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• ffmpeg multiplexing 4 videos into 1 and drawtext problems

  11 décembre 2012, par user1895639

  I have four videos that I would like to multiplex into 1 video and put text in the upper left of each quadrant. I can successfully mux the videos such that vid1 is in the upper left, vid2 is in the upper right, vid3 in the lower left, and vid4 in the lower right.

  I cannot, however, get even simple text to show up with the drawtext command.

  I would like to put the name of the original video file in each quadrant.

  At the moment my command is this :

  ffmpeg.exe -i "vid1.mp4" -i "vid2.mp4" -i "vid3.mp4" -i "vid4.mp4"  -filter_complex "[0:0]scale=iw/2:ih/2,pad=iw*2:ih*2[a];[1:0]scale=iw/2:ih/2[b];[2:0]scale=iw/2:ih/2[c];[3:0]scale=iw/2:ih/2[d];[a][b]overlay=w[x];[x][c]overlay=0:h[y];[y][d]overlay=w:h" -vf [0]drawtext=fontsize=12:fontcolor=white:fontfile="/Windows/Fonts/arial.ttf":text="vid1":x=35:y=35[out] "4UP_Video.mov"

  If I remove the drawtext command I get the same result : nice 4-Up video but no text. My assumption is that for the other quadrants I would add another drawtext command with the input stream #, e.g.

  [1]drawtext ...

  Any help is appreciated !

• Faster frame extraction than ffmpeg

  23 janvier 2013, par Ben Ford

  I have a video analytics program that processes assorted frames from a video. (Several hours long)
  The video is likely going to be an MP4 but may be other formats going forwards.

  At the moment, I have a C# wrapper around an ffmpeg call to extract an individual frame at the requested time. (I'm using the ffmpeg.exe binary. Not the libraries directly)
  At the moment, this all works. But it's slow. Very slow.

  I've found ways to improve the speed by storing the extracted frames in a ramdisk while they're being processed. Changing the stored image format etc...

  I just wanted to check if anyone could think of any way to pull individual frames out. At split-second accuracy.
  I know this is probably possible with DShow etc... I went straight to FFMPEG as I've used it before. But if DShow is likely to be faster I'll gladly change !

• How to make dynamic timestamp in ffpmeg, not static ?

  28 février 2013, par Sergii Rechmp

  I am using ffmpeg (windows pc) with my webcam to record what happens when i'm out of home.
  It works fine, but i can't make dynamic clock and date on screen.
  I have tried

  -vf "[in]drawtext=fontsize=12:fontfile=arial.ttf:text='%date%':x=10:y=25,  
  
  drawtext=fontsize=12:fontfile=arial.ttf:text="%TIME:~0,2%-%TIME:~3,2%-%TIME:~6,2%"

  It works, but it shows time only for start moment, than it wont change during video recording.
  it looks like :
  Is there any method to out time on screen ?
  Thanks.