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• Complex audio volume changes with ffmpeg

  29 juin 2016, par coco

  Using ffmpeg, how much control can we have over the audio levels ? For example, I would like to map an "M" shape over the program’s timeline :

  t0 - t1 : fade in from 0 to 1
  
  t1 - t2 : play at full volume
  
  t2 - t3 : fade out to 25%
  
  t3 - t4 : play at 25% volume
  
  t4 - t5 : fade in (from 25%) to full volume
  
  t5 - t6 : play at full volume
  
  t6 - t7 : fade out from 1 to 0

  Can this be done ? The combinations I’ve tried (of afade and volume, and using timeline editing) have not been successful so far.

  Here is something that is close :

  ina="infile.caf"
  
  out="outfile.mp3"
  
  
  
  time ffmpeg -i $ina -af \
  
  "afade=enable='between(t,0,3)':t=in:ss=0:d=3, \
  
  afade=enable='between(t,7,8)':t=out:st=7:d=1, \
  
  volume=enable='between(t,8,12)':volume=.25:eval=frame, \
  
  afade=enable='between(t,12,13)':t=in:st=12:d=1, \
  
  afade=enable='between(t,15,18)':t=out:st=15:d=3" \
  
  $out

  .. but at the two middle points (the point where it fades out to 25%, and the point where it fades back in to full volume) there are glitches - audible sound clicks.

• Logic and lawyers

  22 mai 2013, par Mans — Law and liberty

  Reading about various patent litigation cases, I am struck by the frequency with which common logical fallacies such as the Appeal to Consequences are committed. We shall look at a couple of recent examples.

  In conjunction with the Federal Circuit ruling in CLS Bank v. Alice Corp., Judge Moore, joined by three others, filed a dissenting opinion wherein we find the following :

  I am concerned that the current interpretation of § 101, and in particular the abstract idea exception, is causing a free fall in the patent system. [...] And let’s be clear : if all of these claims, including the system claims, are not patent-eligible, this case is the death of hundreds of thousands of patents [...].

  A footnote adds :

  If the reasoning of Judge Lourie’s opinion were adopted, it would decimate the electronics and software industries. [...] There has never been a case which could do more damage to the patent system than this one.

  From the above, I get the impression Moore is primarily concerned with protecting the system, maintaining the status quo, less with ruling in line with the logical consequences of statute and case law. Furthermore, her argument rests on the premise that a weaker patent system would “decimate the industries,” a notion supported by little evidence, yet presented by Moore as an obvious truth. In fact, research exists suggesting that many important innovations are never actually patented. Let us also not overlook the fact that European companies do not appear to be suffering from the much weaker patent protection for software afforded there.

  Judge Moore’s reasoning can be summarised in three steps :

  1. Ruling this way could be disruptive to the patent system.
  2. The industry relies on patents.
  3. Therefore we must not rule this way.

  Not only does she commit the aforementioned logical fallacy, she does so by way of invalid arguments.

  The second example of such fallacious reasoning comes from the Supreme Court ruling in Bowman v. Monsanto :

  We have always drawn the boundaries of the exhaustion doctrine to exclude that activity [copying], so that the patentee retains an undiminished right to prohibit others from making the thing his patent protects. [...] That is because, once again, if simple copying were a protected use, a patent would plummet in value after the first sale of the first item containing the invention. The undiluted patent monopoly, it might be said, would extend not for 20 years (as the Patent Act promises), but for only one transaction. And that would result in less incentive for innovation than Congress wanted. Hence our repeated insistence that exhaustion applies only to the particular item sold, and not to reproductions.

  Here we find the same pattern repeated. The aim of the court appears to have been ensuring the continued validity of this class of patents, not reaching a logical conclusion regarding the question of infringement. Once again, we can break the reasoning down into three steps :

  1. A non-infringement ruling would weaken the patent.
  2. Weaker patents would provide less incentive for innovation.
  3. Therefore we must rule infringement.

  As in the first example, the argument presented in step two is at best questionable, and no supporting evidence is provided.

  These are, unfortunately, not the only examples of such fallacies ; one might even describe them as ubiquitous. Does a law education not include any material on logical reasoning ? Ought it not ? While we can never hope to find any kind of universal truth on which to base our laws, we should at least strive to make our system logically consistent. If we do not, notions such as fairness and justice lose their meanings.

• Anomalie #4209 : Les critères {pagination} et {a,b} sont dans un bâteau

  31 octobre 2018, par tcharlss (*´_ゝ｀)

  Rah oui la boulette, dan smon squelette il y avait #GRAND_TOTAL au lieu de #TOTAL_BOUCLE, donc oui l’astuce fonctionne.

  Bon, mais il n’empêche, bug il y a.