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• How to create a circular video and overlay it on an image background while preserving transparency for MP4 output ?

  12 mars, par Mykyta Manuilenko

  I have the following FFmpeg command that overlays a transparent webm video on a background image and preserves the transparency :

  


  ffmpeg -t 5 -framerate 25 -loop 1 -i "bg_image.png" -c:v libvpx-vp9 -i "transparent_video.webm" -y -filter_complex "[0:v]format=yuv420p,pad=ceil(iw/2)*2:ceil(ih/2)*2[bg_image];[1:v]setpts=PTS-STARTPTS,setsar=1,pad=ceil(iw/2)*2:ceil(ih/2)*2[el_out_1];[bg_image][el_out_1]overlay=82:250,format=yuv420p,pad=ceil(iw/2)*2:ceil(ih/2)*2[raw_video];[raw_video]format=yuv420p,pad=ceil(iw/2)*2:ceil(ih/2)*2" -vcodec libx264 -f mp4 -t 5 -an -crf 23 -preset medium -copyts "output.mp4"


  


  It works fine - the transparency is preserved. But now I want to make it a circle but keep the transparency, so I tweaked the FFmpeg command a bit :

  


  ffmpeg -t 5 -framerate 25 -loop 1 -i "bg_image.png" -c:v libvpx-vp9 -i "transparent_video.webm" -y -filter_complex "[0:v]format=yuv420p,pad=ceil(iw/2)*2:ceil(ih/2)*2[bg_image];[1:v]setpts=PTS-STARTPTS,crop=ceil(365.091854095459/2)*2:ceil(365.091854095459/2)*2:180.34759712219238:0,format=rgba,geq=lum='p(X,Y)':a='if(lt(sqrt(pow(X-182.5459270477295,2)+pow(Y-182.5459270477295,2)),182.5459270477295-0.5),255,if(gt(sqrt(pow(X-182.5459270477295,2)+pow(Y-182.5459270477295,2)),182.5459270477295+0.5),0,255*(182.5459270477295+0.5 - sqrt(pow(X-182.5459270477295,2)+pow(Y-182.5459270477295,2)))))',scale=ceil(549.2381964584453/2)*2:ceil(549.2381964584451/2)*2,setsar=1,pad=ceil(iw/2)*2:ceil(ih/2)*2[el_out_1];[bg_image][el_out_1]overlay=84:252,format=yuv420p,pad=ceil(iw/2)*2:ceil(ih/2)*2[raw_video];[raw_video]format=yuv420p,pad=ceil(iw/2)*2:ceil(ih/2)*2" -vcodec libx264 -f mp4 -t 5 -an -crf 23 -preset medium -copyts "output.mp4"


  


  Input a transparent webm video became a circle, but the transparency is lost, instead of transparency I see a black background inside the circle.

  


  Is there any way to create a circular video and overlay it on an image background while preserving transparency ?

  


  Note that I can't output it to webm or mov with ProRes 4444 which natively support alpha channel, the output should only be mp4.

  


• How to add a comment into a mp3, in a specific language, using ffmpeg [duplicate]

  20 août 2021, par Valery Letroye

  I am fighting with ffmpeg to add a comment in french into a mp3. I want that comment to be displayed within the tab "Details" of the "Properties" window that I can open from Windows Explorer (which is using French as "Display Language").

  


  Ie. : I want this view :

  


  

  


  Unfortunately, I can't find how to do it.

  


  In the illustration above, I did edit the comment directly from the "Details" tag of the "Properties" window. If I look at the Exif info of the file with "exiftool test.mp3", I see

  


  Comment (fra)                   : Test Comment FR


  


  Next, if I open the file test.mp3 with mp3tag (where fra is defined as my language via the Options > Advanced), I see correctly the comment :

  


  

  


  Then, if I replace that comment into "Test Comment FR - Edit", within mp3tag, and save it, here is what I get with exiftool :

  


  Comment (fra)                   : Test Comment FR - Edit
Comment                         : Test Comment FR - Edit


  


  mp3tag has updated the Exif info "Comment (fra)" and added the ID3 tag "Comment".

  


  Now, if I try to add the comment with ffmpeg with the following commands (to clean first all metadata of my previous tests) :

  


  ffmpeg -i test.mp3 -map 0 -map_metadata -1 -c copy test-blank.mp3
ffmpeg -y -i test-blank.mp3 -metadata comment="Test Comment FR - ffmpeg" -c copy test.mp3


  


  Here are the Exif info I get :

  


  User Defined Text               : (comment) Test Comment FR - ffmpeg


  


  This info is not displayed in the "Details" tab of the "Properties" window.
Notice that it is however properly displayed by mp3tag.

  


  I did try to specify the language to ffmpeg with -metadata language="fra", or to use the metadata "Comment" or "Comment (fra)" instead of "comment", but nothing helped.

  


  I am totally lost as not an expert in ID3 and ffmpeg... And I didn't find any trick on Google.
NB. : I am using ffmpeg and exiftool in a Shell console on my Synology, to convert mp4 to mp3 (
ffmpeg version 2.7.7 built with gcc 4.9.3).

  


  Is there anyone experienced with ffmpeg who could guide me ?
PS. : I am even not sure that the comment added by ffmpeg would be displayed by a "English" version of Windows...

  


  A big thx in advance !

  


  V.

  


• Why does the video lose few seconds after FFMPEG xfade ?

  25 août 2023, par promaxdev

  I am having a use case where I need to add a few xfade transitions to an existing video at uniform intervals. I followed an approach almost similar to the one explained in the official document here and the SO reply here

  


  Here is the command that I use.

  


  ffmpeg 
-i clean_0.mp4 
-filter_complex "[0] split = 8[i1][i2][i3][i4][i5][i6][i7][i8]; 
    [i1]select='between(t\,0.0\,3.75)',setpts='PTS-STARTPTS'[i11]; 
    [i2]select='between(t\,3.75\,7.5)',setpts='PTS-STARTPTS'[i22]; 
    [i3]select='between(t\,7.5\,11.25)',setpts='PTS-STARTPTS'[i33]; 
    [i4]select='between(t\,11.25\,15.0)',setpts='PTS-STARTPTS'[i44]; 
    [i5]select='between(t\,15.0\,18.75)',setpts='PTS-STARTPTS'[i55]; 
    [i6]select='between(t\,18.75\,22.5)',setpts='PTS-STARTPTS'[i66]; 
    [i7]select='between(t\,22.5\,26.25)',setpts='PTS-STARTPTS'[i77]; 
    [i8]select='between(t\,26.25\,30.0)',setpts='PTS-STARTPTS'[i88]; 
    [i11][i22]xfade=duration=1:offset=2.75:transition=dissolve [c1]; 
    [i33][i44]xfade=duration=1:offset=2.75:transition=distance [c2]; 
    [i55][i66]xfade=duration=1:offset=2.75:transition=fadegrays [c3]; 
    [i77][i88]xfade=duration=1:offset=2.75:transition=pixelize [c4]; 
    [c1][c2][c3][c4]concat=n=4:v=1:a=0 " 
-pix_fmt yuv420p -y clean_out.mp4 


  


  (The above code is executed in a single line broken down for ease of understanding.)

  


  What this does is splits the input video in to parts of equal length in duration and and inserts xfade effects in between and the concats them. So the net effect would be the original video with xfade effects added.

  


  The input video is 30 seconds in length and has 25 fps. But the output video is 26 seconds.

  


  Here are my analysis so far.

  


  

  • the no. of seconds reduced with each added transition. i.e. when 5 transitions are provided, the output video reduces to 25 seconds

  


  • ffprobe at different stages below

    

    • i1, i2,... being copies of input video had 750 frames @ 25fps ie 30 seconds

    


    • i11, i22,... -> had 94 frames @ 25fps resulting in 3.76 seconds (3.76 X 8 = 30.08s)

    


    • c1, c2,.. -> had 163 frames @ 25fps resulting in 6.52 seconds (6.52 X 4 = 26.08s)

    


    


  


  • Enabling trace on ffmpeg showed different filters like 'Parsed_select_', 'Parsed_setpts_' and 'Parsed_xfade_', 'Parsed_concat_' corresponding to the 'select', 'setpts', 'xfade' and concat filters and there was another 'auto_scale_' auto inserted by ffmpeg. But details were found only for Parsed_select_ and Parsed_setpts_* filters in rest of the logs. There was no other trace of Parsed_xfade_* filters. So not much info from there

  


  


  End result is concat of all c* videos resulting in reduced duration

  


  So we can infer that xfade is causing some frames to be lost. (or I am doing it wrong) I need help to find the reason for the reduction in the duration of the final video and fix it.Also, Is there a way to log Xfade trace ?