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• How to effectively kill a frozen subprocess in Python ?

  2 janvier 2014, par Konos5

  I am dealing with a rather odd issue.

  I've written a Python wrapper (in Python 2.6.6) for a year old version of ffmpeg. The problem is that given a very particular video, ffmpeg stops working normally (clunky output, full cpu usage, no end stage etc) and takes the python interpreter down with it.

  Now, if I run ffmpeg with my encoding options directly from a terminal and the problematic video as input, ffmpeg won't immediately respond to Ctrl-c. I'll have to wait for a hefty of 10 seconds or more before it exits and gives me back the prompt. However if I use a 'healthy' video instead, it will simply print Received signal 2: terminating. and gracefully exit.

  In the python wrapper I use p.kill() to no effect. The behavior is exactly the same a.k.a I have to wait 10 sec before the program exits. How can I immediately stop ffmpeg when it freezes with some problematic video ?

  Note that if I do a double Ctrl-c I get the prompt back immediately no matter what.

• running ffmpeg.exe from inside bash file [duplicate]

  3 février 2023, par Martin

  Hello I am trying to run ffmpeg from inside a track_cmd.sh file which I run inside command prompt using the command bash track_cmd.sh
My file looks like this :

  


  echo "try1"
C:\Users\marti\Documents\projects\jan2023-rendertune\RenderTune\node_modules\ffmpeg-ffprobe-static\ffmpeg.exe
echo "try2"
# start /d "path" file.exe
start /d "C:\Users\marti\Documents\projects\jan2023-rendertune\RenderTune\node_modules\ffmpeg-ffprobe-static" ffmpeg.exe
echo "try3"
# start "c:\windows\system32" notepad.exe   
start "C:\Users\marti\Documents\projects\jan2023-rendertune\RenderTune\node_modules\ffmpeg-ffprobe-static" ffmpeg.exe   
echo "try4"
#start "" fullPath/file.exe
start "" C:\\Users\\marti\\Documents\\projects\\jan2023-rendertune\\RenderTune\\node_modules\\ffmpeg-ffprobe-static\\ffmpeg.exe
echo "done"


  


  But none of these lines work :

  


  >bash track_cmd.sh
try1
track_cmd.sh: line 2: C:UsersmartiDocumentsprojectsjan2023-rendertuneRenderTunenode_modulesffmpeg-ffprobe-staticffmpeg.exe: command not found
try2
track_cmd.sh: line 5: start: command not found
try3
track_cmd.sh: line 8: start: command not found
try4
track_cmd.sh: line 11: start: command not found
done


  


  I have tried the examples posted in this question :
Bat file to run a .exe at the command prompt

  


  But none work. If I run the command C:\Users\marti\Documents\projects\jan2023-rendertune\RenderTune\node_modules\ffmpeg-ffprobe-static\ffmpeg.exe inside command prompt, I get ffmpeg, so I know the path works.

  


• Using OpenCV 2.4.4 with FFmpeg in Windows

  22 décembre 2015, par aardvarkk

  I know there are other questions dealing with FFmpeg usage in OpenCV, but most of them appear to be outdated.

  By opening up the makefiles in CMake, I can verify that I’ve got the WITH_FFMPEG flag on. My output folder for the OpenCV build contains a bin folder, within which are Debug and Release folders, each containing a copy of a .dll file entitled opencv_ffmpeg244.dll. I can step into the source code of OpenCV when I create a VideoWriter and verify that the function pointers to the .dll get filled correctly. That much appears to be working.

  If I use the FOURCC code of CV_FOURCC_PROMPT, the following codecs work properly :

  • Microsoft Video 1
  • Intel IYUV codec
  • Logitech Video (I420)
  • Cinepak Codec by Radius
  • Full Frames (Uncompressed)

  The following codecs do not work properly (ie. produce a 0kb video file) :

  • Microsoft RLE

  If my understanding is correct, using FFMPEG should allow for encoding video using a whole bunch of new codecs (x264, DIVX, XVID, and so on). However, none of these appear in the prompt. Manually setting them by their FOURCC codes using the macro CV_FOURCC(...) also doesn’t work. For instance, using this : CV_FOURCC('X','2','6','4') produces the message :

  Could not find encoder for codec id 28: Encoder not found

  and makes a video file of size 0kb.

  Using this : CV_FOURCC('X','V','I','D') produces no error message, and makes a video file of 6kb that will not play in Windows Media Player or VLC.

  I tried manually downloaded the Xvid codec from Xvid.org. Once that was installed, it appeared under the VFW selection in the prompt, and the encoding worked properly. So it’s close to a solution, but if I try to set the FOURCC code directly, it still fails as above ! I have to pick it from the prompt every time. Isn’t FFmpeg supposed to include a whole bunch of codecs ? If so, why am I manually downloading the codec instead of using the one built into FFmpeg ?

  What am I missing here ? Is there a way to check that FFMPEG is "enabled" ? It seems like the only codecs available in the prompt are VFW codecs, not the FFMPEG ones. The .dll has been built and is sitting in the same folder as the executable, but it appears it’s not being used in any way.

  Lots of related questions here. Hoping to find somebody knowledgeable about the FFmpeg implementation in OpenCV and with some knowledge of how all of these pieces fit together.