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• ffmpeg merge silent video with another video+audio

  4 mars 2016, par Mark Dagger

  I want to create, in a single command, a video from 3 sources :

  1. a silent background video ;
  2. a smaller video to be overlayed (same length of 1), KEEPING its AUDIO ;
  3. a PNG logo to be overlayed

  I can create the video but cannot get the audio track. I don’t understand if -vf is supposed to work in this case. This is what I’ve tried to do :

  ffmpeg.exe -y -i MASTER_SILENT_VIDEO.mp4 -vf "movie=SMALLER_VIDEO_WITH_AUDIO.flv, scale=320:-1[inner];movie=MY_LOGO.png[inner2]; [in][inner] overlay=800:480,amerge [step1]; [step1][inner2] overlay=30:30 [out]" completed.mp4

  The "amerge" filter should do the audio merging job, but of course it doesn’t work. I’ve found similar questions involving -map or filtergraph but they refer to mixing a video source and an audio source ; I tried several filtergraph examples without success. Any idea ?

• FFMPEG video editing application. Need time and date stamp burned into video

  11 mai 2022, par Jacob

  I am developing an application for video editing. The main component of this application is to produce a single video file from several video files captured from a camcorder with the time and date stamp displayed on the final rendered video, much like the final product from a security camera. I have figured out, by using FFMPEG, how to burn the date and time into the video with a .SRT file as well as with DrawText like the following :

  


  ffmpeg -y -i video.mp4 -vf “drawtext=fontfile=roboto.ttf:fontsize=12:fontcolor=yellow:text='%{pts\:localtime\:1575526882\:%A, %d, %B %Y %I\\\:%M\\\:%S %p}'" -preset ultrafast -f mp4 output_new.mp4    


  


  I would rather use the DrawText method so the user does not have to wait longer while creating the .SRT files. I am new to FFMPEG and I find their documentation very confusing. I guess I am hoping there is someone out there who has experience with it.

  


  Everything seems to work when I pass in the date created meta data from the video file and drawtext just does its thing. The problem is my application allows for editing of the video. I do this, for lack of better solution, by allowing the user to select beginning and ending frames they do not want, from the UI and then the code simply deletes the frames from the directory where they were split and saved. I then use FFMPEG to iterate through the directory and combine the remaining frames to make a video file.

  


  This approach starts the time and date from the date created metadata ; however, cutting the frames out of the video will make the DT stamp inaccurate, due to the missing frames.

  


  Is there any way to tell FFMPEG to burn in the date and time from date/time retrieved from each individual frame ? I appreciate any advice that you may have.

  


• syncing video thumbnail frames with source video

  12 octobre 2020, par bigless

  We are trying to make video preview for seek bar. One approach is to make tons of images like Youtube does. We chose second one - 160x90(*) preview video without sound with fps limited to max 4 (250ms, based on duration) - one file with native seek sounds good to me.

  


  This is current cmd we use :

  


  ffmpeg -y -i $source$ -vf scale=$width$:$height$ -an -sn -r $fps$ -vcodec libx264 -x264-params keyint=$keyframe_interval$:scenecut=0  


  


  The idea is that browser is able to fetch whole video preview (<10MB) so there is priority to minimize the size. It seems that html5 video player is able to seek to and decode other than keyframes so we set keyframe interval to duration of video with limit of max 384(1920/5px) for best compression ratio.

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  The issue we are facing is frame sync. When I hover seek bar, video preview shows frame that actually lacks 1-2sec behind hovered time. Does anyone got explanation and possibly fix for this ? Is there some time deviation when player decodes frame instead of showing keyframe ?

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