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• Expand (extend) a video to an specific duration

  8 février 2013, par BorrajaX

  Do VLC or FFmpeg (or AVconv) have any feature to force the duration of a video to a certain number of seconds ?

  Let's say I have a... 5 minutes .mp4 video (without audio). Is there a way to have any of the aforementioned tools "expanding" the video to a longer duration ? The video comes from a Power Point slideshow, but it's too short (running too fast, to say so). The idea would be automatically inserting frames so it reaches an specified duration. It looks like something pretty doable (erm... for a total newbie in video encoding/transcoding as I am) : A 5 minutes video, at 30fps means I have 9000 frames... To make it be 10 times longer, get the first "real" frame, copy it ten times, then get the second "real" frame, copy it ten times... and so on.

  I'm using Ubuntu 12.04, but I can install/compile any required software, if needed. So far, I have VLC, AVConv and FFmpeg (FFmpeg in an specific folder, so it won't conflict with AVConv)

  Thank you in advance.

• ERROR : libvpx decoder version must be >=0.9.1 [closed]

  22 novembre 2013, par Baseem Najjar

  Heyo !
  I'm trying to install ffmpeg on my server using the following tutorial :
  https://ffmpeg.org/trac/ffmpeg/wiki/UbuntuCompilationGuideLucid
  When I reach the ffmpeg part and run the ./configure command it gives the following error :

  ERROR: libvpx decoder version must be >=0.9.1

  I must mention that my server has Ubunto 10.10 64bit
  I'm a total newbie in linux so please take it into consideration :)
  Thanks a lot !

  Following LordNeckBeard solution, I got the following error after the checkinstall :

  root@348588:~/libvpx# sudo checkinstall --pkgname=libvpx --pkgversion="$(date +%Y%m%d%H%M)-git" --backup=no--default --deldoc=yes
  
  
  
  checkinstall 1.6.2, Copyright 2009 Felipe Eduardo Sanchez Diaz Duran
  
             This software is released under the GNU GPL.
  
  
  
  
  
  no--default is an invalid value for --backup
  
  
  
  Use --help or -h to get more information

• How can I use ffmpeg's swscale to convert from NV12 to RGB32 ?

  22 avril 2013, par Asik

  Say I have an NV12 frame in memory as an array of bytes. I know :

  • its Width and Height
  • its Stride (total width of a line including padding), which is the same for Y and UV components as per NV12 specification
  • I know where Y begins, U begins at Y + (Stride * Height), and V begins at U + 1 (interleaved with U).

  Now this is what I have so far :

  SwsContext* context = sws_getContext(frameWidth, frameHeight, AV_PIX_FMT_NV12, frameWidth, frameHeight, AV_PIX_FMT_RGB32, 0, nullptr, nullptr, nullptr);
  
  sws_scale(context, 

  So I don't know what the parameters to sws_scale should be :

  • srcSlice : a pointer to the array of bytes ? It should apparently be a
    pointer to a pointer, but what I have is just a single-dimensional
    array of bytes.
  • srcStride : apparently expects an array of strides, but I have just one stride for the entire file. Should I pass an array with just
    one element ?
  • srcSliceY : an offset to the first byte I guess ? Should be 0 then.
  • srcSliceH : the frame height I guess
  • dst : once again, pointer to a pointer, but my destination output is actually just another array of bytes...
  • dstStride : Width * 4 I guess ?

  Any help appreciated.