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• Display formatted date and time over frames using ffmpeg

  28 août 2020, par marcman

  I've gone through a handful of questions on here (this, this, this, etc) concerning overlaying the date and time on videos using ffmpeg, but I haven't been able to figure out the solution.

  


  I personally have found the ffmpeg documentation difficult to parse as well regarding drawing text that updates every (N) frame(s).

  


  I have the exif data from a movie specifying when it was created. I'd like to be able to emblazen that over the movie (as though it were a home video from some old VHS tape). For example, let's say I have a video from January 2, 2012 at 10:33:53. I'd like to be able to show "Jan 2, 2012 10:33:53am" on the lower right in white text. The spatial positioning and color are clear to me, but just how to go from the timestamp information I have to the formatted expansion is proving to be quite difficult for me. I have succeeded in getting a clock starting from 00:00:00.00 and counting up (using timecode and timecode_rate), but unfortunately I can't get much more than that.

  


  My question is : what is the proper datetext command that will allow me to both (a) provide the start time, and (b) format it with the proper expansion.

  


  ---

  


  As a bonus, if you can also point me to how to do this using the wonderful ffmpeg-python library, it would be even better. That library is quite good, but it does not appear to be actively maintained anymore.

  


• 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.

  


• avformat/movenc : creating producer reference time (PRFT) box

  7 mai 2018, par Vishwanath Dixit

  avformat/movenc : creating producer reference time (PRFT) box
  The producer reference time box supplies relative wall-clock times
  
  at which movie fragments, or files containing movie fragments
  
  (such as segments) were produced.
  
  The box is mainly useful in live streaming use cases. A media player
  
  can parse the box and utilize the time fields to measure and improve
  
  the latency during real time playout.
  

  • [DH] doc/muxers.texi
  • [DH] libavformat/movenc.c
  • [DH] libavformat/movenc.h