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• How use FFMPEG to merege multiple audios and videos with delay and offset for any streams

  9 juillet 2020, par Morak

  I want to use FFMPEG to merge multiple audios and videos.

  


  Materials are :

  


  

  1. three short audio clips (S1.mp4, S2.mp4, S3.mp4) without video(files
only have audio stream),

  


  2. three video clips (V1.mp4, V2.mp4, V3.mp4) without sound(files only have video stream).

  


  


  I have start-time of all materials(i.e :

  


  start-time of "S1.mp4" is 0 sec...
start-time of "S2.mp4" is 1220.5 sec...
start-time of "S3.mp4" is 2500.12 sec...


  


  and

  


  start-time of "V1.mp4" is 15.22 sec...
start-time of "V2.mp4" is 853.99 sec...
start-time of "V3.mp4" is 2901.37 sec...)


  


  My goal is :

  


  Merge all videos and audios to single file with entering in their start time.

  


  The requirement is depicted like below(D=delay).

  


  D <—V1.mp4—> D <----------V2.mp4-------------> D <-V3.mp4->blank

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  <------------S1.mp4-----> D <-------S2.mp4—> D <-------S3.mp4------->

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  The command I use is as below, but it does not work as expected.

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  1st:prepare V.mp4(merging all videos) :

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  ffmpeg -itsoffset {OFFSET.V1} -i V1.mp4  -itsoffset {OFFSET.V2} -i V2.mp4  -itsoffset {OFFSET.V3} -i V3.mp4 -map 0:v -map 1:v -map 2:v -c:v copy V.mp4

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  2nd:prepare S.mp4(merging all audios) :

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  ffmpeg -i S1.mp4 -i S2.mp4 -i S3.mp4 -filter_complex "[0]adelay=0[aud1];[1]adelay=1220.5[aud2];[2]adelay=2500.12[aud3];[aud1][aud2][aud3]amix=3[a]" -map "[a]" -c:a copy S.mp4

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  final:merging V.mp4 with S.mp4 :

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  ffmpeg -i V.mp4 -i S.mp4 -map 0:v -map 1:a -vcodec copy -acodec copy final.mp4

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  Any hint is appreciated !

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• How to get iOS App Preview video bitrate in range

  29 avril 2019, par JKaz

  Creating new App Previews for App Store Connect has always been difficult. Time to do it again (new app version) and running into same issue without resolution this time.

  Making the video is easy enough, recording it with Quicktime and either a connected device or through Simulator (and the xcrun simctl io booted recordVideo <filename>.<file extension="extension"></file></filename> Terminal command).

  I can open that in iMovie, create a new App Preview, and export/share the preview with proper size, length, frame rate per Apple specs. But the bit rate is always too low ( 4 mbps) and it’s required to be 10-12 mbps (and I’ve had video reject be/c of that). In the past I could always make some change to the .mp4, in conjunction with something like ffmpeg -i ~/appVideo.mp4 -b:v 11M ~/appPreview.mp4 to get the file into the target range, but that’s not helping today, and neither is Developer Tech Support.

  Apple’s documentation says :

  To export the final video, click Share in the toolbar, then choose App
  Preview. The export settings are automatically configured to meet App
  Store requirements. iMovie exports the final video at the correct
  resolution based on the device from which your clips were captured.

  I’ve done that and more, and bit rate is still out of range (every other attribute is in spec). I’ve tried the recommendations from a bunch of other threads here for http://video.online-convert.com/convert-to-mp4 and others, and none seem to do the trick. Am I missing something obvious re bitrate ? Is it this hard for everyone ?

  Thank you.

• 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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