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• Trying to use ffmpeg to create slideshow from ISO-8601 named pictures. Getting output with no playable streams

  19 juin 2019, par Robert Ellegate

  I’m trying to create a slideshow of images that are irregular in dimension/orientation but all named with the same ISO-8601 date format.

  I’ve normalized the filenames so they are all YYYYMMDD.jpg. I have tried using the globular pattern type for ffmpeg and various methods for inputting the files, including piping the concatenation of the files into ffmpeg.

  Here are the images I’m trying to use :

  $ ls *.jpg | xargs -n1 file
  
  20190411.jpg: JPEG image data, Exif standard: [TIFF image data, big-endian, direntries=4, height=0, orientation=upper-left, width=0], baseline, precision 8, 10128x3984, components 3
  
  20190417.jpg: JPEG image data, Exif standard: [TIFF image data, big-endian, direntries=4, height=0, orientation=lower-right, width=0], baseline, precision 8, 10176x3952, components 3
  
  20190424.jpg: JPEG image data, Exif standard: [TIFF image data, big-endian, direntries=4, height=0, orientation=upper-left, width=0], baseline, precision 8, 12128x3840, components 3
  
  20190429.jpg: JPEG image data, Exif standard: [TIFF image data, big-endian, direntries=4, height=0, orientation=upper-left, width=0], baseline, precision 8, 11104x3888, components 3
  
  20190430.jpg: JPEG image data, Exif standard: [TIFF image data, big-endian, direntries=4, height=0, orientation=lower-right, width=0], baseline, precision 8, 10992x3920, components 3
  
  20190501.jpg: JPEG image data, Exif standard: [TIFF image data, big-endian, direntries=4, height=0, orientation=lower-right, width=0], baseline, precision 8, 10528x3936, components 3
  
  20190502.jpg: JPEG image data, Exif standard: [TIFF image data, big-endian, direntries=4, height=0, orientation=lower-right, width=0], baseline, precision 8, 10992x3792, components 3
  
  20190508.jpg: JPEG image data, Exif standard: [TIFF image data, big-endian, direntries=4, height=0, orientation=lower-right, width=0], baseline, precision 8, 11008x3808, components 3
  
  20190515.jpg: JPEG image data, Exif standard: [TIFF image data, big-endian, direntries=4, height=0, orientation=lower-right, width=0], baseline, precision 8, 10416x3760, components 3
  
  20190516.jpg: JPEG image data, Exif standard: [TIFF image data, big-endian, direntries=4, height=0, orientation=lower-right, width=0], baseline, precision 8, 10928x3760, components 3
  
  20190517.jpg: JPEG image data, Exif standard: [TIFF image data, big-endian, direntries=4, height=0, orientation=lower-right, width=0], baseline, precision 8, 10720x3840, components 3
  
  20190522.jpg: JPEG image data, Exif standard: [TIFF image data, big-endian, direntries=4, height=0, orientation=[*0*], width=0], baseline, precision 8, 6552x1688, components 3
  
  20190523.jpg: JPEG image data, Exif standard: [TIFF image data, big-endian, direntries=4, height=0, orientation=[*0*], width=0], baseline, precision 8, 6572x1700, components 3
  
  20190524.jpg: JPEG image data, Exif standard: [TIFF image data, big-endian, direntries=4, height=0, orientation=[*0*], width=0], baseline, precision 8, 6468x1659, components 3
  
  20190528.jpg: JPEG image data, Exif standard: [TIFF image data, big-endian, direntries=4, height=0, orientation=[*0*], width=0], baseline, precision 8, 5424x1644, components 3
  
  20190529.jpg: JPEG image data, Exif standard: [TIFF image data, big-endian, direntries=7, model=Pixel 2 XL, height=0, manufacturer=Google, orientation=[*0*], datetime=2019:05:29 16:38:01, width=0]
  
  20190531.jpg: JPEG image data, Exif standard: [TIFF image data, big-endian, direntries=4, height=0, orientation=[*0*], width=0], baseline, precision 8, 6584x1693, components 3
  
  20190603.jpg: JPEG image data, Exif standard: [TIFF image data, big-endian, direntries=4, height=0, orientation=[*0*], width=0], baseline, precision 8, 6536x1690, components 3
  
  20190604.jpg: JPEG image data, Exif standard: [TIFF image data, big-endian, direntries=4, height=0, orientation=[*0*], width=0], baseline, precision 8, 5748x1618, components 3
  
  20190606.jpg: JPEG image data, Exif standard: [TIFF image data, big-endian, direntries=4, height=0, orientation=[*0*], width=0], baseline, precision 8, 6196x1690, components 3
  
  20190607.jpg: JPEG image data, Exif standard: [TIFF image data, big-endian, direntries=4, height=0, orientation=[*0*], width=0], baseline, precision 8, 6112x1674, components 3
  
  20190610.jpg: JPEG image data, Exif standard: [TIFF image data, big-endian, direntries=4, height=0, orientation=[*0*], width=0], baseline, precision 8, 6440x1670, components 3
  
  20190611.jpg: JPEG image data, Exif standard: [TIFF image data, big-endian, direntries=4, height=0, orientation=[*0*], width=0], baseline, precision 8, 6312x1694, components 3
  
  20190612.jpg: JPEG image data, Exif standard: [TIFF image data, big-endian, direntries=4, height=0, orientation=[*0*], width=0], baseline, precision 8, 6176x1689, components 3

  And these are the various ffmpeg commands I’ve tried using :

  cat *.jpg | ffmpeg -framerate 1/5 -c:v libx264 -r 30 -pix_fmt yuv420p out.mp4

  cat *.jpg | ffmpeg -f image2pipe -i - output.mkv

  ffmpeg -framerate 1/5 -pattern_type glob -i '*.jpg' out.mp4

  ffmpeg -framerate 1/5 -pattern_type glob -i '*.jpg' -c:v libx264 -vf fps=25 -pix_fmt yuv420p out.mp4

  I’m trying to create a video that shows each image for 5 seconds in order, but I’m getting a mp4 video file with no playable streams.

• opustab : macro constant as a double

  28 avril 2024, par Lynne

  opustab : macro constant as a double
  May increase intermediate precision on some compilers.
  

  • [DH] libavcodec/opustab.c

• waveforms arent as smooth as they should be

  25 mars 2019, par GROVER.

  So I’ve been trying to create a little clone of SoundClouds ’peaks’ waveform. I have noticed that their waveforms are a lot more streamlined
  compared to my sudden shifts in ’loudness’. The dynamic range between peaks never seems to be too steep, and they always represent the perceived loudness of each part of the track pretty well.

  ---

  Here’s an example :

  

  Notice how all the ’drops’ are fairly distinguishable to the ’breakdowns’ in their waveform, but mine is all over the place (apart from the last drop and breakdown, which are kind of similar). There are some minor similarities, but the ’jaggedness’ is still very prominent even in those areas.

  I’m using wav2json as a peaks converter (which is run through the command line and programmed in C++). This is is an example of how I use it :

  /*
  
  *    --channels: mids and min
  
  *    --db-min (minimum level in dB to capture): -35dB
  
  *    --db-max (pretty self explanatory): 6dB
  
  *    -d: use logarithmic instead of linear scale
  
  *    -s (number of peaks to generate): 1800
  
  *    -o (output file): outputfile.json
  
  *    -p (precision of floats): 0
  
  *    -n: no header 
  
  */
  
  exec("wav2json inputfile.wav -s 1800 --channels mid min -d --db-min -35 --db-max 6 -p 0 -o outputfile.json -n");
  
  
  
  $fp     = fopen($tmpOutput, "r");
  
  $json   = fread($fp, filesize($tmpOutput));
  
  // get mids and min from the generated peaks file
  
  $mid    = json_decode($json, true)["mid"];
  
  $min    = json_decode($json, true)["min"];
  
  fclose($fp);
  
  unlink($tmpOutput);
  
  
  
  /* 
  
  *  from here I just combine each mid and min value together and divide by two
  
  *
  
  *  then I normalise all the peaks (instead of each value being between -0.293 to 
  
  *  1.766(just as an example), it is between 0 and 100)
  
  */

  What I’m trying to figure out - and have been trying to for the last few months - is how to get each peak more streamlined and to have the dynamic range of each one look how it actually sounds.

  ---

  What I have tried :

  • ffmpeg eqing
  • actually eqing the highs and lows in a daw and then comparing waveforms
  • using various parameters for wav2json (db min and max, linear etc.)
  • using various compressors and multiband compressors on the track

  All help is appreciated,
  Cheers.