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• Serve a single frame of a video to a user as an image (efficiently)

  23 juillet 2014, par JoeRocc

  Problem :

  I have multiple 60 minute videos on my server (shared hosting). I need to serve a single frame of any one of these videos to a user instantly and efficiently. Expected maximum load is about 100 requests per minute.

  Notes :

  • I am on a shared hosting service, so FFmpeg is not a possibility (is FFmpeg efficient enough for 100 requests per minute anyway ?).
  • I don’t want to store hundreds of thousands of images on my server (my inodes are limited).

  Possible Solutions :

  • Load the video onto the client-side and then extract a frame and paint it to a canvas as per this article. Though I don’t want the user to have to download the whole video just to get a frame (will they have to do this ?).
  • Use some efficient server-side library to efficiently extract a frame and then serve it to the user.
  •  ???

• FFMPEG Command in Android Failing to Execute

  15 janvier 2015, par Zoe

  I’m trying to execute ffmpeg commands through an android app I’m developing.

  I found this post which has been somewhat useful :
  Problems with ffmpeg command line on android

  and I downloaded a static build of ffmpeg from here : http://ffmpeg.gusari.org/static/

  The problem is, when this code runs

  public void merge_video(){
  
  
  
  
  
        String[] ffmpegCommand = new String[5];
  
        ffmpegCommand[0] = "/data/data/com.example.zovideo/ffmpeg";
  
        ffmpegCommand[1] = "-i";
  
        ffmpegCommand[2] = "concat:storage/emulated/0/DCIM/Camera/VID30141106_211509.mp4|storage/emulated/0/DCIM/Camera/VID30141106_211509.mp4";
  
        ffmpegCommand[3] = "copy";
  
        ffmpegCommand[4] = "storage/emulated/0/DCIM/ZoVideo/Output.mp4";  
  
  
  
        try {
  
            Process ffmpegProcess = new ProcessBuilder(ffmpegCommand).redirectErrorStream(true).start();
  
  
  
            String line;
  
            BufferedReader reader = new BufferedReader(new InputStreamReader(ffmpegProcess.getInputStream()));
  
            Log.d(null, "*******Starting FFMPEG");
  
  
  
            while((line = reader.readLine())!=null){
  
  
  
                Log.d(null, "***"+line+"***"); 
  
            }
  
            Log.d(null,"****ending FFMPEG****");
  
  
  
      } catch (IOException e) {
  
          e.printStackTrace();
  
      }
  
    }

  It fails when trying to start the process with

  Java.io.IOException: Error running exec(). Command: [/data/data/com.example.zovideo/ffmpeg, -i, concat:storage/emulated/0/DCIM/Camera/VID30141106_211509.mp4|storage/emulated/0/DCIM/Camera/VID30141106_211509.mp4, copy, storage/emulated/0/DCIM/ZoVideo/Output.mp4] Working Directory: null Environment: [ANDROID_ROOT=/system, EMULATED_STORAGE_SOURCE=/mnt/shell/emulated, LOOP_MOUNTPOINT=/mnt/obb, LD_PRELOAD=libsigchain.so, ANDROID_BOOTLOGO=1, EMULATED_STORAGE_TARGET=/storage/emulated, EXTERNAL_STORAGE=/storage/emulated/legacy, SYSTEMSERVERCLASSPATH=/system/framework/services.jar:/system/framework/ethernet-service.jar:/system/framework/wifi-service.jar, ANDROID_SOCKET_zygote=10, PATH=/sbin:/vendor/bin:/system/sbin:/system/bin:/system/xbin, ANDROID_DATA=/data, ANDROID_ASSETS=/system/app, ASEC_MOUNTPOINT=/mnt/asec, BOOTCLASSPATH=/system/framework/core-libart.jar:/system/framework/conscrypt.jar:/system/framework/okhttp.jar:/system/framework/core-junit.jar:/system/framework/bouncycastle.jar:/system/framework/ext.jar:/system/framework/framework.jar:/system/framework/telephony-common.jar:/system/framework/voip-common.jar:/system/framework/ims-common.jar:/system/framework/mms-common.jar:/system/framework/android.policy.jar:/system/framework/apache-xml.jar, ANDROID_PROPERTY_WORKSPACE=9,0, ANDROID_STORAGE=/storage]

  I understand from the stackoverflow post I mentioned above that the ffmpeg static build needs to be on my device otherwise my app cannot use it.

  However I’m unsure how to get it in the /data/data/com.example.zovideo folder as needed.

  I have done is download the latest static ffmpeg build from http://ffmpeg.gusari.org/static/ and copied it into my libs/armeabi and libs/armeabi-v7a folders but this obviously hasn’t succeeded in getting into the data/data folder when my app is installed onto my device.
  (I feel like I’m being an idiot by copy/pasting the files but I don’t know what else to do. I don’t know how to compile it myself - I have compiled ffmpeg using a Roman10 tutorial but this produces .so files which from which I understand is not what I need)

  So I’m a little stuck.
  Any advice is greatly appreciated. Thanks

• ffmpeg : create a video of 10 seconds before and 10 seconds after the occurrence of a certain event [closed]

  28 août 2023, par pozzugno

  From a video stream (RTSP) transmitted from an IPCam, I'd like to generate a short video starting from 10 seconds before an event and total duration 20 seconds, so the event is in the middle of the video.

  


  The event is an alarm triggered by an external device. I'd like to see what happened immediately before and after this alarm.

  


  Because I need the video before the event (and I don't know when the event will occur), I am forced to receive the stream continuously. The idea is to use segment mux, so I'm testing the following command :

  


  ffmpeg -hide_banner -rtsp_transport tcp -stimeout 10000000 -i rtsp://... -f segment -segment_time 2 -reset_timestamps 1 -segment_wrap 12 -ccopy -map 0:v /var/ramdisk/C1/%d.mp4


  


  In the output folder I will have 12 files : 0.mp4, 1.mp4,... 11.mp4. Each file is a video of duration 2 seconds.

  


  When my Linux service (always running) detects the alarm from the external device, it waits for 10 seconds and launch a new ffmpeg command that concatenate the short video files in one bigger video file. However I'm in trouble with the right command line to do what I need.