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• How to write the *args of function "avfilter_graph_send_command"(ffmpeg) when there has multiple drawtext targets ?

  19 août 2020, par cube_sun

  I add 2 drawtext on ffmpeg drawtext filter, my filters descr is like this
"drawtext=fontfile=simhei.ttf:fontcolor=#ff00ff@%1.0:fontsize=20:box=1.0:boxcolor=#00ff00@%1.0:x=0:y=0:text='123',drawtext=fontfile=simhei.ttf:fontcolor=#ff00ff@%1.0:fontsize=20:box=1.0:boxcolor=#00ff00@%1.0:x=0:y=200:text='456'", so there have two characters watermark on video.
And this filter supports altering parameters via commands : reinit, so I use function : avfilter_graph_send_command(m_filter_graph, "drawtext", "reinit", m_filters_args, NULL, 0, 0) to modify the watermarks on realtime.(m_filters_args is my *arg variate)
I try snprintf the m_filters_args as
"fontfile=simhei.ttf:fontcolor=#ff00ff@%1.0:fontsize=20:box=1.0:boxcolor=#00ff00@%1.0:x=0:y=10:text='112233',fontfile=simhei.ttf:fontcolor=#ff00ff@%1.0:fontsize=20:box=1.0:boxcolor=#00ff00@%1.0:x=0:y=200:text='445566'", but it doesn't work as I wanted, it can only modify one drawtext, I want they can be both modified, I tried some other ways, but all failed.
can u tell me how to write the *arg or there has other ways to solve the problem.

  


  Any help would be very appreciated !

  


• FFmpeg downmuxing multiple tracks with custom "af"s

  26 août 2020, par CasualDemon

  I am trying to do a custom downmix conversion, that is the rough equivalent of :

  


  ffmpeg -y -i "file.mkv" \
 -map 0:1 -c:0 flac -ac:0 4 \
 -map 0:3 -c:1 flac -ac:1 3 \
 -map 0:3 -c:2 flac -ac:2 3 \
 audio.mkv


  


  I tried using the command :

  


  ffmpeg -y -i "file.mkv" \
 -map 0:1 -c:0 flac -af:0 "pan=3.1| FL < FL + 0.6*BL + 0.6*SL | FR < FR + 0.6*BR + 0.6*SR | FC = FC | LFE = LFE" \
 -map 0:3 -c:1 flac -af:1 "pan=2.1| FL < FL + 0.6*BL + 0.6*SL + 0.5*FC | FR < FR + 0.6*BR + 0.6*SR + 0.5*FC | LFE = LFE" \
 -map 0:3 -c:2 flac -af:2 "pan=2.1| FL < FL + 0.6*BL + 0.6*SL + 0.5*FC + 0.5*LFE | FR < FR + 0.6*BR + 0.6*SR + 0.5*FC  + 0.5*LFE" \
 audio.mkv


  


  But it gave an error that only 1 "af" is supported, unlike "ac" :

  


  Only '-af pan=2.1| FL < FL + 0.6*BL + 0.6*SL + 0.5*FC + 0.5*LFE | FR < FR + 0.6*BR + 0.6*SR + 0.5*FC  + 0.5*LFE | LFE = FC' read, ignoring remaining -af options: Use ',' to separate filters


  


  So I tried doing as it said, and separated them with a comma :

  


  ffmpeg -y -i "file.mkv" \
 -map 0:1 -c:0 flac \
 -map 0:3 -c:1 flac \
 -map 0:3 -c:2 flac \
 -af "pan=3.1| FL < FL + 0.6*BL + 0.6*SL | FR < FR + 0.6*BR + 0.6*SR | FC = FC | LFE = LFE,pan=2.1| FL < FL + 0.6*BL + 0.6*SL + 0.5*FC | FR < FR + 0.6*BR + 0.6*SR + 0.5*FC | LFE = LFE,pan=2.1| FL < FL + 0.6*BL + 0.6*SL + 0.5*FC + 0.5*LFE | FR < FR + 0.6*BR + 0.6*SR + 0.5*FC  + 0.5*LFE | LFE = LFE" \
 audio.mkv


  


  Which started the encoding, but I noticed that it was only applying the last pan, and all three tracks were being downmixed to the last 2.1 !

  


  According to the documentation, https://ffmpeg.org/ffmpeg-filters.html#Filtergraph-syntax-1 adding a "," is creating a "filterchain" which I don't think I want, as I am doing the same filter on three different tracks. So I am at a loss of what I am supposed to do from there.

  


  Thanks for any help !

  


• FFmpeg - resize by max width/height, keep aspect ratio and avoid "width/height not divisible by 2" error

  29 août 2020, par Eduard Unruh

  This is the code I'm using to resize the video to either max width 640 or max height 700 and keeping the aspect ratio :

  


  ffmpeg/bin/ffmpeg.exe" -y -i ttt.mp4 -profile:v high -c:v libx264 -filter_complex "scale=iw*min(1\,min(640/iw\,700/ih)):-1" -acodec copy -maxrate 600k -bufsize 300k -crf 18 ttt2.mp4


  


  On some video I either get width not divisible by 2 or height not divisible by 2

  


  I looked up that the solution would be :

  


  -vf "crop=trunc(iw/2)*2:trunc(ih/2)*2"


  


  So I tried :

  


  ffmpeg/bin/ffmpeg.exe" -y -i ttt.mp4 -profile:v high -c:v libx264 -filter_complex "scale=iw*min(1\,min(640/iw\,700/ih)):-1" -vf "crop=trunc(iw/2)*2:trunc(ih/2)*2" -acodec copy -maxrate 600k -bufsize 300k -crf 18 ttt2.mp4


  


  and get the error :

  


  -vf/-af/-filter and -filter_complex cannot be used together for the same stream


  


  so how to do this ??