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• ffmpeg chromakey filter : blend parameter does not what it should

  5 mai 2017, par Mat

  I want to remove greenscreen background and am not completely satisfied with what I have achieved because I still have green borders (especially on semi-transparent areas like hair, when I move my head).

  The documentation for the blend-parameter of chromakey filter says

  blend

  Blend percentage.

  0.0 makes pixels either fully transparent, or not transparent at all.

  Higher values result in semi-transparent pixels, with a higher transparency the more similar the pixels color is to the key color.

  So I reckoned, I could use this to minimise greenscreen bleeding (is this the term ?) when removing the background with a command like this :

  ffmpeg -i DSCN0015.MOV -vf "[in] hqdn3d=4:4:8:8 [dn]; [dn] scale=iw*3:-1 [sc]; [sc] chromakey=0x005d0b:0.125:0.0 [out]" -r 24 -an -c:v ffvhuff 4.mov

  But when I use anything else than 0.0 for blend, it seems to determine some kind of MINIMUM transparency and the entire frame is affected.

  Here are some pics to visualize : the first is the raw material from the camera. the 2nd shows what I get with blend=0.0 and the last one shows the problem : blend=0.5, but the whole frame is almost completely transparent.

  [

  [

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• Convert .mp3/.wav file into g729/amr/g711 codec file and vice versa using PJSIP

  19 septembre 2017, par NandhaKumar

  PJSIP is used for SIP Registering, audio/video Calling and supporting some other VoIP Call features. If you want to create an VoIP Application, you will create an application using their libraries.

  In this library, there are available lot of codecs and some of codecs are available as third party codecs and you can integrate into PJSIP library. Then you can able to support those codecs while calling another SIP user/client.

  Generally In mobile phones, the voice is record as audio file through
  mic and it has passed to PJSIP library. Then those codec/pjmedia library take care
  of other operations like converting into anyother codec format which
  they want to send.

  Instead of that, can we able to pass .mp3/.wav file into PJSIP library and convert it into codec files like .g729/.amr/.g711-u and vice versa

  I don’t about how codec conversion/codec engine internally works around.
  If you know about the codec conversion from .mp3 format is possible using PJSIP library, please suggest me how to solve this problem.

  Thanks in Advance !

• ffmpeg : remove misleading and incorrect warning messages

  15 juin 2017, par wm4

  ffmpeg : remove misleading and incorrect warning messages
  It is wrong/incorrect in two aspects :
  
  1. The pixel format is not enough to guarantee that the resulting file
  
     will be any more compatible with media players.
  
  2. Media players not supporting higher profiles are not necessarily
  
     outdated (in fact this is simply an arrogant statement that
  
     libavcodec can handle these particular features).
  You could add that there are plenty of other ways to produce widely
  
  incompatible files with ffmpeg, and these don't show any warnings.
  What we really want to do here is defaulting to codec profiles that
  
  have wide compatibility, such as main/high for h264. Also, if an
  
  encoder does not accept certain pixfmts, we should automatically
  
  convert them to a pixfmt the encoder can accept. But the existing
  
  message certainly is not appropriate.
  It also works for 2 specific encoders only. Extending it for other
  
  cases would result in a lot of special cases, so this is not the
  
  right place.
  

  • [DH] ffmpeg.c