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• 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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• Convert video from FFMPEG than video is rotated [duplicate]

  25 octobre 2016, par user7050166

  This question already has an answer here :

  • video captured from iphone gets rotated when converted to .mp4 using ffmpeg
    
    8 answers
    

  I have created one Application API, in this Application API When i have upload video from file manager than video is rotated but when i have capture and direct upload than video is perfect work.

  i have use this command transpose=1 but capture video is rotated 90 degree when upload and if i have remove this command than file manager video is rotated.

  so please give me solutions.

  /usr/bin/ffmpeg -i video.mp4 -i watermark.png -filter_complex 'overlay=10:10' -s 640x1280 -b 512k -vcodec mpeg1video -acodec copy -vcodec h264 -acodec aac -strict -2 output_video.mp4

  file manager upload video is auto rotated on 270 degree, i have not use any rotated command but capture video is work perfect.

• 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 :

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  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    


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  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.

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  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.

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  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.

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  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.

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