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• OpenIMAJ not able to access video file

  20 septembre 2014, par Sudh

  I am using OpenIMAJ to draw facial keypoints on a video but it is stuck at the first step itself.
  Here is the code I am trying to run: :

  Video<mbfimage> video;
  
      video = new XuggleVideo("file://E:/AV/out2.flv");//XuggleVideo("file:"+fileName);
  
      VideoDisplay<mbfimage> display = VideoDisplay.createVideoDisplay(video);
  
      display.addVideoListener(
  
               new VideoDisplayListener<mbfimage>() {
  
                      public void beforeUpdate( MBFImage frame ) {
  
  
  
                          FaceDetector fd = new HaarCascadeDetector(40);
  
                          List<detectedface> faces = fd.detectFaces( Transforms.calculateIntensity(frame));
  
  
  
                          for( DetectedFace face : faces ) {
  
                              frame.drawShape(face.getBounds(), RGBColour.RED);
  
                          }
  
                      }
  
  
  
                      public void afterUpdate( VideoDisplay<mbfimage> display ) {
  
                      }
  
        });
  
  </mbfimage></detectedface></mbfimage></mbfimage></mbfimage>

  When I run this It prints

  file :///E :/AV/out2.flv URL file :///E :/AV/out2.flv could not be opened
  by ffmpeg. Trying to open a stream to the URL instead. 11:14:12.505
  [Finalizer] DEBUG com.xuggle.xuggler - Closing dangling Container
  (../../../../../../../csrc/com/xuggle/xuggler/Container.cpp:146)

  on the screen and then just dies out. result is same if I use video = new XuggleVideo(new File("E :/AV/out2.flv")) ;

  Also if I keep file in the project and then do video = new XuggleVideo(new File("out2.flv")) ; I get same result.

  I am able to access the file if I put the link in the browser. What is going wrong ?

  Update : I get just this

  out2.flv 12:03:06.485 [Finalizer] DEBUG com.xuggle.xuggler - Closing
  dangling Container
  (../../../../../../../csrc/com/xuggle/xuggler/Container.cpp:146)

  If I use video = new XuggleVideo("out2.flv");

• lavc/pthread_frame : protect read state access in setup finish function

  11 janvier 2017, par Clément Bœsch

  lavc/pthread_frame : protect read state access in setup finish function
  

  • [DH] libavcodec/pthread_frame.c

• Go / Cgo - How to access a field of a Cstruct - could not make it

  15 août 2021, par ChrisG

  I develope an application in Go for transcode an audio file from one format to another one :

  


  I use the goav library that use Cgo to bind the FFmpeg C-libs :
https://github.com/giorgisio/goav/

  


  ---

  


  The goav library ; package avformat has a typedef that cast the original FFmpeg lib C-Struct AVOutputFormat :

  


  type ( 
   OutputFormat               C.struct_AVOutputFormat
)


  


  In my code i have a variable called outputF of the type OutputFormat that is a C.struct_AVOutputFormat.

  


  The C real AVOutputFormat struct has fields :

  


  name, long_name, mime_type, extensions, audio_codec, video_codec, subtitle_codec,..


  


  and many fields more.

  


  See : https://ffmpeg.org/doxygen/2.6/structAVOutputFormat.html

  


  ---

  


  I verified the situation by fmt.Println(outputF) and reached :

  


  {0x7ffff7f23383 0x7ffff7f23907 0x7ffff7f13c33 0x7ffff7f23383 86017 61 0 128 <nil> 0x7ffff7f8cfa0 <nil> 3344 0x7ffff7e3ec10 0x7ffff7e3f410 0x7ffff7e3ecc0 <nil> 0x7ffff7e3dfc0 <nil> <nil> <nil> <nil> <nil> <nil> 0 0x7ffff7e3e070 0x7ffff7e3e020 <nil>}&#xA;</nil></nil></nil></nil></nil></nil></nil></nil></nil></nil>

  


  The audio codec field is on position 5 and contains 86017

  


  I verified the field name by using the package reflect :

  


  val := reflect.Indirect(reflect.ValueOf(outputF))
fmt.Println(val)
fmt.Println("Fieldname: ", val.Type().Field(4).Name)

Output:
Fieldname:  audio_codec


  


  ---

  


  I try to access the field audio_codec of the original AVOutputFormat using :

  


  fmt.Println(outputF.audio_codec)
ERROR: outputF.audio_codec undefined (cannot refer to unexported field or method audio_codec)


fmt.Println(outputF._audio_codec)
ERROR: outputF._audio_codec undefined (type *avformat.OutputFormat has no field or method _audio_codec)


  


  


  As i read in the Cgo documentation :
Within the Go file, C's struct field names that are keywords in Go can be accessed by prefixing them with an underscore : if x points at a C struct with a field named "type", x._type accesses the field. C struct fields that cannot be expressed in Go, such as bit fields or misaligned data, are omitted in the Go struct, replaced by appropriate padding to reach the next field or the end of the struct.

  


  


  But I have no idea what im doing wrong.

  


  Edit :
Okay for sure no underscore is required as audio_codec is not a keyword in Go. This i understood for now. But still there is the question why im not able to access the CStruct field "audio_codec".