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• ffmpeg missing image frames in generated video from images

  4 août 2013, par sihrc

  Similar question here, but not yet answered.

  Problem :

  I'm combining images (.png) of same resolution/size (they all came from the same matplotlib.pyplot), but the resulting video is missing several frames.

  Command :

  ffmpeg -f image2 -r 1 -i .\\images\\image%02d.png -c:v libx264 -r 30 .\\images\\output.mp4

  Resulting Video

  • Length of 0:09
  • Missing more than half the images

  Images

  • .\images
    • image00.png
    • image01.png
    • image02.png
    • image03.png
    • image04.png
    • image05.png
    • image06.png
    • image07.png
    • . . .

  Notes :

  I followed examples from here. I'm new to using ffmpeg, so I may not be completely sure of what each of the command line options I've used means, though I have a pretty good idea.

  Thanks, any help/advice/suggestions will be greatly appreciated. I am also perfectly willing to provide further information that may help resolve this issue.

• Convert MP3 bitrate from a stream into another stream with ffmpeg

  10 juillet 2013, par Léon Pelletier

  Using ffmpeg, I would like to know if it's possible to convert mp3 bitrate as data chunks are received ?

  That means I would send slowly chunks to ffmpeg so that it outputs a mp3 with another bitrate.

  So in very-pseudo-code, it looks like it :

  1. MP3 Request from user

  2. Send the default mp3 to ffmpeg with parameters to convert to the desired bitrate.

  3. As it's writing a new file, write what as been writen so far in the Response outputstream (I'm in ASP.Net)

  Is that feasable or I need to switch to another technology ?

  [EDIT]

  For now, I'm trying a solution like this : Convert wma stream to mp3 stream with C# and ffmpeg

  [EDIT 2]

  I answered my question, and it is feasible with an url as input and standard output as output. Using an url allows to process a file chunk by chunk, and using stdout, we can access data while it is processed.

• runtime error when linking ffmpeg libraries in qt creator

  6 juillet 2012, par dxthegreat

  I'm quite new around here but i hear that if you want a question answered, stackoverflow is the place to ask it >.<. So i hope that my question isn't too trivial that everyone will get annoyed at my lack of research (I've tried googling for two days already D= no progress !)
  I've also asked this question in the Qt forums, but i figured i'd ask here too.

  so...

  For the last few days I’ve been fiddling around with opengl and the like, trying to write a video player.

  However, when i try to import the ffmpeg libraries (avcodec, avformat, avutils etc), an error occurs on runtime (the program compiles fine). When compiled and run in debug mode, the error message gives me only a memory address and error code 135 (DLL not found).

  This error occurs when i include a function from those libraries in my code (e.g. av_register_all()) and it occurs regardless of whether the function is actually called.

  So i’m thinking that I’m doing something wrong when linking these libraries.
  I’m currently using :
  Windows vista (32bit),
  Qt creator 2.4.1 based on Qt 4.7.4 (32bit),
  Zeranoe’s FFmpeg build git-3233ad4 (2012-06-30)

  My .pro file consists of :

  QT       += core gui opengl
  
  
  
  TARGET = test
  
  TEMPLATE = app
  
  
  
  
  
  SOURCES += main.cpp\
  
          mainwindow.cpp \
  
      glwidget.cpp
  
  
  
  HEADERS += mainwindow.h \
  
      glwidget.h \
  
  
  
  FORMS    += mainwindow.ui
  
  
  
  
  
  LIBS += -L"$$_PRO_FILE_PWD_/libraries/ffmpeg/libs/" -lavcodec -lavformat -lavutil
  
  INCLUDEPATH += libraries/ffmpeg/includes

  I’ve tried many variations to the LIBS += line and checked my filepath many times. However, the DLL not found error occurs in all of these variations =(.

  Is there something I’m forgetting when doing these includes ?

  Thanks in advance >.<,
  (young and naive) aspiring dev