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• Splitting odd and even frames in Gstreamer

  4 avril 2014, par user3498379

  I am building an application whereby I need to split a videostream(RTSP/MJPEG) into individual frames. The extracted frames then need to be put into two named pipes. I need to alternate the frames between two named pipes, i.e. even frames go to pipe one and odd frames go to pipe 2. I have been able to achieve this with ffmpeg using the following command :

  ffmpeg -i "rtsp://<ipaddress>/axis-media/media.amp?videocodec=jpeg" -vf select="mod(n-1\,2)" -vcodec mjpeg -f avi -y  -vf select="not(mod(n-1\,2))" -vcodec mjpeg -f avi -y 
  
  </ipaddress>

  However I have run into an RTP packet size issue with ffmpeg when using large resolutions e.g. 2048x1536. My question is ; is there a gstreamer equivalent command ? I have the basic gstreamer command which extracts images :

   gst-launch rtspsrc location=rtsp://<ipaddress>/axis-media/media.amp?videocodec=jpeg ! decodebin2 ! jpegenc ! multifilesink location="frame%d.jpg"
  
  </ipaddress>

  But now I need the additional piece, any help will be much appreciated.

• ffmpeg fails to output rtp when setting start time (-ss)

  22 janvier 2021, par Max

  I'm using ffmpeg to stream output to an RTP endpoint. This works fine with audio and video, but fails when using the -ss flag. The command I'm using is

  


  ffmpeg \
  -fflags +genpts \
  -re \
  -v info \
  -protocol_whitelist pipe,tls,file,http,https,tcp,rtp \
  -i in.mp4 \
  -map \
  0:v:0 \
  -c:v libx264 \
  -pix_fmt yuv420p \
  -tune zerolatency \
  -preset ultrafast \
  -g 30 \
  -keyint_min 30 \
  -map 0:a:0 \
  -c:a libopus \
  -ab 128k \
  -ac 2 \
  -ar 48000 \
  -f tee \
  [select=v:f=rtp:ssrc=2222:payload_type=101]rtp://1.1.1.1:44973?rtcpport=44663|[select=a:f=rtp:ssrc=1111:payload_type=100]rtp://1.1.1.1:47974?rtcpport=46683'


  


  This command works fine. If I add -ss 5 just before -i in.mp4, ffmpeg flips out. The rtp receiving side reports PLI for every frame, and the ffmpeg output indicates something is wrong :

  


  frame=    0 fps=0.0 q=0.0 size=N/A time=-577014:32:22.77 bitrate=N/A speed=N/A


  


  Also, when running with debug logs, ffmpeg reports cur_dts is invalid many times.

  


  If I output to a file instead of rtp, everything seems to work. Any advice on how to handle this would be most appreciated !

  


• Compare 2 videos at different frames with ffmpeg

  16 juin 2023, par hell

  there is this nice ffmpeg command :

  


  ffmpeg -i video1.mp4 -i video2.mp4 -filter_complex "[0:v][1:v]blend=difference,blackframe=1:10" -f null -'


  


  this command compares 2 videos but always at the same frame.
imagine i want to compare those 2 with 5 frames offset...like frame 0 of video1 with frame 5 of video2, is this possible with ffmpeg ?

  


  i already tried :

  


  'ffmpeg -i video1.mp4 -i video2.mp4 -filter_complex "[0:v]select=gte(n\,0)[video1]; [1:v]select=gte(n\,5)[video2]; [video1][video2]blend=difference,blackframe=1:10" -f null -'


  


  but this command just starts the compare at frame 5 for both...

  


  i had success with image compare of every frame (create image from frame - compare - go next frame) but that was taking forever if i have a longer clip due to creating and checking single images.
cutting and reencoding is also no option due to quality loss and time.

  


  i really appreciate any help, didnt find more on google and ai was useless :(