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• configure : Fix build with MSVC

  7 août, par Zhao Zhili

  configure : Fix build with MSVC
  The copyright message of cl.exe doesn't always begin with Microsoft,
  
  e.g., when local is Chinese.
  Fix regression since 53da090ab7b.
  

  • [DH] configure

• convert mms live audio stream with ffmpeg and upload on rackspace CDN [closed]

  28 mars 2013, par user584569

  im a complete newbie with ffmpeg. The following is the scenario

  I have an mms stream mms ://wms.di-ve.com/vibe which I cannot stream on mobile devices being Microsoft proprietary.
  I know that ffmpeg can do conversions to a stream. The idea is to feed this stream to ffmpeg and its output place it on Rackspace streaming CDN (see :http://www.rackspace.com/knowledge_center/product-faq/cloud-files)
  is this possible ? and if so, how can I do this ?

  Thanks

• Why is ffmpeg's hstack so much slower than overlay and pad ?

  27 janvier 2021, par cgenco

  I'm using ffmpeg to stitch together two videos of people chatting into a video with each of them side-by-side, like this :

  


  

  


  Here's the command I'm currently using to get this done, which runs at 2.5x on my 13" M1 MacBook Pro :

  


  ffmpeg -y -i left.mp4 -i right.mp4 -filter_complex "
  [0:v] crop=w=in_w/2 [croppedLeft];
  [1:v][1:v] overlay=x=overlay_w/4 [shiftedRight];
  [shiftedRight][croppedLeft] overlay [vout];
  [0:a][1:a] amix [aout]
" -map "[vout]" -map "[aout]" -ac 2 out.mp4


  


  This command crops the left video to half of its original width (cropping so the video is centered), then shifts the right video a quarter of its width to the right, then overlays the left video on the left half of the output merged with the shifted right video.

  


  One day on my weekly fun-time read-through the FFmpeg filters documentation I stumbled on a filter named hstack, which is described as being "faster than using overlay and pad filter to create same output."

  


  My ex wife can affirm that there are few higher priorities in my life than going faster, so I altered my ffmpeg script to use hstack instead of two overlays :

  


  ffmpeg -y -i left.mp4 -i right.mp4 -filter_complex "
  [0:v] crop=w=in_w/2 [croppedLeft];
  [1:v] crop=w=in_w/2 [croppedRight];
  [croppedLeft][croppedRight] vstack [vout];
  [0:a][1:a] amix [aout]
" -map "[vout]" -map "[aout]" -ac 2 out.mp4


  


  ...but that command runs painfully slowly, like 0.1x. It takes multiple minutes to render a single second.

  


  So uhhh what's going on here ? Why is hstack taking so long when it's supposed to be faster ?

  


  I've tried this on both the M1 native build from OSXExperts (version N-99816-g3da35b7) and the standard ffmpeg from brew and hstack is just as slow on each.