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• Ffmpeg Command to capture video from Decklink 4k Extreme in Ubuntu Linux

  24 septembre 2016, par George.Ef

  I am trying to capture a video using ffmpeg, from the HDMI input port of the Blackmagic DeckLink 4K Extreme capture card in Ubuntu Linux.

  As per the ffmpeg Documentation I have tried the following :

  ffmpeg -f decklink -video_input 'hdmi' -i 'DeckLink 4K Extreme (1)@14' -acodec copy -vcodec copy ~/testCapture/card1_f14_hdmi.avi

  but no matter what I do I always get this picture as a video
  

  My ffmpeg version is :

  ffmpeg version git-2016-08-15-4899953 Copyright (c) 2000-2016 the FFmpeg developers
  
  built with gcc 4.8 (Ubuntu 4.8.4-2ubuntu1~14.04.3)
  
  configuration: --prefix=/root/ffmpeg_build --pkg-config-flags=--static 
  
  --extra-cflags=-I/root/ffmpeg_build/include 
  
  --extra-ldflags=-L/root/ffmpeg_build/lib 
  
  --bindir=/root/bin --enable-gpl --enable-libass --enable-libfdk-aac 
  
  --enable-libfreetype --enable-libmp3lame --enable-libopus --enable-libtheora 
  
  --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libx265 
  
  --enable-decklink 
  
  --extra-cflags=-I/root/decklinkSDK/Blackmagic_DeckLink_SDK/Linux/include
  
  --extra-ldflags=-L/root/decklinkSDK/Blackmagic_DeckLink_SDK/Linux/include
  
  --enable-nonfree
  
  libavutil      55. 28.100 / 55. 28.100
  
  libavcodec     57. 51.102 / 57. 51.102
  
  libavformat    57. 46.101 / 57. 46.101
  
  libavdevice    57.  0.102 / 57.  0.102
  
  libavfilter     6. 51.100 /  6. 51.100
  
  libswscale      4.  1.100 /  4.  1.100
  
  libswresample   2.  1.100 /  2.  1.100
  
  libpostproc    54.  0.100 / 54.  0.100

  I have two of these cards as per the following :

  ffmpeg -f decklink -list_devices 1 -i dummy
  
  .....
  
  [decklink @ 0x2e9e440] Blackmagic DeckLink devices:
  
  [decklink @ 0x2e9e440]    'DeckLink 4K Extreme (1)'
  
  [decklink @ 0x2e9e440]    'DeckLink 4K Extreme (2)'

  I am able to get a list of the supported formats with the following :

  ffmpeg -f decklink -list_formats 1 -i 'DeckLink 4K Extreme (1)'
  
  ...
  
  [decklink @ 0x36e2440] Supported formats for 'DeckLink 4K Extreme (1)':
  
  [decklink @ 0x36e2440]    1   720x486 at 30000/1001 fps (interlaced, lower field first)
  
  [decklink @ 0x36e2440]    2   720x576 at 25000/1000 fps (interlaced, upper field first)
  
  [decklink @ 0x36e2440]    3   1920x1080 at 24000/1001 fps
  
  [decklink @ 0x36e2440]    4   1920x1080 at 24000/1000 fps
  
  [decklink @ 0x36e2440]    5   1920x1080 at 25000/1000 fps
  
  [decklink @ 0x36e2440]    6   1920x1080 at 30000/1001 fps
  
  [decklink @ 0x36e2440]    7   1920x1080 at 30000/1000 fps
  
  [decklink @ 0x36e2440]    8   1920x1080 at 25000/1000 fps (interlaced, upper field first)
  
  [decklink @ 0x36e2440]    9   1920x1080 at 30000/1001 fps (interlaced, upper field first)
  
  [decklink @ 0x36e2440]    10  1920x1080 at 30000/1000 fps (interlaced, upper field first)
  
  [decklink @ 0x36e2440]    11  1920x1080 at 50000/1000 fps
  
  [decklink @ 0x36e2440]    12  1920x1080 at 60000/1001 fps
  
  [decklink @ 0x36e2440]    13  1920x1080 at 60000/1000 fps
  
  [decklink @ 0x36e2440]    14  1280x720 at 50000/1000 fps
  
  [decklink @ 0x36e2440]    15  1280x720 at 60000/1001 fps
  
  [decklink @ 0x36e2440]    16  1280x720 at 60000/1000 fps
  
  ...
  
  DeckLink 4K Extreme (1): Immediate exit requested

  What should I use with ffmpeg in order to capture an HD video with sound from the HDMI port ?

• Recording real-time video from images with FFmpeg

  17 juillet 2015, par Solarnum

  I am really not sure what else I could be doing to achieve this. I’m trying to record the actions in one of the views in my Android app so that it can be played back later and show the previous actions in real time. The major problem (among others, because there is no way I’m doing this optimally) is that the video takes at least 4 times longer to make than it does to playback. If I ask FFmpeg to create a 5 second video the process will run in the background for 20 seconds and output a greatly accelerated 5 second video.

  My current strategy is to use the -loop 1 parameter on a single image file and continuously write a jpeg to that image file. (If someone has a better idea than this for feeding continuously updated image information to FFmpeg let me know)

  encodingThread = new Thread(new Runnable() {
  
              private boolean running = true;
  
              @Override
  
              public void run() {
  
                  while (running) {
  
                      try {
  
  
  
                          Bitmap bitmap = makeBitmapFromView();
  
  
  
                          String filepath = Environment.getExternalStorageDirectory().getAbsolutePath() + "/test.jpg";
  
                          File file = new File(filepath);
  
                          FileOutputStream fout = new FileOutputStream(file);
  
                          bitmap.compress(Bitmap.CompressFormat.JPEG, 100, fout);
  
                          fout.flush();
  
                          fout.close();
  
                          Thread.sleep(50);
  
                      } catch (IOException e) {
  
                          e.printStackTrace();
  
                      } catch (InterruptedException e) {
  
                          running = false;
  
                      }
  
                  }
  
              }
  
          });
  
          startVideoMaking();
  
          encodingThread.start();

  The startVideoMaking method is as follows :

  private void startVideoMaking(){
  
      ffmpeg.killRunningProcesses();
  
              File outputFile = new File(Environment.getExternalStorageDirectory().getAbsolutePath() + "/testout.mp4");
  
              String path = Environment.getExternalStorageDirectory().getAbsolutePath() + "/test.jpg";
  
              String output = Environment.getExternalStorageDirectory().getAbsolutePath() + "/testout.mp4";
  
  
  
              String command = "-loop 1 -t 5 -re -i " + path + " -c:v libx264 -loglevel verbose -vsync 0 -threads 0 -preset ultrafast -tune zerolatency -y -pix_fmt yuv420p " + output;
  
              executeFFM(command);
  
  }

  Just to make it clear, the FFmpeg command that I am executing is

  ffmpeg -loop 1 -re -i /storage/emulated/0/test.jpg -t 5 -c:v libx264 -loglevel verbose -vsync 0 -threads 0 -preset ultrafast -tune zerolatency -y -pix_fmt yuv420p /storage/emulated/0/testout.mp4

  The makeBitmapFromView() method takes about 50ms to process and writing the bitmap to the sd card takes around 200ms, which is not great.

  I’m pretty lost as to what other solutions there would be to creating a video of a single view in Android. I know there is the MediaCodec class, but I couldn’t get that to work and also it would raise my minimum sdk, which is not ideal. I’m also not sure that the MediaCodec class would even solve my problem.

  Is there some way that I can get FFmpeg to create a 5 second video that is equivalent to 5 seconds of real time ? I have also tried converting a single image, without updating it’s content continuously and had the same results.

  If my question isn’t clear enough let me know.

• ffmpeg - Timecode & Fractional Frame Rate (Duplicating Frames)

  29 mars 2018, par Nimble

  I record two different frame rates using ffmpeg, 60 and 100. Or at least I thought I was recording 60 and 100, now it seems it’s actually 59.94 and 99.98.

  Here is the command I was using :

  ffmpeg -y -thread_queue_size 9999 -guess_layout_max 0 -f dshow -video_size 1920x1080 -rtbufsize 2147.48M -framerate 60 ^
  
  -pixel_format yuyv422 -i video="Game Capture HD60 S (Video) (#01)":audio="ADAT (5+6) (RME Fireface UC)" -map 0:0,0:1 ^
  
  -map 0:1 -c:v h264_nvenc -preset: llhp -pix_fmt yuv420p -b:v 40M -minrate 40M -maxrate 40M -bufsize 40M -b:a 384k -ac 2 ^
  
  -r 60 -af "pan=mono|c0=c0, adelay=84" -vsync 1 -max_muxing_queue_size 9999 -f segment -segment_time 600 ^
  
  -segment_wrap 9 -reset_timestamps 1 C:\Users\djcim\Videos\PC\Camera\CPC%02d.ts ^
  
  -thread_queue_size 9999 -f dshow -video_size 3440x1440 -rtbufsize 2147.48M -framerate 100 -pixel_format nv12 ^
  
  -itsoffset 00:00:00.215 -i video="Video (00 Pro Capture HDMI 4K+)" -thread_queue_size 9999 -guess_layout_max 0 -f dshow ^
  
  -rtbufsize 2147.48M -i audio="SPDIF/ADAT (1+2) (RME Fireface UC)" -map 1:0,2:0 -map 6:0 -c:v h264_nvenc -preset: llhp ^
  
  -pix_fmt nv12 -b:v 250M -minrate 250M -maxrate 250M -bufsize 250M -b:a 384k -ac 2 -r 100 -af "adelay=141|141" -vsync 1 ^
  
  -max_muxing_queue_size 9999 -f segment -segment_time 600 -segment_wrap 9 -reset_timestamps 1 ^
  
  C:\Users\djcim\Videos\PC\PC\PC%02d.ts

  I thought all was well with my frame rates, sure ffmpeg was duplicating frames every once in a while, but I thought it was just a random occurrence caused by ffmpeg dropping a frame during processing and therefore needed to duplicate one to make it up. I didn’t think duplicating a few frames would be noticeable in the footage... until I was reviewing some from the first output, which is actually a camera, and noticed very slight stutters consistently 3 times a minute. This began to bug me, it was very noticeable and I wanted smooth footage. A bit confused I decided to try the first output by itself and watch ffmpeg to see when frames were being duplicated and found that it was duplicating frames every 17 second (16.66 to be more precise).

  After doing the math (1/16.66=.06) I realized that the frame rate of that first capture card was actually 59.94. Doing the same thing for the other output I found that my "100fps" footage is actually 99.98. But what does that really entail ?

  Should I change the fps to 59.94 and 99.98 ? Wont that cause synchronization issues as 99.98 (100*.0002=99.98) isn’t the same standard as 59.94 (60*.001=59.94) ? Or does that mean I just need to set the second output to 99.9 (100*.001=99.9) to match the standard of the first output and drop frames ? If that is the case does this mean in my editing program, Adobe Premiere, I would need to export the final video as 59.94fps not 60fps to avoid duplication of frames ? Or is there some method within timecode that remedies this issue ?

  I guess I just really don’t understand drop frame and non-drop frame timecode / timecode in general. Up until yesterday when something said 60fps I thought it meant literally 60fps but I guess 99% of the time it actually means 59.94. I’d really like to just avoid the duplication of frames as it ruins what would be a smooth experience but don’t know if I can while trying to keep everything synchronized.

  Any help or insight would be appreciated, sorry if my question is a bit confusing I am undoubtedly confused.