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• How to pack the pyav.packet and distribute to another computer

  31 juillet 2024, par lambertk

  I'm currently working on projects which needs to read frames from RTSP server on single entry of computer, do some preprocessing and distribute these frames with preprocessed metadata to different backend for different purpose.

  


  And after googling, I found that PyAV could be the solution which can retrieve the video from RTSP source and make it packets, which could possibly be sent to another computer.

  


  Considering the network bandwidth, transmit the packets instead of the decoded frames could be better choice.

  


  But now comes the problem, socket/MQ, usually only allows to send bytes or string.
  
Encode the PyAV.packet.Packet object into byte is easy by bytes(packet), but I couldn't find out the way to decode it back to PyAV.packet.Packet object.

  


  I've tried to use pickle to serialize the packet, but this method is not implemented in PyAV, and was rejected by the official team.

  


  I've also tried to use another package called msgpack, which also failed to serialize the packet.

  


  I've tried the following code after reading the source code of PyAV

  


  packet_bytes = bytes(packet)
pt = av.packet.Packet(len(packet_bytes))
pt.update(packet_bytes)


  


  the update function seems did not update anything

  


  Is there anyway to decode the bytes back to packet object ?

  


  Or, can someone give out a way to encode the frame packet and the preprocessed metadata (which is differ frame by frame) together (like H264 SEI Message, which I tried, but could not be inserted when using Python) then send to backend ?

  


• ffmpeg simple 5fps webcam capturing but results in poor performance

  16 septembre 2022, par irous

  I'm using Windows 10, intel core i5, 8GB ram. and download ffmpeg from official site : https://www.gyan.dev/ffmpeg/builds/

  


  I'm trying to capture 5fps video from webcam but the output fps is only 3.4 and speed is 0.668x. (I also tried with libx264 but the speed is same 0.5).
  
This is my command :

  


  ffmpeg ^
  -f dshow -r 5 -s 640x480 -i video="Sony Visual Communication Camera" ^
  -f rawvideo output.raw


  


  screenshot of console output :


  


  The cpu usage for above ffmpeg command is about 0.1% and also ram/disk usage is relatively low.
  
If I change the fps to 30 (-r 30), the output is : fps 7.9, speed 0.261x and CPU usage is still very low 0.1%.

  


  But I can easily record 30fps video with the same format yuyv422 in Directshow GraphEdit :


  


  So my question is why does ffmpeg show such poor performance even with 5fps video capturing ? If it can only produce 3.4 fps in the first case why it can output up to 7.9 fps in the latter case (when I set desired fps to 30) ? Did I mis-config ffmpeg ?
  
Any help is appreciated.

  


• FFmpeg : NetStream.Play.StreamNotFound on RMTP stream

  22 juillet 2014, par user2957378

  I want to take snapshots periodically of a RTMP live video stream.
  I can see the rtmp video stream using VLC. This is the rtmp url :

  rtmp://antena3fms35livefs.fplive.net/antena3fms35live-live/stream-antena3_1

  I’m using the following command to capture the snapshots, according to the official FFmpeg site here :

  ffmpeg -i rtmp://antena3fms35livefs.fplive.net/antena3fms35live-live/stream-antena3_1 -f image2 -vf fps=fps=1 out%d.png

  The command produces the following output :

  ffmpeg version N-64667-gd595361 Copyright (c) 2000-2014 the FFmpeg developers
  
    built on Jul 14 2014 22:09:48 with gcc 4.8.3 (GCC)
  
    configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-avisynth --enable-bzl
  
  libilbc --enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amr
  
  enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --ena
  
    libavutil      52. 92.100 / 52. 92.100
  
    libavcodec     55. 69.100 / 55. 69.100
  
    libavformat    55. 47.100 / 55. 47.100
  
    libavdevice    55. 13.102 / 55. 13.102
  
    libavfilter     4. 10.100 /  4. 10.100
  
    libswscale      2.  6.100 /  2.  6.100
  
    libswresample   0. 19.100 /  0. 19.100
  
    libpostproc    52.  3.100 / 52.  3.100
  
  HandShake: client signature does not match!
  
  Closing connection: NetStream.Play.StreamNotFound
  
  rtmp://antena3fms35livefs.fplive.net/antena3fms35live-live/stream-antena3_1: Unknown error occurred

  I’ve tried it with another rmtp streams, but I’m still getting the exact same error.

  What could be the problem ?
  Thank you !