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• Revision 23ebacdb81 : Auto-adaptive encoder frame resizing logic Note : This feature is still in devel

  15 novembre 2014, par Adrian Grange

  Changed Paths :
   Modify /vp9/encoder/vp9_encoder.c

  
   Modify /vp9/encoder/vp9_encoder.h

  
   Modify /vp9/encoder/vp9_firstpass.c

  
   Modify /vp9/encoder/vp9_firstpass.h

  
   Modify /vp9/encoder/vp9_ratectrl.c

  
   Modify /vp9/encoder/vp9_ratectrl.h

  
   Modify /vp9/encoder/vp9_rdopt.c

  
   Modify /vp9/encoder/vp9_speed_features.c

  
  
  Auto-adaptive encoder frame resizing logic

  Note : This feature is still in development.

  Add an option for the encoder to decide the resolution
  at which to encode each frame.

  Each KF/GF/ARF goup is tested to see if it would be
  better encoded at a lower resolution. At present, each
  KF/GF/ARF is coded first at full-size and if the coded
  size exceeds a threshold (twice target data rate) at
  the maximum active Q then the entire group is encoded
  at lower resolution.

  This feature is enabled in vpxenc by setting :
  —resize-allowed=1

  In addition, if the vpxenc command line also specifies
  valid frame dimensions using :
  —resize-width=XXXX & —resize_height=YYYY
  then *all* frames will be encoded at this resolution.

  Change-Id : I13f341e0a82512f9e84e144e0f3b5aed8a65402b

• avcodec/nvenc : De-compensate aspect ratio compensation of DVD-like content.

  28 janvier 2015, par Philip Langdale

  avcodec/nvenc : De-compensate aspect ratio compensation of DVD-like content.
  For reasons we are not privy to, nvidia decided that the nvenc encoder
  
  should apply aspect ratio compensation to ’DVD like’ content, assuming that
  
  the content is not bt.601 compliant, but needs to be bt.601 compliant. In
  
  this context, that means that they make the following, questionable,
  
  assumptions :
  1) If the input dimensions are 720x480 or 720x576, assume the content has
  
  an active area of 704x480 or 704x576.
  2) Assume that whatever the input sample aspect ratio is, it does not account
  
  for the difference between ’physical’ and ’active’ dimensions.
  From, these assumptions, they then conclude that they can ’help’, by adjusting
  
  the sample aspect ratio by a factor of 45/44. And indeed, if you wanted to
  
  display only the 704 wide active area with the same aspect ratio as the full
  
  720 wide image - this would be the correct adjustment factor, but what if you
  
  don’t ? And more importantly, what if you’re used to ffmpeg not making this kind
  
  of adjustment at encode time - because none of the other encoders do this !
  And, what if you had already accounted for bt.601 and your input had the
  
  correct attributes ? Well, it’s going to apply the compensation anyway !
  
  So, if you take some content, and feed it through nvenc repeatedly, it
  
  will keep scaling the aspect ratio every time, stretching your video out
  
  more and more and more.
  So, clearly, regardless of whether you want to apply bt.601 aspect ratio
  
  adjustments or not, this is not the way to do it. With any other ffmpeg
  
  encoder, you would do it as part of defining your input paramters or
  
  do the adjustment at playback time, and there’s no reason by nvenc
  
  should be any different.
  This change adds some logic to undo the compensation that nvenc would
  
  otherwise do.
  nvidia engineers have told us that they will work to make this
  
  compensation mechanism optional in a future release of the nvenc
  
  SDK. At that point, we can adapt accordingly.
  Signed-off-by : Philip Langdale <philipl@overt.org>
  
  Reviewed-by : Timo Rothenpieler <timo@rothenpieler.org>
  
  Signed-off-by : Michael Niedermayer <michaelni@gmx.at>
  

  • [DH] libavcodec/nvenc.c

• VB.Net Stream/Port Image To FFmpgeg using Standard Input

  31 janvier 2015, par Zakir_SZH

  hope all active member of this community are fine.
  in my project i need to convert several image to video file.
  Currently i have to first save the images to PC then use ffmpeg to read that images from the pc and convert it to movie.

  But rather than save image to pc, i want to send image directly to ffmepg using StandardInput call. Ffmped does support that. but i don’t know how to use that.

  i have search internet a lot and all i found is getting output/response from ffmpeg using standarderror as ffmepg write to standerror instead of standardouput.

  below link something similar to what i look for that that code don’t work and also that use mp3 file instead of image/graphics.

  http://tiku.io/questions/3075356/convert-wma-stream-to-mp3-stream-with-c-sharp-and-ffmpeg

  can any one help me out, how to send image from picturebox/graphics object to ffmpeg one by one ?

  thanks in advance

  best regards