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• x264 lib fails to build on Android, other plugins not included

  24 novembre 2022, par SOSparachuter1

  On my x86 windows machine, I'm compiling an Android app that links gstreamer using CMake : https://github.com/henkeldi/gstreamer-android/blob/master/app/src/main/cpp/CMakeLists.txt

  


  I'm using the latest Android binaries provided by gstreamer, so far everything worked and I've successfully linked gstreamer's app plugin. Next I tried to link x264 :

  


  SET(GST_PLUGINS_CORE_LIBS gstx264 gstapp)

SET(GST_PLUGINS_BASE ... x264)


  


  However, doing so results in dozens of these text relocation errors :

  


  ld:error: relocation R_AARCH64_ADD_ABS_L012_NC cannot be used against symbol x264_cabac_range_lps; recompile with -fPIC


  


  Even after I add the flag -fPIC these do not go away. Doing a bit of digging I see that Android does not allow text relocation since Api23, but that was several years ago. Is there still no fix on Android ?

  


  I also noticed that the videoparsersbad and hls plugins are not in the latest Android gstreamer binaries (version 1.21.2). Are these also not supported on Android ?

  


• ffmpeg : transmission problems / artifacts in rtsp screen grab - might be a WiFi problem

  1er décembre 2022, par Jo Kerner

  In short : Is there a way to "force" ffmpeg to not save a grabbed frame if there are transmission problems ? Or any other software that does the same and I just don't know of ?

  


  Long story :

  


  Updating my house surveillance from almost 10 years old DCS-932L cameras to Tapo C100 Cameras, I changed the image delivery method from ftp push to rtsp grab via ffmpeg.

  


  I had written a program in C++ to check for "bad" pictures from the old cameras, where parts of the picture tended to be simply black once every minute or so (I'm grabbing a pic every 2 seconds). The Tapo C100 doesn't feature ftp-push, thus I tried (after a few days trying)

  


  ffmpeg.exe -y -i rtsp://user:pass@10.0.0.%ld:554/stream1 -vframes 1 %scamera\rtsp.jpg -loglevel quiet


  


  This works absolutely perfect in my main house, which features a Fritz !Box 7590 and a set of Fritz !Powerline (510/and two 540e) repeaters, plus one WiFi repeater Fritz 600) as my phone line and the router are in the basement.

  


  In my holiday home, though, it doesn't. The Wifi is managed by a Hybrid DSL/5G - box I have no alternative to, which is a Huawei DN9245W and works as DHCP Server, because this is almost impossible to change. Everything "real" is managed by another Fritz !Box 7590, connected via ethernet, and another set of Fritz !Powerline 510 and two 540e repeaters plus half a dozen Wifi Repeaters, mostly Fritz ! 310, 450E and 600. The house was partially built with local stones, which are very iron-y, and there's a lot of metallized glass. Full set is show in Image

  


  Now, this does produce different artifacts, about two per minute or in every 15th picture, see
Image with artifacts No. 1

  


  Thinking this might be a transmission problem, I tried forcing the streamgrab via TCP, because while rtsp doesn't have error correction, TCP does :

  


  ffmpeg.exe -rtsp_transport tcp -i
rtsp://user:pass@10.0.0.%ld:554/stream1 -y -f image2 -update 1 -r
1 -vframes 1 -qscale:v 30 %scamera\rtsp.jpg -loglevel quiet


  


  Which didn't change the artifacts much, see Image with artifacts No. 2

  


  The house now has a total of 12 Cameras, six of which are each "managed" by an older Dell Optiplex Desktop bought used off ebay with an i3 or i5 processor from about 2015, which goes to about 65% load. My software will check if the grabbed picture is finished saving (to RAMdisk), rename it, check if there are artifacts, if so, drop it, if not, convert to bitmap and then compare it to previous image, guess if there's a change, mark that change with a rhombus and rate it, save that as a jpeg file, and then some other stuff that's not relevant here. See : Image of my program running with six cameras

  


  I did try grabbing keyframes only, but a bunny or deer or burglar hopping through my property doesn't produce a keyframe, so that turned out to be missing the point.

  


  I'm out of ideas here. It does work flawlessly in the main house. It doesn't in the holiday house. I can hardly install more repeaters ; I already tried mesh and not-mesh, and the problem isn't exactly wifi overload, because even with just one camera running, it still persists. In certain places. Some have no problems. Reasons ? No clue. I really hope someone has a good idea.

  


• Why does FFmpeg encode by default ?

  2 décembre 2022, par Hashim Aziz

  By default the following unpresuming FFmpeg command :

  


  ffmpeg -i "input.mp4" "output.mkv"


  


  ...will lossily encode a file unless it has the -c copy flag added, which will then pass the video through without any encoding. I remember not realising this as a beginner to FFmpeg years ago and being surprised when I found out, and ever since then it's something I've wondered about but not got around to asking.

  


  The main justification for this behaviour that comes to mind for me is that encoding is a much more common operation, and it might be annoying to have to pass an extra -encode flag for most uses.

  


  Was this ever one of the reasons cited for this design decision ? Has the issue ever even been discussed in the FFmpeg mailing lists, or has it remained unquestioned since being written during the days of Fabrice Bellard ?