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• 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 ?

  • 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 ?

• FFMPEG - How to record multiple RTMP streams into multiple files

  11 juillet 2014, par user3146313

  I tried the following, but it does not work.

  ffmpeg -i rtmp://83.229.210.89/RAZTV/BTVraztv1 -map 0 -b:v 900k -vcodec libx264 -acodec aac -b:a 256k -strict -2 -t 3600 /media/TV_1T_3T_6/ffmpegtest/ort.mp4 -i rtmp://mirtv.cdnvideo.ru/mirtv-live/mirtv600.sdp -map 1 -b:v 900k -vcodec libx4 -acodec aac -b:a 256k -strict -2 -t 3600 /media/TV_1T_3T_6/ffmpegtest/mir.mp4 -i rtmp://chanson.cdnvideo.ru/chanson-live/shansontv.sdp -map 2 -b:v 900k -vcodec libx264 -acodec aac -b:a 256k -strict -2 -t 3600 /media/TV_1T_3T_6/ffmpegtest/shansontv.mp4 -i rtmp://83.229.210.89:1935/TROTV/BTVtro0 -map 3 -b:v 900k -vcodec libx264 -acodec aac -b:a 256k -strict -2 -t 3600 /media/TV_1T_3T_6/ffmpegtest/tro.mp4

  Looks like it hangs on a second stream and no movement. S.O.S. Please help.
  I have 4 stream URLs. I want them to be recording together at the same time.

  With one ffmpeg command:
  
  I want: rtmp://83.229.210.89/RAZTV/BTVraztv1 to record into file: /media/TV_1T_3T_6/ffmpegtest/ort.mp4
  
  
  
  I want: rtmp://mirtv.cdnvideo.ru/mirtv-live/mirtv600.sdp to record into file: /media/TV_1T_3T_6/ffmpegtest/mir.mp4 
  
  
  
  I want: rtmp://chanson.cdnvideo.ru/chanson-live/shansontv.sdp to record into file: /media/TV_1T_3T_6/ffmpegtest/shansontv.mp4
  
  
  
  I want: rtmp://83.229.210.89:1935/TROTV/BTVtro0  to record into file: /media/TV_1T_3T_6/ffmpegtest/tro.mp4 

  The log that I get right now is :

  ffmpeg version 2.2.4 Copyright (c) 2000-2014 the FFmpeg developers
  
    built on Jul  6 2014 21:42:17 with gcc 4.6 (Ubuntu/Linaro 4.6.3-1ubuntu5)
  
    configuration: --enable-gpl --enable-version3 --enable-nonfree --enable-postproc --enable-libfaac --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libtheora --enable-libvorbis --enable-libx264 --enable-libxvid --enable-x11grab --enable-libvpx --enable-libmp3lame
  
    libavutil      52. 66.100 / 52. 66.100
  
    libavcodec     55. 52.102 / 55. 52.102
  
    libavformat    55. 33.100 / 55. 33.100
  
    libavdevice    55. 10.100 / 55. 10.100
  
    libavfilter     4.  2.100 /  4.  2.100
  
    libswscale      2.  5.102 /  2.  5.102
  
    libswresample   0. 18.100 /  0. 18.100
  
    libpostproc    52.  3.100 / 52.  3.100
  
  [flv @ 0x24981c0] Stream discovered after head already parsed
  
  Input #0, flv, from 'rtmp://83.229.210.89/RAZTV/BTVraztv1':
  
    Metadata:
  
      Server          : NGINX RTMP (github.com/arut/nginx-rtmp-module)
  
      displayWidth    : 720
  
      displayHeight   : 576
  
      fps             : 25
  
      profile         : 
  
      level           : 
  
    Duration: 00:00:00.00, start: 1826.816000, bitrate: N/A
  
      Stream #0:0: Video: h264 (High), yuv420p, 720x576 [SAR 64:45 DAR 16:9], 699 kb/s, 25 fps, 25 tbr, 1k tbn, 50 tbc
  
      Stream #0:1: Audio: aac, 48000 Hz, stereo, fltp, 128 kb/s
  
      Stream #0:2: Data: none
  
  [flv @ 0x261c7e0] Stream discovered after head already parsed
  
  [flv @ 0x261c7e0] negative cts, previous timestamps might be wrong
  
      Last message repeated 8 times
  
  Input #1, flv, from 'rtmp://mirtv.cdnvideo.ru/mirtv-live/mirtv600.sdp':
  
    Metadata:
  
      author          : 
  
      copyright       : 
  
      description     : 
  
      keywords        : 
  
      rating          : 
  
      title           : 
  
      presetname      : Custom
  
      creationdate    : Fri Jul 11 03:34:37 2014
  
                      : 
  
      videodevice     : AVerMedia Hybrid TV Video Capture
  
      avclevel        : 30
  
      avcprofile      : 66
  
      videokeyframe_frequency: 5
  
      audiodevice     : ?8=. 2E>4 (#AB@>9AB2> A ?>445@6
  
      audiochannels   : 1
  
      audioinputvolume: 100
  
    Duration: N/A, start: 0.000000, bitrate: 1038 kb/s
  
      Stream #1:0: Video: h264 (Baseline), yuv420p(tv), 720x576 [SAR 1:1 DAR 5:4], 972 kb/s, 25 fps, 25 tbr, 1k tbn, 50 tbc
  
      Stream #1:1: Audio: mp3, 44100 Hz, mono, s16p, 65 kb/s
  
      Stream #1:2: Data: none

• How to discard context reinits during H264 video decoding from GStreamer webrtcbin

  20 mars 2019, par Szymon Piechaczek

  Gstreamer pipeline is receiving video this way :

  webrtcbin -> rtph264depay -> avdec_h264 -> ...

  I’ve enabled do_nack on rtpbin inside webrtcbin to make video quality better but the problem is that lost buffers from RTP cause ’sometimes’ h264 decoder to Reinit context to ... which makes the whole output video grey (with only movement visible) until the next keyframe is received (but this can happen many seconds later).

  I’ve noticed that EVENT_GAP is emitted right before context reinit but dropping them doesn’t help.

  How to make decoding artifacts acting ’as always’ on the corrupted video, not to fill the whole video with grey ?