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• Building FFMPEG library for iOS5.1 ARMv7

  25 octobre 2012, par Jimmy

  I'm trying to use the FFMPEG library in an XCode 4.5.1 project. And I'm trying to build it for ARMv7

  But I'm running into some major issues, I'm hoping that someone can walk me through how to do it ? I feel a little sketched out reading material thats a couple months old. I'm not aware of the changes.

  New Update (after a lot of time)

  I want to help everyone out that is having this problem because its so frustrating. heres how you do it. I've pasted the configuration stage. This is my ./configure

  ./configure --disable-doc --disable-ffmpeg --disable-ffplay --disable-ffserver --enable-cross-compile --arch=arm --target-os=darwin
  
     --cc=/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/usr/llvm-gcc-4.2/bin/arm-apple-darwin10-llvm-gcc-4.2
  
     --as='gas-preprocessor/gas-preprocessor.pl /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/usr/llvm-gcc-4.2/bin/arm-apple-darwin10-llvm-gcc-4.2'
  
     --sysroot=/applications/xcode.app/contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS5.1.sdk
  
     --cpu=cortex-a8
  
     --extra-ldflags='-isysroot /applications/xcode.app/contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS5.1.sdk'
  
     --enable-pic
  
     --disable-bzlib --disable-gpl --disable-shared --enable-static --disable-mmx --disable-debug --disable-neon
  
     --extra-cflags='-pipe -Os -gdwarf-2 -isysroot /applications/xcode.app/contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS5.1.sdk -m${thumb_opt:-no-thumb} -mthumb-interwork'

  This ended up working for me. I had the following problems.

  • I had to download ( https://github.com/yuvi/gas-preprocessor ) copy the file gas-preprocessor.pl at /usr/local/bin. Set permissions to read write (777)
  • Make sure I'm using the right GCC compiler : /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/usr/llvm-gcc-4.2/bin/arm-apple-darwin10-llvm-gcc-4.2
  • Make sure I'm using the right SDK : /applications/xcode.app/contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS5.1.sdk
  • —extra-cflags="-arch armv7" causes bugs in the configure. take it out. This was causing my gcc compile errors. (specifically this one : error : unrecognized command line option “-arch”.)

  I'll let you guys know how much further I get.

• Recursive ffmpeg batch script within Windows

  30 septembre 2013, par Tisch

  Complete change to the question !

  I now have the following script :

  @echo off
  
  REM keep a counter for files converted
  
  set /A nfile=0
  
  REM do not copy empty folders or any files
  
  @echo Copying directory structure from %0 to %1 ...
  
  xcopy /T %1 %2
  
  REM walk directory structure and convert each file in quiet mode
  
  for /R %1 %%v in (*.mp4, *.aac, *.flv, *.m4a, *.mp3) do (
  
      echo converting "%%~nxv" ...
  
      ffmpeg -v quiet -i "%%v" -vcodec libx264 "%2\%%~nv-converted.mp4"
  
      set /A nfile+=1
  
  )
  
  echo Done! Converted %nfile% file(s)

  Taken from : http://mostlybuggy.wordpress.com/2012/09/25/windows-batch-file-how-to-copy-and-convert-folders-recursively-with-ffmpeg/

  The videos are converting as expected when I run the following command :

  convert ..\..\folder ..\..\converted\

  However, the converted files end up in "converted" and not in their respective sub-folders.

  Any ideas ?

• how to extract thumbnails at specific seconds of a .h264 file ?

  29 juillet 2014, par Bram de Goede

  I want to extract a few screenshots (thumbnails) out of a small (like 10) sec .h264 format video.
  I’ve tried to do it with ffmpeg but I get the following error :

  Generating thumbnail for: /home/pi/video.h264
  
  [h264 @ 0x646fe0] Estimation duration from bitrate, this may be inaccrate
  
  **Seeking in video failed, will use first frame**
  
  [h264 @ 0x646fe0] Estimation duration from bitrate, this may be inaccrate
  
  [swscaler @ 0x8c0840] No accelerated colorspace conversion found from yuv420p to rgb24.

  I used the following code :

  import os
  
  
  
  for root, dirnames, filenames in os.walk('/home/pi/'):
  
    for filename in filenames:
  
      if filename.lower().endswith(('.m4v', '.mov', '.mpeg', 'mp4', '.h264')): 
  
        ifile = os.path.join(root, filename)
  
        ofile = os.path.splitext(ifile)[0] + ".jpg"
  
        try:
  
          with open(ofile) as f: pass
  
        except IOError as e:
  
          print "Generating thumbnail for: " + ifile
  
  
  
          fftoptions = "-s0 -t50"
  
          command = "ffmpegthumbnailer -i %s -o %s %s" % (ifile, ofile, fftoptions)
  
  
  
          p = os.popen(command,"r")
  
          while 1:
  
            line = p.readline()
  
            if not line: break
  
            print line

  The ffmpegthumbnailer seems to have a problem with the .h264 format my pi camera produces.

  Does anyone have a solution ?