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• FFMPEG : using filters for adding transparent watermark

  13 mai 2022, par Sar sinua

  how can i combine these two lines of code for adding transparent watermark (with Dynamic size)

  


  ffmpeg -i 1.gif -i logo.png -filter_complex "[1]format=rgba,colorchannelmixer=aa=0.5[logo];[0][logo]overlay=(W-w)/2:H-h-5" -c:a copy output.gif

ffmpeg -i 1.gif -i logo.png -filter_complex "[1][0]scale2ref=w=oh*mdar:h=ih*0.1[logo][video];[video][logo]overlay=(W-w)/2:H-h-5" -c:a copy output.gif


  


  i have tried the following code :

  


  ffmpeg -i 1.gif -i logo.png -filter_complex "[1][0]scale2ref=w=oh*mdar:h=ih*0.1[logo][video];[1]format=rgba,colorchannelmixer=aa=0.5[logo];[0][logo]overlay=(W-w)/2:H-h-5" -c:a copy output.gif


  


  i got the following Error :
Filter scale2ref has an unconnected output

  


• Ffmpeg it's not setting the correct variable names and hence throwing Unable to choose format

  9 novembre 2024, par Miguel Arrieche

  I'm trying to automate the subtitle addition to a folder with some videos so I wrote the following script :

  


  forfiles /p "C:\Users\titos\Resilio_Sync\4K_Video_Downloader\videoprocess" /m *.mp4 /C "cmd /c set filename=@fname & ffmpeg -i @file -vf subtitles="C:\Users\titos\Resilio_Sync\4K_Video_Downloader\videoprocess\@fname.srt" -f mp4 "C:\Users\titos\Resilio_Sync\4K_Video_Downloader\donesubs\@fname_srt.mp4""


  


  However, the script is throwing me the following error for each video :

  


  [AVFormatContext @ 0000020c20220680] Unable to choose an output format for 'Der'; use a standard extension for the filename or specify the format manually.
[out#0 @ 0000020c20220580] Error initializing the muxer for Der: Invalid argument
Error opening output file Der.
Error opening output files: Invalid argument


  


  In this case, "Der" is the second word of the video's title (And it does the same with each video where it throws the error with the second word). So I think it might be due to the videos containing spaces and ffmpeg not parsing it correctly ? But why is the second word that it gets and not the first one in that case ? And more importantly, what could I do to fix this issue ?

  


  I've honestly found some other threads that discuss similar issues, but quite frankly I'm still too newbie to understand any of the answers in order to adapt it to my script lol. I appreciate your help, thanks a lot in advance :)

  


• how the packuswb instruction works ? (in low level bit operation)

  17 avril 2019, par MaikonNascimento

  Studying ffmpeg convertion from yuv to rgb , I came across the equation being implemented in assembly, yuv2rgb_template.c located in ffmpeg/libswscale/x86.

  I want to know how the instruction packuswb works ? Google says it :

  Converts 4 signed word integers from mm and 4 signed word integers from mm/m64 into 8 unsigned byte integers in mm using unsigned saturation.

      DEST[7:0] ← SaturateSignedWordToUnsignedByte DEST[15:0];
  
      DEST[15:8] ← SaturateSignedWordToUnsignedByte DEST[31:16];
  
      DEST[23:16] ← SaturateSignedWordToUnsignedByte DEST[47:32];
  
      DEST[31:24] ← SaturateSignedWordToUnsignedByte DEST[63:48];
  
      DEST[39:32] ← SaturateSignedWordToUnsignedByte SRC[15:0];
  
      DEST[47:40] ← SaturateSignedWordToUnsignedByte SRC[31:16];
  
      DEST[55:48] ← SaturateSignedWordToUnsignedByte SRC[47:32];
  
      DEST[63:56] ← SaturateSignedWordToUnsignedByte SRC[63:48];

  Since I dont know Assembly x86, it is even hard to simulate it or debug the current code.

  I want to know how they fit 16 bits in 8 bits ?