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

user_77174 0
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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.

capacity-planning ffmpeg encoding logging file
8 Answers

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> /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_29610

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.

user_12761510

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_2535160

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_90440060

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_1041170
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