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• ffmpeg -ss then apply filter then concat producing timestamp errors

  6 août 2020, par Bob Ramsey

  Using ffmpeg, I have split a file into multiple parts using -ss. Then I apply a filter to some of the files, then concat the files back together. When I do that, I get : Non-monotonous DTS in output stream 0:0 ; previous : 341334, current : 340526 ; changing to 341335. This may result in incorrect timestamps in the output file. The output file plays, but there are noticeable skips where the files are joined.

  


  Here's how I am splitting the file :

  


  ffmpeg -i full_source.mp4 -ss 0 -to 14.264250 -c copy  01-plain.mp4
ffmpeg -i full_source.mp4 -ss 14.264250 -to 18.435083 -c copy  01-filtered.mp4

ffmpeg -i full_source.mp4 -ss 18.435083 -to 29.988292 -c copy  02-plain.mp4
ffmpeg -i full_source.mp4 -ss 29.988292 -to 31.865167 -c copy  02-filtered.mp4
...
ffmpeg -i full_source.mp4 -ss 0 -to 14.264250 -c copy  10-plain.mp4
ffmpeg -i full_source.mp4 -ss 234.484203 -to 300.000 -c copy  10-filtered.mp4


  


  Then I apply a different drawtext filter on each of the 10 filtered files and save them with a new name, like :

  


  ffmpeg -hide_banner -loglevel warning -y -i 01-filtered.mp4 -filter_complex "drawtext=fontfile=calibri.ttf:fontsize=24:fontcolor=white:x=300:y=500:text='hello world'" -crf 15 01-filtered-complete.mp4


  


  Finally, I join all of the plain and complete files back together like this :

  


  ffmpeg  -f concat -safe 0 -i mylist.txt -c:a copy -c:v copy  outfile.mp4


  


  And that's where the timing error comes in. I've tried adding -vsync drop in the concat command, but that didn't really work either. Same version of ffmpeg does the split, the filter, and the concat. I've tried different versions, everything from 20170519 to one from May 2020 with the same result. Always making sure that all three steps are done by the same version of ffmpeg.

  


  The only thing I can see is that ffprobe shows a duration of 14.27 for 01-plain.mp4 when it should be 14.264250. All of the other files show a similar rounding difference. The files are 23.98 fps. If I do all of my filters in really long command without splitting the file, I can use the more precise numbers with no problem. It just takes 10 times as long. This is all scripted, it happens a couple of hundred times a day and time is money, so I can't take 10 times as long to do each file.

  


  Any ideas ? Thanks in advance !

  


• libavutil : Add wchartoutf8(), wchartoansi(), utf8toansi(), getenv_utf8(), freeenv_utf...

  20 juin 2022, par Nil Admirari

  libavutil : Add wchartoutf8(), wchartoansi(), utf8toansi(), getenv_utf8(), freeenv_utf8() and getenv_dup()
  wchartoutf8() converts strings returned by WinAPI into UTF-8,
  
  which is FFmpeg's preffered encoding.
  Some external dependencies, such as AviSynth, are still
  
  not Unicode-enabled. utf8toansi() converts UTF-8 strings
  
  into ANSI in two steps : UTF-8 -> wchar_t -> ANSI.
  
  wchartoansi() is responsible for the second step of the conversion.
  
  Conversion in just one step is not supported by WinAPI.
  Since these character converting functions allocate the buffer
  
  of necessary size, they also facilitate the removal of MAX_PATH limit
  
  in places where fixed-size ANSI/WCHAR strings were used
  
  as filename buffers.
  On Windows, getenv_utf8() wraps _wgetenv() converting its input from
  
  and its output to UTF-8. Strings returned by getenv_utf8()
  
  must be freed by freeenv_utf8().
  On all other platforms getenv_utf8() is a wrapper around getenv(),
  
  and freeenv_utf8() is a no-op.
  The value returned by plain getenv() cannot be modified ;
  
  av_strdup() is usually used when modifications are required.
  
  However, on Windows, av_strdup() after getenv_utf8() leads to
  
  unnecessary allocation. getenv_dup() is introduced to avoid
  
  such an allocation. Value returned by getenv_dup() must be freed
  
  by av_free().
  Because of cleanup complexities, in places that only test the existence
  
  of an environment variable or compare its value with a string
  
  consisting entirely of ASCII characters, the use of plain getenv()
  
  is still preferred. (libavutil/log.c check_color_terminal()
  
  is an example of such a place.)
  Plain getenv() is also preffered in UNIX-only code,
  
  such as bktr.c, fbdev_common.c, oss.c in libavdevice
  
  or af_ladspa.c in libavfilter.
  Signed-off-by : Martin Storsjö <martin@martin.st>
  

  • [DH] configure
  • [DH] libavutil/getenv_utf8.h
  • [DH] libavutil/wchar_filename.h

• GOL-1361 : Remove invalid CTTS sample_offset check

  18 avril 2023, par ekir

  GOL-1361 : Remove invalid CTTS sample_offset check
  We checked in this places :
  
  * In 8.6.1.3 of ISO/IEC 14496-12 about the CTTS box
  
  * In Apples MOV spec : https://developer.apple.com/library/archive/documentation/QuickTime/QTFF/QTFFChap2/qtff2.html#//apple_ref/doc/uid/TP40000939-CH204-SW19
  

  • [DH] libavformat/mov.c