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• Create an image in PHP and turn it into a 10-second video [on hold]

  17 septembre 2019, par Emil A.

  I remember being able to create an image in PHP with custom text and background etc, then output it (or save) as a JPG/PNG etc. I want to do this but output this 1 frame as a 10-second MP4-video. How can I achieve this ?

  (Note : The end-result will show an unique and dynamical URL for cases where someone tries to watch the video without permission ; think hotlink-prevention for video.)

• Streaming a video to /dev/video0 using gstreamer and v4l2 shows a black screen [on hold]

  24 septembre 2019, par Lawliet

  I’ve been trying to use a video as a webcam for quite a while now. The command

  gst-launch-1.0 filesrc location=newflag.webm ! decodebin ! videoconvert ! v4l2sink device=/dev/video0

  Using this command, i’m able to watch the stream using VLC but Discord and Firefox display a black screen when using /dev/video0 as a webcam.

  I got it working using ffmpeg to stream the video in yuv420p so I suspect videoconvert converts the stream to YUY2 which is I guess not supported by Discord nor Firefox.

  Any idea on how to get this to work ?

• Source of random Fatal signal 11 (SIGSEGV) error in app using ffmpeg through ndk

  20 janvier 2015, par grzebyk

  I am getting a nasty but well known error while working with FFmpeg and NDK :

  A/libc(9845): Fatal signal 11 (SIGSEGV), code 1, fault addr 0xa0a9f000 in tid 9921 (AsyncTask #4)

  What am I doing ?

  I am developing an application that streams live video feed from a webcam and enables user to pan and tilt the remote camera. I am using FFmpeg library built with NDK to achieve smooth playback with little delay.

  I am using FFMpeg library to connect to the video stream. Then the ndk part creates bitmap, does the image processing and render frames on the SurfaceView videoSurfaceView object which is located in the android activity (java part).

  To move the webcam I created a separate class - public class CameraMover implements Runnable{/**/}. This class is a separate thread that connects through sockets with the remote camera and manages tasks connected ONLY with pan-tilt movement.

  Next in the main activity i created a touch listener

  videoSurfaceView.setOnTouchListener(new View.OnTouchListener() {/**/
  
  cameraMover.setPanTilt(some parameters);
  
  /**/}

  which reads user’s finger movement and sends commands to the camera.

  All tasks - moving camera around, touch interface and video playback are working perfectly when the one of the others is disabled, i.e. when I disable possibility to move camera, I can watch video streaming and register touch events till the end of time (or battery at least). The problem occurs only when task are configured to work simultaneously.

  I am unable to find steps to reproduce the problem. It just happens, but only after user touches the screen to move camera. It can be 15 seconds after first interaction, but sometimes it takes app 10 or more minutes to crash. Usually it is something around a minute.

  What have I done to fix it ?

  • I tried to display millions of logs in logcat to find an error but
    the last log was always different.
  • I created a transparent surface, that I put over the videoSurfaceView and assigned touch listener to it. It all ended in the same error.
  • As I mentioned before, I turned off some functionalities to find which one produces the error, but it appears that error occurs only when everything is working simultaneously.

  Types of the error

  Almost every time the error looks like this :

  A/libc(11528): Fatal signal 11 (SIGSEGV), code 1, fault addr 0x9aa9f00c in tid 11637 (AsyncTask #4)

  the difference between two errors is the number right after libc, addr number and tid number. Rarely the AsyncTask number varies - i received #1 couple times but I was unable to reproduce it.

  Question

  How can i avoid this error ? What can be the source of it ?