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• What codec in OpenCV can do a stronger compression than default 'mp4v' ? [closed]

  7 juillet, par ullix

  My project does video recording from a microscope camera, and one experiment can run for days and even weeks. This takes plenty of filespace, so I want as strong a compression as possible. Quality is not a major concern.

  


  Currently I use the default 'mp4v' codec with opencv on Python. It works.

  


  I tried all codecs Google could find, and surprisingly, only very few worked. And those few that did work were even worse in compression.

  


  Where is the limitation ? Is it Opencv (4.11.0.86) ? Is it FFMPEG (7.1.1) ? Is it the distribution (Ubuntu Mate 25.04) ? Is it the CPU (AMD Ryzen AI 9 HX 370 w/ Radeon 890M × 24) ?

  


  EDIT :
I have uploaded an example clip (1 min) with some explanations to youtube :
https://www.youtube.com/watch?v=wW8w2Pppnng
Frames are FullHD, constant 10FPS

  


  The stripped-down code is :

  


  import cv2
fourcc = cv2.VideoWriter_fourcc(*'mp4v')
out    = cv2.VideoWriter("myvideo.mp4", fourcc, 19,(1920, 1080))
cam    = cv2.VideoCapture(0)
# loop
  success, image = cam.read()              
  cv2.imshow(title, image)                 
  key = cv2.waitKey(1)                     
  out.write(image)
...
out.release()


  


  What alternative codec can I use which gives better compression ?

  


• nginx-rtmp + ffmpeg move mp4's moov to head on the fly

  14 février 2017, par eddie.xie

  I have the following use case :

  1) Alice publish stream to the nginx-rtmp server

  2) The server convert the stream to mp4 (default is flv if I understand correctly, and a codec transformation is needed)

  3) Bob should be able to do range request to that mp4 file while Alice is still publishing

  However it seems ffmpeg command for converting a flv to mp4 can only be done when the mp4 file is fully generated, and then ffmpeg will do second pass and move "moov" to its new file’s head

  Our use case is to allow Bob use range request to retrive the mp4 file while Alice is still publishing (i.e. watch Alice’s video as soon as possible) from time 0 (i.e. from the second Alice started publishing). Thus with mp4’s moov at its head, it’s simple to do range requests and implement the functionality. Raw RTMP doesn’t seem to solve our problem, since we can’t let Bob watch from time 0 of Alice’s recording.

  The question is :
  1) Is it possible to do it while the flv is not fully generated yet ?
  2) Any other idea how shall we use nginx-rtmp/ffmpeg to achieve the functionality we desire ?

  Thanks a bunch

• C# streaming drone video

  13 mars 2020, par jasonmacintosh

  I am currently a student and I have a project which require using the drone and the livestream from its camera

  I managed to find a control program http://www.winardrone.com which can control my ar drone 2.0 , but the problem is that the program doesn’t support my drone’s camera live stream method(TCP)due to the fact that the program is more compatible to the ar drone 1.0(older version drone) which uses(UDP)

  so I have encountered a problem of putting the video stream into my program
  ,there are a really simple solution of using ffmpeg player with cmd command "ffplay tcp ://192.168.1.1:5555", but it does mean that my program have to run in multiple windows and I won’t be able to save my frames with my program to do analyzation

  so could anyone tell me how to Stream my TCP video in my visual studio C# program and capture frames at the same time ?
  just like the program in this video
  https://www.youtube.com/watch?v=4V5B-DPWdOQ

  I wish to get the video image in a program instead of opening a new window

  And sorry for my bad grammar, thanks for your reply