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• Add a text/caption to the first few seconds of a cut video ?

  6 mai 2022, par JR Jr.

  I want to cut a video and at the same time add a caption during the first few seconds of the video using drawtext. I have tried lots of different google searches but all turned out to be totally unhelpful for this specific purpose (even the answers on the SS pages). Also, I am on Windows, I don't care for other OS's, such as Unix/ubuntu/Mac.

  


  Let's use the below cut syntax as an example. It's cutting and changing the format from mkv to mp4, and I want to add a simple title to be displayed in the first 5 seconds of the video, since this will be done to various files and then they will be concatenated together and it's good to let the viewer know which movie each excerpt belongs to (without doing that manually for each single video, the goal is to add these texts to each of the below commands).

  


  "C:\ffmpeg\bin\ffmpeg.exe" -y -i "D:\S01\SATC - S01E03 - Bay of Married Pigs.mkv" -ss 00:18:05 -to 00:19:15 -codec copy "002-SATC - S01E03 - Bay of Married Pigs-00_18_05-00_19_15.mp4"


  


  Let's say I want to add the title "S01E03 - Bay of Married Pigs" in the center of the screen, in white, with font size 12, displayed between 1 and 5 seconds. How do I do that ?

  


  And more importantly, since these syntaxes tend to make the command line insanely long and it needs to be a one liner, is there a smarter way to feed the settings/configuration of the drawtext clause into the command line, as to not make the code very messy, long and chaotic ?
Besides, do white spaces matter/would misplaced blank spaces make the command line crash ?

  


  Been trying this for hours now, so I really appreciate your help on this.

  


• How to use a customized library (built from C++ OpenCV) in Ffmpeg filter ? [duplicate]

  3 septembre 2016, par Codecodeup

  This question already has an answer here :

  • Using C++ library in C code
    
    4 answers
    

  I am writing a C++ library which is based on OpenCV. I want to use it in a Ffmpeg filter (written in C), so I write a wrapper of the library using C. The wrapper consists of a C header file and some C functions which call the C++ functions (in the C++ files). I expect the FFmpeg filter to only include the C header and call the C functions.

  I have built the library as a standalone one, which can be considered as an external library to FFmpeg. I have added it to the DEPENDENCIES list of FFmpeg, together with other external libraries, like openjpeg. I have also added "’—extra-libs=-lstdc++ -lmylibrary’ together with other args, like ’—enable-libopenjpeg’.

  However, I get the following error when compiling FFmpeg :
  .../binutils/2.25/centos6-native/da39a3e/bin/ld : .../mylibrary/0.1/gcc-4.9-glibc-2.20/80414d5/lib/libmylibrary.a(mylibrary_file.cpp.o) : undefined reference to symbol ’_ZdlPv@@GLIBCXX_3.4’
  .../libgcc/4.9.x/gcc-4.9-glibc-2.20/024dbc3/lib/libstdc++.so : error adding symbols : DSO missing from command line

  Here, I tried gcc-4.9-glibc-2.20 and other versions but got the same results.

  I wonder if I missed anything.

  Thanks a lot for your help !

• Record and preview webcamera stream at the same time

  11 juin 2019, par Vlad Popov

  I’m using ffmpeg and Windows 7/10 OS and going to save webcamera stream to file and preview it at the same time (from time to time, not constantly).
  I can solve each of these tasks separately :

  1. Saving webcamera stream to 1-minute files :

  $ffmpeg_exe = "C:\ffmpeg.exe"

  $video_source = "USB Video Device"

  Start-Process $ffmpeg_exe -ArgumentList @("-y -hide_banner -f dshow -rtbufsize 100M -i video=``"$video_source``" -preset ultrafast -strftime 1 -f segment -segment_time 00:01:00 ``"$out_folder\%Y_%m_%d_%H_%M_%S.mp4``"") -Wait -NoNewWindow

  2. Preview webcamera using ffplay :

  $ffplay_exe = "C:\ffplay.exe"

  Start-Process $ffplay_exe -ArgumentList @("-hide_banner -f dshow -i video=``"$video_source``" -preset ultrafast") -Wait -NoNewWindow

  Is there a way to do it using single command ? I think I have to use ffmpeg within named pipes but I don’t understand how to create/operate them. Maybe someone have already working Windows command which will 1) save webcamera video to file 2) also send it to named pipe for another applications like ffplay or VLC ?

  Thanks for your answers,

  —Vlad