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• Add blank screen into video grid

  4 janvier 2017, par mvalencaa

  I’m trying to do a 9 videos grid using FFMPEG, but the last one must be blank.

  | Video 1 | Video 2 | Video 3 |

  | Video 4 | Video 5 | Video 6 |

  | Video 7 | Video 8 | No video |

  So far, I got this :

  ffmpeg  -i video1.mp4 -i video2.mp4 -i video3.mp4 \
  
      -i video4.mp4 -i video5.mp4 -i video6.mp4 \
  
      -i video7.mp4 -i video8.mp4 -i video9.mp4 \
  
  -filter_complex "[0:v][1:v][2:v]hstack=3[h1]; \
  
               [3:v][4:v][5:v]hstack=3[h2]; \
  
               [6:v][7:v][8:v]hstack=3[h3]; \
  
               [h1][h2][h3]vstack=3[v]"  \
  
  -map "[v]" mosaic.mp4

  which produced a perfect grid with 9 videos.

  The next step is remove the last one and add a blank screen with "No video" written.

  I saw at this link someone saying to use

  -f lavfi -i color=s=WxH:color=black

  but I don’t know how (or where) to use it...

  Can anyone please help me ?

• FFMPEG Screen Cutoff

  18 août 2021, par Jackson Medina

  Recently I have been trying to consume the RTSP stream from a Vivitar Folding Drone. By reverse-engineering the .apk file for the Vivitar Folding Drone app, I was able to find that the RTSP address for the drone is rtsp://192.168.1.1:7070/webcam however, whenever I consume this stream through VLC or FFPLAY, most of the feed gets cut off and replaced with a green screen or gray screen (depends on whether I save to a .mjpeg file or a .dump file). What is the cause of this problem and what steps can I take to fix it ?

  


  

  


  When using FFPLAY, I use the following command :
ffplay -i -rtsp_flags rtsp://192.168.1.1:7070/webcam

  


  I also receive this error when I first start consuming the stream with ffplay :

  


  [swscaler @ 00000240daeadf80] deprecated pixel format used, make sure you did set range correctly


  


  I receive this error message for about every frame of the stream :

  


  [mjpeg @ 00000240d6226b00] mjpeg_decode_dc: bad vlc: 0:0 (00000240d6266050)
[mjpeg @ 00000240d6226b00] error dc
[mjpeg @ 00000240d6226b00] error y=1 x=0


  


  NOTE : I am unsure if this is relevant, but the Vivitar Drone creates its own wifi network that must be signed onto if you want to consume the RTSP stream

  


• ffmpeg - Unable to record screen and speaker audio at the same time

  11 janvier 2023, par dems98

  I'm trying to record my screen and speaker audio with ffmpeg but I'm facing various problems.

  


  This is the command I'm using :

  


  ffmpeg -video_size 1920x1080 -framerate 60 -f x11grab -i :0.0 -f pulse -ac 2 -i alsa_output.pci-0000_2d_00.4.analog-stereo.monitor output.mp4


  


  but the output video is really slow and out of sync with the audio.
  
Moreover, I'm getting these warnings :

  


  [x11grab @ 0x563635302480] Thread message queue blocking; consider raising the thread_queue_size option (current value: 8)
[aac @ 0x563635319f40] Queue input is backward in time04.49 bitrate= 466.9kbits/s dup=268 drop=45 speed=1.84x    
[mp4 @ 0x5636353172c0] Non-monotonous DTS in output stream 0:1; previous: 217669, current: 210387; changing to 217670. This may result in incorrect timestamps in the output file.                                                                                        


  


  When recording the screen with alsa source (microphone), the output video has no problems.

  


  How can I solve ?