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• avformat/mlvdec : demux LJ92 huffman comressed frames

  13 décembre 2024, par Peter Ross

  avformat/mlvdec : demux LJ92 huffman comressed frames
  A minimal DNG header is added to each LJ92 compressed frame, allowing
  
  thme to be decoded by the TIFF decoder. The TIFF decoder is responsible
  
  for setting up the MJPEG decoder, signalling the correct s->bayer flag,
  
  and setting pix_fmt.
  The LJ92 compressed frames can be muxed out to DNG files, and manipulated
  
  in DNG software. Tested with darktable and rawtherapee.
  Contributor : South East <8billion.people@gmail.com>
  

  • [DH] libavformat/mlvdec.c

• FFmpeg : Is it better to make a application then using ffmepg directly

  14 juillet 2020, par Mirabeau

  For all my IP camera streams, I use, under Linux, ffmpeg by a bash script which allows me at the same time to manage :

  


  1/ Convert the RTSP streams to HTTP (HLS) for the "Live" and therefore which generates "m3u8" file and *.ts segments

  


  2/ Backup the stream for archiving (in increments of 5 minutes), a cron remove older files (xx days)

  


  ffmpeg -i "rtsp://[IP_CAM01]" -rtsp_transport tcp -c copy -map 0 -f segment -segment_time 300 -segment_atclocktime 1 -segment_format mkv "cam01-% 03d.mkv" -c copy -f segment -segment_list cam01.m3u8 -segment_list_flags + live -segment_time 2 -segment_list_size 20 -segment_wrap 20 cam01-% 03d.ts


  


  The question I ask myself, and the reason for this message is as follows :

  


  

  • would there be an interest (memory / cpu / speed) to develop a program (C/C++/other ?) to do the same thing by using the libraries of ffmpeg ?

  


  • or the "gain" and the interest would be so minimal that it is not worth the expenditure of energy and time ?

  


  


  I appeal to your feedback, your opinions, your tips !, and if you had leads (sample) to attack this kind of development, I am interested.

  


  Thank you very much in advance for your feedback.
(this is my fist question on stackoverflow, Champagne ! ;))

  


• subprocess.run output is empty (python 3.8)

  26 juillet 2022, par Marino Linaje

  I'm trying to capture the output of a command with the following code :

  


  lines = subprocess.run(['ffmpeg', '-hide_banner', '-nostats', '-i', in_filename, '-vn', '-af', 'silencedetect=n={}:d={}'.format(silence_threshold, silence_duration), '-f', 'null', '-'], capture_output=True, text=True, shell=True, check=True, encoding='utf-8').stdout 
print (lines)


  


  But lines is an empty string and nothing is printed.
When capture_output=True is removed, the correct output is showed (without printing it).

  


  I tested many combinations, including removing all the subprocess.run parameters and only include capture_output=True with the same result.

  


  I also tested with few argument for a minimal example : subprocess.run(['ffmpeg', '-version'], capture_output=True, text=True, shell=True, check=True, encoding='utf-8').stdout

  


  Also tested stdout=subprocess.PIPE and stderr=subprocess.PIPE as subprocess.run arguments instead of capture_output=True

  


  I can't figure out what is happening. Thanks in advance !