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• aac : check the maximum number of channels

  27 avril 2013, par Luca Barbato

  aac : check the maximum number of channels
  Broken bitstreams could report a larger than specified number of
  
  channels and cause outbound writes.
  CC:libav-stable@libav.org
  

  • [DBH] libavcodec/aacdec.c

• Trouble trimming video by frame number with ffmpeg

  8 décembre 2023, par jgore200377

  I want to trim/split a video with ffmpeg using frames. The reason why is because I am using a Shot Transition Detection model which returns a probability of transition for every frame in the video.

  


  Using timestamps to cut the video has yielded bad results as the precision is not 100%.

  


  Ive tried this command which just outputs the entire video which is DEFINITELY not what I want

  


  ffmpeg -i video.mp4 -vf "trim=start_frame=100:end_frame=200,setpts=PTS-STARTPTS" -c:a copy output.mp4


  


  Ive also tried using python bindings with ffmpeg-python

  


  import ffmpeg

input_file = ffmpeg.input('video.mp4')
output_file = ffmpeg.output(input_file.trim(start_frame=1300, end_frame=1500), 'test_output.mp4')
ffmpeg.run(output_file)


  


  This doesnt work either and outputs a video with half of it being still with unpredictable length

  


  ---

  


  Ive visited some other sites but none seem to have this nailed down and it would be much appreciated if someone can answer how to use frames to trim/split a video with ffmpeg.

  


• Overlaying frame number with ffmpeg [duplicate]

  30 mars 2024, par DMagma

  This should be simple but it is giving me fits and I haven't been able to find this specific problem. I am trying to overlay the frame number on a set of videos but my ffmpeg command string is ignoring any text overlay that has anything to do with a frame number. For example, these produce the correct overlay

  


  "-vf drawtext=fontfile='Arial.ttf': text='TEST': fontsize=30: fontcolor=yellow@1.0:x=(w-text_w-15):y=15" 
"-vf drawtext=fontfile='Arial.ttf': text='%camera%': fontsize=30: fontcolor=yellow@1.0:x=(w-text_w-15):y=15" 
"-vf drawtext=fontfile='Arial.ttf': text='%vname%': fontsize=30: fontcolor=yellow@1.0:x=(w-text_w-15):y=15" 


  


  but these all ignore the "text" input and instead overlay "fontsize=30" or "start_number=1" to the frames

  


  "-vf drawtext=fontfile='Arial.ttf': text=%{n}: fontsize=30: fontcolor=yellow@1.0:x=(w-text_w-15):y=15" 
"-vf drawtext=fontfile='Arial.ttf': text='%{n}': fontsize=30: fontcolor=yellow@1.0:x=(w-text_w-15):y=15" 
"-vf drawtext=fontfile='Arial.ttf': text='Frame %{frame_num}': start_number=1: fontsize=30: fontcolor=yellow@1.0:x=(w-text_w-15):y=15" 


  


  I am at a loss as to why it is not properly identifying or using the frame number.

  


  I have tried multiple variations such as those shown above including swapping the order of the inputs to no effect.