Recherche avancée

Sur d’autres sites (7107)

• Output image twice in ffplay

  2 mai 2024, par Sun Tzun

  I need to show two similar images from a webcam side-by-side.
I can achieve this with this piped command, but it runs with a few seconds latency :

  


  ffmpeg -f dshow -i video="Logi C310 HD WebCam" -filter_complex "[0:v][0:v]hstack=inputs=2[v]" -map "[v]" -f matroska - | ffplay -


  


  I'd prefer to do the same in just ffplay.

  


  I'd also like to have the resulting image cropped to a square size or to the size of the original image (like if the picture from webcam gets divided by half and the halfs took each other places).

  


  What I need in this end is a tool that helps to align the camera parallelly to the captured object, so any wrong angle would be perfectly visible on video if two opposite sides of the picture are placed alongside.

  


  PS. My platform is Windows 11.

  


• streaming from generated images using ffmpeg / vlc / live555

  10 octobre 2019, par Pavel

  For the life of me I cannot get this to work correctly.

  The idea is : simple python script that loads an image from a url (different every time) and passes it to ffmpeg, eg :

  python fetch.py | ffmpeg -f image2pipe -framerate 1 -i pipe:.jpg -c:a copy -c:v libx264 -r 5 -b 500000 -s 600x480 ../live555/out.264

  What I really need is to make this work with some sort of rtsp server.
  So far a sort of working approach was to use live555MediaServer that is running on the same server and pretty much streams that out.264 file.

  Why I don’t like this approach :

  a. connecting to rtsp stream using vlc works but it’s very unstable (video stops) and there are not errors or anything, if I click play it resumes.
  debug :
  live555 debug: RTSP track Close, 0 track remaining
  It seems like it just streams whatever the file has at that moment of time and does not do it continuously.

  b. I don’t like the "file" approach. Eg. ffmpeg is creating an out.264 file which grows. Ideally it would simply send the stream to the RTSP server via some protocol.

  c. live555MediaServer just sucks

  It looks like there is a way to run vlc server on my server as well, but I cannot figure out how to make ffmpeg feed the vlc server ?

  Any suggestions ?

• avformat_write_header() changes my stream's time_base

  12 avril 2023, par greken

  I have a high framerate camera which can capture >2000 fps. My plan was to assign actual capture timestamps with µs resolution to the frames and encode with H.264 in a matroska file.

  


  So I set the time_base of both the AVStream and the AVCodecContext to {1, 1'000'000}. But after calling avformat_write_header(avFormatContext, nullptr) I notice that the stream's time_base is {1, 1'000}. Now, since my framerate is double this resolution, I get identical consecutive timestamps and half my frames get lost when I extract them from the video file.

  


  Does anyone have an idea why this is happening and what I can do about it ? Preferably in a way that preserves the correct timestamps.