How do I enable FFMPEG logging and where can I find the FFMPEG log file

Question

I want to be able to log FFMPEG processes because I am trying to work out how long a minute of video takes to convert to help with capacity planning of my video encoding server  How do I enable logging and where is the log file saved  I have FFMPEG installed on a CentOS LAMP machine

User · Answer

You can find more debugging info just simply adding the option -loglevel debug  full command will be  ffmpeg -i INPUT OUTPUT -loglevel debug -v verbose

User · Answer

You must declare the reportfile as variable for console    Problem is all the Dokumentations you can find are not running so    I was give 1 day of my live to find the right way       Example  for batch console   cmd exe  K set FFREPORT file  C  ffmpeg proto test log  level 32  amp  amp  C  ffmpeg bin ffmpeg exe -loglevel warning -report -i inputfile f outputfile  Exemple Javascript    var reortlogfile    cmd exe  K set FFREPORT file  C  ffmpeg proto     filename     log  level 32  amp  amp  C  ffmpeg bin ffmpeg exe            You can change the dir and filename how ever you want    Frank from Berlin

User · Answer

If you just want to know how long it takes for the command to execute  you may consider using the time command  You for example use time ffmpeg -i myvideoofoneminute aformat out anotherformat

User · Answer

appears that if you add this to the command line    -loglevel debug   or   -loglevel verbose   You get more verbose debugging output to the command line

User · Answer

ffmpeg logs to stderr  and can log to a file with a different log-level from stderr   The -report command-line option doesn t give you control of the log file name or the log level  so setting the environment variable is preferable    -v is a synonym for -loglevel   Run ffmpeg -v help to see the levels   Run ffmpeg -h full   less to see EVERYTHING  Or consult the online docs  or their wiki pages like the h 264 encode guide       bin bash  of out mkv FFREPORT  level 32 file  of log  ffmpeg -v verbose   -i src mp4 -c a copy -preset slower -c v libx264 -crf 21   of    That will trancode src mp4 with x264  and set the log level for stderr to  verbose   and the log level for out mkv log to  status     AV LOG WARNING 24  AV LOG INFO 32  AV LOG VERBOSE 40  etc     Support for this was added 2 years ago  so you need a non-ancient version of ffmpeg    Always a good idea anyway  for security   bugfixes and speedups     A few codecs  like -c v libx265  write directly to stderr instead of using ffmpeg s logging infrastructure   So their log messages don t end up in the report file   I assume this is a bug   TODO-list item   To log stderr  while still seeing it in a terminal  you can use tee 1      If you use a log level that includes status line updates  the default -v info  or higher   they will be included in the log file  separated with  M  carriage return aka  r    There s no log level that includes encoder stats  like SSIM  but not status-line updates  so the best option is probably to filter that stream   If don t want to filter  e g  so the fps   bitrate at each status-update interval is there in the file   you can use less -r to pass them through directly to your terminal so you can view the files cleanly   If you have  enc logs from several encodes that you want to flip through  less -r   G   enc works great      G means start at the end of the file  for all files    With single-key key bindings like   and   for next file and previous file  you can flip through some log files very nicely    the default bindings are  n and  p    If you do want to filter  sed  s    r    works perfectly for ffmpeg output    In the general case  you need something like vt100 py  but not for just carriage returns    There are  at least  two ways to do this with tee   sed  tee to  dev tty and pipe tee s output into sed  or use a process substitution to tee into a pipe to sed     pass stdout and stderr through to the terminal      and log a filtered version to a file  with only the last status-line update    of   1-x265 mkv  ffmpeg -v info -i   1  -c a copy -c v libx265       of    amp       pipe stdout and stderr    tee  dev tty   sed  s    r     gt  gt    of enc      or with process substitution where tee s arg will be something like  dev fd 123  ffmpeg -v info -i   1  -c a copy -c v libx265       of    amp    tee  gt  sed  s    r     gt  gt    of enc       For testing a few different encode parameters  you can make a function like this one that I used recently to test some stuff   I had it all on one line so I could easily up-arrow and edit it  but I ll un-obfuscate it here    That s why there are  s at the end of each line   ffenc-testclip        v should be set by the caller  to a vertical resolution   We scale to WxH  where W is a multiple of 8  -vf scale -8  v    db 0      convenient to use shell vars to encode settings that you want to include in the filename and the ffmpeg cmdline   of 25s 21 15   v p x265 pre mkv        -e   of enc     amp  amp echo   of enc exists  amp  amp return      early-out if the file exists      encode 25 seconds starting at 21m15s  or the keyframe before that    nice -14 ffmpeg -ss    21 60 15    -i src mp4 -t 25  -map 0 -metadata title  -color primaries bt709 -color trc bt709 -colorspace bt709 -sws flags lanczos print info -c a copy -c v libx265 -b v 1500k -vf scale -8  v  -preset  pre -ssim 1 -x265-params ssim 1 cu-stats 1 deblock  db aq-mode 1 lookahead-slices 0   of    amp     tee  dev tty   sed  s    r     gt  gt    of enc        and use it with nested loops like this  for pre in fast slow   do for v in  360 480 648 792 do  ffenc-testclip  done done  less -r   G   enc         -r is useful if you didn t use sed   Note that it tests for existence of the output video file to avoid spewing extra garbage into the log file if it already exists   Even so  I used and append   gt  gt   redirect   It would be  cleaner  to write a shell function that took args instead of looking at shell variables  but this was convenient and easy to write for my own use   That s also why I saved space by not properly quoting all my variable expansions     v instead of   v

User · Answer

FFmpeg does not write to a specific log file  but rather sends its output to standard error   To capture that  you need to either   capture and parse it as it is generated redirect standard error to a file and read that afterward the process is finished   Example for std error redirection   ffmpeg -i myinput avi  a-bunch-of-important-params  out flv 2 gt   path to out txt   Once the process is done  you can inspect out txt   It s a bit trickier to do the first option  but it is possible    I ve done it myself   So have others    Have a look around SO and the net for details

User · Answer

I find the answer  1 First put in the presets  i have this example  Output format MPEG2 DVD HQ   -vcodec mpeg2video -vstats file MFRfile txt -r 29 97 -s 352x480 -aspect 4 3 -b 4000k -mbd rd -trellis -mv0 -cmp 2 -subcmp 2 -acodec mp2 -ab 192k -ar 48000 -ac 2   If you want a report includes the commands -vstats file MFRfile txt into the presets like the example  this can make a report which it s ubicadet in the folder source of your file Source  you can put any name if you want   i solved my problem  i write many times in this forum  reading a complete  docx about mpeg properties  finally i can do my progress bar reading this txt file generated   Regards

User · Answer

I found the below stuff in ffmpeg Docs  Hope this helps      Reference  http   ffmpeg org ffmpeg html toc-Generic-options        -report    Dump full command line and console output to a file named   program-YYYYMMDD-HHMMSS log in the current directory  This file can be   useful for bug reports  It also implies -loglevel verbose       Note  setting the environment variable FFREPORT to any value has the   same effect

[file] How do I enable FFMPEG logging and where can I find the FFMPEG log file?

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