(!cv_cap_IP.isOpened())
  
  156             {
  
  157                 setExitError(1002);
  
  158                 if(textOutput){cout << "Video Error: Video input will not work.\n";}
  
  159                 MessageBox(hwnd, "Error opening camera.", "Error", MB_ICONEXCLAMATION);
  
  160                 cvDestroyWindow("Camera View");
  
  161                 return;
  
  162             }
  
  163             clickPointStorage.create(color_img_IP.rows, color_img_IP.cols, CV_8UC3);
  
  164    
  
  165             //\*/
  
  166         }
  
  167         clickPointStorage.setTo(Scalar(0, 0, 0));
  
  168         cvNamedWindow("Camera View", 0); // create window
  
  169         cvSetMouseCallback("Camera View", CallBackFunc, NULL);
  
  170         IplImage* IplClickPointStorage = new IplImage(clickPointStorage);
  
  171         IplImage* Ipl_IP_Img;
  
  172         
  
  173         if(!networkCam)
  
  174         {
  
  175             for(;;)
  
  176             {
  
  177                 IplClickPointStorage = new IplImage(clickPointStorage);
  
  178                 cvAdd(cvQueryFrame(cv_cap), IplClickPointStorage, color_img); // get frame
  
  181                 cvShowImage("Camera View", color_img); // show frame
  
  182                 capture = cvWaitKey(10); // wait 10 ms or for key stroke
  
  183                 if(capture == 27 || capture == 13 || capture == 32){break;} // if ESC, Return, or space; close window.
  
  184             }
  
  185             /* clean up */
  
  186             cvReleaseCapture( &cv_cap );
  
  187             delete cv_cap;
  
  188             delete IplClickPointStorage;
  
  189         }
  
  190         else
  
  191         {
  
  192             ///*\
  
  193    
  
  194             for(;;)
  
  195             {
  
  196                 cv_cap_IP.read(color_img_IP);
  
  197                 IplClickPointStorage = new IplImage(clickPointStorage);
  
  198                 Ipl_IP_Img = new IplImage(color_img_IP);
  
  199                 cvAdd(Ipl_IP_Img, IplClickPointStorage, color_img);
  
  200                 cvShowImage("Camera View", color_img); // show frame
  
  201                 capture = cvWaitKey(10); // wait 10 ms or for key stroke
  
  202                 if(capture == 27 || capture == 13 || capture == 32){break;} // if ESC, Return, or space; close window.
  
  203             }
  
  204             cv_cap_IP.release();
  
  205             delete Ipl_IP_Img;
  
  206             delete IplClickPointStorage;
  
  207    
  
  208             //\*/
  
  209         }
  
  210         cvDestroyWindow("Camera View");
  
  211         camviewOn = false;
  
  212     }
  
  213     return;
  
  214    }

  As I said, on one computer I get the above error - both of them give me my own error from here :

  155             if(!cv_cap_IP.isOpened())
  
  156             {
  
  157                 setExitError(1002);
  
  158                 if(textOutput){cout << "Video Error: Video input will not work.\n";}
  
  159                 MessageBox(hwnd, "Error opening camera.", "Error", MB_ICONEXCLAMATION);
  
  160                 cvDestroyWindow("Camera View");
  
  161                 return;
  
  162             }

  ...which of course tells me cv_cap_IP is not open. One of my primary concerns is with the videoFeedAddress variable. No value I enter seems to get a different result.

  I searched the Googles - and come across a number of different "possible" answers - but none of them seem to work for me. If you attempt to google it yourself you may come across some of these :

  1. This is one of the first configurations my code was in. No dice.
  2. This one is talking about files - not cameras. It also mentions codecs - but I wouldn’t be able to watch it in a web browser if that were the problem, right ? (Correct me if I’m wrong here...)
  3. This one has the wrong error code/points to the wrong line of code !
  4. This one mentions compiling OpenCV with ffmpeg support - but I believe 2.4.6.0 already comes with that all set and ready ! Otherwise it’s not that different from what I’ve already tried.
  5. Now THIS one appears to be very similar to what I have, but the only proposed solution doesn’t really help as I had already located a list of connections. I do not believe this is a duplicate, because as per THIS meta discussion I had a lot more information and so didn’t feel comfortable taking over someone else’s question - especially if I end up needing to add even more information later.

  Back to the videoFeedAddress variable : I found THIS site that lists a number of possible addresses to connect to it. since there exists no 7100 anywhere in the list - and the install is the same for the DCS-7010L I used the addresses found next to the DCS-7010L listings. Most of them can be reached through the browser, confirming that they reach the camera - but they don’t seem to affect the outcome when I change them.

  As per many of the above links, I’ve tried many of them both with any without username:password, port number (554), and variations on ?.mjpg (the format) at the end.

  Any ideas ?