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• How to encode a HEVC video from YUV420 Mat data (from a hardware triggered camera) via FFmpeg in Python

  4 juillet 2023, par QuantumRiver

  I am having problems encoding a HEVC video from a series of YUV420 Mat data via FFmpeg.

  


  

  1. I am using python in Ubuntu-20.04 ;

  


  2. I am retrieving frame data from a hardware triggered camera (BASLER), using pypylon ;

  


  3. I want to write a video from that camera in HEVC codec, using my GPU-NVENC ;

  


  4. I guess I have to use FFmpeg to achieve these ;

  


  


  What I have tried :

  


  

  1. I find that FFmpeg supports encoding from a camera, but it seems to only support webcams, not the camera I use (hardware triggered BASLER cameras with pypylon APIs) ;

  


  2. I find that FFmpeg supports transfering a video from one codec to another, which is not my case ;

  


  3. I find that FFmpeg supports encoding a video from a series of jpeg images. But in my case, it will be inefficient if I first save each frame into a picture and then encode them into a video ;

  


  4. The frame data retrieved from camera can be converted to YUV420 (directly from pypylon), which is suitable for HEVC encoding ;

  


  5. I learnt that the basic unit in FFmpeg to encode a video is AVFrame. I guess I have to first turn my YUV420 data into AVFrame, then encode AVFrames into HEVC ;

  


  6. But I do not know how to achieve that in python.

  


  


  My simplified and expected codes :

  


  camera = pylon.InstantCamera(tlf.CreateFirstDevice())
converter = pylon.ImageFormatConverter()
converter.OutputPixelFormat = pylon.PixelType_YUV420
video_handle = xxxxxx  # HEVC
while True:
    grabResult = camera.RetrieveResult(timeout, pylon.TimeoutHandling_ThrowException)
    image = converter.Convert(grabResult).GetArray()
    video_handle.write(frame)  # encode into a hevc video via ffmpeg in NVENC


  


• sorting numerically while creating video for ffmpeg [closed]

  9 février 2024, par kstn

  I have a series of figures with name particles_[time].jpg such as

  


  particles_0.03101765477.jpg
particles_3.1327831317.jpg
particles_6.2345486087.jpg
particles_9.3363140857.jpg


  


  The time is increasing but it has real values. When I used ffmpeg to generate gif with

  


  ffmpeg \
  -framerate 60 \
  -pattern_type glob \
  -i 'figures/particles_*.jpg' \
  -r 15 \
  -vf scale=512:-1 \
  out.gif \
;


  


  , the files are not read in the correct sequential order. How can I fix that ?

  


• Merging Many Webms With FFMPEG

  10 août 2016, par cfog

  We’ve been trying to merge multiple webms together so that they play in series in a new webm using FFMPEG. These webms are from multiple sources (webcams), so the resolution will vary.

  We’re using these options, it works perfectly for 3 files. But, we need to be able to do it for n number video files.

  -filter_complex "[1:v]scale=640:-1[v1]; [0:v][0:a][v1][1:a][2:v]
  
  [2:a]concat=n=3:v=1:a=1[v][a]" -map "[v]" -map "[a]"