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• Is there an efficient way to use ffmpeg to perform a large quantity of cuts from a single file ?

  16 mars 2024, par Giuliano Oliveri

  I'm trying to cut video files into smaller chunks. (each one being one word said in the video, so they're not all of equal size)

  


  I've tried a lot of different approaches to try to be as efficient as possible, but I can't get the runtime to be under 2/3rd of the original video length. That's an issue because I'm trying to process 400+ hours of video.

  


  Is there a more efficient way to do this ? Or am I doomed to run this for weeks ?

  


  Here is the command for my best attempt so far

  


  ffmpeg -hwaccel cuda -hwaccel_output_format cuda -ss start_timestamp -t to_timestamp -i file_name -vf "fps=30,scale_cuda=1280:720" -c:v h264_nvenc -y output_file


  


  Note that the machine running the code has a 4090
This command is then executed via python, which gives it the right timestamps and file paths for each smaller clip in a for loop

  


  I think it's wasting a lot of time calling a new process each time, however I haven't been able to get better results with a split filter ; but here's the ffmpeg-python code for that attempt :

  


  Creation of the stream :

  


  inp = (
    ffmpeg
    .input(file_name, hwaccel="cuda", hwaccel_output_format="cuda")
    .filter("fps",fps=30)
    .filter('scale_cuda', '1280','720')
    .filter_multi_output('split')
)


  


  Which then gets called in a for loop

  


  (
    ffmpeg
    .filter(inp, 'trim', start=row[1]['start'], end=row[1]['end'])
    .filter('setpts', 'PTS-STARTPTS')
    .output(output_file,vcodec='h264_nvenc')
    .run()
)


  


• Android adding Audio to an existing Video

  12 mars 2019, par roma

  I am trying to add a new audio to an existing video in my Android app. i have used FFMPEG but it takes time.. Even i tried with MP4 Parser but still didn’t work.

  For example if i have a 30 seconds video, to add a new audio FFMPEG takes 30 seconds.(Same as duration of video) but i still want it to be fast enough so that it completes this task of adding audio to video in just 4 or 5 seconds.

  If you see in TikTok App it take takes fraction of seconds to add a new audio to an existing video. Can you guys help me or atleast let me know which library or framework or API’s i should use in android to make this task faster enough.

• Why error happened when build ffmpeg by ndk-build ?

  26 mars 2014, par Martin

  I have try build the ffmpeg for Android in Windows 7 , but it error when ndk-build.

  And the error log is like the following :

  Wun@Wun-PC ~/ffmpeg/jni/ffmpeg
  
  $ ndk-build
  
  SharedLibrary  : libffmpeg.so
  
  C:/cygwin/home/Wun/ffmpeg/obj/local/armeabi/libavcodec.a(log2_tab.o):(.rodata+0x0): multiple definition of `ff_log2_tab'
  
  C:/cygwin/home/Wun/ffmpeg/obj/local/armeabi/libavformat.a(log2_tab.o):(.rodata+0x0): first defined here
  
  C:/cygwin/home/Wun/ffmpeg/obj/local/armeabi/libavutil.a(log2_tab.o):(.rodata+0x0): multiple definition of `ff_log2_tab'
  
  C:/cygwin/home/Wun/ffmpeg/obj/local/armeabi/libavformat.a(log2_tab.o):(.rodata+0x0): first defined here
  
  collect2: ld returned 1 exit status
  
  /home/Wun/android-ndk-r8b/build/core/build-binary.mk:378: recipe for target '/home/Wun/ffmpeg/obj/local/armeabi/libffmpeg.so' failed
  
  make: *** [/home/Wun/ffmpeg/obj/local/armeabi/libffmpeg.so] Error 1

  I have already remove the
  OBJS-$(CONFIG_SHARED)                  += log2_tab.o
  in the Makefile of libavformat and libavcodec.

  But the problem still happened...

  Should I delete the libavcodec.a , libavformat.a , libavutil.a and libswscale.a , and rebuild again ??

  Does somebody know how to solve this problem ?

  Thanks in advance.

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