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• ffplay shows no video from Grass Valley KMX in HDMI input even though HDMI from scope bars displays just fine

  14 juin 2023, par Scott Wilkerson

  I'm trying to replace an unsupported video input player that uses a Decklink card to superimpose video on an iControl widget. I was able to get this to work with a Decklink Mini Recorder 4K card with ffplay using this command :

  


  ffplay -f dshow -video_size 1280x720 -left 631 -top 19 -rtbufsize 702000k -framerate 59.94 -i video="Decklink Video Capture":audio="Decklink Audio Capture" -noborder -hide_banner -alwaysontop

  


  I used bars and tone from a handheld scope to test the video window and it worked great. When I put it into production with input from a Grass Valley KMX it only displays black. I can see the video, chroma, audio etc in the video window stats. The KMX video can display just fine with the Black Magic Media Express app. Any ideas what might be tripping it up ?

  


  I tried -videoinput HDMI, which did not work.

  


• Android ffmpeg command shows java.io.IOException : Error running exec()

  26 mai 2023, par Jamal

  I would like to use ffmpeg binary executable in my Android project.for this purpose I have used pre built ffmpeg Android binary from this(https://github.com/hiteshsondhi88/ffmpeg-android/releases/download/v0.3.3/prebuilt-binaries.zip) link.

  



  As per procedure I have to place the executable file into /data/data/com.example.rampedsample directory, here com.example.rampedsample is my project packageName.I couldn't find this location in my device as it is un rooted.So I pasted that executable into Android emulator's com.example.rampedsample directory using DDMS perspective.

  



  In my Activity used the below code

  



   try {
            Process p = Runtime.getRuntime().exec("/data/data/com.example.rampedsample/ffmpeg "+Environment.getExternalStorageDirectory()+"/Movies/ramp_video.mp4"
                    +" -map 0:v -codec copy "+Environment.getExternalStorageDirectory()+"/Movies/ramp_video2.mp4");


        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }


  



  AndroidManifest permission

  



  


  



  error

  



  04-13 16:59:55.314: W/System.err(11387): java.io.IOException: Error running exec(). Command: [/data/data/com.example.rampedsample/ffmpeg, /mnt/sdcard/Movies/ramp_video.mp4, -map, 0:v, -codec, copy, /mnt/sdcard/Movies/ramp_video2.mp4] Working Directory: null Environment: null
04-13 16:59:55.314: W/System.err(11387):    at java.lang.ProcessManager.exec(ProcessManager.java:211)
04-13 16:59:55.355: W/System.err(11387):    at java.lang.Runtime.exec(Runtime.java:168)
04-13 16:59:55.355: W/System.err(11387):    at java.lang.Runtime.exec(Runtime.java:241)
04-13 16:59:55.355: W/System.err(11387):    at java.lang.Runtime.exec(Runtime.java:184)
04-13 16:59:55.355: W/System.err(11387):    at com.example.rampedsample.MainActivity.onCreate(MainActivity.java:18)
04-13 16:59:55.355: W/System.err(11387):    at android.app.Activity.performCreate(Activity.java:5008)
04-13 16:59:55.355: W/System.err(11387):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079)


  


• ImageJ / Fiji shows wrong number of frames in video (FFMPEG import)

  28 avril 2023, par locoric_polska

  I am counting the number of animals in a an area using Fiji. I import the video through the FFMPEG plug-in (videos are mp4 with mpeg-4 codec). However, I noticed that when I import the videos Fiji uploads the wrong number of frames, and I cannot understand why and how.

  


  An example. I have a video shot at 25fps which is 1582s long. If I do the calculations the video should have 39550 frames in total (1582*25). When I open it through a Computer vision package in R, I see that the video correctly contains 39550 frames. However, when loaded in Fiji, the shown number of frames is 49511. So Fiji is adding 9961 frames to the video. This is consistent across all videos that are recorded in 25fps, while it does not appear in videos shot at 24fps.

  


  Curiously, I found that the ratio between the number of frames read by Fiji and the 'real' number of frames is consistent between 0.79 and 0.80. This makes me think that Fiji is expecting the video to be 30fps and (possibly) duplicating frames to adjust the video to this assumption.

  


  Unfortunately, I discovered all this after finishing my analysis and while trying to merge this dataset with another obtained through CV. The number of frame does not match between datasets and I am not sure how to solve this.

  


  Any help would be greatly appreciated !!

  


  An idea is to multiply all the frame numbers by 0.8 to adjust them to the old assumption. This solution assumes that Fiji is duplicating frames throughout the video in a consistent way