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• ffmpeg's segment_atclocktime cuts at inaccurate times for audio

  3 mai 2023, par Ross Richardson

  I am using ffmpeg's segment format to save files of an AAC stream to disk in hourly segments.
The segmenting works well, but the files are segmented/cut at different times in the clock each hour using segment_atclocktime

  


  I would like each to be exactly on the hour, e.g. 12:00:00, 13:00:00 etc. Or at least, beginning after the hour and not before, e.g. 12:00:00, 13:00:01, 14:00:00 etc.

  


  I am using ffmpeg-python to process the AAC stream and send to two outputs : stdout and these segments.
Here's the code :

  


  out1 = ffmpeg.input(stream, loglevel="panic").output("pipe:",
                                                     format="s16le", 
                                                     acodec="pcm_s16le", 
                                                     ac="1", 
                                                     ar="16000")

out2 = ffmpeg.input(stream, loglevel="info").output("rec/%Y-%m-%d-%H%M%S.aac",
                                                     acodec="copy",
                                                     format="segment",
                                                     segment_time="3600",
                                                     segment_atclocktime="1",
                                                     reset_timestamps="1",
                                                     strftime="1")
            
ffmpeg.merge_outputs(out1, out2)
      .run_async(pipe_stdout=True, overwrite_output=True)


  


  Most files are produced at the desired time : 05:00:00, 06:00:00, 07:00:00, but one or two each day start at 08:59:59 (where 09:00:00 would be desired), or even 16:00:24.

  


  I understand the segment needs to begin on a audio sample so it can't be perfect to the hour, but wondering how I can make it more consistent. Ideally, each hour's recording would begin at 00:00 or later, and not begin before the hour.

  


  I have tried using min_seg_duration 3600, reset_timestamps 1
I am not sure how exactly to use segment_clocktime_wrap_duration for audio, or whether segment_time_delta applies to audio.

  


  I'd appreciate any advice or understanding of how segment_atclocktime works with audio, as much on the internet seems video-focused.

  


• FFMPEG | add same effect with different settings several times to an input-file

  3 mai 2019, par Bamba675

  I’m trying to remove (for example) the greenscreen and the bluescreen of a video. To do this, I have to use FFMpeg.

  I already tried this one :

  ffmpeg -i background.mp4 -i greenbluefootage.mp4 -filter_complex "[1:v]chromakey=0x67FF00:0.1:0.1,chromakey=0x0061FF:0.1:0.1[aa];[0:v][aa] overlay" output.mp4

  The problem is, that just one color gets removed.
  I simply want to remove both colors (make them transparent) so the background can shine through.

• doc/ffplay, ffplay : add information regarding volume control

  27 septembre 2015, par Ganesh Ajjanagadde

  doc/ffplay, ffplay : add information regarding volume control
  ffplay now supports dynamic volume control. This documents the supported
  
  behavior.
  Signed-off-by : Ganesh Ajjanagadde <gajjanagadde@gmail.com>
  
  Reviewed-by : Stefano Sabatini <stefasab@gmail.com>
  
  Signed-off-by : Marton Balint <cus@passwd.hu>
  

  • [DH] doc/ffplay.texi
  • [DH] ffplay.c