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• JavaCV - How to handle cases where FFmpegFrameFilter.pull() returns null

  20 juin 2018, par Gensoukyou1337

  Currently I have the basic workflow of pulling frames from one video using FFmpegFrameGrabber, filtering them using an FFmpegFrameFilter, and recording them in an FFmpegFrameRecorder, as follows :

              framesLen = vCap.getLengthInFrames();
  
              try {
  
                  Frame f;
  
                  for(int i = 0; i < framesLen; i++) {
  
                      f = vCap.grab();
  
                      if(f != null) {
  
                          vFilter.push(f);
  
                          Frame filtered;// = vFilter.pull();
  
                          vRec.setFrameNumber(i);
  
                          while((filtered = vFilter.pull()) != null) {
  
                              Log.i("ffmpeg_recorder", "processing frame "+i +" "+f+" "+filtered);
  
                              vRec.record(filtered);
  
                          }
  
                          i++;
  
                      }
  
                  }
  
              } catch (FFmpegFrameGrabber.Exception e) {
  
                  exception = e;
  
              } catch (FFmpegFrameRecorder.Exception e) {
  
                  exception = e;
  
              } catch (FFmpegFrameFilter.Exception e) {
  
                  exception = e;
  
              }
  
  
  
              try {
  
                  vCap.flush();
  
                  vCap.release();
  
                  vRec.stop();
  
                  vRec.release();
  
              } catch (FFmpegFrameGrabber.Exception e) {
  
                  exception = e;
  
              } catch (FFmpegFrameRecorder.Exception e) {
  
                  exception = e;
  
              }
  
  
  
              if (exception != null) {
  
                  Log.e("ffmpeg_exception", exception.getMessage()+"");
  
                  return null;
  
              } else {
  
                  return outFile+"";
  
              }

  My current problem is that sometimes FFmpegFrameFilter.pull() would return null in that loop, ending with vRec recording a null frame, causing the final video to get stuck for a few seconds in the same frame.

  What’s happening in the FFmpegFrameFilter when its pull() returns null ? Is it the case when I try to pull() when it hasn’t finished processing the current frame ? If that’s so, should I just put an empty while loop like this ?

  ...
  
  while((filtered = vFilter.pull()) == null) {/*block until it's NOT null*/}
  
  vRec.record(filtered);
  
  ...

  EDIT :

  OK, my proposed solution above doesn’t work - it just goes into an infinite loop. Though I really don’t want to skip those frames.

• python imageio.get_reader() returns format error

  19 août 2020, par tristan_jia

  import imageio

reader = imageio.get_reader("./t.mp4")


  


  As shown above, with python 3.6.10, it returns :

  


  >>> reader = imageio.get_reader("../")&#xA;Traceback (most recent call last):&#xA;  File "<stdin>", line 1, in <module>&#xA;  File "/home/tristan_jia/workspace/py3.6/venv/lib/python3.6/site-packages/imageio/core/functions.py", line 129, in get_reader&#xA;    return format.get_reader(request)&#xA;  File "/home/tristan_jia/workspace/py3.6/venv/lib/python3.6/site-packages/imageio/core/format.py", line 168, in get_reader&#xA;    return self.Reader(self, request)&#xA;  File "/home/tristan_jia/workspace/py3.6/venv/lib/python3.6/site-packages/imageio/core/format.py", line 217, in __init__&#xA;    self._open(**self.request.kwargs.copy())&#xA;  File "/home/tristan_jia/workspace/py3.6/venv/lib/python3.6/site-packages/imageio/plugins/ffmpeg.py", line 357, in _open&#xA;    self._initialize()&#xA;  File "/home/tristan_jia/workspace/py3.6/venv/lib/python3.6/site-packages/imageio/plugins/ffmpeg.py", line 430, in _initialize&#xA;    shell=ISWIN)&#xA;  File "/usr/lib64/python3.6/subprocess.py", line 729, in __init__&#xA;    restore_signals, start_new_session)&#xA;  File "/usr/lib64/python3.6/subprocess.py", line 1364, in _execute_child&#xA;    raise child_exception_type(errno_num, err_msg, err_filename)&#xA;OSError: [Errno 8] Exec format error: &#x27;/home/tristan_jia/.imageio/ffmpeg/ffmpeg-linux64-v3.3.1&#x27;&#xA;&#xA;</module></stdin>

  


  I searched everywhere but haven't seen any similar questions. The script runs on Opensuse Leap 15.1, is it related to the system I use ?

  


• arm : Consistently use proper interworking function returns

  3 octobre 2024, par Martin Storsjö

  arm : Consistently use proper interworking function returns
  Use "bx lr", or "pop lr", which do proper mode switching
  
  between thumb and arm modes. A plain "mov pc, lr" does not switch
  
  from thumb mode to arm mode (while in arm mode, it does switch
  
  mode for a thumb caller).
  This is normally not an issue, as CONFIG_THUMB only is enabled if
  
  the C compiler defaults to thumb ; but stick to patterns that can
  
  do mode switching if needed, for consistency.
  Signed-off-by : Martin Storsjö <martin@martin.st>
  

  • [DH] libswresample/arm/resample.S
  • [DH] libswscale/arm/hscale.S
  • [DH] libswscale/arm/output.S
  • [DH] libswscale/arm/yuv2rgb_neon.S