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• avutil/common: add av_rint64_clip

  1 November 2015, by Ganesh Ajjanagadde

  avutil/common: add av_rint64_clip
  The rationale for this function is reflected in the documentation for
  
  it, and is copied here:
  Clip a double value into the long long amin-amax range.
  
  This function is needed because conversion of floating point to integers when
  
  it does not fit in the integer’s representation does not necessarily saturate
  
  correctly (usually converted to a cvttsd2si on x86) which saturates numbers
  
  > INT64_MAX to INT64_MIN. The standard marks such conversions as undefined
  
  behavior, allowing this sort of mathematically bogus conversions. This provides
  
  a safe alternative that is slower obviously but assures safety and better
  
  mathematical behavior.
  
  API:
  
  @param a value to clip
  
  @param amin minimum value of the clip range
  
  @param amax maximum value of the clip range
  
  @return clipped value
  Note that a priori if one can guarantee from the calling side that the
  
  double is in range, it is safe to simply do an explicit/implicit cast,
  
  and that will be far faster. However, otherwise this function should be
  
  used.
  avutil minor version is bumped.
  Reviewed-by: Ronald S. Bultje <rsbultje@gmail.com>
  
  Signed-off-by: Ganesh Ajjanagadde <gajjanagadde@gmail.com>
  

  • [DH] libavutil/common.h
  • [DH] libavutil/version.h

• Best way to record a HTML Canvas/WebGL animation server-side into a video?

  14 December 2016, by Abhinav

  I have a set of animations which I can make in Canvas (fabric.js) or WebGL (three.js). I need to record them automatically, server-side, through a script and output a video file.

  The animations include:
  

  1. Pictures
     
  2. Videos (with audio)
     
  3. Other animations/effects

  I have researched a lot during last few months on this.

  Results
  1. User PhantomJS + FFMPEG
  Run HTML Canvas animations on headless browser(PhantomJS) and record with FFMPEG. Here the issue is PhantomJS supports neither WebGL nor Video element. http://phantomjs.org/supported-web-standards.html

  2. Use Websockets to send data back to server using DataURL
  Here again, we will need to run the animations on browser (which we can’t because we have to do everything on server).

  3. Use node-canvas
  This is a library by TJ Holowaychuk which allows rendering HTML Canvas on Node.js. But it has its own limitations plus I haven’t really explored this field much.
  (If someone could shed more light on this library)

  If anyone has done it before or can guide me somewhere useful.
  All we need to do is use some data to create animations and record it into a video, everything on server side.

• Revision 41eb20d1e9: Add encoder control for setting color space This commit adds encoder side contr

  13 January 2015, by Yaowu Xu

  Changed Paths:
   Modify /vp9/common/vp9_enums.h

  
   Modify /vp9/common/vp9_onyxc_int.h

  
   Modify /vp9/decoder/vp9_decodeframe.c

  
   Modify /vp9/encoder/vp9_bitstream.c

  
   Modify /vp9/encoder/vp9_encoder.c

  
   Modify /vp9/encoder/vp9_encoder.h

  
   Modify /vp9/vp9_cx_iface.c

  
   Modify /vpx/vp8cx.h

  
   Modify /vpxenc.c

  
  
  Add encoder control for setting color space

  This commit adds encoder side control for vp9 to set color space info
  in the output compressed bitstream.

  It also amends the "vp9_encoder_params_get_to_decoder" test to verify
  the correct color space information is passed from the encoder end to
  decoder end.

  Change-Id: Ibf5fba2edcb2a8dc37557f6fae5c7816efa52650
  (cherry picked from commit e94b415c3479129944a69fafbeacf550fb9237b7)