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• create bar type wave forms using ffmpeg

  8 juillet 2016, par Ashish Joshi

  i am trying to create wave forms from mp3 using ffmpeg.
  i have successfully created waveforms like below

  

  now i am having troubles with generating like below sample image...

  

  the code i am using to generate vertical line is provided below...

  while (!feof($handle) && $data_point < $data_size) {
  
              if ($data_point++ % DETAIL == 0) {
  
                  $bytes = array();
  
  
  
                  // get number of bytes depending on bitrate
  
                  for ($i = 0; $i < $byte; $i++) {
  
                      $bytes[$i] = fgetc($handle);
  
                  }
  
  
  
                  switch ($byte) {
  
                  // get value for 8-bit wav
  
                  case 1:
  
                      $data = findValues($bytes[0], $bytes[1]);
  
                      break;
  
                  // get value for 16-bit wav
  
                  case 2:
  
                      if (ord($bytes[1]) & 128) {
  
                          $temp = 0;
  
                      } else {
  
                          $temp = 128;
  
                      }
  
  
  
                      $temp = chr((ord($bytes[1]) & 100) + $temp);
  
                      $data = floor(findValues($bytes[0], $temp) / 256);
  
                      break;
  
                  }
  
  
  
                  // skip bytes for memory optimization
  
                  fseek($handle, $ratio, SEEK_CUR);
  
  
  
                  // draw this data point
  
                  // relative value based on height of image being generated
  
                  // data values can range between 0 and 255
  
                  $v = (int) ($data / 255 * $height);
  
  
  
                  // don't print flat values on the canvas if not necessary
  
                  if (!($v / $height == 0.5 && !$draw_flat))
  
                  // draw the line on the image using the $v value and centering it vertically on the canvas
  
                  {
  
                      imageline($img,
  
                          // x1
  
                          (int) ($data_point / DETAIL),
  
                          // y1: height of the image minus $v as a percentage of the height for the wave amplitude
  
                          $height * $wav - $v,
  
                          // x2
  
                          (int) ($data_point / DETAIL),
  
                          // y2: same as y1, but from the bottom of the image
  
                          $height * $wav - ($height - $v), imagecolorallocate($img, $r, $g, $b));
  
                  }
  
  
  
                  imageline($img1,
  
                      // x1
  
                      (int) ($data_point / DETAIL),
  
                      // y1: height of the image minus $v as a percentage of the height for the wave amplitude
  
                      $height * $wav - $v,
  
                      // x2
  
                      (int) ($data_point / DETAIL),
  
                      // y2: same as y1, but from the bottom of the image
  
                      $height * $wav - ($height - $v), imagecolorallocate($img1, $r1, $g1, $b1));
  
  
  
              }

  any help is appreciated...

• FFMPEG equalizer clipping audio despite low volume

  23 juillet 2023, par Tom

  I'm using ffmpeg to equalise audio transferred from historic gramophone records, using standard eqs of the era.

  


  The frequency and gain values are taken from the graphic eq settings listed on the Audacity website - https://plugins.audacityteam.org/additional-resources/eq-curves/playback-equalization-for-78-rpm-shellacs-and-early-33-lps

  


  An example of the Blumlien300 curve here - https://2850314611-files.gitbook.io/ /files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FklCVENFte0GRy5IqVz0W%2Fuploads%2FJHS6Mv121GX1h898xy4K%2FBlumlein300_3.2.2.txt?alt=media&token=8d04df05-366d-47f8-8c82-149fa5eda59a

  


  The audio file I'm testing with has a digital peak of -35db, the highest gain value applied on this eq is 17db. When I run the ffmpeg command though, it reports the audio is clipping and the result is a horribly distorted recording.

  


  Can anyone advise why this is happening ? I run the same file through the same eq settings in Audacity and the result is as expected.

  


  set eq="equalizer=f=22050:g=-0.4,equalizer=f=21203.720228928225:g=-0.4,equalizer=f=20389.920705063967:g=-0.4,equalizer=f=19607.354835383569:g=-0.4,equalizer=f=18854.823871147240:g=-0.4,equalizer=f=18131.175071633737:g=-0.4,equalizer=f=17435.299938351014:g=-0.4,equalizer=f=16766.132517017904:g=-0.4,equalizer=f=16122.647764715837:g=-0.4,equalizer=f=15503.859979709296:g=-0.4,equalizer=f=14908.821291529812:g=-0.4,equalizer=f=14336.620209010769:g=-0.4,equalizer=f=13786.380224048187:g=-0.4,equalizer=f=13257.258468950000:g=-0.4,equalizer=f=12748.444425315412:g=-0.4,equalizer=f=12259.158682468413:g=-0.4,equalizer=f=11788.651743541806:g=-0.4,equalizer=f=11336.202877384472:g=-0.4,equalizer=f=10901.119014532051:g=-0.4,equalizer=f=10482.733685550458:g=-0.4,equalizer=f=10080.406000125797:g=-0.4,equalizer=f=9693.519665336817:g=-0.4,equalizer=f=9321.482041606178:g=-0.4,equalizer=f=8963.723234884175:g=-0.4,equalizer=f=8619.695223674737:g=-0.4,equalizer=f=8288.871019565895:g=-0.4,equalizer=f=7970.743859979441:g=-0.4,equalizer=f=7664.826431902562:g=-0.4,equalizer=f=7370.650125412990:g=-0.4,equalizer=f=7087.764315853595:g=-0.4,equalizer=f=6815.735673557399:g=-0.4,equalizer=f=6554.147500065165:g=-0.4,equalizer=f=6302.599089819104:g=-0.4,equalizer=f=6060.705116354743:g=-0.4,equalizer=f=5828.095042050793:g=-0.4,equalizer=f=5604.412550532827:g=-0.4,equalizer=f=5389.315000861326:g=-0.4,equalizer=f=5182.472902668021:g=-0.394052055589,equalizer=f=4983.569411436476:g=-0.386751590389,equalizer=f=4792.299843153906:g=-0.376185664074,equalizer=f=4608.371207590573:g=-0.362543760251,equalizer=f=4431.501759492006:g=-0.345993198097,equalizer=f=4261.420566996452:g=-0.330710126890,equalizer=f=4097.867096616487:g=-0.318503033191,equalizer=f=3940.590814149046:g=-0.309564283335,equalizer=f=3789.350800902538:g=-0.303741189604,equalizer=f=3643.915384653179:g=-0.300601888512,equalizer=f=3504.061784765236:g=-0.3,equalizer=f=3369.575770931567:g=-0.3,equalizer=f=3240.251335011708:g=-0.3,equalizer=f=3115.890375464830:g=-0.3,equalizer=f=2996.302393894170:g=-0.3,equalizer=f=2881.304203238093:g=-0.3,equalizer=f=2770.719647160795:g=-0.3,equalizer=f=2664.379330212802:g=-0.3,equalizer=f=2562.120358347913:g=-0.3,equalizer=f=2463.786089399117:g=-0.3,equalizer=f=2369.225893131248:g=-0.3,equalizer=f=2278.294920502843:g=-0.3,equalizer=f=2190.853881783698:g=-0.3,equalizer=f=2106.768833188346:g=-0.296437432785,equalizer=f=2025.910971698469:g=-0.290217913930,equalizer=f=1948.156437760116:g=-0.280922418484,equalizer=f=1873.386125553329:g=-0.268550946447,equalizer=f=1801.485500543704:g=-0.253103497820,equalizer=f=1732.344424036255:g=-0.235614749092,equalizer=f=1665.856984462975:g=-0.218076286078,equalizer=f=1601.921335145533:g=-0.200537822606,equalizer=f=1540.439538284674:g=-0.184632657170,equalizer=f=1481.317414937308:g=-0.168779161348,equalizer=f=1424.464400751469:g=-0.152925665153,equalizer=f=1369.793407238189:g=-0.137072168707,equalizer=f=1317.220688367753:g=-0.121218672255,equalizer=f=1266.665712285991:g=-0.105365175802,equalizer=f=1218.051037954117:g=-0.088396941462,equalizer=f=1171.302196523118:g=-0.070858476440,equalizer=f=1126.347577261013:g=-0.053320011417,equalizer=f=1083.118317858216:g=-0.034770724190,equalizer=f=1041.548198942992:g=-0.013200571808,equalizer=f=1001.573542645411:g=0.011445558081,equalizer=f=963.133115054414:g=0.039167665478,equalizer=f=926.168032418592:g=0.069965750383,equalizer=f=890.621670946974:g=0.103839812794,equalizer=f=856.439580071665:g=0.140789852714,equalizer=f=823.569399039473:g=0.180815870141,equalizer=f=791.960776704742:g=0.223158863450,equalizer=f=761.565294400547:g=0.266149082252,equalizer=f=732.336391770094:g=0.311823093692,equalizer=f=704.229295444710:g=0.360237839089,equalizer=f=677.200950459179:g=0.413174176689,equalizer=f=651.209954299352:g=0.471478099167,equalizer=f=626.216493481026:g=0.535493496953,equalizer=f=602.182282562909:g=0.606978871276,equalizer=f=579.070505500287:g=0.684199304160,equalizer=f=556.845759249530:g=0.767096732395,equalizer=f=535.473999537060:g=0.853776460170,equalizer=f=514.922488709709:g=0.943323717867,equalizer=f=495.159745586582:g=1.036571598687,equalizer=f=476.155497235608:g=1.135335711982,equalizer=f=457.880632600910:g=1.237175803242,equalizer=f=440.307157909949:g=1.342335109599,equalizer=f=423.408153792158:g=1.453088412615,equalizer=f=407.157734043353:g=1.569993670188,equalizer=f=391.531005972773:g=1.688508164136,equalizer=f=376.504032271996:g=1.808802987893,equalizer=f=362.053794347337:g=1.934465396527,equalizer=f=348.158157059540:g=2.065823830001,equalizer=f=334.795834816768:g=2.204891058267,equalizer=f=321.946358968944:g=2.352009664049,equalizer=f=309.590046453497:g=2.509552803849,equalizer=f=297.707969644483:g=2.678532979186,equalizer=f=286.281927358906:g=2.856115742576,equalizer=f=275.294416975809:g=3.041612670003,equalizer=f=264.728607625441:g=3.230723044219,equalizer=f=254.568314407418:g=3.422700948357,equalizer=f=244.797973598401:g=3.621312762050,equalizer=f=235.402618811295:g=3.826195809769,equalizer=f=226.367858069467:g=4.034154835453,equalizer=f=217.679851760848:g=4.246639157749,equalizer=f=209.325291438168:g=4.468048945659,equalizer=f=201.291379432825:g=4.698686666092,equalizer=f=193.565809251186:g=4.938552319047,equalizer=f=186.136746723276:g=5.187645904525,equalizer=f=178.992811874976:g=5.445967422525,equalizer=f=172.123061495972:g=5.712025685327,equalizer=f=165.516972376744:g=5.984236264250,equalizer=f=159.164425188922:g=6.258981796419,equalizer=f=153.055688984312:g=6.515823590632,equalizer=f=147.181406288853:g=6.777692051390,equalizer=f=141.532578768664:g=7.044587178695,equalizer=f=136.100553446236:g=7.314095599483,equalizer=f=130.877009445637:g=7.583605034445,equalizer=f=125.853945246444:g=7.853114469407,equalizer=f=121.023666426868:g=8.146285201135,equalizer=f=116.378773877299:g=8.444439101287,equalizer=f=111.912152466211:g=8.742593001439,equalizer=f=107.616960141075:g=9.042209423688,equalizer=f=103.486617447577:g=9.344900874707,equalizer=f=99.514797451091:g=9.650668303691,equalizer=f=95.695416044961:g=9.959511710641,equalizer=f=92.022622630759:g=10.271431095557,equalizer=f=88.490791156230:g=10.586541422511,equalizer=f=85.094511497198:g=10.906991735356,equalizer=f=81.828581170245:g=11.233594002758,equalizer=f=78.687997363448:g=11.556996378650,equalizer=f=75.667949272979:g=11.873211536187,equalizer=f=72.763810733831:g=12.194794278600,equalizer=f=69.971133133372:g=12.521192148224,equalizer=f=67.285638596875:g=12.846501740168,equalizer=f=64.703213434600:g=13.169127539473,equalizer=f=62.219901840358:g=13.492484068742,equalizer=f=59.831899831942:g=13.820346094285,equalizer=f=57.535549424116:g=14.145340590334,equalizer=f=55.327333025244:g=14.467659297988,equalizer=f=53.203868048980:g=14.789401139821,equalizer=f=51.161901732761:g=15.111142981226,equalizer=f=49.198306155165:g=15.437629968456,equalizer=f=47.310073444503:g=15.770860796927,equalizer=f=45.494311171305:g=16.104091624940,equalizer=f=43.748237917649:g=16.412536097232,equalizer=f=42.069179016527:g=16.579143834849,equalizer=f=40.454562454745:g=16.588876722789,equalizer=f=38.901914933067:g=16.461103901687,equalizer=f=37.408858077565:g=16.215674576171,equalizer=f=35.973104796389:g=15.850016386783,equalizer=f=34.592455776352:g=15.350234288456,equalizer=f=33.264796113983:g=14.615823142814,equalizer=f=31.988092075884:g=13.626809695512,equalizer=f=30.760387983412:g=12.332756508563,equalizer=f=29.579803216941:g=10.518513413063,equalizer=f=28.444529335092:g=8.346792732977,equalizer=f=27.352827304528:g=5.833681758551,equalizer=f=26.303024836072:g=3.097942665008,equalizer=f=25.293513823067:g=0.163604913582,equalizer=f=24.322747878043:g=-2.887748621210,equalizer=f=23.389239963935:g=-6.091081601564,equalizer=f=22.491560116216:g=-9.478973229620,equalizer=f=21.628333252442:g=-12.539218030638,equalizer=f=20.798237065887:g=-14.384804507659,equalizer=f=20:g=-15"
ffmpeg -i "File.wav" -af %eq% -c:a pcm_s24le out.wav


  


• Timeline editing with ffmpeg-python

  25 mai 2023, par Synthels

  I'm trying to draw a box on one part of the screen at a specific instance in time. I've tried looking through the documentation for ffmpeg-python, but am unable to locate any instance of support for the enable option.

  


  I tried using

  


  (
ffmpeg
  .input(video)
  .drawbox(x, y, w, h, enable=f"between(t,{timestamp},{total_time})")
  .output("out.mp4")
  .run()
)


  


  hoping that it would be passed to ffmpeg as a kwarg, but this has no effect on the video and the box never gets drawn.