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• lavu/riscv : helper macro for VTYPE encoding

  5 octobre 2022, par Rémi Denis-Courmont

  lavu/riscv : helper macro for VTYPE encoding
  On most cases, the vector type (VTYPE) for the RISC-V Vector extension
  
  is supplied as an immediate value, with either of the VSETVLI or
  
  VSETIVLI instructions. There is however a third instruction VSETVL
  
  which takes the vector type from a general purpose register. That is so
  
  the type can be selected at run-time.
  This introduces a macro to load a (valid) vector type into a register.
  
  The syntax follows that of VSETVLI and VSETIVLI, with element size,
  
  group multiplier, then tail and mask policies.
  

  • [DH] libavutil/riscv/asm.S

• How to detetc hardware acceleration in ffmpeg

  19 décembre 2020, par Ali Razmkhah

  I am writing c++ program to screen record by ffmpeg 4.3 ! I need to detect hardware acceleration support such as h264_qsv or h264_nvenc without running ffmpeg.exe !

  


  I explored ffmpeg.exe source code and found no results ! some solutions are deprecated or dose not work on 4.3 !
As instance,

  


  avcodec_find_encoder_by_name("h264_qsv")


  


  returns null even it is exist and works properly !

  


• Capture & save MJPG CCTV stream to file w. FFMPEG

  21 juin 2021, par GBano

  I've been trying to record an IP-cam stream (Foscam, mjpg) via http with ffmpeg.
Can't get the rtsp stream for some reason, but the http/mjpg works fine (VLC IDed it as mjpg).

  


  The stream URL looks like this :
http://192.168.1.123:456/videostream.cgi?user=USERNAME&pwd=PWD

  


  So I created the string (w.o line wrap) :
ffmpeg -i -loglevel debug http://192.168.1.123:456/videostream.cgi?user=USERNAME&pwd=PWD /home/user/Videos/camera.mp4

  


  Some examples I saw are using -c copy and map 0 options as well but I left this out since I defined source and destination clearly and this is just a video, no audio.
segment_time and segment_format I also left out for now (I'd like segments later though- when it's working).

  


  FFMPEG returns : "bash: /home/user/Videos/camera.mp4: No such file or directory"

  


  So I tried a random mjpg stream from the net (Insecam is a nice source for this...) : http://58.69.178.54:80/mjpg/video.mjpg

  


  Leading to :
ffmpeg copy -i -loglevel debug -hide_banner http://58.69.178.54:80/mjpg/video.mjpg /home/user/Videos/camera.mp4

  


  Returns : -loglevel: "No such file or directory" (the same with segment options included, copy excluded).

  


  Shouldn't FFMPEG create the destination file ?

  


  One example mixed FFMPEG with CVLC (Save continuous RTSP stream to 5-10 minute long mp4 files) so I just tried with cvlc.
cvlc http://58.69.178.54:80/mjpg/video.mjpg copy /home/user/Videos/camera.mp4
This opens the stream in a VLC window (despite that I use Cvlc) but does not create a destination file.

  


  I suspect I must have missed something simple & silly, but what ?