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• Using ffmpeg to cut audio from/to position

  8 mars 2023, par Mike

  I need to cut parts from an audio file from position to position. When I tried this command

  



  ffmpeg -ss 132 -t 139 -i original.mp3 new.mp3


  



  it started at the second 132, and added the next 139 seconds to the new file.

  



  What I need is from second 132 to second 139.

  



  And when I tried

  



  ffmpeg -ss 132 -to 139 -i original.mp3 new.mp3


  



  it gives me an error :

  



  Unrecognized option 'to'
Failed to set value '139' for option 'to'


  



  (I don't want to tell how many seconds to take, just from/to).

  



  —
I have ffmpeg version 0.8.20-6:0.8.20-0+deb7u1 (built on Jan 19 2017 11:13:36 with gcc 4.7.2). And when I try to update it (apt-get install ffmpeg), it tells me "ffmpeg is already the newest version".

  


• Bicubic interpolation results different from FFMPEG

  18 novembre 2019, par Pedro Pereira

  I just implemented bicubic interpolation for resizing images.
  I have a test image 6x6 pixels (grayscale), its columns are black and white (x3).
  I am comparing the results of my code with the results from the tool ffmpeg and they are not correct. I can not understand why, I think I may be calculating the neighbourhood of pixels wrong or maybe the distance of the resized pixel to the original ones.
  Can someone look into my code (I will simplify it for better reading) and tell me where the error is ?

      // Iterate through each line
  
      for(int lin = 0; lin < dstHeight; lin++){
  
          // Original coordinates
  
          float linInOriginal = (lin - 0.5) / scaleHeightRatio;
  
  
  
          // Calculate original pixels coordinates to interpolate
  
          int linTopFurther = clamp(floor(linInOriginal) - 1, 0, srcHeight - 1);
  
          int linTop = clamp(floor(linInOriginal), 0, srcHeight - 1);
  
          int linBottom = clamp(ceil(linInOriginal), 0, srcHeight - 1);
  
          int linBottomFurther = clamp(ceil(linInOriginal) + 1, 0, srcHeight - 1);
  
  
  
          // Calculate distance to the top left pixel
  
          float linDist = linInOriginal - floor(linInOriginal);
  
  
  
          // Iterate through each column
  
          for(int col = 0; col < dstWidth; col++){
  
              // Original coordinates
  
              float colInOriginal = (col - 0.5) / scaleWidthRatio;
  
  
  
              // Calculate original pixels coordinates to interpolate
  
              int colLeftFurther = clamp(floor(colInOriginal) - 1, 0, srcWidth - 1);
  
              int colLeft = clamp(floor(colInOriginal), 0, srcWidth - 1);
  
              int colRight = clamp(ceil(colInOriginal), 0, srcWidth - 1);
  
              int colRightFurther = clamp(ceil(colInOriginal) + 1, 0, srcWidth - 1);
  
  
  
              // Calculate distance to the top left pixel
  
              float colDist = colInOriginal - floor(colInOriginal);
  
  
  
              // Gets the original pixels values
  
              // 1st row
  
              uint8_t p00 = srcSlice[0][linTopFurther * srcWidth + colLeftFurther];
  
              // ...
  
  
  
              // 2nd row
  
              uint8_t p01 = srcSlice[0][linTop * srcWidth + colLeftFurther];
  
              // ...
  
  
  
              // 3rd row
  
              // ...
  
  
  
              // 4th row
  
              // ...
  
  
  
              // Bilinear interpolation operation
  
              // Y
  
              float value = cubicInterpolate(
  
                  cubicInterpolate(static_cast<float>(p00), static_cast<float>(p10), static_cast<float>(p20), static_cast<float>(p30), colDist),
  
                  cubicInterpolate(static_cast<float>(p01), static_cast<float>(p11), static_cast<float>(p21), static_cast<float>(p31), colDist),
  
                  cubicInterpolate(static_cast<float>(p02), static_cast<float>(p12), static_cast<float>(p22), static_cast<float>(p32), colDist),
  
                  cubicInterpolate(static_cast<float>(p03), static_cast<float>(p13), static_cast<float>(p23), static_cast<float>(p33), colDist),
  
                  linDist);
  
  
  
              dstSlice[0][lin * dstWidth + col] = double2uint8_t(clamp(value, 0.0f, 255.0f));
  
          }
  
      }
  
  </float></float></float></float></float></float></float></float></float></float></float></float></float></float></float></float>

• how how can I add black bars to video 1920x800 to be 1920x1080 with ffmpeg

  21 septembre 2022, par Glomi babel

  I have video 1920x800 without black bars and I need add black bars to put subtitles there. Video should 1920x1080p. The problem is using movavi video has worse quality than original. a lot of worse quality. I put same features from mediainfo of original video.
I heard about ffmpeg can edit videos without re-encoding. Therefore I would like if you can help me with my problem
I only installed ffmpeg. need to know all
thanks