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• How to overlay images sequence from pipe over a video stream with ffmpeg ?

  7 juin 2018, par Dotan Simha

  I’m trying to figure out an issue with ffmpeg.
  I have the following installation :
   DeckLink Mini Recorder Card (for HDMI input)
   DeckLink Mini Monitor Card (for HDMI output)

  I’ve successfully managed to take the HDMI input from the Decklink card and output is as-is to the output card with the following command :

  ffmpeg -f decklink -video_input hdmi -raw_format yuv422p10 -i "DeckLink Mini Recorder" -f decklink -pix_fmt uyvy422 "DeckLink Mini Monitor"

  I tried to add a complex-filter to add an overlay of an image, with the following command, and it works :

  ffmpeg -f decklink -video_input hdmi -raw_format yuv422p10 -i "DeckLink Mini Recorder" -i ./tools/bin/windows/2.png -y -filter_complex "[0:1][1:0]overlay=10:10" -f decklink -pix_fmt uyvy422 "DeckLink Mini Monitor"

  I’m getting a realtime feed from the decklink recorder, the image is added to the stream, and it outputs it to the output HDMI card. Everything seems to work.

  Now I tried to change the static image path to use stdin (pipe:0), and I have a tool that constantly streaming PNG images to stdout :

  ffmpeg -f decklink -video_input hdmi -raw_format yuv422p10 -i "DeckLink Mini Recorder" -i pipe:0 -y -filter_complex "[0:1][1:0]overlay=10:10" -f decklink -pix_fmt uyvy422 "DeckLink Mini Monitor"

  The result that i’m getting on the output HDMI card is a static image, of the first frame.
  The output of ffmpeg also changes now, and it looks like it stuck of the first-second of the stream :

  ```
  frame= 30 fps=7.4 q=-0.0 size=N/A time=00:00:01.00 bitrate=N/A speed=0.247x

  frames : 30,
  currentFps : 7,
  currentKbps : NaN,
  targetSize : NaN,
  timemark : ’00:00:01.00’
  ```

  It just remains on 00:00:01.00 and never changes.

  I tried to find the issue, and did the following :

  • Tried to stream Decklink Recorder -> static png file overlay -> Decklink Monitor = IS WORKS

  • Tried to stream static png file -> Decklink Monitor = IS WORKS

  • Tried to stream pipe:0 (PNG files) -> Decklink Monitor = IS WORKS

  • Tried to stream Decklink Recorder -> pipe:0 (PNG files overlay) -> RAW AVI file IS WORKS

  The only issue is with :
   Tried to stream Decklink Recorder -> pipe:0 (PNG files) overlay -> Decklink Monitor DOES NOT WORK

  I suspect that Decklink output is more strict, and my pipe:0 with the PNG images is not stable, and the combination of both causes it to freeze.

  Any idea how to solve it ? :(

  Thanks !

• FFMPEG : change input without stoping proccess

  10 juillet 2018, par admin883

  how i can change input on ffmpeg without stop process on linux Debian 9 ?
  im user decklink input and i need to change to file mp4 input.

  ffmpeg -f decklink -i 'DeckLink Mini Recorder' -vf setpts=PTS-STARTPTS -pix_fmt uyvy422 -s 1920x1080 -r 25000/1000 -f decklink 'DeckLink Mini Monitor'

• Record only audio using ffmpeg commands in OSX Terminal

  27 septembre 2017, par Swati

  I have tried multiple commands, the file is created but no audio.

  ffmpeg -f avfoundation -framerate 30 -i "Built In Input" -acodec aac -ab 64000 -ar 48000 -ac 2 -f flv test.wav
  
  
  
  ffmpeg -f avfoundation -i ":Built In Input" -acodec libmp3lame -ab 32k -ac 1 -f flv test.wav
  
  
  
  ffmpeg -f avfoundation -i ":1" -r 25  -c:v libx264 -preset fast -crf 22 -c:a libfdk_aac  -b:a 128k -ar 44100 -s 640x480  test.mp4
  
  
  
  ffmpeg -f avfoundation -i ":1" -acodec libmp3lame -ab 32k -ac 1 -f mp3 swati.mp3
  
  
  
  
  
  
  
  
  
  ffmpeg -f avfoundation -framerate 30 -i ":1" -ab 128000 -ac 2 -f flv /Users/admin/Documents/swati.flv

  Result in terminal :
  video:0kB audio:686kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead : 0.810823%

  Above line indicates audio exists but i cant hear anything
  any suggestions what should I do ?