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• Extract part of a video using ffmpeg_extract_subclip - get a clip longer than expected

  4 juin 2020, par rightly0716

  I'm trying to extract a part of a video and find the solution on this page very helpful : 
Extract part of a video using ffmpeg_extract_subclip - black frames

  



  The function write_videofile helps get what I need exactly but a bit slow. The ffmpeg_extract_subclip function is indeed very fast, but somehow generates a weird clip that is slightly longer than what I need. For example, if I use the cmd below (no matter with or without -copyinkf),

  



  ffmpeg -y -ss 218.00 -i input.mp4 -t 7.00 -vcodec copy -acodec copy output.mp4


  



  My output.mp4 will be 9 second long, with the last two seconds frozen with no audio. Anyone saw a similar issue before ? Thanks a lot !

  


• Combining two FFMPEG filters into single command

  31 mai 2022, par shawn

  I would like to combine two filters and commands to a single ffmpeg command. What I want to achieve is overlay a static image on the video and draw a 90 degree rotated text as well.

  


  Can anyone help with this ?

  


  ffmpeg -y -i input.mp4 -i line.png -filter_complex "[0:v][1:v] overlay=105:625" -c:a copy output_video.mp4


  


  ffmpeg -y -i input.mp4 -i line.png -filter_complex "color=black:100x100[c];[c][0]scale2ref[ct][mv];[ct]setsar=1,split=2[t1][t2];


[t1]drawtext=fontfile=/Library/Fonts/GenerisSansW01Heavy.ttf:
text=$TITLE:line_spacing=10:fontsize=23:fontcolor=white,split[text1][alpha1];
[text1][alpha1]alphamerge,rotate=270*PI/180:ow=rotw(270*PI/180):oh=roth(270*PI/180):c=black@0[txta1]; 

[t2]drawtext=fontfile=/Library/Fonts/GenerisSansW01Heavy.ttf:
text=$CONTENTS:line_spacing=0.5:fontsize=18:fontcolor=white,split[text2][alpha2];
[text2][alpha2]alphamerge,rotate=270*PI/180:ow=rotw(270*PI/180):oh=roth(270*PI/180):c=black@0[txta2]; 


[mv][txta1]overlay=x='min(0,-H*sin(270*PI/180))+40':y='min(0,W*sin(270*PI/180))+751':shortest=1[mv1]; 
[mv1][txta2]overlay=x='min(0,-H*sin(270*PI/180))+138':y='min(0,W*sin(270*PI/180))+752':shortest=1" -c:a copy output_video.mp4


  


• dts to m4a (aac) ffmpeg to qaac output issue

  10 avril 2014, par user8979

  Looking to encode 2 dts 5.1 audio sources (Sonic Landscape and The Digital Experience) to m4a (aac) 5.1 with qaac 2.35. Input piped to qaac using :

  ffmpeg -report -loglevel verbose -i "input.file" -vn -f wav -codec:a pcm_f32le - | qaac --cvbr 160 --quality 2 --rate=keep --ignorelength --no-delay - -o "output.m4a"

  • Sonic Landscape duration : 18.848s, qaac output duration : 18.859s

    • output .m4a duration mismatch
    • mediainfo reports output is 2ch while mediatab and ffmpeg report output is 5.1ch (lfe)
      
      

  • The Digital Experience duration : 32.875s, qaac output duration : 32.875s

    • mediainfo reports output is 2ch while mediatab and ffmpeg report output is 5.1ch (lfe)
      
      

  1. what caused the duration mismatch in the first one ? how can it be fixed ?
  2. is the output 2ch or 5.1ch ?
     
     • if it is 2ch, what qaac option(s) leave the channels in output same as input ?
     • if the output is 5.1ch, does qaac then always preserve channels unless explicitly told otherwise ?