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• shared library built with g++ compile is works and with automake compile can not be used

  23 avril 2013, par user2310175

  I'm building a shared libraries on CentOS 6.2.
  The shared library will be build have some cpp files,headers,c shared libraries
  and ffmpeg.The shared library is used to convert videos. When i use the g++ compile like this :

  g++    DataType.h    h264function.h  h264function.cpp videoconvert.h videoconvert.cpp      stdafx.h stdafx.cpp YV12toRGB.h YV12toRGB.cpp -lMPCtrl -lavcodec -lavformat -lavutil -   lhcnetsdk -lPlayCtrl -lpthread -fPIC -shared -o libtest.so

  It can work properly,and the video can be converted as standard h264 coded.That seems the files used for building the library is

  good.But when i use the autotools to make the library,it can not work correct.Here is my configure.in and Makefile.am :

  Makefile.am :

  prefix=/usr
  
  lib_LTLIBRARIES=libhikvisiontranso.la
  
  
  
  libhikvisiontranso_la_SOURCES=stdafx.h stdafx.cpp videoconvert.h videoconvert.cpp 
  
  h264function.h h264function.cpp YV12toRGB.h YV12toRGB.cpp DataType.h 
  
  
  
  libhikvisiontranso_la_LDFLAGS=-avoid-version -shared 
  
  libhikvisiontranso_la_LIBADD=-lpthread -lMPCtrl -lhcnetsdk -lPlayCtrl -lavformat -    lavcodec -lavutil
  
  ACLOCAL_AMFLAGS= -I m4

  configure.in :

  #                                               -*- Autoconf -*-
  
  # Process this file with autoconf to produce a configure script.
  
  
  
  AC_PREREQ([2.63])
  
  AC_INIT([hikvisiontranso],[1.0], [songxiawuren@gmail.com])
  
  AM_INIT_AUTOMAKE([libhikvisiontranso.so],[1.0])
  
  AC_CONFIG_SRCDIR([DataType.h])
  
  AC_CONFIG_HEADERS([config.h])
  
  AC_CONFIG_MACRO_DIR([m4])
  
  AT_INIT
  
  # Checks for programs.
  
  AC_PROG_CXX
  
  AC_PROG_CC
  
  
  
  # Checks for libraries.
  
  
  
  # Checks for header files.
  
  AC_CHECK_HEADERS([inttypes.h limits.h stddef.h stdint.h stdlib.h string.h])
  
  
  
  # Checks for typedefs, structures, and compiler characteristics.
  
  AC_HEADER_STDBOOL
  
  AC_C_INLINE
  
  AC_TYPE_INT16_T
  
  AC_TYPE_INT32_T
  
  AC_TYPE_INT64_T
  
  AC_TYPE_INT8_T
  
  AC_TYPE_SIZE_T
  
  AC_TYPE_UINT16_T
  
  AC_TYPE_UINT32_T
  
  AC_TYPE_UINT64_T
  
  AC_TYPE_UINT8_T
  
  
  
  # Checks for library functions.
  
  AC_FUNC_MALLOC
  
  AC_PROG_LIBTOOL
  
  AC_CONFIG_FILES([Makefile])
  
  AC_OUTPUT

  The wrong output is :

  SDL Init
  
  
  
  init console=1
  
  
  
  Output #0, avi, to '/home/ningge/Desktop/HaikangDvr.avi':
  
  
  
  Stream #0.0: Invalid Codec type -1
  
  
  
  Height = 576; Width = 704;totalfram=90000
  
  
  
  Segmentation fault (core dumped)

  The right is :

  SDL Init
  
  
  
  init console=1
  
  
  
  Output #0, avi, to '/home/ningge/Desktop/HaikangDvr.avi':
  
  
  
  Stream #0.0: Video: mpeg4, yuv420p, 704x576, q=2-31, 200 kb/s, 90k tbn, 25 tbc
  
  
  
  Height = 576; Width = 704;totalfram=90000
  
  
  
  CSDLInit goOut 

  I hope someone can help me to find what's wrong with automake.

• C - FFmpeg streaming from a C program ?

  8 août 2016, par golmschenk

  I’m looking to replicate an FFmpeg command-line command in my C code. Specifically I would like to be able to run :

  ffmpeg -re -i video.mp4 -f mpegts udp://localhost:7777

  One thing I’ve noticed when looking at people’s code who have used the libraries of FFmpeg in their own code is that they often have a few hundred lines of code for a single command similar to an FFmpeg command-line command. I’m guessing this is just because they are doing something very specific, because if I can run that short command on my command line and get what I want it should probably only take about ten lines of code to do the same thing in my C code. This should only take about that much work right ? Why would it take much more ?

  I’m having a bit of difficulty finding explanations on how to use the streaming capabilities of the FFmpeg libraries that aren’t overly complex because they’re for a very specific purpose. Can anyone explain how I might go about writing the code for the above command ? Or at the very least point me to some documentation explaining how to write such a script/program ? Thank you much !

  EDIT : I do hope to run this from an iPhone app eventually so I won’t just be able to straight up call FFmpeg from my program. I’ll need to use the libraries used by FFmpeg.

• 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.