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• Capture user-defined segment of RTSP video using FFmpeg

  10 janvier 2019, par Tom Larcher

  I’m endeavouring to capture a segment of video from an RTSP (static not live) video stream using FFmpeg, however I’m not certain how this is achieved.

  I am presently able to cut a segment of video from a local video file using a command similar to the one below :

  ffmpeg -y -i input_video.mp4 -ss 0:04:41.215 -to 0:07:17.335 output_video.mp4

  However commands similar to the above don’t seem to be working for remote (RTSP) video files. I’ve taken a look around for ways in which this can be achieved, to no avail. I’ve come across information on capturing individual frames as well as methods of capturing RTSP video files for storage locally, but I can’t seem to connect the dots to capture only a selected portion of the RTSP video.

  Any help on this would be immensely appreciated.

• Revision eec3def7c5 : Modified no memory rate control. This 2-pass rate control setting allocates bit

  16 octobre 2013, par Paul Wilkins

  Changed Paths :
   Modify /vp9/encoder/vp9_onyx_if.c

  
   Modify /vp9/encoder/vp9_onyx_int.h

  
   Modify /vp9/encoder/vp9_ratectrl.c

  
  
  Modified no memory rate control.

  This 2-pass rate control setting allocates bits based
  on first pass stats to each kf group, gf group and individual
  frame but does not correct the bits left and allocation after
  each frame.

  In other words it recommends a bit allocation for each frame
  but does not try and correct any over or under spend on a
  frame over the remainder of the clip. This reduces the accuracy
  of rate control in terms of hitting an average bitrate but prevents
  problems that may arise because early frames either use to many
  or too few bits. This mode is currently more inclined to undershoot
  than overshoot (particularly at higher data rates).

  Also minor changes to rate of adaption when recode loop is not
  enabled.

  This mode is currently enabled by default for VBR.
  It gives the following % performance gains.

  derf +0.467, +1.072
  yt 2.962, 2.645
  stdhd 1.682, 1.595,
  yt-hd 2.3, 2.174

  Change-Id : I3c84a9bf8884e5b345698ff0e19187f792c2f3a0

• Ffmpeg gdigrab records black window when capturing graphics-intensive flight simulator

  23 mars 2021, par iter

  I am trying to capture video from XPlane, a popular flight simulator. I'm running on Windows.

  



  Normally, I can capture individual windows using gdigrab, but when I use it on an XPlane window like so...

  



  ffmpeg -f gdigrab -framerate 30 -i "X-System" -b:v 300K capture.mp4


  



  ...I get a video file that's the right dimensions but is all black. I imagine this may have something to do with how XPlane talks directly to the GPU. I should add that if I capture the entire desktop like so...

  



  ffmpeg -f gdigrab -framerate 30 -i desktop -b:v 300K capture.mp4


  



  ...I get everything including the simulator window, but naturally with unrelated windows in the capture, including windows sitting on top of the simulator window.

  



  Is there a way for gdigrab to capture video this GPU-intensive window alone ? Is there a different tool I can use ?