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• How to specify —extra-cflags and —extra-ldflags when cross compiling ?

  29 avril 2024, par H. Yong

  I am using the cross compiler aarch64-none-linux-gnu.

  


  Now I am trying to compile ffmpeg for aarch64 for a board with arm cpu.

  


  My question is when I run script like :

  


  export SYSROOT=/mnt/d/Libs/cross-compilers/arm-gnu-toolchain-13.2.Rel1-x86_64-aarch64-none-linux-gnu/aarch64-none-linux-gnu/libc

./configure --prefix=/usr/local \
    --enable-cross-compile \
    --cross-prefix=${CROSS_PREFIX} \
    --sysroot=${SYSROOT} \
    --arch=aarch64 \
    --target-os=linux \
    --host-os=linux \
    --enable-libvpx \
    --extra-cflags="-I/usr/local/include/vpx" \
    --extra-ldflags="-L/usr/local/lib"


  


  Does the compiler will search headers in /usr/local/include/vpx or ${SYSROOT}/usr/local/include/vpx (the absolute path) ?

  


  In other words, will the compiler add $SYSROOT prefix to the -I/usr/local/include/vpx and -L/usr/local/lib automatically ?

  


• avdevice/decklink_common : Fix "Cross-compiling FFmpeg on Debian for Windows with...

  25 novembre 2014, par Carl Eugen Hoyos

  avdevice/decklink_common : Fix "Cross-compiling FFmpeg on Debian for Windows with MinGW-w64"
  Fixes Ticket4130
  Requested and Tested by : Zeranoe
  
  Signed-off-by : Michael Niedermayer <michaelni@gmx.at>
  

  • [DH] libavdevice/decklink_common.h

• Cross Fade Arbitrary Number of Videos ffmpeg Efficiently

  15 avril 2022, par jippyjoe4

  I have a series of videos named 'cut_xxx.mp4' where xxx represents a number 000 through 999. I want to do a cross fade on an arbitrary number of them to create a compilation, and each fade should last 4 seconds long. Currently, I'm doing this with Python, but I suspect this is not the most efficient way :

  


  import subprocess    
def get_length(filename):
  result = subprocess.run(["ffprobe", "-v", "error", "-show_entries",
                          "format=duration", "-of",
                          "default=noprint_wrappers=1:nokey=1", filename],
    stdout=subprocess.PIPE,
    stderr=subprocess.STDOUT)
  return float(result.stdout)

CROSS_FADE_DURATION = 4

basevideo = 'cut_000.mp4'
for ii in range(total_videos - 1):
  fade_start = math.floor(get_length(basevideo) - CROSS_FADE_DURATION) # new one
  outfile = f'cross_fade_{ii}.mp4'
  append_video = f'cut_{str(ii+1).zfill(3)}.mp4'
  cfcmd = f'ffmpeg -y -i {basevideo} -i {append_video} -filter_complex "xfade=offset={fade_start}:duration={CROSS_FADE_DURATION}" -an {outfile}'
  basevideo = outfile
  subprocess.call(cfcmd)
  print(fade_start)


  


  I specifically remove the audio with -an because I'll add an audio track later. The issue I see here is that I'm compressing the video over and over again with each individual video file I add to the compilation because I'm only adding one video at a time and then re-encoding.

  


  There should be a way to cross fade multiple videos together into a compilation, but I'm not sure what this would look like or how I would get it to work for an arbitrary number of video files of different durations. Any idea on what that monolithic ffmppeg command would look like or how I could automatically generate it given a list of videos and their durations ?