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• Ffmpeg won't copy excerpt of video correctly

  5 mai 2022, par JR Jr.

  I am using a DOS batch to automate and copy excerpts of various high definition videos (mkv's with more than 1GB each).
The script is very convenient and runs fast and fine, but Ffmpeg is not doing its job correctly (it seems Murphy's law is inexorably enthralled into technology, things never come easy, which is why I love and hate it).

  


  Anyway, to cut a long story short, each time the batch job runs, a code like below is executed (pardon me the indiscrete folder name, it's about the 90's TV show, it's not porn !).

  


  call "C:\ffmpeg\bin\ffmpeg.exe" -y -i "D:\100\Sexo\S01\SATC - S01E03 - Bay of Married Pigs.mkv" -ss 00:18:05 -to 00:19:15 -codec copy "002-SATC - S01E03 - Bay of Married Pigs-00_18_05-00_19_15.mp4"


  


  The problem is that the first 6 seconds or so of the resulting video has no video, only audio with a frozen image that only starts to move after about 6 seconds, which is a huge defect, not to mention very annoying (a big let down, after all my meticulous scripting work :(). And this happens for most of the files, except a few ones.

  


  Even though this is copying and changing the format from mkv to mp4, per another thread on this site (https://askubuntu.com/questions/396883/how-to-simply-convert-video-files-i-e-mkv-to-mp4), this is not re-encoding, so this is not the issue. Actually, the same problem occurs even if I don't change the format from mkv to mp4.

  


  Even though I foresee a "there's no way to fix this", let me ask : is there a way to fix this ? Hopefully there is a way.

  


• 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

• Why does libmp3lame add zeros to the start of the MP3 ?

  29 mars 2016, par Phlox Midas

  I have a uncompressed .wav file that I turn into a 96k MP3 file :

  ffmpeg.exe -i song.wav -vn -b:a 96000 -ac 2 -ar 48000 -acodec libmp3lame -y song.mp3

  The input file has 637386 samples. The output has 639360 samples. The extra samples in the MP3 are all zeros at the beginning of the file. This happens in every file I’ve translated and with more codecs than just libmp3lame. Is this an FFMPEG bug or a codec bug ? Why are these added ? Is there a way to stop them from being added ?

  Edit : Simplified example and console output :

  ffmpeg.exe -i song.wav -y song.mp3
  
  
  
  ffmpeg version N-55796-gb74213d Copyright (c) 2000-2013 the FFmpeg developers
  
    built on Aug 26 2013 19:43:51 with gcc 4.7.3 (GCC)
  
    configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-avisynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libcaca --enable-libfreetype --enable-libgsm --enable-libilbc --enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libxavs --enable-libxvid --enable-zlib
  
    libavutil      52. 42.100 / 52. 42.100
  
    libavcodec     55. 29.100 / 55. 29.100
  
    libavformat    55. 14.102 / 55. 14.102
  
    libavdevice    55.  3.100 / 55.  3.100
  
    libavfilter     3. 82.102 /  3. 82.102
  
    libswscale      2.  5.100 /  2.  5.100
  
    libswresample   0. 17.103 /  0. 17.103
  
    libpostproc    52.  3.100 / 52.  3.100
  
  Guessed Channel Layout for  Input Stream #0.0 : stereo
  
  Input #0, wav, from 'song.wav':
  
    Duration: 00:00:13.28, bitrate: 1538 kb/s
  
      Stream #0:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 48000 Hz, stereo, s16, 1536 kb/s
  
  Output #0, mp3, to 'song.mp3':
  
    Metadata:
  
      TSSE            : Lavf55.14.102
  
      Stream #0:0: Audio: mp3 (libmp3lame), 48000 Hz, stereo, s16p
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (pcm_s16le -> libmp3lame)
  
  Press [q] to stop, [?] for help
  
  size=     208kB time=00:00:13.29 bitrate= 128.4kbits/s
  
  video:0kB audio:208kB subtitle:0 global headers:0kB muxing overhead 0.111205%

  Number of samples in wav : 637386

  Number of samples in mp3 : 639984